core.c revision 8c8a743c5087bac9caac8155b8f3b367e75cdd0b
1/* 2 * kernel/sched/core.c 3 * 4 * Kernel scheduler and related syscalls 5 * 6 * Copyright (C) 1991-2002 Linus Torvalds 7 * 8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and 9 * make semaphores SMP safe 10 * 1998-11-19 Implemented schedule_timeout() and related stuff 11 * by Andrea Arcangeli 12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar: 13 * hybrid priority-list and round-robin design with 14 * an array-switch method of distributing timeslices 15 * and per-CPU runqueues. Cleanups and useful suggestions 16 * by Davide Libenzi, preemptible kernel bits by Robert Love. 17 * 2003-09-03 Interactivity tuning by Con Kolivas. 18 * 2004-04-02 Scheduler domains code by Nick Piggin 19 * 2007-04-15 Work begun on replacing all interactivity tuning with a 20 * fair scheduling design by Con Kolivas. 21 * 2007-05-05 Load balancing (smp-nice) and other improvements 22 * by Peter Williams 23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith 24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri 25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins, 26 * Thomas Gleixner, Mike Kravetz 27 */ 28 29#include <linux/mm.h> 30#include <linux/module.h> 31#include <linux/nmi.h> 32#include <linux/init.h> 33#include <linux/uaccess.h> 34#include <linux/highmem.h> 35#include <asm/mmu_context.h> 36#include <linux/interrupt.h> 37#include <linux/capability.h> 38#include <linux/completion.h> 39#include <linux/kernel_stat.h> 40#include <linux/debug_locks.h> 41#include <linux/perf_event.h> 42#include <linux/security.h> 43#include <linux/notifier.h> 44#include <linux/profile.h> 45#include <linux/freezer.h> 46#include <linux/vmalloc.h> 47#include <linux/blkdev.h> 48#include <linux/delay.h> 49#include <linux/pid_namespace.h> 50#include <linux/smp.h> 51#include <linux/threads.h> 52#include <linux/timer.h> 53#include <linux/rcupdate.h> 54#include <linux/cpu.h> 55#include <linux/cpuset.h> 56#include <linux/percpu.h> 57#include <linux/proc_fs.h> 58#include <linux/seq_file.h> 59#include <linux/sysctl.h> 60#include <linux/syscalls.h> 61#include <linux/times.h> 62#include <linux/tsacct_kern.h> 63#include <linux/kprobes.h> 64#include <linux/delayacct.h> 65#include <linux/unistd.h> 66#include <linux/pagemap.h> 67#include <linux/hrtimer.h> 68#include <linux/tick.h> 69#include <linux/debugfs.h> 70#include <linux/ctype.h> 71#include <linux/ftrace.h> 72#include <linux/slab.h> 73#include <linux/init_task.h> 74#include <linux/binfmts.h> 75#include <linux/context_tracking.h> 76 77#include <asm/switch_to.h> 78#include <asm/tlb.h> 79#include <asm/irq_regs.h> 80#include <asm/mutex.h> 81#ifdef CONFIG_PARAVIRT 82#include <asm/paravirt.h> 83#endif 84 85#include "sched.h" 86#include "../workqueue_internal.h" 87#include "../smpboot.h" 88 89#define CREATE_TRACE_POINTS 90#include <trace/events/sched.h> 91 92void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period) 93{ 94 unsigned long delta; 95 ktime_t soft, hard, now; 96 97 for (;;) { 98 if (hrtimer_active(period_timer)) 99 break; 100 101 now = hrtimer_cb_get_time(period_timer); 102 hrtimer_forward(period_timer, now, period); 103 104 soft = hrtimer_get_softexpires(period_timer); 105 hard = hrtimer_get_expires(period_timer); 106 delta = ktime_to_ns(ktime_sub(hard, soft)); 107 __hrtimer_start_range_ns(period_timer, soft, delta, 108 HRTIMER_MODE_ABS_PINNED, 0); 109 } 110} 111 112DEFINE_MUTEX(sched_domains_mutex); 113DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); 114 115static void update_rq_clock_task(struct rq *rq, s64 delta); 116 117void update_rq_clock(struct rq *rq) 118{ 119 s64 delta; 120 121 if (rq->skip_clock_update > 0) 122 return; 123 124 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; 125 rq->clock += delta; 126 update_rq_clock_task(rq, delta); 127} 128 129/* 130 * Debugging: various feature bits 131 */ 132 133#define SCHED_FEAT(name, enabled) \ 134 (1UL << __SCHED_FEAT_##name) * enabled | 135 136const_debug unsigned int sysctl_sched_features = 137#include "features.h" 138 0; 139 140#undef SCHED_FEAT 141 142#ifdef CONFIG_SCHED_DEBUG 143#define SCHED_FEAT(name, enabled) \ 144 #name , 145 146static const char * const sched_feat_names[] = { 147#include "features.h" 148}; 149 150#undef SCHED_FEAT 151 152static int sched_feat_show(struct seq_file *m, void *v) 153{ 154 int i; 155 156 for (i = 0; i < __SCHED_FEAT_NR; i++) { 157 if (!(sysctl_sched_features & (1UL << i))) 158 seq_puts(m, "NO_"); 159 seq_printf(m, "%s ", sched_feat_names[i]); 160 } 161 seq_puts(m, "\n"); 162 163 return 0; 164} 165 166#ifdef HAVE_JUMP_LABEL 167 168#define jump_label_key__true STATIC_KEY_INIT_TRUE 169#define jump_label_key__false STATIC_KEY_INIT_FALSE 170 171#define SCHED_FEAT(name, enabled) \ 172 jump_label_key__##enabled , 173 174struct static_key sched_feat_keys[__SCHED_FEAT_NR] = { 175#include "features.h" 176}; 177 178#undef SCHED_FEAT 179 180static void sched_feat_disable(int i) 181{ 182 if (static_key_enabled(&sched_feat_keys[i])) 183 static_key_slow_dec(&sched_feat_keys[i]); 184} 185 186static void sched_feat_enable(int i) 187{ 188 if (!static_key_enabled(&sched_feat_keys[i])) 189 static_key_slow_inc(&sched_feat_keys[i]); 190} 191#else 192static void sched_feat_disable(int i) { }; 193static void sched_feat_enable(int i) { }; 194#endif /* HAVE_JUMP_LABEL */ 195 196static int sched_feat_set(char *cmp) 197{ 198 int i; 199 int neg = 0; 200 201 if (strncmp(cmp, "NO_", 3) == 0) { 202 neg = 1; 203 cmp += 3; 204 } 205 206 for (i = 0; i < __SCHED_FEAT_NR; i++) { 207 if (strcmp(cmp, sched_feat_names[i]) == 0) { 208 if (neg) { 209 sysctl_sched_features &= ~(1UL << i); 210 sched_feat_disable(i); 211 } else { 212 sysctl_sched_features |= (1UL << i); 213 sched_feat_enable(i); 214 } 215 break; 216 } 217 } 218 219 return i; 220} 221 222static ssize_t 223sched_feat_write(struct file *filp, const char __user *ubuf, 224 size_t cnt, loff_t *ppos) 225{ 226 char buf[64]; 227 char *cmp; 228 int i; 229 230 if (cnt > 63) 231 cnt = 63; 232 233 if (copy_from_user(&buf, ubuf, cnt)) 234 return -EFAULT; 235 236 buf[cnt] = 0; 237 cmp = strstrip(buf); 238 239 i = sched_feat_set(cmp); 240 if (i == __SCHED_FEAT_NR) 241 return -EINVAL; 242 243 *ppos += cnt; 244 245 return cnt; 246} 247 248static int sched_feat_open(struct inode *inode, struct file *filp) 249{ 250 return single_open(filp, sched_feat_show, NULL); 251} 252 253static const struct file_operations sched_feat_fops = { 254 .open = sched_feat_open, 255 .write = sched_feat_write, 256 .read = seq_read, 257 .llseek = seq_lseek, 258 .release = single_release, 259}; 260 261static __init int sched_init_debug(void) 262{ 263 debugfs_create_file("sched_features", 0644, NULL, NULL, 264 &sched_feat_fops); 265 266 return 0; 267} 268late_initcall(sched_init_debug); 269#endif /* CONFIG_SCHED_DEBUG */ 270 271/* 272 * Number of tasks to iterate in a single balance run. 273 * Limited because this is done with IRQs disabled. 274 */ 275const_debug unsigned int sysctl_sched_nr_migrate = 32; 276 277/* 278 * period over which we average the RT time consumption, measured 279 * in ms. 280 * 281 * default: 1s 282 */ 283const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC; 284 285/* 286 * period over which we measure -rt task cpu usage in us. 287 * default: 1s 288 */ 289unsigned int sysctl_sched_rt_period = 1000000; 290 291__read_mostly int scheduler_running; 292 293/* 294 * part of the period that we allow rt tasks to run in us. 295 * default: 0.95s 296 */ 297int sysctl_sched_rt_runtime = 950000; 298 299 300 301/* 302 * __task_rq_lock - lock the rq @p resides on. 303 */ 304static inline struct rq *__task_rq_lock(struct task_struct *p) 305 __acquires(rq->lock) 306{ 307 struct rq *rq; 308 309 lockdep_assert_held(&p->pi_lock); 310 311 for (;;) { 312 rq = task_rq(p); 313 raw_spin_lock(&rq->lock); 314 if (likely(rq == task_rq(p))) 315 return rq; 316 raw_spin_unlock(&rq->lock); 317 } 318} 319 320/* 321 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on. 322 */ 323static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags) 324 __acquires(p->pi_lock) 325 __acquires(rq->lock) 326{ 327 struct rq *rq; 328 329 for (;;) { 330 raw_spin_lock_irqsave(&p->pi_lock, *flags); 331 rq = task_rq(p); 332 raw_spin_lock(&rq->lock); 333 if (likely(rq == task_rq(p))) 334 return rq; 335 raw_spin_unlock(&rq->lock); 336 raw_spin_unlock_irqrestore(&p->pi_lock, *flags); 337 } 338} 339 340static void __task_rq_unlock(struct rq *rq) 341 __releases(rq->lock) 342{ 343 raw_spin_unlock(&rq->lock); 344} 345 346static inline void 347task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags) 348 __releases(rq->lock) 349 __releases(p->pi_lock) 350{ 351 raw_spin_unlock(&rq->lock); 352 raw_spin_unlock_irqrestore(&p->pi_lock, *flags); 353} 354 355/* 356 * this_rq_lock - lock this runqueue and disable interrupts. 357 */ 358static struct rq *this_rq_lock(void) 359 __acquires(rq->lock) 360{ 361 struct rq *rq; 362 363 local_irq_disable(); 364 rq = this_rq(); 365 raw_spin_lock(&rq->lock); 366 367 return rq; 368} 369 370#ifdef CONFIG_SCHED_HRTICK 371/* 372 * Use HR-timers to deliver accurate preemption points. 373 */ 374 375static void hrtick_clear(struct rq *rq) 376{ 377 if (hrtimer_active(&rq->hrtick_timer)) 378 hrtimer_cancel(&rq->hrtick_timer); 379} 380 381/* 382 * High-resolution timer tick. 383 * Runs from hardirq context with interrupts disabled. 384 */ 385static enum hrtimer_restart hrtick(struct hrtimer *timer) 386{ 387 struct rq *rq = container_of(timer, struct rq, hrtick_timer); 388 389 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); 390 391 raw_spin_lock(&rq->lock); 392 update_rq_clock(rq); 393 rq->curr->sched_class->task_tick(rq, rq->curr, 1); 394 raw_spin_unlock(&rq->lock); 395 396 return HRTIMER_NORESTART; 397} 398 399#ifdef CONFIG_SMP 400 401static int __hrtick_restart(struct rq *rq) 402{ 403 struct hrtimer *timer = &rq->hrtick_timer; 404 ktime_t time = hrtimer_get_softexpires(timer); 405 406 return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0); 407} 408 409/* 410 * called from hardirq (IPI) context 411 */ 412static void __hrtick_start(void *arg) 413{ 414 struct rq *rq = arg; 415 416 raw_spin_lock(&rq->lock); 417 __hrtick_restart(rq); 418 rq->hrtick_csd_pending = 0; 419 raw_spin_unlock(&rq->lock); 420} 421 422/* 423 * Called to set the hrtick timer state. 424 * 425 * called with rq->lock held and irqs disabled 426 */ 427void hrtick_start(struct rq *rq, u64 delay) 428{ 429 struct hrtimer *timer = &rq->hrtick_timer; 430 ktime_t time = ktime_add_ns(timer->base->get_time(), delay); 431 432 hrtimer_set_expires(timer, time); 433 434 if (rq == this_rq()) { 435 __hrtick_restart(rq); 436 } else if (!rq->hrtick_csd_pending) { 437 __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0); 438 rq->hrtick_csd_pending = 1; 439 } 440} 441 442static int 443hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu) 444{ 445 int cpu = (int)(long)hcpu; 446 447 switch (action) { 448 case CPU_UP_CANCELED: 449 case CPU_UP_CANCELED_FROZEN: 450 case CPU_DOWN_PREPARE: 451 case CPU_DOWN_PREPARE_FROZEN: 452 case CPU_DEAD: 453 case CPU_DEAD_FROZEN: 454 hrtick_clear(cpu_rq(cpu)); 455 return NOTIFY_OK; 456 } 457 458 return NOTIFY_DONE; 459} 460 461static __init void init_hrtick(void) 462{ 463 hotcpu_notifier(hotplug_hrtick, 0); 464} 465#else 466/* 467 * Called to set the hrtick timer state. 468 * 469 * called with rq->lock held and irqs disabled 470 */ 471void hrtick_start(struct rq *rq, u64 delay) 472{ 473 __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0, 474 HRTIMER_MODE_REL_PINNED, 0); 475} 476 477static inline void init_hrtick(void) 478{ 479} 480#endif /* CONFIG_SMP */ 481 482static void init_rq_hrtick(struct rq *rq) 483{ 484#ifdef CONFIG_SMP 485 rq->hrtick_csd_pending = 0; 486 487 rq->hrtick_csd.flags = 0; 488 rq->hrtick_csd.func = __hrtick_start; 489 rq->hrtick_csd.info = rq; 490#endif 491 492 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 493 rq->hrtick_timer.function = hrtick; 494} 495#else /* CONFIG_SCHED_HRTICK */ 496static inline void hrtick_clear(struct rq *rq) 497{ 498} 499 500static inline void init_rq_hrtick(struct rq *rq) 501{ 502} 503 504static inline void init_hrtick(void) 505{ 506} 507#endif /* CONFIG_SCHED_HRTICK */ 508 509/* 510 * resched_task - mark a task 'to be rescheduled now'. 511 * 512 * On UP this means the setting of the need_resched flag, on SMP it 513 * might also involve a cross-CPU call to trigger the scheduler on 514 * the target CPU. 515 */ 516void resched_task(struct task_struct *p) 517{ 518 int cpu; 519 520 lockdep_assert_held(&task_rq(p)->lock); 521 522 if (test_tsk_need_resched(p)) 523 return; 524 525 set_tsk_need_resched(p); 526 527 cpu = task_cpu(p); 528 if (cpu == smp_processor_id()) { 529 set_preempt_need_resched(); 530 return; 531 } 532 533 /* NEED_RESCHED must be visible before we test polling */ 534 smp_mb(); 535 if (!tsk_is_polling(p)) 536 smp_send_reschedule(cpu); 537} 538 539void resched_cpu(int cpu) 540{ 541 struct rq *rq = cpu_rq(cpu); 542 unsigned long flags; 543 544 if (!raw_spin_trylock_irqsave(&rq->lock, flags)) 545 return; 546 resched_task(cpu_curr(cpu)); 547 raw_spin_unlock_irqrestore(&rq->lock, flags); 548} 549 550#ifdef CONFIG_SMP 551#ifdef CONFIG_NO_HZ_COMMON 552/* 553 * In the semi idle case, use the nearest busy cpu for migrating timers 554 * from an idle cpu. This is good for power-savings. 555 * 556 * We don't do similar optimization for completely idle system, as 557 * selecting an idle cpu will add more delays to the timers than intended 558 * (as that cpu's timer base may not be uptodate wrt jiffies etc). 559 */ 560int get_nohz_timer_target(void) 561{ 562 int cpu = smp_processor_id(); 563 int i; 564 struct sched_domain *sd; 565 566 rcu_read_lock(); 567 for_each_domain(cpu, sd) { 568 for_each_cpu(i, sched_domain_span(sd)) { 569 if (!idle_cpu(i)) { 570 cpu = i; 571 goto unlock; 572 } 573 } 574 } 575unlock: 576 rcu_read_unlock(); 577 return cpu; 578} 579/* 580 * When add_timer_on() enqueues a timer into the timer wheel of an 581 * idle CPU then this timer might expire before the next timer event 582 * which is scheduled to wake up that CPU. In case of a completely 583 * idle system the next event might even be infinite time into the 584 * future. wake_up_idle_cpu() ensures that the CPU is woken up and 585 * leaves the inner idle loop so the newly added timer is taken into 586 * account when the CPU goes back to idle and evaluates the timer 587 * wheel for the next timer event. 588 */ 589static void wake_up_idle_cpu(int cpu) 590{ 591 struct rq *rq = cpu_rq(cpu); 592 593 if (cpu == smp_processor_id()) 594 return; 595 596 /* 597 * This is safe, as this function is called with the timer 598 * wheel base lock of (cpu) held. When the CPU is on the way 599 * to idle and has not yet set rq->curr to idle then it will 600 * be serialized on the timer wheel base lock and take the new 601 * timer into account automatically. 602 */ 603 if (rq->curr != rq->idle) 604 return; 605 606 /* 607 * We can set TIF_RESCHED on the idle task of the other CPU 608 * lockless. The worst case is that the other CPU runs the 609 * idle task through an additional NOOP schedule() 610 */ 611 set_tsk_need_resched(rq->idle); 612 613 /* NEED_RESCHED must be visible before we test polling */ 614 smp_mb(); 615 if (!tsk_is_polling(rq->idle)) 616 smp_send_reschedule(cpu); 617} 618 619static bool wake_up_full_nohz_cpu(int cpu) 620{ 621 if (tick_nohz_full_cpu(cpu)) { 622 if (cpu != smp_processor_id() || 623 tick_nohz_tick_stopped()) 624 smp_send_reschedule(cpu); 625 return true; 626 } 627 628 return false; 629} 630 631void wake_up_nohz_cpu(int cpu) 632{ 633 if (!wake_up_full_nohz_cpu(cpu)) 634 wake_up_idle_cpu(cpu); 635} 636 637static inline bool got_nohz_idle_kick(void) 638{ 639 int cpu = smp_processor_id(); 640 641 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu))) 642 return false; 643 644 if (idle_cpu(cpu) && !need_resched()) 645 return true; 646 647 /* 648 * We can't run Idle Load Balance on this CPU for this time so we 649 * cancel it and clear NOHZ_BALANCE_KICK 650 */ 651 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); 652 return false; 653} 654 655#else /* CONFIG_NO_HZ_COMMON */ 656 657static inline bool got_nohz_idle_kick(void) 658{ 659 return false; 660} 661 662#endif /* CONFIG_NO_HZ_COMMON */ 663 664#ifdef CONFIG_NO_HZ_FULL 665bool sched_can_stop_tick(void) 666{ 667 struct rq *rq; 668 669 rq = this_rq(); 670 671 /* Make sure rq->nr_running update is visible after the IPI */ 672 smp_rmb(); 673 674 /* More than one running task need preemption */ 675 if (rq->nr_running > 1) 676 return false; 677 678 return true; 679} 680#endif /* CONFIG_NO_HZ_FULL */ 681 682void sched_avg_update(struct rq *rq) 683{ 684 s64 period = sched_avg_period(); 685 686 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) { 687 /* 688 * Inline assembly required to prevent the compiler 689 * optimising this loop into a divmod call. 690 * See __iter_div_u64_rem() for another example of this. 691 */ 692 asm("" : "+rm" (rq->age_stamp)); 693 rq->age_stamp += period; 694 rq->rt_avg /= 2; 695 } 696} 697 698#endif /* CONFIG_SMP */ 699 700#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ 701 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) 702/* 703 * Iterate task_group tree rooted at *from, calling @down when first entering a 704 * node and @up when leaving it for the final time. 705 * 706 * Caller must hold rcu_lock or sufficient equivalent. 707 */ 708int walk_tg_tree_from(struct task_group *from, 709 tg_visitor down, tg_visitor up, void *data) 710{ 711 struct task_group *parent, *child; 712 int ret; 713 714 parent = from; 715 716down: 717 ret = (*down)(parent, data); 718 if (ret) 719 goto out; 720 list_for_each_entry_rcu(child, &parent->children, siblings) { 721 parent = child; 722 goto down; 723 724up: 725 continue; 726 } 727 ret = (*up)(parent, data); 728 if (ret || parent == from) 729 goto out; 730 731 child = parent; 732 parent = parent->parent; 733 if (parent) 734 goto up; 735out: 736 return ret; 737} 738 739int tg_nop(struct task_group *tg, void *data) 740{ 741 return 0; 742} 743#endif 744 745static void set_load_weight(struct task_struct *p) 746{ 747 int prio = p->static_prio - MAX_RT_PRIO; 748 struct load_weight *load = &p->se.load; 749 750 /* 751 * SCHED_IDLE tasks get minimal weight: 752 */ 753 if (p->policy == SCHED_IDLE) { 754 load->weight = scale_load(WEIGHT_IDLEPRIO); 755 load->inv_weight = WMULT_IDLEPRIO; 756 return; 757 } 758 759 load->weight = scale_load(prio_to_weight[prio]); 760 load->inv_weight = prio_to_wmult[prio]; 761} 762 763static void enqueue_task(struct rq *rq, struct task_struct *p, int flags) 764{ 765 update_rq_clock(rq); 766 sched_info_queued(rq, p); 767 p->sched_class->enqueue_task(rq, p, flags); 768} 769 770static void dequeue_task(struct rq *rq, struct task_struct *p, int flags) 771{ 772 update_rq_clock(rq); 773 sched_info_dequeued(rq, p); 774 p->sched_class->dequeue_task(rq, p, flags); 775} 776 777void activate_task(struct rq *rq, struct task_struct *p, int flags) 778{ 779 if (task_contributes_to_load(p)) 780 rq->nr_uninterruptible--; 781 782 enqueue_task(rq, p, flags); 783} 784 785void deactivate_task(struct rq *rq, struct task_struct *p, int flags) 786{ 787 if (task_contributes_to_load(p)) 788 rq->nr_uninterruptible++; 789 790 dequeue_task(rq, p, flags); 791} 792 793static void update_rq_clock_task(struct rq *rq, s64 delta) 794{ 795/* 796 * In theory, the compile should just see 0 here, and optimize out the call 797 * to sched_rt_avg_update. But I don't trust it... 798 */ 799#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 800 s64 steal = 0, irq_delta = 0; 801#endif 802#ifdef CONFIG_IRQ_TIME_ACCOUNTING 803 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; 804 805 /* 806 * Since irq_time is only updated on {soft,}irq_exit, we might run into 807 * this case when a previous update_rq_clock() happened inside a 808 * {soft,}irq region. 809 * 810 * When this happens, we stop ->clock_task and only update the 811 * prev_irq_time stamp to account for the part that fit, so that a next 812 * update will consume the rest. This ensures ->clock_task is 813 * monotonic. 814 * 815 * It does however cause some slight miss-attribution of {soft,}irq 816 * time, a more accurate solution would be to update the irq_time using 817 * the current rq->clock timestamp, except that would require using 818 * atomic ops. 819 */ 820 if (irq_delta > delta) 821 irq_delta = delta; 822 823 rq->prev_irq_time += irq_delta; 824 delta -= irq_delta; 825#endif 826#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING 827 if (static_key_false((¶virt_steal_rq_enabled))) { 828 u64 st; 829 830 steal = paravirt_steal_clock(cpu_of(rq)); 831 steal -= rq->prev_steal_time_rq; 832 833 if (unlikely(steal > delta)) 834 steal = delta; 835 836 st = steal_ticks(steal); 837 steal = st * TICK_NSEC; 838 839 rq->prev_steal_time_rq += steal; 840 841 delta -= steal; 842 } 843#endif 844 845 rq->clock_task += delta; 846 847#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 848 if ((irq_delta + steal) && sched_feat(NONTASK_POWER)) 849 sched_rt_avg_update(rq, irq_delta + steal); 850#endif 851} 852 853void sched_set_stop_task(int cpu, struct task_struct *stop) 854{ 855 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; 856 struct task_struct *old_stop = cpu_rq(cpu)->stop; 857 858 if (stop) { 859 /* 860 * Make it appear like a SCHED_FIFO task, its something 861 * userspace knows about and won't get confused about. 862 * 863 * Also, it will make PI more or less work without too 864 * much confusion -- but then, stop work should not 865 * rely on PI working anyway. 866 */ 867 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); 868 869 stop->sched_class = &stop_sched_class; 870 } 871 872 cpu_rq(cpu)->stop = stop; 873 874 if (old_stop) { 875 /* 876 * Reset it back to a normal scheduling class so that 877 * it can die in pieces. 878 */ 879 old_stop->sched_class = &rt_sched_class; 880 } 881} 882 883/* 884 * __normal_prio - return the priority that is based on the static prio 885 */ 886static inline int __normal_prio(struct task_struct *p) 887{ 888 return p->static_prio; 889} 890 891/* 892 * Calculate the expected normal priority: i.e. priority 893 * without taking RT-inheritance into account. Might be 894 * boosted by interactivity modifiers. Changes upon fork, 895 * setprio syscalls, and whenever the interactivity 896 * estimator recalculates. 897 */ 898static inline int normal_prio(struct task_struct *p) 899{ 900 int prio; 901 902 if (task_has_rt_policy(p)) 903 prio = MAX_RT_PRIO-1 - p->rt_priority; 904 else 905 prio = __normal_prio(p); 906 return prio; 907} 908 909/* 910 * Calculate the current priority, i.e. the priority 911 * taken into account by the scheduler. This value might 912 * be boosted by RT tasks, or might be boosted by 913 * interactivity modifiers. Will be RT if the task got 914 * RT-boosted. If not then it returns p->normal_prio. 915 */ 916static int effective_prio(struct task_struct *p) 917{ 918 p->normal_prio = normal_prio(p); 919 /* 920 * If we are RT tasks or we were boosted to RT priority, 921 * keep the priority unchanged. Otherwise, update priority 922 * to the normal priority: 923 */ 924 if (!rt_prio(p->prio)) 925 return p->normal_prio; 926 return p->prio; 927} 928 929/** 930 * task_curr - is this task currently executing on a CPU? 931 * @p: the task in question. 932 * 933 * Return: 1 if the task is currently executing. 0 otherwise. 934 */ 935inline int task_curr(const struct task_struct *p) 936{ 937 return cpu_curr(task_cpu(p)) == p; 938} 939 940static inline void check_class_changed(struct rq *rq, struct task_struct *p, 941 const struct sched_class *prev_class, 942 int oldprio) 943{ 944 if (prev_class != p->sched_class) { 945 if (prev_class->switched_from) 946 prev_class->switched_from(rq, p); 947 p->sched_class->switched_to(rq, p); 948 } else if (oldprio != p->prio) 949 p->sched_class->prio_changed(rq, p, oldprio); 950} 951 952void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) 953{ 954 const struct sched_class *class; 955 956 if (p->sched_class == rq->curr->sched_class) { 957 rq->curr->sched_class->check_preempt_curr(rq, p, flags); 958 } else { 959 for_each_class(class) { 960 if (class == rq->curr->sched_class) 961 break; 962 if (class == p->sched_class) { 963 resched_task(rq->curr); 964 break; 965 } 966 } 967 } 968 969 /* 970 * A queue event has occurred, and we're going to schedule. In 971 * this case, we can save a useless back to back clock update. 972 */ 973 if (rq->curr->on_rq && test_tsk_need_resched(rq->curr)) 974 rq->skip_clock_update = 1; 975} 976 977#ifdef CONFIG_SMP 978void set_task_cpu(struct task_struct *p, unsigned int new_cpu) 979{ 980#ifdef CONFIG_SCHED_DEBUG 981 /* 982 * We should never call set_task_cpu() on a blocked task, 983 * ttwu() will sort out the placement. 984 */ 985 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && 986 !(task_preempt_count(p) & PREEMPT_ACTIVE)); 987 988#ifdef CONFIG_LOCKDEP 989 /* 990 * The caller should hold either p->pi_lock or rq->lock, when changing 991 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. 992 * 993 * sched_move_task() holds both and thus holding either pins the cgroup, 994 * see task_group(). 995 * 996 * Furthermore, all task_rq users should acquire both locks, see 997 * task_rq_lock(). 998 */ 999 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || 1000 lockdep_is_held(&task_rq(p)->lock))); 1001#endif 1002#endif 1003 1004 trace_sched_migrate_task(p, new_cpu); 1005 1006 if (task_cpu(p) != new_cpu) { 1007 if (p->sched_class->migrate_task_rq) 1008 p->sched_class->migrate_task_rq(p, new_cpu); 1009 p->se.nr_migrations++; 1010 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0); 1011 } 1012 1013 __set_task_cpu(p, new_cpu); 1014} 1015 1016static void __migrate_swap_task(struct task_struct *p, int cpu) 1017{ 1018 if (p->on_rq) { 1019 struct rq *src_rq, *dst_rq; 1020 1021 src_rq = task_rq(p); 1022 dst_rq = cpu_rq(cpu); 1023 1024 deactivate_task(src_rq, p, 0); 1025 set_task_cpu(p, cpu); 1026 activate_task(dst_rq, p, 0); 1027 check_preempt_curr(dst_rq, p, 0); 1028 } else { 1029 /* 1030 * Task isn't running anymore; make it appear like we migrated 1031 * it before it went to sleep. This means on wakeup we make the 1032 * previous cpu our targer instead of where it really is. 1033 */ 1034 p->wake_cpu = cpu; 1035 } 1036} 1037 1038struct migration_swap_arg { 1039 struct task_struct *src_task, *dst_task; 1040 int src_cpu, dst_cpu; 1041}; 1042 1043static int migrate_swap_stop(void *data) 1044{ 1045 struct migration_swap_arg *arg = data; 1046 struct rq *src_rq, *dst_rq; 1047 int ret = -EAGAIN; 1048 1049 src_rq = cpu_rq(arg->src_cpu); 1050 dst_rq = cpu_rq(arg->dst_cpu); 1051 1052 double_rq_lock(src_rq, dst_rq); 1053 if (task_cpu(arg->dst_task) != arg->dst_cpu) 1054 goto unlock; 1055 1056 if (task_cpu(arg->src_task) != arg->src_cpu) 1057 goto unlock; 1058 1059 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task))) 1060 goto unlock; 1061 1062 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task))) 1063 goto unlock; 1064 1065 __migrate_swap_task(arg->src_task, arg->dst_cpu); 1066 __migrate_swap_task(arg->dst_task, arg->src_cpu); 1067 1068 ret = 0; 1069 1070unlock: 1071 double_rq_unlock(src_rq, dst_rq); 1072 1073 return ret; 1074} 1075 1076/* 1077 * Cross migrate two tasks 1078 */ 1079int migrate_swap(struct task_struct *cur, struct task_struct *p) 1080{ 1081 struct migration_swap_arg arg; 1082 int ret = -EINVAL; 1083 1084 get_online_cpus(); 1085 1086 arg = (struct migration_swap_arg){ 1087 .src_task = cur, 1088 .src_cpu = task_cpu(cur), 1089 .dst_task = p, 1090 .dst_cpu = task_cpu(p), 1091 }; 1092 1093 if (arg.src_cpu == arg.dst_cpu) 1094 goto out; 1095 1096 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu)) 1097 goto out; 1098 1099 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task))) 1100 goto out; 1101 1102 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task))) 1103 goto out; 1104 1105 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg); 1106 1107out: 1108 put_online_cpus(); 1109 return ret; 1110} 1111 1112struct migration_arg { 1113 struct task_struct *task; 1114 int dest_cpu; 1115}; 1116 1117static int migration_cpu_stop(void *data); 1118 1119/* 1120 * wait_task_inactive - wait for a thread to unschedule. 1121 * 1122 * If @match_state is nonzero, it's the @p->state value just checked and 1123 * not expected to change. If it changes, i.e. @p might have woken up, 1124 * then return zero. When we succeed in waiting for @p to be off its CPU, 1125 * we return a positive number (its total switch count). If a second call 1126 * a short while later returns the same number, the caller can be sure that 1127 * @p has remained unscheduled the whole time. 1128 * 1129 * The caller must ensure that the task *will* unschedule sometime soon, 1130 * else this function might spin for a *long* time. This function can't 1131 * be called with interrupts off, or it may introduce deadlock with 1132 * smp_call_function() if an IPI is sent by the same process we are 1133 * waiting to become inactive. 1134 */ 1135unsigned long wait_task_inactive(struct task_struct *p, long match_state) 1136{ 1137 unsigned long flags; 1138 int running, on_rq; 1139 unsigned long ncsw; 1140 struct rq *rq; 1141 1142 for (;;) { 1143 /* 1144 * We do the initial early heuristics without holding 1145 * any task-queue locks at all. We'll only try to get 1146 * the runqueue lock when things look like they will 1147 * work out! 1148 */ 1149 rq = task_rq(p); 1150 1151 /* 1152 * If the task is actively running on another CPU 1153 * still, just relax and busy-wait without holding 1154 * any locks. 1155 * 1156 * NOTE! Since we don't hold any locks, it's not 1157 * even sure that "rq" stays as the right runqueue! 1158 * But we don't care, since "task_running()" will 1159 * return false if the runqueue has changed and p 1160 * is actually now running somewhere else! 1161 */ 1162 while (task_running(rq, p)) { 1163 if (match_state && unlikely(p->state != match_state)) 1164 return 0; 1165 cpu_relax(); 1166 } 1167 1168 /* 1169 * Ok, time to look more closely! We need the rq 1170 * lock now, to be *sure*. If we're wrong, we'll 1171 * just go back and repeat. 1172 */ 1173 rq = task_rq_lock(p, &flags); 1174 trace_sched_wait_task(p); 1175 running = task_running(rq, p); 1176 on_rq = p->on_rq; 1177 ncsw = 0; 1178 if (!match_state || p->state == match_state) 1179 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ 1180 task_rq_unlock(rq, p, &flags); 1181 1182 /* 1183 * If it changed from the expected state, bail out now. 1184 */ 1185 if (unlikely(!ncsw)) 1186 break; 1187 1188 /* 1189 * Was it really running after all now that we 1190 * checked with the proper locks actually held? 1191 * 1192 * Oops. Go back and try again.. 1193 */ 1194 if (unlikely(running)) { 1195 cpu_relax(); 1196 continue; 1197 } 1198 1199 /* 1200 * It's not enough that it's not actively running, 1201 * it must be off the runqueue _entirely_, and not 1202 * preempted! 1203 * 1204 * So if it was still runnable (but just not actively 1205 * running right now), it's preempted, and we should 1206 * yield - it could be a while. 1207 */ 1208 if (unlikely(on_rq)) { 1209 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ); 1210 1211 set_current_state(TASK_UNINTERRUPTIBLE); 1212 schedule_hrtimeout(&to, HRTIMER_MODE_REL); 1213 continue; 1214 } 1215 1216 /* 1217 * Ahh, all good. It wasn't running, and it wasn't 1218 * runnable, which means that it will never become 1219 * running in the future either. We're all done! 1220 */ 1221 break; 1222 } 1223 1224 return ncsw; 1225} 1226 1227/*** 1228 * kick_process - kick a running thread to enter/exit the kernel 1229 * @p: the to-be-kicked thread 1230 * 1231 * Cause a process which is running on another CPU to enter 1232 * kernel-mode, without any delay. (to get signals handled.) 1233 * 1234 * NOTE: this function doesn't have to take the runqueue lock, 1235 * because all it wants to ensure is that the remote task enters 1236 * the kernel. If the IPI races and the task has been migrated 1237 * to another CPU then no harm is done and the purpose has been 1238 * achieved as well. 1239 */ 1240void kick_process(struct task_struct *p) 1241{ 1242 int cpu; 1243 1244 preempt_disable(); 1245 cpu = task_cpu(p); 1246 if ((cpu != smp_processor_id()) && task_curr(p)) 1247 smp_send_reschedule(cpu); 1248 preempt_enable(); 1249} 1250EXPORT_SYMBOL_GPL(kick_process); 1251#endif /* CONFIG_SMP */ 1252 1253#ifdef CONFIG_SMP 1254/* 1255 * ->cpus_allowed is protected by both rq->lock and p->pi_lock 1256 */ 1257static int select_fallback_rq(int cpu, struct task_struct *p) 1258{ 1259 int nid = cpu_to_node(cpu); 1260 const struct cpumask *nodemask = NULL; 1261 enum { cpuset, possible, fail } state = cpuset; 1262 int dest_cpu; 1263 1264 /* 1265 * If the node that the cpu is on has been offlined, cpu_to_node() 1266 * will return -1. There is no cpu on the node, and we should 1267 * select the cpu on the other node. 1268 */ 1269 if (nid != -1) { 1270 nodemask = cpumask_of_node(nid); 1271 1272 /* Look for allowed, online CPU in same node. */ 1273 for_each_cpu(dest_cpu, nodemask) { 1274 if (!cpu_online(dest_cpu)) 1275 continue; 1276 if (!cpu_active(dest_cpu)) 1277 continue; 1278 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 1279 return dest_cpu; 1280 } 1281 } 1282 1283 for (;;) { 1284 /* Any allowed, online CPU? */ 1285 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { 1286 if (!cpu_online(dest_cpu)) 1287 continue; 1288 if (!cpu_active(dest_cpu)) 1289 continue; 1290 goto out; 1291 } 1292 1293 switch (state) { 1294 case cpuset: 1295 /* No more Mr. Nice Guy. */ 1296 cpuset_cpus_allowed_fallback(p); 1297 state = possible; 1298 break; 1299 1300 case possible: 1301 do_set_cpus_allowed(p, cpu_possible_mask); 1302 state = fail; 1303 break; 1304 1305 case fail: 1306 BUG(); 1307 break; 1308 } 1309 } 1310 1311out: 1312 if (state != cpuset) { 1313 /* 1314 * Don't tell them about moving exiting tasks or 1315 * kernel threads (both mm NULL), since they never 1316 * leave kernel. 1317 */ 1318 if (p->mm && printk_ratelimit()) { 1319 printk_sched("process %d (%s) no longer affine to cpu%d\n", 1320 task_pid_nr(p), p->comm, cpu); 1321 } 1322 } 1323 1324 return dest_cpu; 1325} 1326 1327/* 1328 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. 1329 */ 1330static inline 1331int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) 1332{ 1333 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags); 1334 1335 /* 1336 * In order not to call set_task_cpu() on a blocking task we need 1337 * to rely on ttwu() to place the task on a valid ->cpus_allowed 1338 * cpu. 1339 * 1340 * Since this is common to all placement strategies, this lives here. 1341 * 1342 * [ this allows ->select_task() to simply return task_cpu(p) and 1343 * not worry about this generic constraint ] 1344 */ 1345 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) || 1346 !cpu_online(cpu))) 1347 cpu = select_fallback_rq(task_cpu(p), p); 1348 1349 return cpu; 1350} 1351 1352static void update_avg(u64 *avg, u64 sample) 1353{ 1354 s64 diff = sample - *avg; 1355 *avg += diff >> 3; 1356} 1357#endif 1358 1359static void 1360ttwu_stat(struct task_struct *p, int cpu, int wake_flags) 1361{ 1362#ifdef CONFIG_SCHEDSTATS 1363 struct rq *rq = this_rq(); 1364 1365#ifdef CONFIG_SMP 1366 int this_cpu = smp_processor_id(); 1367 1368 if (cpu == this_cpu) { 1369 schedstat_inc(rq, ttwu_local); 1370 schedstat_inc(p, se.statistics.nr_wakeups_local); 1371 } else { 1372 struct sched_domain *sd; 1373 1374 schedstat_inc(p, se.statistics.nr_wakeups_remote); 1375 rcu_read_lock(); 1376 for_each_domain(this_cpu, sd) { 1377 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { 1378 schedstat_inc(sd, ttwu_wake_remote); 1379 break; 1380 } 1381 } 1382 rcu_read_unlock(); 1383 } 1384 1385 if (wake_flags & WF_MIGRATED) 1386 schedstat_inc(p, se.statistics.nr_wakeups_migrate); 1387 1388#endif /* CONFIG_SMP */ 1389 1390 schedstat_inc(rq, ttwu_count); 1391 schedstat_inc(p, se.statistics.nr_wakeups); 1392 1393 if (wake_flags & WF_SYNC) 1394 schedstat_inc(p, se.statistics.nr_wakeups_sync); 1395 1396#endif /* CONFIG_SCHEDSTATS */ 1397} 1398 1399static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) 1400{ 1401 activate_task(rq, p, en_flags); 1402 p->on_rq = 1; 1403 1404 /* if a worker is waking up, notify workqueue */ 1405 if (p->flags & PF_WQ_WORKER) 1406 wq_worker_waking_up(p, cpu_of(rq)); 1407} 1408 1409/* 1410 * Mark the task runnable and perform wakeup-preemption. 1411 */ 1412static void 1413ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) 1414{ 1415 check_preempt_curr(rq, p, wake_flags); 1416 trace_sched_wakeup(p, true); 1417 1418 p->state = TASK_RUNNING; 1419#ifdef CONFIG_SMP 1420 if (p->sched_class->task_woken) 1421 p->sched_class->task_woken(rq, p); 1422 1423 if (rq->idle_stamp) { 1424 u64 delta = rq_clock(rq) - rq->idle_stamp; 1425 u64 max = 2*rq->max_idle_balance_cost; 1426 1427 update_avg(&rq->avg_idle, delta); 1428 1429 if (rq->avg_idle > max) 1430 rq->avg_idle = max; 1431 1432 rq->idle_stamp = 0; 1433 } 1434#endif 1435} 1436 1437static void 1438ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags) 1439{ 1440#ifdef CONFIG_SMP 1441 if (p->sched_contributes_to_load) 1442 rq->nr_uninterruptible--; 1443#endif 1444 1445 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING); 1446 ttwu_do_wakeup(rq, p, wake_flags); 1447} 1448 1449/* 1450 * Called in case the task @p isn't fully descheduled from its runqueue, 1451 * in this case we must do a remote wakeup. Its a 'light' wakeup though, 1452 * since all we need to do is flip p->state to TASK_RUNNING, since 1453 * the task is still ->on_rq. 1454 */ 1455static int ttwu_remote(struct task_struct *p, int wake_flags) 1456{ 1457 struct rq *rq; 1458 int ret = 0; 1459 1460 rq = __task_rq_lock(p); 1461 if (p->on_rq) { 1462 /* check_preempt_curr() may use rq clock */ 1463 update_rq_clock(rq); 1464 ttwu_do_wakeup(rq, p, wake_flags); 1465 ret = 1; 1466 } 1467 __task_rq_unlock(rq); 1468 1469 return ret; 1470} 1471 1472#ifdef CONFIG_SMP 1473static void sched_ttwu_pending(void) 1474{ 1475 struct rq *rq = this_rq(); 1476 struct llist_node *llist = llist_del_all(&rq->wake_list); 1477 struct task_struct *p; 1478 1479 raw_spin_lock(&rq->lock); 1480 1481 while (llist) { 1482 p = llist_entry(llist, struct task_struct, wake_entry); 1483 llist = llist_next(llist); 1484 ttwu_do_activate(rq, p, 0); 1485 } 1486 1487 raw_spin_unlock(&rq->lock); 1488} 1489 1490void scheduler_ipi(void) 1491{ 1492 /* 1493 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting 1494 * TIF_NEED_RESCHED remotely (for the first time) will also send 1495 * this IPI. 1496 */ 1497 if (tif_need_resched()) 1498 set_preempt_need_resched(); 1499 1500 if (llist_empty(&this_rq()->wake_list) 1501 && !tick_nohz_full_cpu(smp_processor_id()) 1502 && !got_nohz_idle_kick()) 1503 return; 1504 1505 /* 1506 * Not all reschedule IPI handlers call irq_enter/irq_exit, since 1507 * traditionally all their work was done from the interrupt return 1508 * path. Now that we actually do some work, we need to make sure 1509 * we do call them. 1510 * 1511 * Some archs already do call them, luckily irq_enter/exit nest 1512 * properly. 1513 * 1514 * Arguably we should visit all archs and update all handlers, 1515 * however a fair share of IPIs are still resched only so this would 1516 * somewhat pessimize the simple resched case. 1517 */ 1518 irq_enter(); 1519 tick_nohz_full_check(); 1520 sched_ttwu_pending(); 1521 1522 /* 1523 * Check if someone kicked us for doing the nohz idle load balance. 1524 */ 1525 if (unlikely(got_nohz_idle_kick())) { 1526 this_rq()->idle_balance = 1; 1527 raise_softirq_irqoff(SCHED_SOFTIRQ); 1528 } 1529 irq_exit(); 1530} 1531 1532static void ttwu_queue_remote(struct task_struct *p, int cpu) 1533{ 1534 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) 1535 smp_send_reschedule(cpu); 1536} 1537 1538bool cpus_share_cache(int this_cpu, int that_cpu) 1539{ 1540 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); 1541} 1542#endif /* CONFIG_SMP */ 1543 1544static void ttwu_queue(struct task_struct *p, int cpu) 1545{ 1546 struct rq *rq = cpu_rq(cpu); 1547 1548#if defined(CONFIG_SMP) 1549 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { 1550 sched_clock_cpu(cpu); /* sync clocks x-cpu */ 1551 ttwu_queue_remote(p, cpu); 1552 return; 1553 } 1554#endif 1555 1556 raw_spin_lock(&rq->lock); 1557 ttwu_do_activate(rq, p, 0); 1558 raw_spin_unlock(&rq->lock); 1559} 1560 1561/** 1562 * try_to_wake_up - wake up a thread 1563 * @p: the thread to be awakened 1564 * @state: the mask of task states that can be woken 1565 * @wake_flags: wake modifier flags (WF_*) 1566 * 1567 * Put it on the run-queue if it's not already there. The "current" 1568 * thread is always on the run-queue (except when the actual 1569 * re-schedule is in progress), and as such you're allowed to do 1570 * the simpler "current->state = TASK_RUNNING" to mark yourself 1571 * runnable without the overhead of this. 1572 * 1573 * Return: %true if @p was woken up, %false if it was already running. 1574 * or @state didn't match @p's state. 1575 */ 1576static int 1577try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) 1578{ 1579 unsigned long flags; 1580 int cpu, success = 0; 1581 1582 /* 1583 * If we are going to wake up a thread waiting for CONDITION we 1584 * need to ensure that CONDITION=1 done by the caller can not be 1585 * reordered with p->state check below. This pairs with mb() in 1586 * set_current_state() the waiting thread does. 1587 */ 1588 smp_mb__before_spinlock(); 1589 raw_spin_lock_irqsave(&p->pi_lock, flags); 1590 if (!(p->state & state)) 1591 goto out; 1592 1593 success = 1; /* we're going to change ->state */ 1594 cpu = task_cpu(p); 1595 1596 if (p->on_rq && ttwu_remote(p, wake_flags)) 1597 goto stat; 1598 1599#ifdef CONFIG_SMP 1600 /* 1601 * If the owning (remote) cpu is still in the middle of schedule() with 1602 * this task as prev, wait until its done referencing the task. 1603 */ 1604 while (p->on_cpu) 1605 cpu_relax(); 1606 /* 1607 * Pairs with the smp_wmb() in finish_lock_switch(). 1608 */ 1609 smp_rmb(); 1610 1611 p->sched_contributes_to_load = !!task_contributes_to_load(p); 1612 p->state = TASK_WAKING; 1613 1614 if (p->sched_class->task_waking) 1615 p->sched_class->task_waking(p); 1616 1617 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags); 1618 if (task_cpu(p) != cpu) { 1619 wake_flags |= WF_MIGRATED; 1620 set_task_cpu(p, cpu); 1621 } 1622#endif /* CONFIG_SMP */ 1623 1624 ttwu_queue(p, cpu); 1625stat: 1626 ttwu_stat(p, cpu, wake_flags); 1627out: 1628 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1629 1630 return success; 1631} 1632 1633/** 1634 * try_to_wake_up_local - try to wake up a local task with rq lock held 1635 * @p: the thread to be awakened 1636 * 1637 * Put @p on the run-queue if it's not already there. The caller must 1638 * ensure that this_rq() is locked, @p is bound to this_rq() and not 1639 * the current task. 1640 */ 1641static void try_to_wake_up_local(struct task_struct *p) 1642{ 1643 struct rq *rq = task_rq(p); 1644 1645 if (WARN_ON_ONCE(rq != this_rq()) || 1646 WARN_ON_ONCE(p == current)) 1647 return; 1648 1649 lockdep_assert_held(&rq->lock); 1650 1651 if (!raw_spin_trylock(&p->pi_lock)) { 1652 raw_spin_unlock(&rq->lock); 1653 raw_spin_lock(&p->pi_lock); 1654 raw_spin_lock(&rq->lock); 1655 } 1656 1657 if (!(p->state & TASK_NORMAL)) 1658 goto out; 1659 1660 if (!p->on_rq) 1661 ttwu_activate(rq, p, ENQUEUE_WAKEUP); 1662 1663 ttwu_do_wakeup(rq, p, 0); 1664 ttwu_stat(p, smp_processor_id(), 0); 1665out: 1666 raw_spin_unlock(&p->pi_lock); 1667} 1668 1669/** 1670 * wake_up_process - Wake up a specific process 1671 * @p: The process to be woken up. 1672 * 1673 * Attempt to wake up the nominated process and move it to the set of runnable 1674 * processes. 1675 * 1676 * Return: 1 if the process was woken up, 0 if it was already running. 1677 * 1678 * It may be assumed that this function implies a write memory barrier before 1679 * changing the task state if and only if any tasks are woken up. 1680 */ 1681int wake_up_process(struct task_struct *p) 1682{ 1683 WARN_ON(task_is_stopped_or_traced(p)); 1684 return try_to_wake_up(p, TASK_NORMAL, 0); 1685} 1686EXPORT_SYMBOL(wake_up_process); 1687 1688int wake_up_state(struct task_struct *p, unsigned int state) 1689{ 1690 return try_to_wake_up(p, state, 0); 1691} 1692 1693/* 1694 * Perform scheduler related setup for a newly forked process p. 1695 * p is forked by current. 1696 * 1697 * __sched_fork() is basic setup used by init_idle() too: 1698 */ 1699static void __sched_fork(struct task_struct *p) 1700{ 1701 p->on_rq = 0; 1702 1703 p->se.on_rq = 0; 1704 p->se.exec_start = 0; 1705 p->se.sum_exec_runtime = 0; 1706 p->se.prev_sum_exec_runtime = 0; 1707 p->se.nr_migrations = 0; 1708 p->se.vruntime = 0; 1709 INIT_LIST_HEAD(&p->se.group_node); 1710 1711#ifdef CONFIG_SCHEDSTATS 1712 memset(&p->se.statistics, 0, sizeof(p->se.statistics)); 1713#endif 1714 1715 INIT_LIST_HEAD(&p->rt.run_list); 1716 1717#ifdef CONFIG_PREEMPT_NOTIFIERS 1718 INIT_HLIST_HEAD(&p->preempt_notifiers); 1719#endif 1720 1721#ifdef CONFIG_NUMA_BALANCING 1722 if (p->mm && atomic_read(&p->mm->mm_users) == 1) { 1723 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay); 1724 p->mm->numa_next_reset = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset); 1725 p->mm->numa_scan_seq = 0; 1726 } 1727 1728 p->node_stamp = 0ULL; 1729 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0; 1730 p->numa_migrate_seq = 1; 1731 p->numa_scan_period = sysctl_numa_balancing_scan_delay; 1732 p->numa_preferred_nid = -1; 1733 p->numa_work.next = &p->numa_work; 1734 p->numa_faults = NULL; 1735 p->numa_faults_buffer = NULL; 1736 1737 INIT_LIST_HEAD(&p->numa_entry); 1738 p->numa_group = NULL; 1739#endif /* CONFIG_NUMA_BALANCING */ 1740} 1741 1742#ifdef CONFIG_NUMA_BALANCING 1743#ifdef CONFIG_SCHED_DEBUG 1744void set_numabalancing_state(bool enabled) 1745{ 1746 if (enabled) 1747 sched_feat_set("NUMA"); 1748 else 1749 sched_feat_set("NO_NUMA"); 1750} 1751#else 1752__read_mostly bool numabalancing_enabled; 1753 1754void set_numabalancing_state(bool enabled) 1755{ 1756 numabalancing_enabled = enabled; 1757} 1758#endif /* CONFIG_SCHED_DEBUG */ 1759#endif /* CONFIG_NUMA_BALANCING */ 1760 1761/* 1762 * fork()/clone()-time setup: 1763 */ 1764void sched_fork(struct task_struct *p) 1765{ 1766 unsigned long flags; 1767 int cpu = get_cpu(); 1768 1769 __sched_fork(p); 1770 /* 1771 * We mark the process as running here. This guarantees that 1772 * nobody will actually run it, and a signal or other external 1773 * event cannot wake it up and insert it on the runqueue either. 1774 */ 1775 p->state = TASK_RUNNING; 1776 1777 /* 1778 * Make sure we do not leak PI boosting priority to the child. 1779 */ 1780 p->prio = current->normal_prio; 1781 1782 /* 1783 * Revert to default priority/policy on fork if requested. 1784 */ 1785 if (unlikely(p->sched_reset_on_fork)) { 1786 if (task_has_rt_policy(p)) { 1787 p->policy = SCHED_NORMAL; 1788 p->static_prio = NICE_TO_PRIO(0); 1789 p->rt_priority = 0; 1790 } else if (PRIO_TO_NICE(p->static_prio) < 0) 1791 p->static_prio = NICE_TO_PRIO(0); 1792 1793 p->prio = p->normal_prio = __normal_prio(p); 1794 set_load_weight(p); 1795 1796 /* 1797 * We don't need the reset flag anymore after the fork. It has 1798 * fulfilled its duty: 1799 */ 1800 p->sched_reset_on_fork = 0; 1801 } 1802 1803 if (!rt_prio(p->prio)) 1804 p->sched_class = &fair_sched_class; 1805 1806 if (p->sched_class->task_fork) 1807 p->sched_class->task_fork(p); 1808 1809 /* 1810 * The child is not yet in the pid-hash so no cgroup attach races, 1811 * and the cgroup is pinned to this child due to cgroup_fork() 1812 * is ran before sched_fork(). 1813 * 1814 * Silence PROVE_RCU. 1815 */ 1816 raw_spin_lock_irqsave(&p->pi_lock, flags); 1817 set_task_cpu(p, cpu); 1818 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1819 1820#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) 1821 if (likely(sched_info_on())) 1822 memset(&p->sched_info, 0, sizeof(p->sched_info)); 1823#endif 1824#if defined(CONFIG_SMP) 1825 p->on_cpu = 0; 1826#endif 1827 init_task_preempt_count(p); 1828#ifdef CONFIG_SMP 1829 plist_node_init(&p->pushable_tasks, MAX_PRIO); 1830#endif 1831 1832 put_cpu(); 1833} 1834 1835/* 1836 * wake_up_new_task - wake up a newly created task for the first time. 1837 * 1838 * This function will do some initial scheduler statistics housekeeping 1839 * that must be done for every newly created context, then puts the task 1840 * on the runqueue and wakes it. 1841 */ 1842void wake_up_new_task(struct task_struct *p) 1843{ 1844 unsigned long flags; 1845 struct rq *rq; 1846 1847 raw_spin_lock_irqsave(&p->pi_lock, flags); 1848#ifdef CONFIG_SMP 1849 /* 1850 * Fork balancing, do it here and not earlier because: 1851 * - cpus_allowed can change in the fork path 1852 * - any previously selected cpu might disappear through hotplug 1853 */ 1854 set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); 1855#endif 1856 1857 /* Initialize new task's runnable average */ 1858 init_task_runnable_average(p); 1859 rq = __task_rq_lock(p); 1860 activate_task(rq, p, 0); 1861 p->on_rq = 1; 1862 trace_sched_wakeup_new(p, true); 1863 check_preempt_curr(rq, p, WF_FORK); 1864#ifdef CONFIG_SMP 1865 if (p->sched_class->task_woken) 1866 p->sched_class->task_woken(rq, p); 1867#endif 1868 task_rq_unlock(rq, p, &flags); 1869} 1870 1871#ifdef CONFIG_PREEMPT_NOTIFIERS 1872 1873/** 1874 * preempt_notifier_register - tell me when current is being preempted & rescheduled 1875 * @notifier: notifier struct to register 1876 */ 1877void preempt_notifier_register(struct preempt_notifier *notifier) 1878{ 1879 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); 1880} 1881EXPORT_SYMBOL_GPL(preempt_notifier_register); 1882 1883/** 1884 * preempt_notifier_unregister - no longer interested in preemption notifications 1885 * @notifier: notifier struct to unregister 1886 * 1887 * This is safe to call from within a preemption notifier. 1888 */ 1889void preempt_notifier_unregister(struct preempt_notifier *notifier) 1890{ 1891 hlist_del(¬ifier->link); 1892} 1893EXPORT_SYMBOL_GPL(preempt_notifier_unregister); 1894 1895static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1896{ 1897 struct preempt_notifier *notifier; 1898 1899 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) 1900 notifier->ops->sched_in(notifier, raw_smp_processor_id()); 1901} 1902 1903static void 1904fire_sched_out_preempt_notifiers(struct task_struct *curr, 1905 struct task_struct *next) 1906{ 1907 struct preempt_notifier *notifier; 1908 1909 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) 1910 notifier->ops->sched_out(notifier, next); 1911} 1912 1913#else /* !CONFIG_PREEMPT_NOTIFIERS */ 1914 1915static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1916{ 1917} 1918 1919static void 1920fire_sched_out_preempt_notifiers(struct task_struct *curr, 1921 struct task_struct *next) 1922{ 1923} 1924 1925#endif /* CONFIG_PREEMPT_NOTIFIERS */ 1926 1927/** 1928 * prepare_task_switch - prepare to switch tasks 1929 * @rq: the runqueue preparing to switch 1930 * @prev: the current task that is being switched out 1931 * @next: the task we are going to switch to. 1932 * 1933 * This is called with the rq lock held and interrupts off. It must 1934 * be paired with a subsequent finish_task_switch after the context 1935 * switch. 1936 * 1937 * prepare_task_switch sets up locking and calls architecture specific 1938 * hooks. 1939 */ 1940static inline void 1941prepare_task_switch(struct rq *rq, struct task_struct *prev, 1942 struct task_struct *next) 1943{ 1944 trace_sched_switch(prev, next); 1945 sched_info_switch(rq, prev, next); 1946 perf_event_task_sched_out(prev, next); 1947 fire_sched_out_preempt_notifiers(prev, next); 1948 prepare_lock_switch(rq, next); 1949 prepare_arch_switch(next); 1950} 1951 1952/** 1953 * finish_task_switch - clean up after a task-switch 1954 * @rq: runqueue associated with task-switch 1955 * @prev: the thread we just switched away from. 1956 * 1957 * finish_task_switch must be called after the context switch, paired 1958 * with a prepare_task_switch call before the context switch. 1959 * finish_task_switch will reconcile locking set up by prepare_task_switch, 1960 * and do any other architecture-specific cleanup actions. 1961 * 1962 * Note that we may have delayed dropping an mm in context_switch(). If 1963 * so, we finish that here outside of the runqueue lock. (Doing it 1964 * with the lock held can cause deadlocks; see schedule() for 1965 * details.) 1966 */ 1967static void finish_task_switch(struct rq *rq, struct task_struct *prev) 1968 __releases(rq->lock) 1969{ 1970 struct mm_struct *mm = rq->prev_mm; 1971 long prev_state; 1972 1973 rq->prev_mm = NULL; 1974 1975 /* 1976 * A task struct has one reference for the use as "current". 1977 * If a task dies, then it sets TASK_DEAD in tsk->state and calls 1978 * schedule one last time. The schedule call will never return, and 1979 * the scheduled task must drop that reference. 1980 * The test for TASK_DEAD must occur while the runqueue locks are 1981 * still held, otherwise prev could be scheduled on another cpu, die 1982 * there before we look at prev->state, and then the reference would 1983 * be dropped twice. 1984 * Manfred Spraul <manfred@colorfullife.com> 1985 */ 1986 prev_state = prev->state; 1987 vtime_task_switch(prev); 1988 finish_arch_switch(prev); 1989 perf_event_task_sched_in(prev, current); 1990 finish_lock_switch(rq, prev); 1991 finish_arch_post_lock_switch(); 1992 1993 fire_sched_in_preempt_notifiers(current); 1994 if (mm) 1995 mmdrop(mm); 1996 if (unlikely(prev_state == TASK_DEAD)) { 1997 task_numa_free(prev); 1998 1999 /* 2000 * Remove function-return probe instances associated with this 2001 * task and put them back on the free list. 2002 */ 2003 kprobe_flush_task(prev); 2004 put_task_struct(prev); 2005 } 2006 2007 tick_nohz_task_switch(current); 2008} 2009 2010#ifdef CONFIG_SMP 2011 2012/* assumes rq->lock is held */ 2013static inline void pre_schedule(struct rq *rq, struct task_struct *prev) 2014{ 2015 if (prev->sched_class->pre_schedule) 2016 prev->sched_class->pre_schedule(rq, prev); 2017} 2018 2019/* rq->lock is NOT held, but preemption is disabled */ 2020static inline void post_schedule(struct rq *rq) 2021{ 2022 if (rq->post_schedule) { 2023 unsigned long flags; 2024 2025 raw_spin_lock_irqsave(&rq->lock, flags); 2026 if (rq->curr->sched_class->post_schedule) 2027 rq->curr->sched_class->post_schedule(rq); 2028 raw_spin_unlock_irqrestore(&rq->lock, flags); 2029 2030 rq->post_schedule = 0; 2031 } 2032} 2033 2034#else 2035 2036static inline void pre_schedule(struct rq *rq, struct task_struct *p) 2037{ 2038} 2039 2040static inline void post_schedule(struct rq *rq) 2041{ 2042} 2043 2044#endif 2045 2046/** 2047 * schedule_tail - first thing a freshly forked thread must call. 2048 * @prev: the thread we just switched away from. 2049 */ 2050asmlinkage void schedule_tail(struct task_struct *prev) 2051 __releases(rq->lock) 2052{ 2053 struct rq *rq = this_rq(); 2054 2055 finish_task_switch(rq, prev); 2056 2057 /* 2058 * FIXME: do we need to worry about rq being invalidated by the 2059 * task_switch? 2060 */ 2061 post_schedule(rq); 2062 2063#ifdef __ARCH_WANT_UNLOCKED_CTXSW 2064 /* In this case, finish_task_switch does not reenable preemption */ 2065 preempt_enable(); 2066#endif 2067 if (current->set_child_tid) 2068 put_user(task_pid_vnr(current), current->set_child_tid); 2069} 2070 2071/* 2072 * context_switch - switch to the new MM and the new 2073 * thread's register state. 2074 */ 2075static inline void 2076context_switch(struct rq *rq, struct task_struct *prev, 2077 struct task_struct *next) 2078{ 2079 struct mm_struct *mm, *oldmm; 2080 2081 prepare_task_switch(rq, prev, next); 2082 2083 mm = next->mm; 2084 oldmm = prev->active_mm; 2085 /* 2086 * For paravirt, this is coupled with an exit in switch_to to 2087 * combine the page table reload and the switch backend into 2088 * one hypercall. 2089 */ 2090 arch_start_context_switch(prev); 2091 2092 if (!mm) { 2093 next->active_mm = oldmm; 2094 atomic_inc(&oldmm->mm_count); 2095 enter_lazy_tlb(oldmm, next); 2096 } else 2097 switch_mm(oldmm, mm, next); 2098 2099 if (!prev->mm) { 2100 prev->active_mm = NULL; 2101 rq->prev_mm = oldmm; 2102 } 2103 /* 2104 * Since the runqueue lock will be released by the next 2105 * task (which is an invalid locking op but in the case 2106 * of the scheduler it's an obvious special-case), so we 2107 * do an early lockdep release here: 2108 */ 2109#ifndef __ARCH_WANT_UNLOCKED_CTXSW 2110 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 2111#endif 2112 2113 context_tracking_task_switch(prev, next); 2114 /* Here we just switch the register state and the stack. */ 2115 switch_to(prev, next, prev); 2116 2117 barrier(); 2118 /* 2119 * this_rq must be evaluated again because prev may have moved 2120 * CPUs since it called schedule(), thus the 'rq' on its stack 2121 * frame will be invalid. 2122 */ 2123 finish_task_switch(this_rq(), prev); 2124} 2125 2126/* 2127 * nr_running and nr_context_switches: 2128 * 2129 * externally visible scheduler statistics: current number of runnable 2130 * threads, total number of context switches performed since bootup. 2131 */ 2132unsigned long nr_running(void) 2133{ 2134 unsigned long i, sum = 0; 2135 2136 for_each_online_cpu(i) 2137 sum += cpu_rq(i)->nr_running; 2138 2139 return sum; 2140} 2141 2142unsigned long long nr_context_switches(void) 2143{ 2144 int i; 2145 unsigned long long sum = 0; 2146 2147 for_each_possible_cpu(i) 2148 sum += cpu_rq(i)->nr_switches; 2149 2150 return sum; 2151} 2152 2153unsigned long nr_iowait(void) 2154{ 2155 unsigned long i, sum = 0; 2156 2157 for_each_possible_cpu(i) 2158 sum += atomic_read(&cpu_rq(i)->nr_iowait); 2159 2160 return sum; 2161} 2162 2163unsigned long nr_iowait_cpu(int cpu) 2164{ 2165 struct rq *this = cpu_rq(cpu); 2166 return atomic_read(&this->nr_iowait); 2167} 2168 2169#ifdef CONFIG_SMP 2170 2171/* 2172 * sched_exec - execve() is a valuable balancing opportunity, because at 2173 * this point the task has the smallest effective memory and cache footprint. 2174 */ 2175void sched_exec(void) 2176{ 2177 struct task_struct *p = current; 2178 unsigned long flags; 2179 int dest_cpu; 2180 2181 raw_spin_lock_irqsave(&p->pi_lock, flags); 2182 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0); 2183 if (dest_cpu == smp_processor_id()) 2184 goto unlock; 2185 2186 if (likely(cpu_active(dest_cpu))) { 2187 struct migration_arg arg = { p, dest_cpu }; 2188 2189 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2190 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); 2191 return; 2192 } 2193unlock: 2194 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2195} 2196 2197#endif 2198 2199DEFINE_PER_CPU(struct kernel_stat, kstat); 2200DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); 2201 2202EXPORT_PER_CPU_SYMBOL(kstat); 2203EXPORT_PER_CPU_SYMBOL(kernel_cpustat); 2204 2205/* 2206 * Return any ns on the sched_clock that have not yet been accounted in 2207 * @p in case that task is currently running. 2208 * 2209 * Called with task_rq_lock() held on @rq. 2210 */ 2211static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq) 2212{ 2213 u64 ns = 0; 2214 2215 if (task_current(rq, p)) { 2216 update_rq_clock(rq); 2217 ns = rq_clock_task(rq) - p->se.exec_start; 2218 if ((s64)ns < 0) 2219 ns = 0; 2220 } 2221 2222 return ns; 2223} 2224 2225unsigned long long task_delta_exec(struct task_struct *p) 2226{ 2227 unsigned long flags; 2228 struct rq *rq; 2229 u64 ns = 0; 2230 2231 rq = task_rq_lock(p, &flags); 2232 ns = do_task_delta_exec(p, rq); 2233 task_rq_unlock(rq, p, &flags); 2234 2235 return ns; 2236} 2237 2238/* 2239 * Return accounted runtime for the task. 2240 * In case the task is currently running, return the runtime plus current's 2241 * pending runtime that have not been accounted yet. 2242 */ 2243unsigned long long task_sched_runtime(struct task_struct *p) 2244{ 2245 unsigned long flags; 2246 struct rq *rq; 2247 u64 ns = 0; 2248 2249 rq = task_rq_lock(p, &flags); 2250 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq); 2251 task_rq_unlock(rq, p, &flags); 2252 2253 return ns; 2254} 2255 2256/* 2257 * This function gets called by the timer code, with HZ frequency. 2258 * We call it with interrupts disabled. 2259 */ 2260void scheduler_tick(void) 2261{ 2262 int cpu = smp_processor_id(); 2263 struct rq *rq = cpu_rq(cpu); 2264 struct task_struct *curr = rq->curr; 2265 2266 sched_clock_tick(); 2267 2268 raw_spin_lock(&rq->lock); 2269 update_rq_clock(rq); 2270 curr->sched_class->task_tick(rq, curr, 0); 2271 update_cpu_load_active(rq); 2272 raw_spin_unlock(&rq->lock); 2273 2274 perf_event_task_tick(); 2275 2276#ifdef CONFIG_SMP 2277 rq->idle_balance = idle_cpu(cpu); 2278 trigger_load_balance(rq, cpu); 2279#endif 2280 rq_last_tick_reset(rq); 2281} 2282 2283#ifdef CONFIG_NO_HZ_FULL 2284/** 2285 * scheduler_tick_max_deferment 2286 * 2287 * Keep at least one tick per second when a single 2288 * active task is running because the scheduler doesn't 2289 * yet completely support full dynticks environment. 2290 * 2291 * This makes sure that uptime, CFS vruntime, load 2292 * balancing, etc... continue to move forward, even 2293 * with a very low granularity. 2294 * 2295 * Return: Maximum deferment in nanoseconds. 2296 */ 2297u64 scheduler_tick_max_deferment(void) 2298{ 2299 struct rq *rq = this_rq(); 2300 unsigned long next, now = ACCESS_ONCE(jiffies); 2301 2302 next = rq->last_sched_tick + HZ; 2303 2304 if (time_before_eq(next, now)) 2305 return 0; 2306 2307 return jiffies_to_usecs(next - now) * NSEC_PER_USEC; 2308} 2309#endif 2310 2311notrace unsigned long get_parent_ip(unsigned long addr) 2312{ 2313 if (in_lock_functions(addr)) { 2314 addr = CALLER_ADDR2; 2315 if (in_lock_functions(addr)) 2316 addr = CALLER_ADDR3; 2317 } 2318 return addr; 2319} 2320 2321#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ 2322 defined(CONFIG_PREEMPT_TRACER)) 2323 2324void __kprobes preempt_count_add(int val) 2325{ 2326#ifdef CONFIG_DEBUG_PREEMPT 2327 /* 2328 * Underflow? 2329 */ 2330 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) 2331 return; 2332#endif 2333 __preempt_count_add(val); 2334#ifdef CONFIG_DEBUG_PREEMPT 2335 /* 2336 * Spinlock count overflowing soon? 2337 */ 2338 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= 2339 PREEMPT_MASK - 10); 2340#endif 2341 if (preempt_count() == val) 2342 trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 2343} 2344EXPORT_SYMBOL(preempt_count_add); 2345 2346void __kprobes preempt_count_sub(int val) 2347{ 2348#ifdef CONFIG_DEBUG_PREEMPT 2349 /* 2350 * Underflow? 2351 */ 2352 if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) 2353 return; 2354 /* 2355 * Is the spinlock portion underflowing? 2356 */ 2357 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && 2358 !(preempt_count() & PREEMPT_MASK))) 2359 return; 2360#endif 2361 2362 if (preempt_count() == val) 2363 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 2364 __preempt_count_sub(val); 2365} 2366EXPORT_SYMBOL(preempt_count_sub); 2367 2368#endif 2369 2370/* 2371 * Print scheduling while atomic bug: 2372 */ 2373static noinline void __schedule_bug(struct task_struct *prev) 2374{ 2375 if (oops_in_progress) 2376 return; 2377 2378 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", 2379 prev->comm, prev->pid, preempt_count()); 2380 2381 debug_show_held_locks(prev); 2382 print_modules(); 2383 if (irqs_disabled()) 2384 print_irqtrace_events(prev); 2385 dump_stack(); 2386 add_taint(TAINT_WARN, LOCKDEP_STILL_OK); 2387} 2388 2389/* 2390 * Various schedule()-time debugging checks and statistics: 2391 */ 2392static inline void schedule_debug(struct task_struct *prev) 2393{ 2394 /* 2395 * Test if we are atomic. Since do_exit() needs to call into 2396 * schedule() atomically, we ignore that path for now. 2397 * Otherwise, whine if we are scheduling when we should not be. 2398 */ 2399 if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) 2400 __schedule_bug(prev); 2401 rcu_sleep_check(); 2402 2403 profile_hit(SCHED_PROFILING, __builtin_return_address(0)); 2404 2405 schedstat_inc(this_rq(), sched_count); 2406} 2407 2408static void put_prev_task(struct rq *rq, struct task_struct *prev) 2409{ 2410 if (prev->on_rq || rq->skip_clock_update < 0) 2411 update_rq_clock(rq); 2412 prev->sched_class->put_prev_task(rq, prev); 2413} 2414 2415/* 2416 * Pick up the highest-prio task: 2417 */ 2418static inline struct task_struct * 2419pick_next_task(struct rq *rq) 2420{ 2421 const struct sched_class *class; 2422 struct task_struct *p; 2423 2424 /* 2425 * Optimization: we know that if all tasks are in 2426 * the fair class we can call that function directly: 2427 */ 2428 if (likely(rq->nr_running == rq->cfs.h_nr_running)) { 2429 p = fair_sched_class.pick_next_task(rq); 2430 if (likely(p)) 2431 return p; 2432 } 2433 2434 for_each_class(class) { 2435 p = class->pick_next_task(rq); 2436 if (p) 2437 return p; 2438 } 2439 2440 BUG(); /* the idle class will always have a runnable task */ 2441} 2442 2443/* 2444 * __schedule() is the main scheduler function. 2445 * 2446 * The main means of driving the scheduler and thus entering this function are: 2447 * 2448 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. 2449 * 2450 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return 2451 * paths. For example, see arch/x86/entry_64.S. 2452 * 2453 * To drive preemption between tasks, the scheduler sets the flag in timer 2454 * interrupt handler scheduler_tick(). 2455 * 2456 * 3. Wakeups don't really cause entry into schedule(). They add a 2457 * task to the run-queue and that's it. 2458 * 2459 * Now, if the new task added to the run-queue preempts the current 2460 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets 2461 * called on the nearest possible occasion: 2462 * 2463 * - If the kernel is preemptible (CONFIG_PREEMPT=y): 2464 * 2465 * - in syscall or exception context, at the next outmost 2466 * preempt_enable(). (this might be as soon as the wake_up()'s 2467 * spin_unlock()!) 2468 * 2469 * - in IRQ context, return from interrupt-handler to 2470 * preemptible context 2471 * 2472 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set) 2473 * then at the next: 2474 * 2475 * - cond_resched() call 2476 * - explicit schedule() call 2477 * - return from syscall or exception to user-space 2478 * - return from interrupt-handler to user-space 2479 */ 2480static void __sched __schedule(void) 2481{ 2482 struct task_struct *prev, *next; 2483 unsigned long *switch_count; 2484 struct rq *rq; 2485 int cpu; 2486 2487need_resched: 2488 preempt_disable(); 2489 cpu = smp_processor_id(); 2490 rq = cpu_rq(cpu); 2491 rcu_note_context_switch(cpu); 2492 prev = rq->curr; 2493 2494 schedule_debug(prev); 2495 2496 if (sched_feat(HRTICK)) 2497 hrtick_clear(rq); 2498 2499 /* 2500 * Make sure that signal_pending_state()->signal_pending() below 2501 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE) 2502 * done by the caller to avoid the race with signal_wake_up(). 2503 */ 2504 smp_mb__before_spinlock(); 2505 raw_spin_lock_irq(&rq->lock); 2506 2507 switch_count = &prev->nivcsw; 2508 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { 2509 if (unlikely(signal_pending_state(prev->state, prev))) { 2510 prev->state = TASK_RUNNING; 2511 } else { 2512 deactivate_task(rq, prev, DEQUEUE_SLEEP); 2513 prev->on_rq = 0; 2514 2515 /* 2516 * If a worker went to sleep, notify and ask workqueue 2517 * whether it wants to wake up a task to maintain 2518 * concurrency. 2519 */ 2520 if (prev->flags & PF_WQ_WORKER) { 2521 struct task_struct *to_wakeup; 2522 2523 to_wakeup = wq_worker_sleeping(prev, cpu); 2524 if (to_wakeup) 2525 try_to_wake_up_local(to_wakeup); 2526 } 2527 } 2528 switch_count = &prev->nvcsw; 2529 } 2530 2531 pre_schedule(rq, prev); 2532 2533 if (unlikely(!rq->nr_running)) 2534 idle_balance(cpu, rq); 2535 2536 put_prev_task(rq, prev); 2537 next = pick_next_task(rq); 2538 clear_tsk_need_resched(prev); 2539 clear_preempt_need_resched(); 2540 rq->skip_clock_update = 0; 2541 2542 if (likely(prev != next)) { 2543 rq->nr_switches++; 2544 rq->curr = next; 2545 ++*switch_count; 2546 2547 context_switch(rq, prev, next); /* unlocks the rq */ 2548 /* 2549 * The context switch have flipped the stack from under us 2550 * and restored the local variables which were saved when 2551 * this task called schedule() in the past. prev == current 2552 * is still correct, but it can be moved to another cpu/rq. 2553 */ 2554 cpu = smp_processor_id(); 2555 rq = cpu_rq(cpu); 2556 } else 2557 raw_spin_unlock_irq(&rq->lock); 2558 2559 post_schedule(rq); 2560 2561 sched_preempt_enable_no_resched(); 2562 if (need_resched()) 2563 goto need_resched; 2564} 2565 2566static inline void sched_submit_work(struct task_struct *tsk) 2567{ 2568 if (!tsk->state || tsk_is_pi_blocked(tsk)) 2569 return; 2570 /* 2571 * If we are going to sleep and we have plugged IO queued, 2572 * make sure to submit it to avoid deadlocks. 2573 */ 2574 if (blk_needs_flush_plug(tsk)) 2575 blk_schedule_flush_plug(tsk); 2576} 2577 2578asmlinkage void __sched schedule(void) 2579{ 2580 struct task_struct *tsk = current; 2581 2582 sched_submit_work(tsk); 2583 __schedule(); 2584} 2585EXPORT_SYMBOL(schedule); 2586 2587#ifdef CONFIG_CONTEXT_TRACKING 2588asmlinkage void __sched schedule_user(void) 2589{ 2590 /* 2591 * If we come here after a random call to set_need_resched(), 2592 * or we have been woken up remotely but the IPI has not yet arrived, 2593 * we haven't yet exited the RCU idle mode. Do it here manually until 2594 * we find a better solution. 2595 */ 2596 user_exit(); 2597 schedule(); 2598 user_enter(); 2599} 2600#endif 2601 2602/** 2603 * schedule_preempt_disabled - called with preemption disabled 2604 * 2605 * Returns with preemption disabled. Note: preempt_count must be 1 2606 */ 2607void __sched schedule_preempt_disabled(void) 2608{ 2609 sched_preempt_enable_no_resched(); 2610 schedule(); 2611 preempt_disable(); 2612} 2613 2614#ifdef CONFIG_PREEMPT 2615/* 2616 * this is the entry point to schedule() from in-kernel preemption 2617 * off of preempt_enable. Kernel preemptions off return from interrupt 2618 * occur there and call schedule directly. 2619 */ 2620asmlinkage void __sched notrace preempt_schedule(void) 2621{ 2622 /* 2623 * If there is a non-zero preempt_count or interrupts are disabled, 2624 * we do not want to preempt the current task. Just return.. 2625 */ 2626 if (likely(!preemptible())) 2627 return; 2628 2629 do { 2630 __preempt_count_add(PREEMPT_ACTIVE); 2631 __schedule(); 2632 __preempt_count_sub(PREEMPT_ACTIVE); 2633 2634 /* 2635 * Check again in case we missed a preemption opportunity 2636 * between schedule and now. 2637 */ 2638 barrier(); 2639 } while (need_resched()); 2640} 2641EXPORT_SYMBOL(preempt_schedule); 2642 2643/* 2644 * this is the entry point to schedule() from kernel preemption 2645 * off of irq context. 2646 * Note, that this is called and return with irqs disabled. This will 2647 * protect us against recursive calling from irq. 2648 */ 2649asmlinkage void __sched preempt_schedule_irq(void) 2650{ 2651 enum ctx_state prev_state; 2652 2653 /* Catch callers which need to be fixed */ 2654 BUG_ON(preempt_count() || !irqs_disabled()); 2655 2656 prev_state = exception_enter(); 2657 2658 do { 2659 __preempt_count_add(PREEMPT_ACTIVE); 2660 local_irq_enable(); 2661 __schedule(); 2662 local_irq_disable(); 2663 __preempt_count_sub(PREEMPT_ACTIVE); 2664 2665 /* 2666 * Check again in case we missed a preemption opportunity 2667 * between schedule and now. 2668 */ 2669 barrier(); 2670 } while (need_resched()); 2671 2672 exception_exit(prev_state); 2673} 2674 2675#endif /* CONFIG_PREEMPT */ 2676 2677int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags, 2678 void *key) 2679{ 2680 return try_to_wake_up(curr->private, mode, wake_flags); 2681} 2682EXPORT_SYMBOL(default_wake_function); 2683 2684/* 2685 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just 2686 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve 2687 * number) then we wake all the non-exclusive tasks and one exclusive task. 2688 * 2689 * There are circumstances in which we can try to wake a task which has already 2690 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns 2691 * zero in this (rare) case, and we handle it by continuing to scan the queue. 2692 */ 2693static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, 2694 int nr_exclusive, int wake_flags, void *key) 2695{ 2696 wait_queue_t *curr, *next; 2697 2698 list_for_each_entry_safe(curr, next, &q->task_list, task_list) { 2699 unsigned flags = curr->flags; 2700 2701 if (curr->func(curr, mode, wake_flags, key) && 2702 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) 2703 break; 2704 } 2705} 2706 2707/** 2708 * __wake_up - wake up threads blocked on a waitqueue. 2709 * @q: the waitqueue 2710 * @mode: which threads 2711 * @nr_exclusive: how many wake-one or wake-many threads to wake up 2712 * @key: is directly passed to the wakeup function 2713 * 2714 * It may be assumed that this function implies a write memory barrier before 2715 * changing the task state if and only if any tasks are woken up. 2716 */ 2717void __wake_up(wait_queue_head_t *q, unsigned int mode, 2718 int nr_exclusive, void *key) 2719{ 2720 unsigned long flags; 2721 2722 spin_lock_irqsave(&q->lock, flags); 2723 __wake_up_common(q, mode, nr_exclusive, 0, key); 2724 spin_unlock_irqrestore(&q->lock, flags); 2725} 2726EXPORT_SYMBOL(__wake_up); 2727 2728/* 2729 * Same as __wake_up but called with the spinlock in wait_queue_head_t held. 2730 */ 2731void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr) 2732{ 2733 __wake_up_common(q, mode, nr, 0, NULL); 2734} 2735EXPORT_SYMBOL_GPL(__wake_up_locked); 2736 2737void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key) 2738{ 2739 __wake_up_common(q, mode, 1, 0, key); 2740} 2741EXPORT_SYMBOL_GPL(__wake_up_locked_key); 2742 2743/** 2744 * __wake_up_sync_key - wake up threads blocked on a waitqueue. 2745 * @q: the waitqueue 2746 * @mode: which threads 2747 * @nr_exclusive: how many wake-one or wake-many threads to wake up 2748 * @key: opaque value to be passed to wakeup targets 2749 * 2750 * The sync wakeup differs that the waker knows that it will schedule 2751 * away soon, so while the target thread will be woken up, it will not 2752 * be migrated to another CPU - ie. the two threads are 'synchronized' 2753 * with each other. This can prevent needless bouncing between CPUs. 2754 * 2755 * On UP it can prevent extra preemption. 2756 * 2757 * It may be assumed that this function implies a write memory barrier before 2758 * changing the task state if and only if any tasks are woken up. 2759 */ 2760void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, 2761 int nr_exclusive, void *key) 2762{ 2763 unsigned long flags; 2764 int wake_flags = WF_SYNC; 2765 2766 if (unlikely(!q)) 2767 return; 2768 2769 if (unlikely(nr_exclusive != 1)) 2770 wake_flags = 0; 2771 2772 spin_lock_irqsave(&q->lock, flags); 2773 __wake_up_common(q, mode, nr_exclusive, wake_flags, key); 2774 spin_unlock_irqrestore(&q->lock, flags); 2775} 2776EXPORT_SYMBOL_GPL(__wake_up_sync_key); 2777 2778/* 2779 * __wake_up_sync - see __wake_up_sync_key() 2780 */ 2781void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive) 2782{ 2783 __wake_up_sync_key(q, mode, nr_exclusive, NULL); 2784} 2785EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */ 2786 2787/** 2788 * complete: - signals a single thread waiting on this completion 2789 * @x: holds the state of this particular completion 2790 * 2791 * This will wake up a single thread waiting on this completion. Threads will be 2792 * awakened in the same order in which they were queued. 2793 * 2794 * See also complete_all(), wait_for_completion() and related routines. 2795 * 2796 * It may be assumed that this function implies a write memory barrier before 2797 * changing the task state if and only if any tasks are woken up. 2798 */ 2799void complete(struct completion *x) 2800{ 2801 unsigned long flags; 2802 2803 spin_lock_irqsave(&x->wait.lock, flags); 2804 x->done++; 2805 __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL); 2806 spin_unlock_irqrestore(&x->wait.lock, flags); 2807} 2808EXPORT_SYMBOL(complete); 2809 2810/** 2811 * complete_all: - signals all threads waiting on this completion 2812 * @x: holds the state of this particular completion 2813 * 2814 * This will wake up all threads waiting on this particular completion event. 2815 * 2816 * It may be assumed that this function implies a write memory barrier before 2817 * changing the task state if and only if any tasks are woken up. 2818 */ 2819void complete_all(struct completion *x) 2820{ 2821 unsigned long flags; 2822 2823 spin_lock_irqsave(&x->wait.lock, flags); 2824 x->done += UINT_MAX/2; 2825 __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL); 2826 spin_unlock_irqrestore(&x->wait.lock, flags); 2827} 2828EXPORT_SYMBOL(complete_all); 2829 2830static inline long __sched 2831do_wait_for_common(struct completion *x, 2832 long (*action)(long), long timeout, int state) 2833{ 2834 if (!x->done) { 2835 DECLARE_WAITQUEUE(wait, current); 2836 2837 __add_wait_queue_tail_exclusive(&x->wait, &wait); 2838 do { 2839 if (signal_pending_state(state, current)) { 2840 timeout = -ERESTARTSYS; 2841 break; 2842 } 2843 __set_current_state(state); 2844 spin_unlock_irq(&x->wait.lock); 2845 timeout = action(timeout); 2846 spin_lock_irq(&x->wait.lock); 2847 } while (!x->done && timeout); 2848 __remove_wait_queue(&x->wait, &wait); 2849 if (!x->done) 2850 return timeout; 2851 } 2852 x->done--; 2853 return timeout ?: 1; 2854} 2855 2856static inline long __sched 2857__wait_for_common(struct completion *x, 2858 long (*action)(long), long timeout, int state) 2859{ 2860 might_sleep(); 2861 2862 spin_lock_irq(&x->wait.lock); 2863 timeout = do_wait_for_common(x, action, timeout, state); 2864 spin_unlock_irq(&x->wait.lock); 2865 return timeout; 2866} 2867 2868static long __sched 2869wait_for_common(struct completion *x, long timeout, int state) 2870{ 2871 return __wait_for_common(x, schedule_timeout, timeout, state); 2872} 2873 2874static long __sched 2875wait_for_common_io(struct completion *x, long timeout, int state) 2876{ 2877 return __wait_for_common(x, io_schedule_timeout, timeout, state); 2878} 2879 2880/** 2881 * wait_for_completion: - waits for completion of a task 2882 * @x: holds the state of this particular completion 2883 * 2884 * This waits to be signaled for completion of a specific task. It is NOT 2885 * interruptible and there is no timeout. 2886 * 2887 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout 2888 * and interrupt capability. Also see complete(). 2889 */ 2890void __sched wait_for_completion(struct completion *x) 2891{ 2892 wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); 2893} 2894EXPORT_SYMBOL(wait_for_completion); 2895 2896/** 2897 * wait_for_completion_timeout: - waits for completion of a task (w/timeout) 2898 * @x: holds the state of this particular completion 2899 * @timeout: timeout value in jiffies 2900 * 2901 * This waits for either a completion of a specific task to be signaled or for a 2902 * specified timeout to expire. The timeout is in jiffies. It is not 2903 * interruptible. 2904 * 2905 * Return: 0 if timed out, and positive (at least 1, or number of jiffies left 2906 * till timeout) if completed. 2907 */ 2908unsigned long __sched 2909wait_for_completion_timeout(struct completion *x, unsigned long timeout) 2910{ 2911 return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE); 2912} 2913EXPORT_SYMBOL(wait_for_completion_timeout); 2914 2915/** 2916 * wait_for_completion_io: - waits for completion of a task 2917 * @x: holds the state of this particular completion 2918 * 2919 * This waits to be signaled for completion of a specific task. It is NOT 2920 * interruptible and there is no timeout. The caller is accounted as waiting 2921 * for IO. 2922 */ 2923void __sched wait_for_completion_io(struct completion *x) 2924{ 2925 wait_for_common_io(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); 2926} 2927EXPORT_SYMBOL(wait_for_completion_io); 2928 2929/** 2930 * wait_for_completion_io_timeout: - waits for completion of a task (w/timeout) 2931 * @x: holds the state of this particular completion 2932 * @timeout: timeout value in jiffies 2933 * 2934 * This waits for either a completion of a specific task to be signaled or for a 2935 * specified timeout to expire. The timeout is in jiffies. It is not 2936 * interruptible. The caller is accounted as waiting for IO. 2937 * 2938 * Return: 0 if timed out, and positive (at least 1, or number of jiffies left 2939 * till timeout) if completed. 2940 */ 2941unsigned long __sched 2942wait_for_completion_io_timeout(struct completion *x, unsigned long timeout) 2943{ 2944 return wait_for_common_io(x, timeout, TASK_UNINTERRUPTIBLE); 2945} 2946EXPORT_SYMBOL(wait_for_completion_io_timeout); 2947 2948/** 2949 * wait_for_completion_interruptible: - waits for completion of a task (w/intr) 2950 * @x: holds the state of this particular completion 2951 * 2952 * This waits for completion of a specific task to be signaled. It is 2953 * interruptible. 2954 * 2955 * Return: -ERESTARTSYS if interrupted, 0 if completed. 2956 */ 2957int __sched wait_for_completion_interruptible(struct completion *x) 2958{ 2959 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE); 2960 if (t == -ERESTARTSYS) 2961 return t; 2962 return 0; 2963} 2964EXPORT_SYMBOL(wait_for_completion_interruptible); 2965 2966/** 2967 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr)) 2968 * @x: holds the state of this particular completion 2969 * @timeout: timeout value in jiffies 2970 * 2971 * This waits for either a completion of a specific task to be signaled or for a 2972 * specified timeout to expire. It is interruptible. The timeout is in jiffies. 2973 * 2974 * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1, 2975 * or number of jiffies left till timeout) if completed. 2976 */ 2977long __sched 2978wait_for_completion_interruptible_timeout(struct completion *x, 2979 unsigned long timeout) 2980{ 2981 return wait_for_common(x, timeout, TASK_INTERRUPTIBLE); 2982} 2983EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); 2984 2985/** 2986 * wait_for_completion_killable: - waits for completion of a task (killable) 2987 * @x: holds the state of this particular completion 2988 * 2989 * This waits to be signaled for completion of a specific task. It can be 2990 * interrupted by a kill signal. 2991 * 2992 * Return: -ERESTARTSYS if interrupted, 0 if completed. 2993 */ 2994int __sched wait_for_completion_killable(struct completion *x) 2995{ 2996 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE); 2997 if (t == -ERESTARTSYS) 2998 return t; 2999 return 0; 3000} 3001EXPORT_SYMBOL(wait_for_completion_killable); 3002 3003/** 3004 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable)) 3005 * @x: holds the state of this particular completion 3006 * @timeout: timeout value in jiffies 3007 * 3008 * This waits for either a completion of a specific task to be 3009 * signaled or for a specified timeout to expire. It can be 3010 * interrupted by a kill signal. The timeout is in jiffies. 3011 * 3012 * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1, 3013 * or number of jiffies left till timeout) if completed. 3014 */ 3015long __sched 3016wait_for_completion_killable_timeout(struct completion *x, 3017 unsigned long timeout) 3018{ 3019 return wait_for_common(x, timeout, TASK_KILLABLE); 3020} 3021EXPORT_SYMBOL(wait_for_completion_killable_timeout); 3022 3023/** 3024 * try_wait_for_completion - try to decrement a completion without blocking 3025 * @x: completion structure 3026 * 3027 * Return: 0 if a decrement cannot be done without blocking 3028 * 1 if a decrement succeeded. 3029 * 3030 * If a completion is being used as a counting completion, 3031 * attempt to decrement the counter without blocking. This 3032 * enables us to avoid waiting if the resource the completion 3033 * is protecting is not available. 3034 */ 3035bool try_wait_for_completion(struct completion *x) 3036{ 3037 unsigned long flags; 3038 int ret = 1; 3039 3040 spin_lock_irqsave(&x->wait.lock, flags); 3041 if (!x->done) 3042 ret = 0; 3043 else 3044 x->done--; 3045 spin_unlock_irqrestore(&x->wait.lock, flags); 3046 return ret; 3047} 3048EXPORT_SYMBOL(try_wait_for_completion); 3049 3050/** 3051 * completion_done - Test to see if a completion has any waiters 3052 * @x: completion structure 3053 * 3054 * Return: 0 if there are waiters (wait_for_completion() in progress) 3055 * 1 if there are no waiters. 3056 * 3057 */ 3058bool completion_done(struct completion *x) 3059{ 3060 unsigned long flags; 3061 int ret = 1; 3062 3063 spin_lock_irqsave(&x->wait.lock, flags); 3064 if (!x->done) 3065 ret = 0; 3066 spin_unlock_irqrestore(&x->wait.lock, flags); 3067 return ret; 3068} 3069EXPORT_SYMBOL(completion_done); 3070 3071static long __sched 3072sleep_on_common(wait_queue_head_t *q, int state, long timeout) 3073{ 3074 unsigned long flags; 3075 wait_queue_t wait; 3076 3077 init_waitqueue_entry(&wait, current); 3078 3079 __set_current_state(state); 3080 3081 spin_lock_irqsave(&q->lock, flags); 3082 __add_wait_queue(q, &wait); 3083 spin_unlock(&q->lock); 3084 timeout = schedule_timeout(timeout); 3085 spin_lock_irq(&q->lock); 3086 __remove_wait_queue(q, &wait); 3087 spin_unlock_irqrestore(&q->lock, flags); 3088 3089 return timeout; 3090} 3091 3092void __sched interruptible_sleep_on(wait_queue_head_t *q) 3093{ 3094 sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 3095} 3096EXPORT_SYMBOL(interruptible_sleep_on); 3097 3098long __sched 3099interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout) 3100{ 3101 return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout); 3102} 3103EXPORT_SYMBOL(interruptible_sleep_on_timeout); 3104 3105void __sched sleep_on(wait_queue_head_t *q) 3106{ 3107 sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 3108} 3109EXPORT_SYMBOL(sleep_on); 3110 3111long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout) 3112{ 3113 return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout); 3114} 3115EXPORT_SYMBOL(sleep_on_timeout); 3116 3117#ifdef CONFIG_RT_MUTEXES 3118 3119/* 3120 * rt_mutex_setprio - set the current priority of a task 3121 * @p: task 3122 * @prio: prio value (kernel-internal form) 3123 * 3124 * This function changes the 'effective' priority of a task. It does 3125 * not touch ->normal_prio like __setscheduler(). 3126 * 3127 * Used by the rt_mutex code to implement priority inheritance logic. 3128 */ 3129void rt_mutex_setprio(struct task_struct *p, int prio) 3130{ 3131 int oldprio, on_rq, running; 3132 struct rq *rq; 3133 const struct sched_class *prev_class; 3134 3135 BUG_ON(prio < 0 || prio > MAX_PRIO); 3136 3137 rq = __task_rq_lock(p); 3138 3139 /* 3140 * Idle task boosting is a nono in general. There is one 3141 * exception, when PREEMPT_RT and NOHZ is active: 3142 * 3143 * The idle task calls get_next_timer_interrupt() and holds 3144 * the timer wheel base->lock on the CPU and another CPU wants 3145 * to access the timer (probably to cancel it). We can safely 3146 * ignore the boosting request, as the idle CPU runs this code 3147 * with interrupts disabled and will complete the lock 3148 * protected section without being interrupted. So there is no 3149 * real need to boost. 3150 */ 3151 if (unlikely(p == rq->idle)) { 3152 WARN_ON(p != rq->curr); 3153 WARN_ON(p->pi_blocked_on); 3154 goto out_unlock; 3155 } 3156 3157 trace_sched_pi_setprio(p, prio); 3158 oldprio = p->prio; 3159 prev_class = p->sched_class; 3160 on_rq = p->on_rq; 3161 running = task_current(rq, p); 3162 if (on_rq) 3163 dequeue_task(rq, p, 0); 3164 if (running) 3165 p->sched_class->put_prev_task(rq, p); 3166 3167 if (rt_prio(prio)) 3168 p->sched_class = &rt_sched_class; 3169 else 3170 p->sched_class = &fair_sched_class; 3171 3172 p->prio = prio; 3173 3174 if (running) 3175 p->sched_class->set_curr_task(rq); 3176 if (on_rq) 3177 enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0); 3178 3179 check_class_changed(rq, p, prev_class, oldprio); 3180out_unlock: 3181 __task_rq_unlock(rq); 3182} 3183#endif 3184void set_user_nice(struct task_struct *p, long nice) 3185{ 3186 int old_prio, delta, on_rq; 3187 unsigned long flags; 3188 struct rq *rq; 3189 3190 if (TASK_NICE(p) == nice || nice < -20 || nice > 19) 3191 return; 3192 /* 3193 * We have to be careful, if called from sys_setpriority(), 3194 * the task might be in the middle of scheduling on another CPU. 3195 */ 3196 rq = task_rq_lock(p, &flags); 3197 /* 3198 * The RT priorities are set via sched_setscheduler(), but we still 3199 * allow the 'normal' nice value to be set - but as expected 3200 * it wont have any effect on scheduling until the task is 3201 * SCHED_FIFO/SCHED_RR: 3202 */ 3203 if (task_has_rt_policy(p)) { 3204 p->static_prio = NICE_TO_PRIO(nice); 3205 goto out_unlock; 3206 } 3207 on_rq = p->on_rq; 3208 if (on_rq) 3209 dequeue_task(rq, p, 0); 3210 3211 p->static_prio = NICE_TO_PRIO(nice); 3212 set_load_weight(p); 3213 old_prio = p->prio; 3214 p->prio = effective_prio(p); 3215 delta = p->prio - old_prio; 3216 3217 if (on_rq) { 3218 enqueue_task(rq, p, 0); 3219 /* 3220 * If the task increased its priority or is running and 3221 * lowered its priority, then reschedule its CPU: 3222 */ 3223 if (delta < 0 || (delta > 0 && task_running(rq, p))) 3224 resched_task(rq->curr); 3225 } 3226out_unlock: 3227 task_rq_unlock(rq, p, &flags); 3228} 3229EXPORT_SYMBOL(set_user_nice); 3230 3231/* 3232 * can_nice - check if a task can reduce its nice value 3233 * @p: task 3234 * @nice: nice value 3235 */ 3236int can_nice(const struct task_struct *p, const int nice) 3237{ 3238 /* convert nice value [19,-20] to rlimit style value [1,40] */ 3239 int nice_rlim = 20 - nice; 3240 3241 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || 3242 capable(CAP_SYS_NICE)); 3243} 3244 3245#ifdef __ARCH_WANT_SYS_NICE 3246 3247/* 3248 * sys_nice - change the priority of the current process. 3249 * @increment: priority increment 3250 * 3251 * sys_setpriority is a more generic, but much slower function that 3252 * does similar things. 3253 */ 3254SYSCALL_DEFINE1(nice, int, increment) 3255{ 3256 long nice, retval; 3257 3258 /* 3259 * Setpriority might change our priority at the same moment. 3260 * We don't have to worry. Conceptually one call occurs first 3261 * and we have a single winner. 3262 */ 3263 if (increment < -40) 3264 increment = -40; 3265 if (increment > 40) 3266 increment = 40; 3267 3268 nice = TASK_NICE(current) + increment; 3269 if (nice < -20) 3270 nice = -20; 3271 if (nice > 19) 3272 nice = 19; 3273 3274 if (increment < 0 && !can_nice(current, nice)) 3275 return -EPERM; 3276 3277 retval = security_task_setnice(current, nice); 3278 if (retval) 3279 return retval; 3280 3281 set_user_nice(current, nice); 3282 return 0; 3283} 3284 3285#endif 3286 3287/** 3288 * task_prio - return the priority value of a given task. 3289 * @p: the task in question. 3290 * 3291 * Return: The priority value as seen by users in /proc. 3292 * RT tasks are offset by -200. Normal tasks are centered 3293 * around 0, value goes from -16 to +15. 3294 */ 3295int task_prio(const struct task_struct *p) 3296{ 3297 return p->prio - MAX_RT_PRIO; 3298} 3299 3300/** 3301 * task_nice - return the nice value of a given task. 3302 * @p: the task in question. 3303 * 3304 * Return: The nice value [ -20 ... 0 ... 19 ]. 3305 */ 3306int task_nice(const struct task_struct *p) 3307{ 3308 return TASK_NICE(p); 3309} 3310EXPORT_SYMBOL(task_nice); 3311 3312/** 3313 * idle_cpu - is a given cpu idle currently? 3314 * @cpu: the processor in question. 3315 * 3316 * Return: 1 if the CPU is currently idle. 0 otherwise. 3317 */ 3318int idle_cpu(int cpu) 3319{ 3320 struct rq *rq = cpu_rq(cpu); 3321 3322 if (rq->curr != rq->idle) 3323 return 0; 3324 3325 if (rq->nr_running) 3326 return 0; 3327 3328#ifdef CONFIG_SMP 3329 if (!llist_empty(&rq->wake_list)) 3330 return 0; 3331#endif 3332 3333 return 1; 3334} 3335 3336/** 3337 * idle_task - return the idle task for a given cpu. 3338 * @cpu: the processor in question. 3339 * 3340 * Return: The idle task for the cpu @cpu. 3341 */ 3342struct task_struct *idle_task(int cpu) 3343{ 3344 return cpu_rq(cpu)->idle; 3345} 3346 3347/** 3348 * find_process_by_pid - find a process with a matching PID value. 3349 * @pid: the pid in question. 3350 * 3351 * The task of @pid, if found. %NULL otherwise. 3352 */ 3353static struct task_struct *find_process_by_pid(pid_t pid) 3354{ 3355 return pid ? find_task_by_vpid(pid) : current; 3356} 3357 3358/* Actually do priority change: must hold rq lock. */ 3359static void 3360__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio) 3361{ 3362 p->policy = policy; 3363 p->rt_priority = prio; 3364 p->normal_prio = normal_prio(p); 3365 /* we are holding p->pi_lock already */ 3366 p->prio = rt_mutex_getprio(p); 3367 if (rt_prio(p->prio)) 3368 p->sched_class = &rt_sched_class; 3369 else 3370 p->sched_class = &fair_sched_class; 3371 set_load_weight(p); 3372} 3373 3374/* 3375 * check the target process has a UID that matches the current process's 3376 */ 3377static bool check_same_owner(struct task_struct *p) 3378{ 3379 const struct cred *cred = current_cred(), *pcred; 3380 bool match; 3381 3382 rcu_read_lock(); 3383 pcred = __task_cred(p); 3384 match = (uid_eq(cred->euid, pcred->euid) || 3385 uid_eq(cred->euid, pcred->uid)); 3386 rcu_read_unlock(); 3387 return match; 3388} 3389 3390static int __sched_setscheduler(struct task_struct *p, int policy, 3391 const struct sched_param *param, bool user) 3392{ 3393 int retval, oldprio, oldpolicy = -1, on_rq, running; 3394 unsigned long flags; 3395 const struct sched_class *prev_class; 3396 struct rq *rq; 3397 int reset_on_fork; 3398 3399 /* may grab non-irq protected spin_locks */ 3400 BUG_ON(in_interrupt()); 3401recheck: 3402 /* double check policy once rq lock held */ 3403 if (policy < 0) { 3404 reset_on_fork = p->sched_reset_on_fork; 3405 policy = oldpolicy = p->policy; 3406 } else { 3407 reset_on_fork = !!(policy & SCHED_RESET_ON_FORK); 3408 policy &= ~SCHED_RESET_ON_FORK; 3409 3410 if (policy != SCHED_FIFO && policy != SCHED_RR && 3411 policy != SCHED_NORMAL && policy != SCHED_BATCH && 3412 policy != SCHED_IDLE) 3413 return -EINVAL; 3414 } 3415 3416 /* 3417 * Valid priorities for SCHED_FIFO and SCHED_RR are 3418 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, 3419 * SCHED_BATCH and SCHED_IDLE is 0. 3420 */ 3421 if (param->sched_priority < 0 || 3422 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) || 3423 (!p->mm && param->sched_priority > MAX_RT_PRIO-1)) 3424 return -EINVAL; 3425 if (rt_policy(policy) != (param->sched_priority != 0)) 3426 return -EINVAL; 3427 3428 /* 3429 * Allow unprivileged RT tasks to decrease priority: 3430 */ 3431 if (user && !capable(CAP_SYS_NICE)) { 3432 if (rt_policy(policy)) { 3433 unsigned long rlim_rtprio = 3434 task_rlimit(p, RLIMIT_RTPRIO); 3435 3436 /* can't set/change the rt policy */ 3437 if (policy != p->policy && !rlim_rtprio) 3438 return -EPERM; 3439 3440 /* can't increase priority */ 3441 if (param->sched_priority > p->rt_priority && 3442 param->sched_priority > rlim_rtprio) 3443 return -EPERM; 3444 } 3445 3446 /* 3447 * Treat SCHED_IDLE as nice 20. Only allow a switch to 3448 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. 3449 */ 3450 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) { 3451 if (!can_nice(p, TASK_NICE(p))) 3452 return -EPERM; 3453 } 3454 3455 /* can't change other user's priorities */ 3456 if (!check_same_owner(p)) 3457 return -EPERM; 3458 3459 /* Normal users shall not reset the sched_reset_on_fork flag */ 3460 if (p->sched_reset_on_fork && !reset_on_fork) 3461 return -EPERM; 3462 } 3463 3464 if (user) { 3465 retval = security_task_setscheduler(p); 3466 if (retval) 3467 return retval; 3468 } 3469 3470 /* 3471 * make sure no PI-waiters arrive (or leave) while we are 3472 * changing the priority of the task: 3473 * 3474 * To be able to change p->policy safely, the appropriate 3475 * runqueue lock must be held. 3476 */ 3477 rq = task_rq_lock(p, &flags); 3478 3479 /* 3480 * Changing the policy of the stop threads its a very bad idea 3481 */ 3482 if (p == rq->stop) { 3483 task_rq_unlock(rq, p, &flags); 3484 return -EINVAL; 3485 } 3486 3487 /* 3488 * If not changing anything there's no need to proceed further: 3489 */ 3490 if (unlikely(policy == p->policy && (!rt_policy(policy) || 3491 param->sched_priority == p->rt_priority))) { 3492 task_rq_unlock(rq, p, &flags); 3493 return 0; 3494 } 3495 3496#ifdef CONFIG_RT_GROUP_SCHED 3497 if (user) { 3498 /* 3499 * Do not allow realtime tasks into groups that have no runtime 3500 * assigned. 3501 */ 3502 if (rt_bandwidth_enabled() && rt_policy(policy) && 3503 task_group(p)->rt_bandwidth.rt_runtime == 0 && 3504 !task_group_is_autogroup(task_group(p))) { 3505 task_rq_unlock(rq, p, &flags); 3506 return -EPERM; 3507 } 3508 } 3509#endif 3510 3511 /* recheck policy now with rq lock held */ 3512 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { 3513 policy = oldpolicy = -1; 3514 task_rq_unlock(rq, p, &flags); 3515 goto recheck; 3516 } 3517 on_rq = p->on_rq; 3518 running = task_current(rq, p); 3519 if (on_rq) 3520 dequeue_task(rq, p, 0); 3521 if (running) 3522 p->sched_class->put_prev_task(rq, p); 3523 3524 p->sched_reset_on_fork = reset_on_fork; 3525 3526 oldprio = p->prio; 3527 prev_class = p->sched_class; 3528 __setscheduler(rq, p, policy, param->sched_priority); 3529 3530 if (running) 3531 p->sched_class->set_curr_task(rq); 3532 if (on_rq) 3533 enqueue_task(rq, p, 0); 3534 3535 check_class_changed(rq, p, prev_class, oldprio); 3536 task_rq_unlock(rq, p, &flags); 3537 3538 rt_mutex_adjust_pi(p); 3539 3540 return 0; 3541} 3542 3543/** 3544 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. 3545 * @p: the task in question. 3546 * @policy: new policy. 3547 * @param: structure containing the new RT priority. 3548 * 3549 * Return: 0 on success. An error code otherwise. 3550 * 3551 * NOTE that the task may be already dead. 3552 */ 3553int sched_setscheduler(struct task_struct *p, int policy, 3554 const struct sched_param *param) 3555{ 3556 return __sched_setscheduler(p, policy, param, true); 3557} 3558EXPORT_SYMBOL_GPL(sched_setscheduler); 3559 3560/** 3561 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. 3562 * @p: the task in question. 3563 * @policy: new policy. 3564 * @param: structure containing the new RT priority. 3565 * 3566 * Just like sched_setscheduler, only don't bother checking if the 3567 * current context has permission. For example, this is needed in 3568 * stop_machine(): we create temporary high priority worker threads, 3569 * but our caller might not have that capability. 3570 * 3571 * Return: 0 on success. An error code otherwise. 3572 */ 3573int sched_setscheduler_nocheck(struct task_struct *p, int policy, 3574 const struct sched_param *param) 3575{ 3576 return __sched_setscheduler(p, policy, param, false); 3577} 3578 3579static int 3580do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) 3581{ 3582 struct sched_param lparam; 3583 struct task_struct *p; 3584 int retval; 3585 3586 if (!param || pid < 0) 3587 return -EINVAL; 3588 if (copy_from_user(&lparam, param, sizeof(struct sched_param))) 3589 return -EFAULT; 3590 3591 rcu_read_lock(); 3592 retval = -ESRCH; 3593 p = find_process_by_pid(pid); 3594 if (p != NULL) 3595 retval = sched_setscheduler(p, policy, &lparam); 3596 rcu_read_unlock(); 3597 3598 return retval; 3599} 3600 3601/** 3602 * sys_sched_setscheduler - set/change the scheduler policy and RT priority 3603 * @pid: the pid in question. 3604 * @policy: new policy. 3605 * @param: structure containing the new RT priority. 3606 * 3607 * Return: 0 on success. An error code otherwise. 3608 */ 3609SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, 3610 struct sched_param __user *, param) 3611{ 3612 /* negative values for policy are not valid */ 3613 if (policy < 0) 3614 return -EINVAL; 3615 3616 return do_sched_setscheduler(pid, policy, param); 3617} 3618 3619/** 3620 * sys_sched_setparam - set/change the RT priority of a thread 3621 * @pid: the pid in question. 3622 * @param: structure containing the new RT priority. 3623 * 3624 * Return: 0 on success. An error code otherwise. 3625 */ 3626SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) 3627{ 3628 return do_sched_setscheduler(pid, -1, param); 3629} 3630 3631/** 3632 * sys_sched_getscheduler - get the policy (scheduling class) of a thread 3633 * @pid: the pid in question. 3634 * 3635 * Return: On success, the policy of the thread. Otherwise, a negative error 3636 * code. 3637 */ 3638SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) 3639{ 3640 struct task_struct *p; 3641 int retval; 3642 3643 if (pid < 0) 3644 return -EINVAL; 3645 3646 retval = -ESRCH; 3647 rcu_read_lock(); 3648 p = find_process_by_pid(pid); 3649 if (p) { 3650 retval = security_task_getscheduler(p); 3651 if (!retval) 3652 retval = p->policy 3653 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); 3654 } 3655 rcu_read_unlock(); 3656 return retval; 3657} 3658 3659/** 3660 * sys_sched_getparam - get the RT priority of a thread 3661 * @pid: the pid in question. 3662 * @param: structure containing the RT priority. 3663 * 3664 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error 3665 * code. 3666 */ 3667SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) 3668{ 3669 struct sched_param lp; 3670 struct task_struct *p; 3671 int retval; 3672 3673 if (!param || pid < 0) 3674 return -EINVAL; 3675 3676 rcu_read_lock(); 3677 p = find_process_by_pid(pid); 3678 retval = -ESRCH; 3679 if (!p) 3680 goto out_unlock; 3681 3682 retval = security_task_getscheduler(p); 3683 if (retval) 3684 goto out_unlock; 3685 3686 lp.sched_priority = p->rt_priority; 3687 rcu_read_unlock(); 3688 3689 /* 3690 * This one might sleep, we cannot do it with a spinlock held ... 3691 */ 3692 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; 3693 3694 return retval; 3695 3696out_unlock: 3697 rcu_read_unlock(); 3698 return retval; 3699} 3700 3701long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) 3702{ 3703 cpumask_var_t cpus_allowed, new_mask; 3704 struct task_struct *p; 3705 int retval; 3706 3707 get_online_cpus(); 3708 rcu_read_lock(); 3709 3710 p = find_process_by_pid(pid); 3711 if (!p) { 3712 rcu_read_unlock(); 3713 put_online_cpus(); 3714 return -ESRCH; 3715 } 3716 3717 /* Prevent p going away */ 3718 get_task_struct(p); 3719 rcu_read_unlock(); 3720 3721 if (p->flags & PF_NO_SETAFFINITY) { 3722 retval = -EINVAL; 3723 goto out_put_task; 3724 } 3725 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { 3726 retval = -ENOMEM; 3727 goto out_put_task; 3728 } 3729 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { 3730 retval = -ENOMEM; 3731 goto out_free_cpus_allowed; 3732 } 3733 retval = -EPERM; 3734 if (!check_same_owner(p)) { 3735 rcu_read_lock(); 3736 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { 3737 rcu_read_unlock(); 3738 goto out_unlock; 3739 } 3740 rcu_read_unlock(); 3741 } 3742 3743 retval = security_task_setscheduler(p); 3744 if (retval) 3745 goto out_unlock; 3746 3747 cpuset_cpus_allowed(p, cpus_allowed); 3748 cpumask_and(new_mask, in_mask, cpus_allowed); 3749again: 3750 retval = set_cpus_allowed_ptr(p, new_mask); 3751 3752 if (!retval) { 3753 cpuset_cpus_allowed(p, cpus_allowed); 3754 if (!cpumask_subset(new_mask, cpus_allowed)) { 3755 /* 3756 * We must have raced with a concurrent cpuset 3757 * update. Just reset the cpus_allowed to the 3758 * cpuset's cpus_allowed 3759 */ 3760 cpumask_copy(new_mask, cpus_allowed); 3761 goto again; 3762 } 3763 } 3764out_unlock: 3765 free_cpumask_var(new_mask); 3766out_free_cpus_allowed: 3767 free_cpumask_var(cpus_allowed); 3768out_put_task: 3769 put_task_struct(p); 3770 put_online_cpus(); 3771 return retval; 3772} 3773 3774static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, 3775 struct cpumask *new_mask) 3776{ 3777 if (len < cpumask_size()) 3778 cpumask_clear(new_mask); 3779 else if (len > cpumask_size()) 3780 len = cpumask_size(); 3781 3782 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; 3783} 3784 3785/** 3786 * sys_sched_setaffinity - set the cpu affinity of a process 3787 * @pid: pid of the process 3788 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 3789 * @user_mask_ptr: user-space pointer to the new cpu mask 3790 * 3791 * Return: 0 on success. An error code otherwise. 3792 */ 3793SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, 3794 unsigned long __user *, user_mask_ptr) 3795{ 3796 cpumask_var_t new_mask; 3797 int retval; 3798 3799 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) 3800 return -ENOMEM; 3801 3802 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); 3803 if (retval == 0) 3804 retval = sched_setaffinity(pid, new_mask); 3805 free_cpumask_var(new_mask); 3806 return retval; 3807} 3808 3809long sched_getaffinity(pid_t pid, struct cpumask *mask) 3810{ 3811 struct task_struct *p; 3812 unsigned long flags; 3813 int retval; 3814 3815 get_online_cpus(); 3816 rcu_read_lock(); 3817 3818 retval = -ESRCH; 3819 p = find_process_by_pid(pid); 3820 if (!p) 3821 goto out_unlock; 3822 3823 retval = security_task_getscheduler(p); 3824 if (retval) 3825 goto out_unlock; 3826 3827 raw_spin_lock_irqsave(&p->pi_lock, flags); 3828 cpumask_and(mask, &p->cpus_allowed, cpu_online_mask); 3829 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 3830 3831out_unlock: 3832 rcu_read_unlock(); 3833 put_online_cpus(); 3834 3835 return retval; 3836} 3837 3838/** 3839 * sys_sched_getaffinity - get the cpu affinity of a process 3840 * @pid: pid of the process 3841 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 3842 * @user_mask_ptr: user-space pointer to hold the current cpu mask 3843 * 3844 * Return: 0 on success. An error code otherwise. 3845 */ 3846SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, 3847 unsigned long __user *, user_mask_ptr) 3848{ 3849 int ret; 3850 cpumask_var_t mask; 3851 3852 if ((len * BITS_PER_BYTE) < nr_cpu_ids) 3853 return -EINVAL; 3854 if (len & (sizeof(unsigned long)-1)) 3855 return -EINVAL; 3856 3857 if (!alloc_cpumask_var(&mask, GFP_KERNEL)) 3858 return -ENOMEM; 3859 3860 ret = sched_getaffinity(pid, mask); 3861 if (ret == 0) { 3862 size_t retlen = min_t(size_t, len, cpumask_size()); 3863 3864 if (copy_to_user(user_mask_ptr, mask, retlen)) 3865 ret = -EFAULT; 3866 else 3867 ret = retlen; 3868 } 3869 free_cpumask_var(mask); 3870 3871 return ret; 3872} 3873 3874/** 3875 * sys_sched_yield - yield the current processor to other threads. 3876 * 3877 * This function yields the current CPU to other tasks. If there are no 3878 * other threads running on this CPU then this function will return. 3879 * 3880 * Return: 0. 3881 */ 3882SYSCALL_DEFINE0(sched_yield) 3883{ 3884 struct rq *rq = this_rq_lock(); 3885 3886 schedstat_inc(rq, yld_count); 3887 current->sched_class->yield_task(rq); 3888 3889 /* 3890 * Since we are going to call schedule() anyway, there's 3891 * no need to preempt or enable interrupts: 3892 */ 3893 __release(rq->lock); 3894 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 3895 do_raw_spin_unlock(&rq->lock); 3896 sched_preempt_enable_no_resched(); 3897 3898 schedule(); 3899 3900 return 0; 3901} 3902 3903static void __cond_resched(void) 3904{ 3905 __preempt_count_add(PREEMPT_ACTIVE); 3906 __schedule(); 3907 __preempt_count_sub(PREEMPT_ACTIVE); 3908} 3909 3910int __sched _cond_resched(void) 3911{ 3912 if (should_resched()) { 3913 __cond_resched(); 3914 return 1; 3915 } 3916 return 0; 3917} 3918EXPORT_SYMBOL(_cond_resched); 3919 3920/* 3921 * __cond_resched_lock() - if a reschedule is pending, drop the given lock, 3922 * call schedule, and on return reacquire the lock. 3923 * 3924 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level 3925 * operations here to prevent schedule() from being called twice (once via 3926 * spin_unlock(), once by hand). 3927 */ 3928int __cond_resched_lock(spinlock_t *lock) 3929{ 3930 int resched = should_resched(); 3931 int ret = 0; 3932 3933 lockdep_assert_held(lock); 3934 3935 if (spin_needbreak(lock) || resched) { 3936 spin_unlock(lock); 3937 if (resched) 3938 __cond_resched(); 3939 else 3940 cpu_relax(); 3941 ret = 1; 3942 spin_lock(lock); 3943 } 3944 return ret; 3945} 3946EXPORT_SYMBOL(__cond_resched_lock); 3947 3948int __sched __cond_resched_softirq(void) 3949{ 3950 BUG_ON(!in_softirq()); 3951 3952 if (should_resched()) { 3953 local_bh_enable(); 3954 __cond_resched(); 3955 local_bh_disable(); 3956 return 1; 3957 } 3958 return 0; 3959} 3960EXPORT_SYMBOL(__cond_resched_softirq); 3961 3962/** 3963 * yield - yield the current processor to other threads. 3964 * 3965 * Do not ever use this function, there's a 99% chance you're doing it wrong. 3966 * 3967 * The scheduler is at all times free to pick the calling task as the most 3968 * eligible task to run, if removing the yield() call from your code breaks 3969 * it, its already broken. 3970 * 3971 * Typical broken usage is: 3972 * 3973 * while (!event) 3974 * yield(); 3975 * 3976 * where one assumes that yield() will let 'the other' process run that will 3977 * make event true. If the current task is a SCHED_FIFO task that will never 3978 * happen. Never use yield() as a progress guarantee!! 3979 * 3980 * If you want to use yield() to wait for something, use wait_event(). 3981 * If you want to use yield() to be 'nice' for others, use cond_resched(). 3982 * If you still want to use yield(), do not! 3983 */ 3984void __sched yield(void) 3985{ 3986 set_current_state(TASK_RUNNING); 3987 sys_sched_yield(); 3988} 3989EXPORT_SYMBOL(yield); 3990 3991/** 3992 * yield_to - yield the current processor to another thread in 3993 * your thread group, or accelerate that thread toward the 3994 * processor it's on. 3995 * @p: target task 3996 * @preempt: whether task preemption is allowed or not 3997 * 3998 * It's the caller's job to ensure that the target task struct 3999 * can't go away on us before we can do any checks. 4000 * 4001 * Return: 4002 * true (>0) if we indeed boosted the target task. 4003 * false (0) if we failed to boost the target. 4004 * -ESRCH if there's no task to yield to. 4005 */ 4006bool __sched yield_to(struct task_struct *p, bool preempt) 4007{ 4008 struct task_struct *curr = current; 4009 struct rq *rq, *p_rq; 4010 unsigned long flags; 4011 int yielded = 0; 4012 4013 local_irq_save(flags); 4014 rq = this_rq(); 4015 4016again: 4017 p_rq = task_rq(p); 4018 /* 4019 * If we're the only runnable task on the rq and target rq also 4020 * has only one task, there's absolutely no point in yielding. 4021 */ 4022 if (rq->nr_running == 1 && p_rq->nr_running == 1) { 4023 yielded = -ESRCH; 4024 goto out_irq; 4025 } 4026 4027 double_rq_lock(rq, p_rq); 4028 while (task_rq(p) != p_rq) { 4029 double_rq_unlock(rq, p_rq); 4030 goto again; 4031 } 4032 4033 if (!curr->sched_class->yield_to_task) 4034 goto out_unlock; 4035 4036 if (curr->sched_class != p->sched_class) 4037 goto out_unlock; 4038 4039 if (task_running(p_rq, p) || p->state) 4040 goto out_unlock; 4041 4042 yielded = curr->sched_class->yield_to_task(rq, p, preempt); 4043 if (yielded) { 4044 schedstat_inc(rq, yld_count); 4045 /* 4046 * Make p's CPU reschedule; pick_next_entity takes care of 4047 * fairness. 4048 */ 4049 if (preempt && rq != p_rq) 4050 resched_task(p_rq->curr); 4051 } 4052 4053out_unlock: 4054 double_rq_unlock(rq, p_rq); 4055out_irq: 4056 local_irq_restore(flags); 4057 4058 if (yielded > 0) 4059 schedule(); 4060 4061 return yielded; 4062} 4063EXPORT_SYMBOL_GPL(yield_to); 4064 4065/* 4066 * This task is about to go to sleep on IO. Increment rq->nr_iowait so 4067 * that process accounting knows that this is a task in IO wait state. 4068 */ 4069void __sched io_schedule(void) 4070{ 4071 struct rq *rq = raw_rq(); 4072 4073 delayacct_blkio_start(); 4074 atomic_inc(&rq->nr_iowait); 4075 blk_flush_plug(current); 4076 current->in_iowait = 1; 4077 schedule(); 4078 current->in_iowait = 0; 4079 atomic_dec(&rq->nr_iowait); 4080 delayacct_blkio_end(); 4081} 4082EXPORT_SYMBOL(io_schedule); 4083 4084long __sched io_schedule_timeout(long timeout) 4085{ 4086 struct rq *rq = raw_rq(); 4087 long ret; 4088 4089 delayacct_blkio_start(); 4090 atomic_inc(&rq->nr_iowait); 4091 blk_flush_plug(current); 4092 current->in_iowait = 1; 4093 ret = schedule_timeout(timeout); 4094 current->in_iowait = 0; 4095 atomic_dec(&rq->nr_iowait); 4096 delayacct_blkio_end(); 4097 return ret; 4098} 4099 4100/** 4101 * sys_sched_get_priority_max - return maximum RT priority. 4102 * @policy: scheduling class. 4103 * 4104 * Return: On success, this syscall returns the maximum 4105 * rt_priority that can be used by a given scheduling class. 4106 * On failure, a negative error code is returned. 4107 */ 4108SYSCALL_DEFINE1(sched_get_priority_max, int, policy) 4109{ 4110 int ret = -EINVAL; 4111 4112 switch (policy) { 4113 case SCHED_FIFO: 4114 case SCHED_RR: 4115 ret = MAX_USER_RT_PRIO-1; 4116 break; 4117 case SCHED_NORMAL: 4118 case SCHED_BATCH: 4119 case SCHED_IDLE: 4120 ret = 0; 4121 break; 4122 } 4123 return ret; 4124} 4125 4126/** 4127 * sys_sched_get_priority_min - return minimum RT priority. 4128 * @policy: scheduling class. 4129 * 4130 * Return: On success, this syscall returns the minimum 4131 * rt_priority that can be used by a given scheduling class. 4132 * On failure, a negative error code is returned. 4133 */ 4134SYSCALL_DEFINE1(sched_get_priority_min, int, policy) 4135{ 4136 int ret = -EINVAL; 4137 4138 switch (policy) { 4139 case SCHED_FIFO: 4140 case SCHED_RR: 4141 ret = 1; 4142 break; 4143 case SCHED_NORMAL: 4144 case SCHED_BATCH: 4145 case SCHED_IDLE: 4146 ret = 0; 4147 } 4148 return ret; 4149} 4150 4151/** 4152 * sys_sched_rr_get_interval - return the default timeslice of a process. 4153 * @pid: pid of the process. 4154 * @interval: userspace pointer to the timeslice value. 4155 * 4156 * this syscall writes the default timeslice value of a given process 4157 * into the user-space timespec buffer. A value of '0' means infinity. 4158 * 4159 * Return: On success, 0 and the timeslice is in @interval. Otherwise, 4160 * an error code. 4161 */ 4162SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, 4163 struct timespec __user *, interval) 4164{ 4165 struct task_struct *p; 4166 unsigned int time_slice; 4167 unsigned long flags; 4168 struct rq *rq; 4169 int retval; 4170 struct timespec t; 4171 4172 if (pid < 0) 4173 return -EINVAL; 4174 4175 retval = -ESRCH; 4176 rcu_read_lock(); 4177 p = find_process_by_pid(pid); 4178 if (!p) 4179 goto out_unlock; 4180 4181 retval = security_task_getscheduler(p); 4182 if (retval) 4183 goto out_unlock; 4184 4185 rq = task_rq_lock(p, &flags); 4186 time_slice = p->sched_class->get_rr_interval(rq, p); 4187 task_rq_unlock(rq, p, &flags); 4188 4189 rcu_read_unlock(); 4190 jiffies_to_timespec(time_slice, &t); 4191 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; 4192 return retval; 4193 4194out_unlock: 4195 rcu_read_unlock(); 4196 return retval; 4197} 4198 4199static const char stat_nam[] = TASK_STATE_TO_CHAR_STR; 4200 4201void sched_show_task(struct task_struct *p) 4202{ 4203 unsigned long free = 0; 4204 int ppid; 4205 unsigned state; 4206 4207 state = p->state ? __ffs(p->state) + 1 : 0; 4208 printk(KERN_INFO "%-15.15s %c", p->comm, 4209 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); 4210#if BITS_PER_LONG == 32 4211 if (state == TASK_RUNNING) 4212 printk(KERN_CONT " running "); 4213 else 4214 printk(KERN_CONT " %08lx ", thread_saved_pc(p)); 4215#else 4216 if (state == TASK_RUNNING) 4217 printk(KERN_CONT " running task "); 4218 else 4219 printk(KERN_CONT " %016lx ", thread_saved_pc(p)); 4220#endif 4221#ifdef CONFIG_DEBUG_STACK_USAGE 4222 free = stack_not_used(p); 4223#endif 4224 rcu_read_lock(); 4225 ppid = task_pid_nr(rcu_dereference(p->real_parent)); 4226 rcu_read_unlock(); 4227 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, 4228 task_pid_nr(p), ppid, 4229 (unsigned long)task_thread_info(p)->flags); 4230 4231 print_worker_info(KERN_INFO, p); 4232 show_stack(p, NULL); 4233} 4234 4235void show_state_filter(unsigned long state_filter) 4236{ 4237 struct task_struct *g, *p; 4238 4239#if BITS_PER_LONG == 32 4240 printk(KERN_INFO 4241 " task PC stack pid father\n"); 4242#else 4243 printk(KERN_INFO 4244 " task PC stack pid father\n"); 4245#endif 4246 rcu_read_lock(); 4247 do_each_thread(g, p) { 4248 /* 4249 * reset the NMI-timeout, listing all files on a slow 4250 * console might take a lot of time: 4251 */ 4252 touch_nmi_watchdog(); 4253 if (!state_filter || (p->state & state_filter)) 4254 sched_show_task(p); 4255 } while_each_thread(g, p); 4256 4257 touch_all_softlockup_watchdogs(); 4258 4259#ifdef CONFIG_SCHED_DEBUG 4260 sysrq_sched_debug_show(); 4261#endif 4262 rcu_read_unlock(); 4263 /* 4264 * Only show locks if all tasks are dumped: 4265 */ 4266 if (!state_filter) 4267 debug_show_all_locks(); 4268} 4269 4270void init_idle_bootup_task(struct task_struct *idle) 4271{ 4272 idle->sched_class = &idle_sched_class; 4273} 4274 4275/** 4276 * init_idle - set up an idle thread for a given CPU 4277 * @idle: task in question 4278 * @cpu: cpu the idle task belongs to 4279 * 4280 * NOTE: this function does not set the idle thread's NEED_RESCHED 4281 * flag, to make booting more robust. 4282 */ 4283void init_idle(struct task_struct *idle, int cpu) 4284{ 4285 struct rq *rq = cpu_rq(cpu); 4286 unsigned long flags; 4287 4288 raw_spin_lock_irqsave(&rq->lock, flags); 4289 4290 __sched_fork(idle); 4291 idle->state = TASK_RUNNING; 4292 idle->se.exec_start = sched_clock(); 4293 4294 do_set_cpus_allowed(idle, cpumask_of(cpu)); 4295 /* 4296 * We're having a chicken and egg problem, even though we are 4297 * holding rq->lock, the cpu isn't yet set to this cpu so the 4298 * lockdep check in task_group() will fail. 4299 * 4300 * Similar case to sched_fork(). / Alternatively we could 4301 * use task_rq_lock() here and obtain the other rq->lock. 4302 * 4303 * Silence PROVE_RCU 4304 */ 4305 rcu_read_lock(); 4306 __set_task_cpu(idle, cpu); 4307 rcu_read_unlock(); 4308 4309 rq->curr = rq->idle = idle; 4310#if defined(CONFIG_SMP) 4311 idle->on_cpu = 1; 4312#endif 4313 raw_spin_unlock_irqrestore(&rq->lock, flags); 4314 4315 /* Set the preempt count _outside_ the spinlocks! */ 4316 init_idle_preempt_count(idle, cpu); 4317 4318 /* 4319 * The idle tasks have their own, simple scheduling class: 4320 */ 4321 idle->sched_class = &idle_sched_class; 4322 ftrace_graph_init_idle_task(idle, cpu); 4323 vtime_init_idle(idle, cpu); 4324#if defined(CONFIG_SMP) 4325 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); 4326#endif 4327} 4328 4329#ifdef CONFIG_SMP 4330void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) 4331{ 4332 if (p->sched_class && p->sched_class->set_cpus_allowed) 4333 p->sched_class->set_cpus_allowed(p, new_mask); 4334 4335 cpumask_copy(&p->cpus_allowed, new_mask); 4336 p->nr_cpus_allowed = cpumask_weight(new_mask); 4337} 4338 4339/* 4340 * This is how migration works: 4341 * 4342 * 1) we invoke migration_cpu_stop() on the target CPU using 4343 * stop_one_cpu(). 4344 * 2) stopper starts to run (implicitly forcing the migrated thread 4345 * off the CPU) 4346 * 3) it checks whether the migrated task is still in the wrong runqueue. 4347 * 4) if it's in the wrong runqueue then the migration thread removes 4348 * it and puts it into the right queue. 4349 * 5) stopper completes and stop_one_cpu() returns and the migration 4350 * is done. 4351 */ 4352 4353/* 4354 * Change a given task's CPU affinity. Migrate the thread to a 4355 * proper CPU and schedule it away if the CPU it's executing on 4356 * is removed from the allowed bitmask. 4357 * 4358 * NOTE: the caller must have a valid reference to the task, the 4359 * task must not exit() & deallocate itself prematurely. The 4360 * call is not atomic; no spinlocks may be held. 4361 */ 4362int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) 4363{ 4364 unsigned long flags; 4365 struct rq *rq; 4366 unsigned int dest_cpu; 4367 int ret = 0; 4368 4369 rq = task_rq_lock(p, &flags); 4370 4371 if (cpumask_equal(&p->cpus_allowed, new_mask)) 4372 goto out; 4373 4374 if (!cpumask_intersects(new_mask, cpu_active_mask)) { 4375 ret = -EINVAL; 4376 goto out; 4377 } 4378 4379 do_set_cpus_allowed(p, new_mask); 4380 4381 /* Can the task run on the task's current CPU? If so, we're done */ 4382 if (cpumask_test_cpu(task_cpu(p), new_mask)) 4383 goto out; 4384 4385 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); 4386 if (p->on_rq) { 4387 struct migration_arg arg = { p, dest_cpu }; 4388 /* Need help from migration thread: drop lock and wait. */ 4389 task_rq_unlock(rq, p, &flags); 4390 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); 4391 tlb_migrate_finish(p->mm); 4392 return 0; 4393 } 4394out: 4395 task_rq_unlock(rq, p, &flags); 4396 4397 return ret; 4398} 4399EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); 4400 4401/* 4402 * Move (not current) task off this cpu, onto dest cpu. We're doing 4403 * this because either it can't run here any more (set_cpus_allowed() 4404 * away from this CPU, or CPU going down), or because we're 4405 * attempting to rebalance this task on exec (sched_exec). 4406 * 4407 * So we race with normal scheduler movements, but that's OK, as long 4408 * as the task is no longer on this CPU. 4409 * 4410 * Returns non-zero if task was successfully migrated. 4411 */ 4412static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) 4413{ 4414 struct rq *rq_dest, *rq_src; 4415 int ret = 0; 4416 4417 if (unlikely(!cpu_active(dest_cpu))) 4418 return ret; 4419 4420 rq_src = cpu_rq(src_cpu); 4421 rq_dest = cpu_rq(dest_cpu); 4422 4423 raw_spin_lock(&p->pi_lock); 4424 double_rq_lock(rq_src, rq_dest); 4425 /* Already moved. */ 4426 if (task_cpu(p) != src_cpu) 4427 goto done; 4428 /* Affinity changed (again). */ 4429 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 4430 goto fail; 4431 4432 /* 4433 * If we're not on a rq, the next wake-up will ensure we're 4434 * placed properly. 4435 */ 4436 if (p->on_rq) { 4437 dequeue_task(rq_src, p, 0); 4438 set_task_cpu(p, dest_cpu); 4439 enqueue_task(rq_dest, p, 0); 4440 check_preempt_curr(rq_dest, p, 0); 4441 } 4442done: 4443 ret = 1; 4444fail: 4445 double_rq_unlock(rq_src, rq_dest); 4446 raw_spin_unlock(&p->pi_lock); 4447 return ret; 4448} 4449 4450#ifdef CONFIG_NUMA_BALANCING 4451/* Migrate current task p to target_cpu */ 4452int migrate_task_to(struct task_struct *p, int target_cpu) 4453{ 4454 struct migration_arg arg = { p, target_cpu }; 4455 int curr_cpu = task_cpu(p); 4456 4457 if (curr_cpu == target_cpu) 4458 return 0; 4459 4460 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p))) 4461 return -EINVAL; 4462 4463 /* TODO: This is not properly updating schedstats */ 4464 4465 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg); 4466} 4467#endif 4468 4469/* 4470 * migration_cpu_stop - this will be executed by a highprio stopper thread 4471 * and performs thread migration by bumping thread off CPU then 4472 * 'pushing' onto another runqueue. 4473 */ 4474static int migration_cpu_stop(void *data) 4475{ 4476 struct migration_arg *arg = data; 4477 4478 /* 4479 * The original target cpu might have gone down and we might 4480 * be on another cpu but it doesn't matter. 4481 */ 4482 local_irq_disable(); 4483 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu); 4484 local_irq_enable(); 4485 return 0; 4486} 4487 4488#ifdef CONFIG_HOTPLUG_CPU 4489 4490/* 4491 * Ensures that the idle task is using init_mm right before its cpu goes 4492 * offline. 4493 */ 4494void idle_task_exit(void) 4495{ 4496 struct mm_struct *mm = current->active_mm; 4497 4498 BUG_ON(cpu_online(smp_processor_id())); 4499 4500 if (mm != &init_mm) 4501 switch_mm(mm, &init_mm, current); 4502 mmdrop(mm); 4503} 4504 4505/* 4506 * Since this CPU is going 'away' for a while, fold any nr_active delta 4507 * we might have. Assumes we're called after migrate_tasks() so that the 4508 * nr_active count is stable. 4509 * 4510 * Also see the comment "Global load-average calculations". 4511 */ 4512static void calc_load_migrate(struct rq *rq) 4513{ 4514 long delta = calc_load_fold_active(rq); 4515 if (delta) 4516 atomic_long_add(delta, &calc_load_tasks); 4517} 4518 4519/* 4520 * Migrate all tasks from the rq, sleeping tasks will be migrated by 4521 * try_to_wake_up()->select_task_rq(). 4522 * 4523 * Called with rq->lock held even though we'er in stop_machine() and 4524 * there's no concurrency possible, we hold the required locks anyway 4525 * because of lock validation efforts. 4526 */ 4527static void migrate_tasks(unsigned int dead_cpu) 4528{ 4529 struct rq *rq = cpu_rq(dead_cpu); 4530 struct task_struct *next, *stop = rq->stop; 4531 int dest_cpu; 4532 4533 /* 4534 * Fudge the rq selection such that the below task selection loop 4535 * doesn't get stuck on the currently eligible stop task. 4536 * 4537 * We're currently inside stop_machine() and the rq is either stuck 4538 * in the stop_machine_cpu_stop() loop, or we're executing this code, 4539 * either way we should never end up calling schedule() until we're 4540 * done here. 4541 */ 4542 rq->stop = NULL; 4543 4544 /* 4545 * put_prev_task() and pick_next_task() sched 4546 * class method both need to have an up-to-date 4547 * value of rq->clock[_task] 4548 */ 4549 update_rq_clock(rq); 4550 4551 for ( ; ; ) { 4552 /* 4553 * There's this thread running, bail when that's the only 4554 * remaining thread. 4555 */ 4556 if (rq->nr_running == 1) 4557 break; 4558 4559 next = pick_next_task(rq); 4560 BUG_ON(!next); 4561 next->sched_class->put_prev_task(rq, next); 4562 4563 /* Find suitable destination for @next, with force if needed. */ 4564 dest_cpu = select_fallback_rq(dead_cpu, next); 4565 raw_spin_unlock(&rq->lock); 4566 4567 __migrate_task(next, dead_cpu, dest_cpu); 4568 4569 raw_spin_lock(&rq->lock); 4570 } 4571 4572 rq->stop = stop; 4573} 4574 4575#endif /* CONFIG_HOTPLUG_CPU */ 4576 4577#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) 4578 4579static struct ctl_table sd_ctl_dir[] = { 4580 { 4581 .procname = "sched_domain", 4582 .mode = 0555, 4583 }, 4584 {} 4585}; 4586 4587static struct ctl_table sd_ctl_root[] = { 4588 { 4589 .procname = "kernel", 4590 .mode = 0555, 4591 .child = sd_ctl_dir, 4592 }, 4593 {} 4594}; 4595 4596static struct ctl_table *sd_alloc_ctl_entry(int n) 4597{ 4598 struct ctl_table *entry = 4599 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL); 4600 4601 return entry; 4602} 4603 4604static void sd_free_ctl_entry(struct ctl_table **tablep) 4605{ 4606 struct ctl_table *entry; 4607 4608 /* 4609 * In the intermediate directories, both the child directory and 4610 * procname are dynamically allocated and could fail but the mode 4611 * will always be set. In the lowest directory the names are 4612 * static strings and all have proc handlers. 4613 */ 4614 for (entry = *tablep; entry->mode; entry++) { 4615 if (entry->child) 4616 sd_free_ctl_entry(&entry->child); 4617 if (entry->proc_handler == NULL) 4618 kfree(entry->procname); 4619 } 4620 4621 kfree(*tablep); 4622 *tablep = NULL; 4623} 4624 4625static int min_load_idx = 0; 4626static int max_load_idx = CPU_LOAD_IDX_MAX-1; 4627 4628static void 4629set_table_entry(struct ctl_table *entry, 4630 const char *procname, void *data, int maxlen, 4631 umode_t mode, proc_handler *proc_handler, 4632 bool load_idx) 4633{ 4634 entry->procname = procname; 4635 entry->data = data; 4636 entry->maxlen = maxlen; 4637 entry->mode = mode; 4638 entry->proc_handler = proc_handler; 4639 4640 if (load_idx) { 4641 entry->extra1 = &min_load_idx; 4642 entry->extra2 = &max_load_idx; 4643 } 4644} 4645 4646static struct ctl_table * 4647sd_alloc_ctl_domain_table(struct sched_domain *sd) 4648{ 4649 struct ctl_table *table = sd_alloc_ctl_entry(13); 4650 4651 if (table == NULL) 4652 return NULL; 4653 4654 set_table_entry(&table[0], "min_interval", &sd->min_interval, 4655 sizeof(long), 0644, proc_doulongvec_minmax, false); 4656 set_table_entry(&table[1], "max_interval", &sd->max_interval, 4657 sizeof(long), 0644, proc_doulongvec_minmax, false); 4658 set_table_entry(&table[2], "busy_idx", &sd->busy_idx, 4659 sizeof(int), 0644, proc_dointvec_minmax, true); 4660 set_table_entry(&table[3], "idle_idx", &sd->idle_idx, 4661 sizeof(int), 0644, proc_dointvec_minmax, true); 4662 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx, 4663 sizeof(int), 0644, proc_dointvec_minmax, true); 4664 set_table_entry(&table[5], "wake_idx", &sd->wake_idx, 4665 sizeof(int), 0644, proc_dointvec_minmax, true); 4666 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx, 4667 sizeof(int), 0644, proc_dointvec_minmax, true); 4668 set_table_entry(&table[7], "busy_factor", &sd->busy_factor, 4669 sizeof(int), 0644, proc_dointvec_minmax, false); 4670 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct, 4671 sizeof(int), 0644, proc_dointvec_minmax, false); 4672 set_table_entry(&table[9], "cache_nice_tries", 4673 &sd->cache_nice_tries, 4674 sizeof(int), 0644, proc_dointvec_minmax, false); 4675 set_table_entry(&table[10], "flags", &sd->flags, 4676 sizeof(int), 0644, proc_dointvec_minmax, false); 4677 set_table_entry(&table[11], "name", sd->name, 4678 CORENAME_MAX_SIZE, 0444, proc_dostring, false); 4679 /* &table[12] is terminator */ 4680 4681 return table; 4682} 4683 4684static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu) 4685{ 4686 struct ctl_table *entry, *table; 4687 struct sched_domain *sd; 4688 int domain_num = 0, i; 4689 char buf[32]; 4690 4691 for_each_domain(cpu, sd) 4692 domain_num++; 4693 entry = table = sd_alloc_ctl_entry(domain_num + 1); 4694 if (table == NULL) 4695 return NULL; 4696 4697 i = 0; 4698 for_each_domain(cpu, sd) { 4699 snprintf(buf, 32, "domain%d", i); 4700 entry->procname = kstrdup(buf, GFP_KERNEL); 4701 entry->mode = 0555; 4702 entry->child = sd_alloc_ctl_domain_table(sd); 4703 entry++; 4704 i++; 4705 } 4706 return table; 4707} 4708 4709static struct ctl_table_header *sd_sysctl_header; 4710static void register_sched_domain_sysctl(void) 4711{ 4712 int i, cpu_num = num_possible_cpus(); 4713 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1); 4714 char buf[32]; 4715 4716 WARN_ON(sd_ctl_dir[0].child); 4717 sd_ctl_dir[0].child = entry; 4718 4719 if (entry == NULL) 4720 return; 4721 4722 for_each_possible_cpu(i) { 4723 snprintf(buf, 32, "cpu%d", i); 4724 entry->procname = kstrdup(buf, GFP_KERNEL); 4725 entry->mode = 0555; 4726 entry->child = sd_alloc_ctl_cpu_table(i); 4727 entry++; 4728 } 4729 4730 WARN_ON(sd_sysctl_header); 4731 sd_sysctl_header = register_sysctl_table(sd_ctl_root); 4732} 4733 4734/* may be called multiple times per register */ 4735static void unregister_sched_domain_sysctl(void) 4736{ 4737 if (sd_sysctl_header) 4738 unregister_sysctl_table(sd_sysctl_header); 4739 sd_sysctl_header = NULL; 4740 if (sd_ctl_dir[0].child) 4741 sd_free_ctl_entry(&sd_ctl_dir[0].child); 4742} 4743#else 4744static void register_sched_domain_sysctl(void) 4745{ 4746} 4747static void unregister_sched_domain_sysctl(void) 4748{ 4749} 4750#endif 4751 4752static void set_rq_online(struct rq *rq) 4753{ 4754 if (!rq->online) { 4755 const struct sched_class *class; 4756 4757 cpumask_set_cpu(rq->cpu, rq->rd->online); 4758 rq->online = 1; 4759 4760 for_each_class(class) { 4761 if (class->rq_online) 4762 class->rq_online(rq); 4763 } 4764 } 4765} 4766 4767static void set_rq_offline(struct rq *rq) 4768{ 4769 if (rq->online) { 4770 const struct sched_class *class; 4771 4772 for_each_class(class) { 4773 if (class->rq_offline) 4774 class->rq_offline(rq); 4775 } 4776 4777 cpumask_clear_cpu(rq->cpu, rq->rd->online); 4778 rq->online = 0; 4779 } 4780} 4781 4782/* 4783 * migration_call - callback that gets triggered when a CPU is added. 4784 * Here we can start up the necessary migration thread for the new CPU. 4785 */ 4786static int 4787migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) 4788{ 4789 int cpu = (long)hcpu; 4790 unsigned long flags; 4791 struct rq *rq = cpu_rq(cpu); 4792 4793 switch (action & ~CPU_TASKS_FROZEN) { 4794 4795 case CPU_UP_PREPARE: 4796 rq->calc_load_update = calc_load_update; 4797 break; 4798 4799 case CPU_ONLINE: 4800 /* Update our root-domain */ 4801 raw_spin_lock_irqsave(&rq->lock, flags); 4802 if (rq->rd) { 4803 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 4804 4805 set_rq_online(rq); 4806 } 4807 raw_spin_unlock_irqrestore(&rq->lock, flags); 4808 break; 4809 4810#ifdef CONFIG_HOTPLUG_CPU 4811 case CPU_DYING: 4812 sched_ttwu_pending(); 4813 /* Update our root-domain */ 4814 raw_spin_lock_irqsave(&rq->lock, flags); 4815 if (rq->rd) { 4816 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 4817 set_rq_offline(rq); 4818 } 4819 migrate_tasks(cpu); 4820 BUG_ON(rq->nr_running != 1); /* the migration thread */ 4821 raw_spin_unlock_irqrestore(&rq->lock, flags); 4822 break; 4823 4824 case CPU_DEAD: 4825 calc_load_migrate(rq); 4826 break; 4827#endif 4828 } 4829 4830 update_max_interval(); 4831 4832 return NOTIFY_OK; 4833} 4834 4835/* 4836 * Register at high priority so that task migration (migrate_all_tasks) 4837 * happens before everything else. This has to be lower priority than 4838 * the notifier in the perf_event subsystem, though. 4839 */ 4840static struct notifier_block migration_notifier = { 4841 .notifier_call = migration_call, 4842 .priority = CPU_PRI_MIGRATION, 4843}; 4844 4845static int sched_cpu_active(struct notifier_block *nfb, 4846 unsigned long action, void *hcpu) 4847{ 4848 switch (action & ~CPU_TASKS_FROZEN) { 4849 case CPU_STARTING: 4850 case CPU_DOWN_FAILED: 4851 set_cpu_active((long)hcpu, true); 4852 return NOTIFY_OK; 4853 default: 4854 return NOTIFY_DONE; 4855 } 4856} 4857 4858static int sched_cpu_inactive(struct notifier_block *nfb, 4859 unsigned long action, void *hcpu) 4860{ 4861 switch (action & ~CPU_TASKS_FROZEN) { 4862 case CPU_DOWN_PREPARE: 4863 set_cpu_active((long)hcpu, false); 4864 return NOTIFY_OK; 4865 default: 4866 return NOTIFY_DONE; 4867 } 4868} 4869 4870static int __init migration_init(void) 4871{ 4872 void *cpu = (void *)(long)smp_processor_id(); 4873 int err; 4874 4875 /* Initialize migration for the boot CPU */ 4876 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu); 4877 BUG_ON(err == NOTIFY_BAD); 4878 migration_call(&migration_notifier, CPU_ONLINE, cpu); 4879 register_cpu_notifier(&migration_notifier); 4880 4881 /* Register cpu active notifiers */ 4882 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE); 4883 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE); 4884 4885 return 0; 4886} 4887early_initcall(migration_init); 4888#endif 4889 4890#ifdef CONFIG_SMP 4891 4892static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */ 4893 4894#ifdef CONFIG_SCHED_DEBUG 4895 4896static __read_mostly int sched_debug_enabled; 4897 4898static int __init sched_debug_setup(char *str) 4899{ 4900 sched_debug_enabled = 1; 4901 4902 return 0; 4903} 4904early_param("sched_debug", sched_debug_setup); 4905 4906static inline bool sched_debug(void) 4907{ 4908 return sched_debug_enabled; 4909} 4910 4911static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, 4912 struct cpumask *groupmask) 4913{ 4914 struct sched_group *group = sd->groups; 4915 char str[256]; 4916 4917 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd)); 4918 cpumask_clear(groupmask); 4919 4920 printk(KERN_DEBUG "%*s domain %d: ", level, "", level); 4921 4922 if (!(sd->flags & SD_LOAD_BALANCE)) { 4923 printk("does not load-balance\n"); 4924 if (sd->parent) 4925 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" 4926 " has parent"); 4927 return -1; 4928 } 4929 4930 printk(KERN_CONT "span %s level %s\n", str, sd->name); 4931 4932 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { 4933 printk(KERN_ERR "ERROR: domain->span does not contain " 4934 "CPU%d\n", cpu); 4935 } 4936 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) { 4937 printk(KERN_ERR "ERROR: domain->groups does not contain" 4938 " CPU%d\n", cpu); 4939 } 4940 4941 printk(KERN_DEBUG "%*s groups:", level + 1, ""); 4942 do { 4943 if (!group) { 4944 printk("\n"); 4945 printk(KERN_ERR "ERROR: group is NULL\n"); 4946 break; 4947 } 4948 4949 /* 4950 * Even though we initialize ->power to something semi-sane, 4951 * we leave power_orig unset. This allows us to detect if 4952 * domain iteration is still funny without causing /0 traps. 4953 */ 4954 if (!group->sgp->power_orig) { 4955 printk(KERN_CONT "\n"); 4956 printk(KERN_ERR "ERROR: domain->cpu_power not " 4957 "set\n"); 4958 break; 4959 } 4960 4961 if (!cpumask_weight(sched_group_cpus(group))) { 4962 printk(KERN_CONT "\n"); 4963 printk(KERN_ERR "ERROR: empty group\n"); 4964 break; 4965 } 4966 4967 if (!(sd->flags & SD_OVERLAP) && 4968 cpumask_intersects(groupmask, sched_group_cpus(group))) { 4969 printk(KERN_CONT "\n"); 4970 printk(KERN_ERR "ERROR: repeated CPUs\n"); 4971 break; 4972 } 4973 4974 cpumask_or(groupmask, groupmask, sched_group_cpus(group)); 4975 4976 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group)); 4977 4978 printk(KERN_CONT " %s", str); 4979 if (group->sgp->power != SCHED_POWER_SCALE) { 4980 printk(KERN_CONT " (cpu_power = %d)", 4981 group->sgp->power); 4982 } 4983 4984 group = group->next; 4985 } while (group != sd->groups); 4986 printk(KERN_CONT "\n"); 4987 4988 if (!cpumask_equal(sched_domain_span(sd), groupmask)) 4989 printk(KERN_ERR "ERROR: groups don't span domain->span\n"); 4990 4991 if (sd->parent && 4992 !cpumask_subset(groupmask, sched_domain_span(sd->parent))) 4993 printk(KERN_ERR "ERROR: parent span is not a superset " 4994 "of domain->span\n"); 4995 return 0; 4996} 4997 4998static void sched_domain_debug(struct sched_domain *sd, int cpu) 4999{ 5000 int level = 0; 5001 5002 if (!sched_debug_enabled) 5003 return; 5004 5005 if (!sd) { 5006 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); 5007 return; 5008 } 5009 5010 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); 5011 5012 for (;;) { 5013 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) 5014 break; 5015 level++; 5016 sd = sd->parent; 5017 if (!sd) 5018 break; 5019 } 5020} 5021#else /* !CONFIG_SCHED_DEBUG */ 5022# define sched_domain_debug(sd, cpu) do { } while (0) 5023static inline bool sched_debug(void) 5024{ 5025 return false; 5026} 5027#endif /* CONFIG_SCHED_DEBUG */ 5028 5029static int sd_degenerate(struct sched_domain *sd) 5030{ 5031 if (cpumask_weight(sched_domain_span(sd)) == 1) 5032 return 1; 5033 5034 /* Following flags need at least 2 groups */ 5035 if (sd->flags & (SD_LOAD_BALANCE | 5036 SD_BALANCE_NEWIDLE | 5037 SD_BALANCE_FORK | 5038 SD_BALANCE_EXEC | 5039 SD_SHARE_CPUPOWER | 5040 SD_SHARE_PKG_RESOURCES)) { 5041 if (sd->groups != sd->groups->next) 5042 return 0; 5043 } 5044 5045 /* Following flags don't use groups */ 5046 if (sd->flags & (SD_WAKE_AFFINE)) 5047 return 0; 5048 5049 return 1; 5050} 5051 5052static int 5053sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) 5054{ 5055 unsigned long cflags = sd->flags, pflags = parent->flags; 5056 5057 if (sd_degenerate(parent)) 5058 return 1; 5059 5060 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) 5061 return 0; 5062 5063 /* Flags needing groups don't count if only 1 group in parent */ 5064 if (parent->groups == parent->groups->next) { 5065 pflags &= ~(SD_LOAD_BALANCE | 5066 SD_BALANCE_NEWIDLE | 5067 SD_BALANCE_FORK | 5068 SD_BALANCE_EXEC | 5069 SD_SHARE_CPUPOWER | 5070 SD_SHARE_PKG_RESOURCES | 5071 SD_PREFER_SIBLING); 5072 if (nr_node_ids == 1) 5073 pflags &= ~SD_SERIALIZE; 5074 } 5075 if (~cflags & pflags) 5076 return 0; 5077 5078 return 1; 5079} 5080 5081static void free_rootdomain(struct rcu_head *rcu) 5082{ 5083 struct root_domain *rd = container_of(rcu, struct root_domain, rcu); 5084 5085 cpupri_cleanup(&rd->cpupri); 5086 free_cpumask_var(rd->rto_mask); 5087 free_cpumask_var(rd->online); 5088 free_cpumask_var(rd->span); 5089 kfree(rd); 5090} 5091 5092static void rq_attach_root(struct rq *rq, struct root_domain *rd) 5093{ 5094 struct root_domain *old_rd = NULL; 5095 unsigned long flags; 5096 5097 raw_spin_lock_irqsave(&rq->lock, flags); 5098 5099 if (rq->rd) { 5100 old_rd = rq->rd; 5101 5102 if (cpumask_test_cpu(rq->cpu, old_rd->online)) 5103 set_rq_offline(rq); 5104 5105 cpumask_clear_cpu(rq->cpu, old_rd->span); 5106 5107 /* 5108 * If we dont want to free the old_rt yet then 5109 * set old_rd to NULL to skip the freeing later 5110 * in this function: 5111 */ 5112 if (!atomic_dec_and_test(&old_rd->refcount)) 5113 old_rd = NULL; 5114 } 5115 5116 atomic_inc(&rd->refcount); 5117 rq->rd = rd; 5118 5119 cpumask_set_cpu(rq->cpu, rd->span); 5120 if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) 5121 set_rq_online(rq); 5122 5123 raw_spin_unlock_irqrestore(&rq->lock, flags); 5124 5125 if (old_rd) 5126 call_rcu_sched(&old_rd->rcu, free_rootdomain); 5127} 5128 5129static int init_rootdomain(struct root_domain *rd) 5130{ 5131 memset(rd, 0, sizeof(*rd)); 5132 5133 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL)) 5134 goto out; 5135 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL)) 5136 goto free_span; 5137 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) 5138 goto free_online; 5139 5140 if (cpupri_init(&rd->cpupri) != 0) 5141 goto free_rto_mask; 5142 return 0; 5143 5144free_rto_mask: 5145 free_cpumask_var(rd->rto_mask); 5146free_online: 5147 free_cpumask_var(rd->online); 5148free_span: 5149 free_cpumask_var(rd->span); 5150out: 5151 return -ENOMEM; 5152} 5153 5154/* 5155 * By default the system creates a single root-domain with all cpus as 5156 * members (mimicking the global state we have today). 5157 */ 5158struct root_domain def_root_domain; 5159 5160static void init_defrootdomain(void) 5161{ 5162 init_rootdomain(&def_root_domain); 5163 5164 atomic_set(&def_root_domain.refcount, 1); 5165} 5166 5167static struct root_domain *alloc_rootdomain(void) 5168{ 5169 struct root_domain *rd; 5170 5171 rd = kmalloc(sizeof(*rd), GFP_KERNEL); 5172 if (!rd) 5173 return NULL; 5174 5175 if (init_rootdomain(rd) != 0) { 5176 kfree(rd); 5177 return NULL; 5178 } 5179 5180 return rd; 5181} 5182 5183static void free_sched_groups(struct sched_group *sg, int free_sgp) 5184{ 5185 struct sched_group *tmp, *first; 5186 5187 if (!sg) 5188 return; 5189 5190 first = sg; 5191 do { 5192 tmp = sg->next; 5193 5194 if (free_sgp && atomic_dec_and_test(&sg->sgp->ref)) 5195 kfree(sg->sgp); 5196 5197 kfree(sg); 5198 sg = tmp; 5199 } while (sg != first); 5200} 5201 5202static void free_sched_domain(struct rcu_head *rcu) 5203{ 5204 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); 5205 5206 /* 5207 * If its an overlapping domain it has private groups, iterate and 5208 * nuke them all. 5209 */ 5210 if (sd->flags & SD_OVERLAP) { 5211 free_sched_groups(sd->groups, 1); 5212 } else if (atomic_dec_and_test(&sd->groups->ref)) { 5213 kfree(sd->groups->sgp); 5214 kfree(sd->groups); 5215 } 5216 kfree(sd); 5217} 5218 5219static void destroy_sched_domain(struct sched_domain *sd, int cpu) 5220{ 5221 call_rcu(&sd->rcu, free_sched_domain); 5222} 5223 5224static void destroy_sched_domains(struct sched_domain *sd, int cpu) 5225{ 5226 for (; sd; sd = sd->parent) 5227 destroy_sched_domain(sd, cpu); 5228} 5229 5230/* 5231 * Keep a special pointer to the highest sched_domain that has 5232 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this 5233 * allows us to avoid some pointer chasing select_idle_sibling(). 5234 * 5235 * Also keep a unique ID per domain (we use the first cpu number in 5236 * the cpumask of the domain), this allows us to quickly tell if 5237 * two cpus are in the same cache domain, see cpus_share_cache(). 5238 */ 5239DEFINE_PER_CPU(struct sched_domain *, sd_llc); 5240DEFINE_PER_CPU(int, sd_llc_size); 5241DEFINE_PER_CPU(int, sd_llc_id); 5242DEFINE_PER_CPU(struct sched_domain *, sd_numa); 5243 5244static void update_top_cache_domain(int cpu) 5245{ 5246 struct sched_domain *sd; 5247 int id = cpu; 5248 int size = 1; 5249 5250 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); 5251 if (sd) { 5252 id = cpumask_first(sched_domain_span(sd)); 5253 size = cpumask_weight(sched_domain_span(sd)); 5254 } 5255 5256 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); 5257 per_cpu(sd_llc_size, cpu) = size; 5258 per_cpu(sd_llc_id, cpu) = id; 5259 5260 sd = lowest_flag_domain(cpu, SD_NUMA); 5261 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); 5262} 5263 5264/* 5265 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must 5266 * hold the hotplug lock. 5267 */ 5268static void 5269cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) 5270{ 5271 struct rq *rq = cpu_rq(cpu); 5272 struct sched_domain *tmp; 5273 5274 /* Remove the sched domains which do not contribute to scheduling. */ 5275 for (tmp = sd; tmp; ) { 5276 struct sched_domain *parent = tmp->parent; 5277 if (!parent) 5278 break; 5279 5280 if (sd_parent_degenerate(tmp, parent)) { 5281 tmp->parent = parent->parent; 5282 if (parent->parent) 5283 parent->parent->child = tmp; 5284 /* 5285 * Transfer SD_PREFER_SIBLING down in case of a 5286 * degenerate parent; the spans match for this 5287 * so the property transfers. 5288 */ 5289 if (parent->flags & SD_PREFER_SIBLING) 5290 tmp->flags |= SD_PREFER_SIBLING; 5291 destroy_sched_domain(parent, cpu); 5292 } else 5293 tmp = tmp->parent; 5294 } 5295 5296 if (sd && sd_degenerate(sd)) { 5297 tmp = sd; 5298 sd = sd->parent; 5299 destroy_sched_domain(tmp, cpu); 5300 if (sd) 5301 sd->child = NULL; 5302 } 5303 5304 sched_domain_debug(sd, cpu); 5305 5306 rq_attach_root(rq, rd); 5307 tmp = rq->sd; 5308 rcu_assign_pointer(rq->sd, sd); 5309 destroy_sched_domains(tmp, cpu); 5310 5311 update_top_cache_domain(cpu); 5312} 5313 5314/* cpus with isolated domains */ 5315static cpumask_var_t cpu_isolated_map; 5316 5317/* Setup the mask of cpus configured for isolated domains */ 5318static int __init isolated_cpu_setup(char *str) 5319{ 5320 alloc_bootmem_cpumask_var(&cpu_isolated_map); 5321 cpulist_parse(str, cpu_isolated_map); 5322 return 1; 5323} 5324 5325__setup("isolcpus=", isolated_cpu_setup); 5326 5327static const struct cpumask *cpu_cpu_mask(int cpu) 5328{ 5329 return cpumask_of_node(cpu_to_node(cpu)); 5330} 5331 5332struct sd_data { 5333 struct sched_domain **__percpu sd; 5334 struct sched_group **__percpu sg; 5335 struct sched_group_power **__percpu sgp; 5336}; 5337 5338struct s_data { 5339 struct sched_domain ** __percpu sd; 5340 struct root_domain *rd; 5341}; 5342 5343enum s_alloc { 5344 sa_rootdomain, 5345 sa_sd, 5346 sa_sd_storage, 5347 sa_none, 5348}; 5349 5350struct sched_domain_topology_level; 5351 5352typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu); 5353typedef const struct cpumask *(*sched_domain_mask_f)(int cpu); 5354 5355#define SDTL_OVERLAP 0x01 5356 5357struct sched_domain_topology_level { 5358 sched_domain_init_f init; 5359 sched_domain_mask_f mask; 5360 int flags; 5361 int numa_level; 5362 struct sd_data data; 5363}; 5364 5365/* 5366 * Build an iteration mask that can exclude certain CPUs from the upwards 5367 * domain traversal. 5368 * 5369 * Asymmetric node setups can result in situations where the domain tree is of 5370 * unequal depth, make sure to skip domains that already cover the entire 5371 * range. 5372 * 5373 * In that case build_sched_domains() will have terminated the iteration early 5374 * and our sibling sd spans will be empty. Domains should always include the 5375 * cpu they're built on, so check that. 5376 * 5377 */ 5378static void build_group_mask(struct sched_domain *sd, struct sched_group *sg) 5379{ 5380 const struct cpumask *span = sched_domain_span(sd); 5381 struct sd_data *sdd = sd->private; 5382 struct sched_domain *sibling; 5383 int i; 5384 5385 for_each_cpu(i, span) { 5386 sibling = *per_cpu_ptr(sdd->sd, i); 5387 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 5388 continue; 5389 5390 cpumask_set_cpu(i, sched_group_mask(sg)); 5391 } 5392} 5393 5394/* 5395 * Return the canonical balance cpu for this group, this is the first cpu 5396 * of this group that's also in the iteration mask. 5397 */ 5398int group_balance_cpu(struct sched_group *sg) 5399{ 5400 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg)); 5401} 5402 5403static int 5404build_overlap_sched_groups(struct sched_domain *sd, int cpu) 5405{ 5406 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg; 5407 const struct cpumask *span = sched_domain_span(sd); 5408 struct cpumask *covered = sched_domains_tmpmask; 5409 struct sd_data *sdd = sd->private; 5410 struct sched_domain *child; 5411 int i; 5412 5413 cpumask_clear(covered); 5414 5415 for_each_cpu(i, span) { 5416 struct cpumask *sg_span; 5417 5418 if (cpumask_test_cpu(i, covered)) 5419 continue; 5420 5421 child = *per_cpu_ptr(sdd->sd, i); 5422 5423 /* See the comment near build_group_mask(). */ 5424 if (!cpumask_test_cpu(i, sched_domain_span(child))) 5425 continue; 5426 5427 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 5428 GFP_KERNEL, cpu_to_node(cpu)); 5429 5430 if (!sg) 5431 goto fail; 5432 5433 sg_span = sched_group_cpus(sg); 5434 if (child->child) { 5435 child = child->child; 5436 cpumask_copy(sg_span, sched_domain_span(child)); 5437 } else 5438 cpumask_set_cpu(i, sg_span); 5439 5440 cpumask_or(covered, covered, sg_span); 5441 5442 sg->sgp = *per_cpu_ptr(sdd->sgp, i); 5443 if (atomic_inc_return(&sg->sgp->ref) == 1) 5444 build_group_mask(sd, sg); 5445 5446 /* 5447 * Initialize sgp->power such that even if we mess up the 5448 * domains and no possible iteration will get us here, we won't 5449 * die on a /0 trap. 5450 */ 5451 sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span); 5452 5453 /* 5454 * Make sure the first group of this domain contains the 5455 * canonical balance cpu. Otherwise the sched_domain iteration 5456 * breaks. See update_sg_lb_stats(). 5457 */ 5458 if ((!groups && cpumask_test_cpu(cpu, sg_span)) || 5459 group_balance_cpu(sg) == cpu) 5460 groups = sg; 5461 5462 if (!first) 5463 first = sg; 5464 if (last) 5465 last->next = sg; 5466 last = sg; 5467 last->next = first; 5468 } 5469 sd->groups = groups; 5470 5471 return 0; 5472 5473fail: 5474 free_sched_groups(first, 0); 5475 5476 return -ENOMEM; 5477} 5478 5479static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg) 5480{ 5481 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 5482 struct sched_domain *child = sd->child; 5483 5484 if (child) 5485 cpu = cpumask_first(sched_domain_span(child)); 5486 5487 if (sg) { 5488 *sg = *per_cpu_ptr(sdd->sg, cpu); 5489 (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu); 5490 atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */ 5491 } 5492 5493 return cpu; 5494} 5495 5496/* 5497 * build_sched_groups will build a circular linked list of the groups 5498 * covered by the given span, and will set each group's ->cpumask correctly, 5499 * and ->cpu_power to 0. 5500 * 5501 * Assumes the sched_domain tree is fully constructed 5502 */ 5503static int 5504build_sched_groups(struct sched_domain *sd, int cpu) 5505{ 5506 struct sched_group *first = NULL, *last = NULL; 5507 struct sd_data *sdd = sd->private; 5508 const struct cpumask *span = sched_domain_span(sd); 5509 struct cpumask *covered; 5510 int i; 5511 5512 get_group(cpu, sdd, &sd->groups); 5513 atomic_inc(&sd->groups->ref); 5514 5515 if (cpu != cpumask_first(span)) 5516 return 0; 5517 5518 lockdep_assert_held(&sched_domains_mutex); 5519 covered = sched_domains_tmpmask; 5520 5521 cpumask_clear(covered); 5522 5523 for_each_cpu(i, span) { 5524 struct sched_group *sg; 5525 int group, j; 5526 5527 if (cpumask_test_cpu(i, covered)) 5528 continue; 5529 5530 group = get_group(i, sdd, &sg); 5531 cpumask_clear(sched_group_cpus(sg)); 5532 sg->sgp->power = 0; 5533 cpumask_setall(sched_group_mask(sg)); 5534 5535 for_each_cpu(j, span) { 5536 if (get_group(j, sdd, NULL) != group) 5537 continue; 5538 5539 cpumask_set_cpu(j, covered); 5540 cpumask_set_cpu(j, sched_group_cpus(sg)); 5541 } 5542 5543 if (!first) 5544 first = sg; 5545 if (last) 5546 last->next = sg; 5547 last = sg; 5548 } 5549 last->next = first; 5550 5551 return 0; 5552} 5553 5554/* 5555 * Initialize sched groups cpu_power. 5556 * 5557 * cpu_power indicates the capacity of sched group, which is used while 5558 * distributing the load between different sched groups in a sched domain. 5559 * Typically cpu_power for all the groups in a sched domain will be same unless 5560 * there are asymmetries in the topology. If there are asymmetries, group 5561 * having more cpu_power will pickup more load compared to the group having 5562 * less cpu_power. 5563 */ 5564static void init_sched_groups_power(int cpu, struct sched_domain *sd) 5565{ 5566 struct sched_group *sg = sd->groups; 5567 5568 WARN_ON(!sg); 5569 5570 do { 5571 sg->group_weight = cpumask_weight(sched_group_cpus(sg)); 5572 sg = sg->next; 5573 } while (sg != sd->groups); 5574 5575 if (cpu != group_balance_cpu(sg)) 5576 return; 5577 5578 update_group_power(sd, cpu); 5579 atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight); 5580} 5581 5582int __weak arch_sd_sibling_asym_packing(void) 5583{ 5584 return 0*SD_ASYM_PACKING; 5585} 5586 5587/* 5588 * Initializers for schedule domains 5589 * Non-inlined to reduce accumulated stack pressure in build_sched_domains() 5590 */ 5591 5592#ifdef CONFIG_SCHED_DEBUG 5593# define SD_INIT_NAME(sd, type) sd->name = #type 5594#else 5595# define SD_INIT_NAME(sd, type) do { } while (0) 5596#endif 5597 5598#define SD_INIT_FUNC(type) \ 5599static noinline struct sched_domain * \ 5600sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \ 5601{ \ 5602 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \ 5603 *sd = SD_##type##_INIT; \ 5604 SD_INIT_NAME(sd, type); \ 5605 sd->private = &tl->data; \ 5606 return sd; \ 5607} 5608 5609SD_INIT_FUNC(CPU) 5610#ifdef CONFIG_SCHED_SMT 5611 SD_INIT_FUNC(SIBLING) 5612#endif 5613#ifdef CONFIG_SCHED_MC 5614 SD_INIT_FUNC(MC) 5615#endif 5616#ifdef CONFIG_SCHED_BOOK 5617 SD_INIT_FUNC(BOOK) 5618#endif 5619 5620static int default_relax_domain_level = -1; 5621int sched_domain_level_max; 5622 5623static int __init setup_relax_domain_level(char *str) 5624{ 5625 if (kstrtoint(str, 0, &default_relax_domain_level)) 5626 pr_warn("Unable to set relax_domain_level\n"); 5627 5628 return 1; 5629} 5630__setup("relax_domain_level=", setup_relax_domain_level); 5631 5632static void set_domain_attribute(struct sched_domain *sd, 5633 struct sched_domain_attr *attr) 5634{ 5635 int request; 5636 5637 if (!attr || attr->relax_domain_level < 0) { 5638 if (default_relax_domain_level < 0) 5639 return; 5640 else 5641 request = default_relax_domain_level; 5642 } else 5643 request = attr->relax_domain_level; 5644 if (request < sd->level) { 5645 /* turn off idle balance on this domain */ 5646 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 5647 } else { 5648 /* turn on idle balance on this domain */ 5649 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 5650 } 5651} 5652 5653static void __sdt_free(const struct cpumask *cpu_map); 5654static int __sdt_alloc(const struct cpumask *cpu_map); 5655 5656static void __free_domain_allocs(struct s_data *d, enum s_alloc what, 5657 const struct cpumask *cpu_map) 5658{ 5659 switch (what) { 5660 case sa_rootdomain: 5661 if (!atomic_read(&d->rd->refcount)) 5662 free_rootdomain(&d->rd->rcu); /* fall through */ 5663 case sa_sd: 5664 free_percpu(d->sd); /* fall through */ 5665 case sa_sd_storage: 5666 __sdt_free(cpu_map); /* fall through */ 5667 case sa_none: 5668 break; 5669 } 5670} 5671 5672static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, 5673 const struct cpumask *cpu_map) 5674{ 5675 memset(d, 0, sizeof(*d)); 5676 5677 if (__sdt_alloc(cpu_map)) 5678 return sa_sd_storage; 5679 d->sd = alloc_percpu(struct sched_domain *); 5680 if (!d->sd) 5681 return sa_sd_storage; 5682 d->rd = alloc_rootdomain(); 5683 if (!d->rd) 5684 return sa_sd; 5685 return sa_rootdomain; 5686} 5687 5688/* 5689 * NULL the sd_data elements we've used to build the sched_domain and 5690 * sched_group structure so that the subsequent __free_domain_allocs() 5691 * will not free the data we're using. 5692 */ 5693static void claim_allocations(int cpu, struct sched_domain *sd) 5694{ 5695 struct sd_data *sdd = sd->private; 5696 5697 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); 5698 *per_cpu_ptr(sdd->sd, cpu) = NULL; 5699 5700 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) 5701 *per_cpu_ptr(sdd->sg, cpu) = NULL; 5702 5703 if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref)) 5704 *per_cpu_ptr(sdd->sgp, cpu) = NULL; 5705} 5706 5707#ifdef CONFIG_SCHED_SMT 5708static const struct cpumask *cpu_smt_mask(int cpu) 5709{ 5710 return topology_thread_cpumask(cpu); 5711} 5712#endif 5713 5714/* 5715 * Topology list, bottom-up. 5716 */ 5717static struct sched_domain_topology_level default_topology[] = { 5718#ifdef CONFIG_SCHED_SMT 5719 { sd_init_SIBLING, cpu_smt_mask, }, 5720#endif 5721#ifdef CONFIG_SCHED_MC 5722 { sd_init_MC, cpu_coregroup_mask, }, 5723#endif 5724#ifdef CONFIG_SCHED_BOOK 5725 { sd_init_BOOK, cpu_book_mask, }, 5726#endif 5727 { sd_init_CPU, cpu_cpu_mask, }, 5728 { NULL, }, 5729}; 5730 5731static struct sched_domain_topology_level *sched_domain_topology = default_topology; 5732 5733#define for_each_sd_topology(tl) \ 5734 for (tl = sched_domain_topology; tl->init; tl++) 5735 5736#ifdef CONFIG_NUMA 5737 5738static int sched_domains_numa_levels; 5739static int *sched_domains_numa_distance; 5740static struct cpumask ***sched_domains_numa_masks; 5741static int sched_domains_curr_level; 5742 5743static inline int sd_local_flags(int level) 5744{ 5745 if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE) 5746 return 0; 5747 5748 return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE; 5749} 5750 5751static struct sched_domain * 5752sd_numa_init(struct sched_domain_topology_level *tl, int cpu) 5753{ 5754 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); 5755 int level = tl->numa_level; 5756 int sd_weight = cpumask_weight( 5757 sched_domains_numa_masks[level][cpu_to_node(cpu)]); 5758 5759 *sd = (struct sched_domain){ 5760 .min_interval = sd_weight, 5761 .max_interval = 2*sd_weight, 5762 .busy_factor = 32, 5763 .imbalance_pct = 125, 5764 .cache_nice_tries = 2, 5765 .busy_idx = 3, 5766 .idle_idx = 2, 5767 .newidle_idx = 0, 5768 .wake_idx = 0, 5769 .forkexec_idx = 0, 5770 5771 .flags = 1*SD_LOAD_BALANCE 5772 | 1*SD_BALANCE_NEWIDLE 5773 | 0*SD_BALANCE_EXEC 5774 | 0*SD_BALANCE_FORK 5775 | 0*SD_BALANCE_WAKE 5776 | 0*SD_WAKE_AFFINE 5777 | 0*SD_SHARE_CPUPOWER 5778 | 0*SD_SHARE_PKG_RESOURCES 5779 | 1*SD_SERIALIZE 5780 | 0*SD_PREFER_SIBLING 5781 | 1*SD_NUMA 5782 | sd_local_flags(level) 5783 , 5784 .last_balance = jiffies, 5785 .balance_interval = sd_weight, 5786 }; 5787 SD_INIT_NAME(sd, NUMA); 5788 sd->private = &tl->data; 5789 5790 /* 5791 * Ugly hack to pass state to sd_numa_mask()... 5792 */ 5793 sched_domains_curr_level = tl->numa_level; 5794 5795 return sd; 5796} 5797 5798static const struct cpumask *sd_numa_mask(int cpu) 5799{ 5800 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; 5801} 5802 5803static void sched_numa_warn(const char *str) 5804{ 5805 static int done = false; 5806 int i,j; 5807 5808 if (done) 5809 return; 5810 5811 done = true; 5812 5813 printk(KERN_WARNING "ERROR: %s\n\n", str); 5814 5815 for (i = 0; i < nr_node_ids; i++) { 5816 printk(KERN_WARNING " "); 5817 for (j = 0; j < nr_node_ids; j++) 5818 printk(KERN_CONT "%02d ", node_distance(i,j)); 5819 printk(KERN_CONT "\n"); 5820 } 5821 printk(KERN_WARNING "\n"); 5822} 5823 5824static bool find_numa_distance(int distance) 5825{ 5826 int i; 5827 5828 if (distance == node_distance(0, 0)) 5829 return true; 5830 5831 for (i = 0; i < sched_domains_numa_levels; i++) { 5832 if (sched_domains_numa_distance[i] == distance) 5833 return true; 5834 } 5835 5836 return false; 5837} 5838 5839static void sched_init_numa(void) 5840{ 5841 int next_distance, curr_distance = node_distance(0, 0); 5842 struct sched_domain_topology_level *tl; 5843 int level = 0; 5844 int i, j, k; 5845 5846 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL); 5847 if (!sched_domains_numa_distance) 5848 return; 5849 5850 /* 5851 * O(nr_nodes^2) deduplicating selection sort -- in order to find the 5852 * unique distances in the node_distance() table. 5853 * 5854 * Assumes node_distance(0,j) includes all distances in 5855 * node_distance(i,j) in order to avoid cubic time. 5856 */ 5857 next_distance = curr_distance; 5858 for (i = 0; i < nr_node_ids; i++) { 5859 for (j = 0; j < nr_node_ids; j++) { 5860 for (k = 0; k < nr_node_ids; k++) { 5861 int distance = node_distance(i, k); 5862 5863 if (distance > curr_distance && 5864 (distance < next_distance || 5865 next_distance == curr_distance)) 5866 next_distance = distance; 5867 5868 /* 5869 * While not a strong assumption it would be nice to know 5870 * about cases where if node A is connected to B, B is not 5871 * equally connected to A. 5872 */ 5873 if (sched_debug() && node_distance(k, i) != distance) 5874 sched_numa_warn("Node-distance not symmetric"); 5875 5876 if (sched_debug() && i && !find_numa_distance(distance)) 5877 sched_numa_warn("Node-0 not representative"); 5878 } 5879 if (next_distance != curr_distance) { 5880 sched_domains_numa_distance[level++] = next_distance; 5881 sched_domains_numa_levels = level; 5882 curr_distance = next_distance; 5883 } else break; 5884 } 5885 5886 /* 5887 * In case of sched_debug() we verify the above assumption. 5888 */ 5889 if (!sched_debug()) 5890 break; 5891 } 5892 /* 5893 * 'level' contains the number of unique distances, excluding the 5894 * identity distance node_distance(i,i). 5895 * 5896 * The sched_domains_numa_distance[] array includes the actual distance 5897 * numbers. 5898 */ 5899 5900 /* 5901 * Here, we should temporarily reset sched_domains_numa_levels to 0. 5902 * If it fails to allocate memory for array sched_domains_numa_masks[][], 5903 * the array will contain less then 'level' members. This could be 5904 * dangerous when we use it to iterate array sched_domains_numa_masks[][] 5905 * in other functions. 5906 * 5907 * We reset it to 'level' at the end of this function. 5908 */ 5909 sched_domains_numa_levels = 0; 5910 5911 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); 5912 if (!sched_domains_numa_masks) 5913 return; 5914 5915 /* 5916 * Now for each level, construct a mask per node which contains all 5917 * cpus of nodes that are that many hops away from us. 5918 */ 5919 for (i = 0; i < level; i++) { 5920 sched_domains_numa_masks[i] = 5921 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); 5922 if (!sched_domains_numa_masks[i]) 5923 return; 5924 5925 for (j = 0; j < nr_node_ids; j++) { 5926 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); 5927 if (!mask) 5928 return; 5929 5930 sched_domains_numa_masks[i][j] = mask; 5931 5932 for (k = 0; k < nr_node_ids; k++) { 5933 if (node_distance(j, k) > sched_domains_numa_distance[i]) 5934 continue; 5935 5936 cpumask_or(mask, mask, cpumask_of_node(k)); 5937 } 5938 } 5939 } 5940 5941 tl = kzalloc((ARRAY_SIZE(default_topology) + level) * 5942 sizeof(struct sched_domain_topology_level), GFP_KERNEL); 5943 if (!tl) 5944 return; 5945 5946 /* 5947 * Copy the default topology bits.. 5948 */ 5949 for (i = 0; default_topology[i].init; i++) 5950 tl[i] = default_topology[i]; 5951 5952 /* 5953 * .. and append 'j' levels of NUMA goodness. 5954 */ 5955 for (j = 0; j < level; i++, j++) { 5956 tl[i] = (struct sched_domain_topology_level){ 5957 .init = sd_numa_init, 5958 .mask = sd_numa_mask, 5959 .flags = SDTL_OVERLAP, 5960 .numa_level = j, 5961 }; 5962 } 5963 5964 sched_domain_topology = tl; 5965 5966 sched_domains_numa_levels = level; 5967} 5968 5969static void sched_domains_numa_masks_set(int cpu) 5970{ 5971 int i, j; 5972 int node = cpu_to_node(cpu); 5973 5974 for (i = 0; i < sched_domains_numa_levels; i++) { 5975 for (j = 0; j < nr_node_ids; j++) { 5976 if (node_distance(j, node) <= sched_domains_numa_distance[i]) 5977 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]); 5978 } 5979 } 5980} 5981 5982static void sched_domains_numa_masks_clear(int cpu) 5983{ 5984 int i, j; 5985 for (i = 0; i < sched_domains_numa_levels; i++) { 5986 for (j = 0; j < nr_node_ids; j++) 5987 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); 5988 } 5989} 5990 5991/* 5992 * Update sched_domains_numa_masks[level][node] array when new cpus 5993 * are onlined. 5994 */ 5995static int sched_domains_numa_masks_update(struct notifier_block *nfb, 5996 unsigned long action, 5997 void *hcpu) 5998{ 5999 int cpu = (long)hcpu; 6000 6001 switch (action & ~CPU_TASKS_FROZEN) { 6002 case CPU_ONLINE: 6003 sched_domains_numa_masks_set(cpu); 6004 break; 6005 6006 case CPU_DEAD: 6007 sched_domains_numa_masks_clear(cpu); 6008 break; 6009 6010 default: 6011 return NOTIFY_DONE; 6012 } 6013 6014 return NOTIFY_OK; 6015} 6016#else 6017static inline void sched_init_numa(void) 6018{ 6019} 6020 6021static int sched_domains_numa_masks_update(struct notifier_block *nfb, 6022 unsigned long action, 6023 void *hcpu) 6024{ 6025 return 0; 6026} 6027#endif /* CONFIG_NUMA */ 6028 6029static int __sdt_alloc(const struct cpumask *cpu_map) 6030{ 6031 struct sched_domain_topology_level *tl; 6032 int j; 6033 6034 for_each_sd_topology(tl) { 6035 struct sd_data *sdd = &tl->data; 6036 6037 sdd->sd = alloc_percpu(struct sched_domain *); 6038 if (!sdd->sd) 6039 return -ENOMEM; 6040 6041 sdd->sg = alloc_percpu(struct sched_group *); 6042 if (!sdd->sg) 6043 return -ENOMEM; 6044 6045 sdd->sgp = alloc_percpu(struct sched_group_power *); 6046 if (!sdd->sgp) 6047 return -ENOMEM; 6048 6049 for_each_cpu(j, cpu_map) { 6050 struct sched_domain *sd; 6051 struct sched_group *sg; 6052 struct sched_group_power *sgp; 6053 6054 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), 6055 GFP_KERNEL, cpu_to_node(j)); 6056 if (!sd) 6057 return -ENOMEM; 6058 6059 *per_cpu_ptr(sdd->sd, j) = sd; 6060 6061 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 6062 GFP_KERNEL, cpu_to_node(j)); 6063 if (!sg) 6064 return -ENOMEM; 6065 6066 sg->next = sg; 6067 6068 *per_cpu_ptr(sdd->sg, j) = sg; 6069 6070 sgp = kzalloc_node(sizeof(struct sched_group_power) + cpumask_size(), 6071 GFP_KERNEL, cpu_to_node(j)); 6072 if (!sgp) 6073 return -ENOMEM; 6074 6075 *per_cpu_ptr(sdd->sgp, j) = sgp; 6076 } 6077 } 6078 6079 return 0; 6080} 6081 6082static void __sdt_free(const struct cpumask *cpu_map) 6083{ 6084 struct sched_domain_topology_level *tl; 6085 int j; 6086 6087 for_each_sd_topology(tl) { 6088 struct sd_data *sdd = &tl->data; 6089 6090 for_each_cpu(j, cpu_map) { 6091 struct sched_domain *sd; 6092 6093 if (sdd->sd) { 6094 sd = *per_cpu_ptr(sdd->sd, j); 6095 if (sd && (sd->flags & SD_OVERLAP)) 6096 free_sched_groups(sd->groups, 0); 6097 kfree(*per_cpu_ptr(sdd->sd, j)); 6098 } 6099 6100 if (sdd->sg) 6101 kfree(*per_cpu_ptr(sdd->sg, j)); 6102 if (sdd->sgp) 6103 kfree(*per_cpu_ptr(sdd->sgp, j)); 6104 } 6105 free_percpu(sdd->sd); 6106 sdd->sd = NULL; 6107 free_percpu(sdd->sg); 6108 sdd->sg = NULL; 6109 free_percpu(sdd->sgp); 6110 sdd->sgp = NULL; 6111 } 6112} 6113 6114struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, 6115 const struct cpumask *cpu_map, struct sched_domain_attr *attr, 6116 struct sched_domain *child, int cpu) 6117{ 6118 struct sched_domain *sd = tl->init(tl, cpu); 6119 if (!sd) 6120 return child; 6121 6122 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); 6123 if (child) { 6124 sd->level = child->level + 1; 6125 sched_domain_level_max = max(sched_domain_level_max, sd->level); 6126 child->parent = sd; 6127 sd->child = child; 6128 } 6129 set_domain_attribute(sd, attr); 6130 6131 return sd; 6132} 6133 6134/* 6135 * Build sched domains for a given set of cpus and attach the sched domains 6136 * to the individual cpus 6137 */ 6138static int build_sched_domains(const struct cpumask *cpu_map, 6139 struct sched_domain_attr *attr) 6140{ 6141 enum s_alloc alloc_state; 6142 struct sched_domain *sd; 6143 struct s_data d; 6144 int i, ret = -ENOMEM; 6145 6146 alloc_state = __visit_domain_allocation_hell(&d, cpu_map); 6147 if (alloc_state != sa_rootdomain) 6148 goto error; 6149 6150 /* Set up domains for cpus specified by the cpu_map. */ 6151 for_each_cpu(i, cpu_map) { 6152 struct sched_domain_topology_level *tl; 6153 6154 sd = NULL; 6155 for_each_sd_topology(tl) { 6156 sd = build_sched_domain(tl, cpu_map, attr, sd, i); 6157 if (tl == sched_domain_topology) 6158 *per_cpu_ptr(d.sd, i) = sd; 6159 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) 6160 sd->flags |= SD_OVERLAP; 6161 if (cpumask_equal(cpu_map, sched_domain_span(sd))) 6162 break; 6163 } 6164 } 6165 6166 /* Build the groups for the domains */ 6167 for_each_cpu(i, cpu_map) { 6168 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6169 sd->span_weight = cpumask_weight(sched_domain_span(sd)); 6170 if (sd->flags & SD_OVERLAP) { 6171 if (build_overlap_sched_groups(sd, i)) 6172 goto error; 6173 } else { 6174 if (build_sched_groups(sd, i)) 6175 goto error; 6176 } 6177 } 6178 } 6179 6180 /* Calculate CPU power for physical packages and nodes */ 6181 for (i = nr_cpumask_bits-1; i >= 0; i--) { 6182 if (!cpumask_test_cpu(i, cpu_map)) 6183 continue; 6184 6185 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6186 claim_allocations(i, sd); 6187 init_sched_groups_power(i, sd); 6188 } 6189 } 6190 6191 /* Attach the domains */ 6192 rcu_read_lock(); 6193 for_each_cpu(i, cpu_map) { 6194 sd = *per_cpu_ptr(d.sd, i); 6195 cpu_attach_domain(sd, d.rd, i); 6196 } 6197 rcu_read_unlock(); 6198 6199 ret = 0; 6200error: 6201 __free_domain_allocs(&d, alloc_state, cpu_map); 6202 return ret; 6203} 6204 6205static cpumask_var_t *doms_cur; /* current sched domains */ 6206static int ndoms_cur; /* number of sched domains in 'doms_cur' */ 6207static struct sched_domain_attr *dattr_cur; 6208 /* attribues of custom domains in 'doms_cur' */ 6209 6210/* 6211 * Special case: If a kmalloc of a doms_cur partition (array of 6212 * cpumask) fails, then fallback to a single sched domain, 6213 * as determined by the single cpumask fallback_doms. 6214 */ 6215static cpumask_var_t fallback_doms; 6216 6217/* 6218 * arch_update_cpu_topology lets virtualized architectures update the 6219 * cpu core maps. It is supposed to return 1 if the topology changed 6220 * or 0 if it stayed the same. 6221 */ 6222int __attribute__((weak)) arch_update_cpu_topology(void) 6223{ 6224 return 0; 6225} 6226 6227cpumask_var_t *alloc_sched_domains(unsigned int ndoms) 6228{ 6229 int i; 6230 cpumask_var_t *doms; 6231 6232 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL); 6233 if (!doms) 6234 return NULL; 6235 for (i = 0; i < ndoms; i++) { 6236 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { 6237 free_sched_domains(doms, i); 6238 return NULL; 6239 } 6240 } 6241 return doms; 6242} 6243 6244void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) 6245{ 6246 unsigned int i; 6247 for (i = 0; i < ndoms; i++) 6248 free_cpumask_var(doms[i]); 6249 kfree(doms); 6250} 6251 6252/* 6253 * Set up scheduler domains and groups. Callers must hold the hotplug lock. 6254 * For now this just excludes isolated cpus, but could be used to 6255 * exclude other special cases in the future. 6256 */ 6257static int init_sched_domains(const struct cpumask *cpu_map) 6258{ 6259 int err; 6260 6261 arch_update_cpu_topology(); 6262 ndoms_cur = 1; 6263 doms_cur = alloc_sched_domains(ndoms_cur); 6264 if (!doms_cur) 6265 doms_cur = &fallback_doms; 6266 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map); 6267 err = build_sched_domains(doms_cur[0], NULL); 6268 register_sched_domain_sysctl(); 6269 6270 return err; 6271} 6272 6273/* 6274 * Detach sched domains from a group of cpus specified in cpu_map 6275 * These cpus will now be attached to the NULL domain 6276 */ 6277static void detach_destroy_domains(const struct cpumask *cpu_map) 6278{ 6279 int i; 6280 6281 rcu_read_lock(); 6282 for_each_cpu(i, cpu_map) 6283 cpu_attach_domain(NULL, &def_root_domain, i); 6284 rcu_read_unlock(); 6285} 6286 6287/* handle null as "default" */ 6288static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 6289 struct sched_domain_attr *new, int idx_new) 6290{ 6291 struct sched_domain_attr tmp; 6292 6293 /* fast path */ 6294 if (!new && !cur) 6295 return 1; 6296 6297 tmp = SD_ATTR_INIT; 6298 return !memcmp(cur ? (cur + idx_cur) : &tmp, 6299 new ? (new + idx_new) : &tmp, 6300 sizeof(struct sched_domain_attr)); 6301} 6302 6303/* 6304 * Partition sched domains as specified by the 'ndoms_new' 6305 * cpumasks in the array doms_new[] of cpumasks. This compares 6306 * doms_new[] to the current sched domain partitioning, doms_cur[]. 6307 * It destroys each deleted domain and builds each new domain. 6308 * 6309 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. 6310 * The masks don't intersect (don't overlap.) We should setup one 6311 * sched domain for each mask. CPUs not in any of the cpumasks will 6312 * not be load balanced. If the same cpumask appears both in the 6313 * current 'doms_cur' domains and in the new 'doms_new', we can leave 6314 * it as it is. 6315 * 6316 * The passed in 'doms_new' should be allocated using 6317 * alloc_sched_domains. This routine takes ownership of it and will 6318 * free_sched_domains it when done with it. If the caller failed the 6319 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, 6320 * and partition_sched_domains() will fallback to the single partition 6321 * 'fallback_doms', it also forces the domains to be rebuilt. 6322 * 6323 * If doms_new == NULL it will be replaced with cpu_online_mask. 6324 * ndoms_new == 0 is a special case for destroying existing domains, 6325 * and it will not create the default domain. 6326 * 6327 * Call with hotplug lock held 6328 */ 6329void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], 6330 struct sched_domain_attr *dattr_new) 6331{ 6332 int i, j, n; 6333 int new_topology; 6334 6335 mutex_lock(&sched_domains_mutex); 6336 6337 /* always unregister in case we don't destroy any domains */ 6338 unregister_sched_domain_sysctl(); 6339 6340 /* Let architecture update cpu core mappings. */ 6341 new_topology = arch_update_cpu_topology(); 6342 6343 n = doms_new ? ndoms_new : 0; 6344 6345 /* Destroy deleted domains */ 6346 for (i = 0; i < ndoms_cur; i++) { 6347 for (j = 0; j < n && !new_topology; j++) { 6348 if (cpumask_equal(doms_cur[i], doms_new[j]) 6349 && dattrs_equal(dattr_cur, i, dattr_new, j)) 6350 goto match1; 6351 } 6352 /* no match - a current sched domain not in new doms_new[] */ 6353 detach_destroy_domains(doms_cur[i]); 6354match1: 6355 ; 6356 } 6357 6358 n = ndoms_cur; 6359 if (doms_new == NULL) { 6360 n = 0; 6361 doms_new = &fallback_doms; 6362 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); 6363 WARN_ON_ONCE(dattr_new); 6364 } 6365 6366 /* Build new domains */ 6367 for (i = 0; i < ndoms_new; i++) { 6368 for (j = 0; j < n && !new_topology; j++) { 6369 if (cpumask_equal(doms_new[i], doms_cur[j]) 6370 && dattrs_equal(dattr_new, i, dattr_cur, j)) 6371 goto match2; 6372 } 6373 /* no match - add a new doms_new */ 6374 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); 6375match2: 6376 ; 6377 } 6378 6379 /* Remember the new sched domains */ 6380 if (doms_cur != &fallback_doms) 6381 free_sched_domains(doms_cur, ndoms_cur); 6382 kfree(dattr_cur); /* kfree(NULL) is safe */ 6383 doms_cur = doms_new; 6384 dattr_cur = dattr_new; 6385 ndoms_cur = ndoms_new; 6386 6387 register_sched_domain_sysctl(); 6388 6389 mutex_unlock(&sched_domains_mutex); 6390} 6391 6392static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */ 6393 6394/* 6395 * Update cpusets according to cpu_active mask. If cpusets are 6396 * disabled, cpuset_update_active_cpus() becomes a simple wrapper 6397 * around partition_sched_domains(). 6398 * 6399 * If we come here as part of a suspend/resume, don't touch cpusets because we 6400 * want to restore it back to its original state upon resume anyway. 6401 */ 6402static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, 6403 void *hcpu) 6404{ 6405 switch (action) { 6406 case CPU_ONLINE_FROZEN: 6407 case CPU_DOWN_FAILED_FROZEN: 6408 6409 /* 6410 * num_cpus_frozen tracks how many CPUs are involved in suspend 6411 * resume sequence. As long as this is not the last online 6412 * operation in the resume sequence, just build a single sched 6413 * domain, ignoring cpusets. 6414 */ 6415 num_cpus_frozen--; 6416 if (likely(num_cpus_frozen)) { 6417 partition_sched_domains(1, NULL, NULL); 6418 break; 6419 } 6420 6421 /* 6422 * This is the last CPU online operation. So fall through and 6423 * restore the original sched domains by considering the 6424 * cpuset configurations. 6425 */ 6426 6427 case CPU_ONLINE: 6428 case CPU_DOWN_FAILED: 6429 cpuset_update_active_cpus(true); 6430 break; 6431 default: 6432 return NOTIFY_DONE; 6433 } 6434 return NOTIFY_OK; 6435} 6436 6437static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, 6438 void *hcpu) 6439{ 6440 switch (action) { 6441 case CPU_DOWN_PREPARE: 6442 cpuset_update_active_cpus(false); 6443 break; 6444 case CPU_DOWN_PREPARE_FROZEN: 6445 num_cpus_frozen++; 6446 partition_sched_domains(1, NULL, NULL); 6447 break; 6448 default: 6449 return NOTIFY_DONE; 6450 } 6451 return NOTIFY_OK; 6452} 6453 6454void __init sched_init_smp(void) 6455{ 6456 cpumask_var_t non_isolated_cpus; 6457 6458 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); 6459 alloc_cpumask_var(&fallback_doms, GFP_KERNEL); 6460 6461 sched_init_numa(); 6462 6463 get_online_cpus(); 6464 mutex_lock(&sched_domains_mutex); 6465 init_sched_domains(cpu_active_mask); 6466 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); 6467 if (cpumask_empty(non_isolated_cpus)) 6468 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus); 6469 mutex_unlock(&sched_domains_mutex); 6470 put_online_cpus(); 6471 6472 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE); 6473 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE); 6474 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE); 6475 6476 init_hrtick(); 6477 6478 /* Move init over to a non-isolated CPU */ 6479 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) 6480 BUG(); 6481 sched_init_granularity(); 6482 free_cpumask_var(non_isolated_cpus); 6483 6484 init_sched_rt_class(); 6485} 6486#else 6487void __init sched_init_smp(void) 6488{ 6489 sched_init_granularity(); 6490} 6491#endif /* CONFIG_SMP */ 6492 6493const_debug unsigned int sysctl_timer_migration = 1; 6494 6495int in_sched_functions(unsigned long addr) 6496{ 6497 return in_lock_functions(addr) || 6498 (addr >= (unsigned long)__sched_text_start 6499 && addr < (unsigned long)__sched_text_end); 6500} 6501 6502#ifdef CONFIG_CGROUP_SCHED 6503/* 6504 * Default task group. 6505 * Every task in system belongs to this group at bootup. 6506 */ 6507struct task_group root_task_group; 6508LIST_HEAD(task_groups); 6509#endif 6510 6511DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); 6512 6513void __init sched_init(void) 6514{ 6515 int i, j; 6516 unsigned long alloc_size = 0, ptr; 6517 6518#ifdef CONFIG_FAIR_GROUP_SCHED 6519 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 6520#endif 6521#ifdef CONFIG_RT_GROUP_SCHED 6522 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 6523#endif 6524#ifdef CONFIG_CPUMASK_OFFSTACK 6525 alloc_size += num_possible_cpus() * cpumask_size(); 6526#endif 6527 if (alloc_size) { 6528 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); 6529 6530#ifdef CONFIG_FAIR_GROUP_SCHED 6531 root_task_group.se = (struct sched_entity **)ptr; 6532 ptr += nr_cpu_ids * sizeof(void **); 6533 6534 root_task_group.cfs_rq = (struct cfs_rq **)ptr; 6535 ptr += nr_cpu_ids * sizeof(void **); 6536 6537#endif /* CONFIG_FAIR_GROUP_SCHED */ 6538#ifdef CONFIG_RT_GROUP_SCHED 6539 root_task_group.rt_se = (struct sched_rt_entity **)ptr; 6540 ptr += nr_cpu_ids * sizeof(void **); 6541 6542 root_task_group.rt_rq = (struct rt_rq **)ptr; 6543 ptr += nr_cpu_ids * sizeof(void **); 6544 6545#endif /* CONFIG_RT_GROUP_SCHED */ 6546#ifdef CONFIG_CPUMASK_OFFSTACK 6547 for_each_possible_cpu(i) { 6548 per_cpu(load_balance_mask, i) = (void *)ptr; 6549 ptr += cpumask_size(); 6550 } 6551#endif /* CONFIG_CPUMASK_OFFSTACK */ 6552 } 6553 6554#ifdef CONFIG_SMP 6555 init_defrootdomain(); 6556#endif 6557 6558 init_rt_bandwidth(&def_rt_bandwidth, 6559 global_rt_period(), global_rt_runtime()); 6560 6561#ifdef CONFIG_RT_GROUP_SCHED 6562 init_rt_bandwidth(&root_task_group.rt_bandwidth, 6563 global_rt_period(), global_rt_runtime()); 6564#endif /* CONFIG_RT_GROUP_SCHED */ 6565 6566#ifdef CONFIG_CGROUP_SCHED 6567 list_add(&root_task_group.list, &task_groups); 6568 INIT_LIST_HEAD(&root_task_group.children); 6569 INIT_LIST_HEAD(&root_task_group.siblings); 6570 autogroup_init(&init_task); 6571 6572#endif /* CONFIG_CGROUP_SCHED */ 6573 6574 for_each_possible_cpu(i) { 6575 struct rq *rq; 6576 6577 rq = cpu_rq(i); 6578 raw_spin_lock_init(&rq->lock); 6579 rq->nr_running = 0; 6580 rq->calc_load_active = 0; 6581 rq->calc_load_update = jiffies + LOAD_FREQ; 6582 init_cfs_rq(&rq->cfs); 6583 init_rt_rq(&rq->rt, rq); 6584#ifdef CONFIG_FAIR_GROUP_SCHED 6585 root_task_group.shares = ROOT_TASK_GROUP_LOAD; 6586 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); 6587 /* 6588 * How much cpu bandwidth does root_task_group get? 6589 * 6590 * In case of task-groups formed thr' the cgroup filesystem, it 6591 * gets 100% of the cpu resources in the system. This overall 6592 * system cpu resource is divided among the tasks of 6593 * root_task_group and its child task-groups in a fair manner, 6594 * based on each entity's (task or task-group's) weight 6595 * (se->load.weight). 6596 * 6597 * In other words, if root_task_group has 10 tasks of weight 6598 * 1024) and two child groups A0 and A1 (of weight 1024 each), 6599 * then A0's share of the cpu resource is: 6600 * 6601 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% 6602 * 6603 * We achieve this by letting root_task_group's tasks sit 6604 * directly in rq->cfs (i.e root_task_group->se[] = NULL). 6605 */ 6606 init_cfs_bandwidth(&root_task_group.cfs_bandwidth); 6607 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); 6608#endif /* CONFIG_FAIR_GROUP_SCHED */ 6609 6610 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; 6611#ifdef CONFIG_RT_GROUP_SCHED 6612 INIT_LIST_HEAD(&rq->leaf_rt_rq_list); 6613 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); 6614#endif 6615 6616 for (j = 0; j < CPU_LOAD_IDX_MAX; j++) 6617 rq->cpu_load[j] = 0; 6618 6619 rq->last_load_update_tick = jiffies; 6620 6621#ifdef CONFIG_SMP 6622 rq->sd = NULL; 6623 rq->rd = NULL; 6624 rq->cpu_power = SCHED_POWER_SCALE; 6625 rq->post_schedule = 0; 6626 rq->active_balance = 0; 6627 rq->next_balance = jiffies; 6628 rq->push_cpu = 0; 6629 rq->cpu = i; 6630 rq->online = 0; 6631 rq->idle_stamp = 0; 6632 rq->avg_idle = 2*sysctl_sched_migration_cost; 6633 rq->max_idle_balance_cost = sysctl_sched_migration_cost; 6634 6635 INIT_LIST_HEAD(&rq->cfs_tasks); 6636 6637 rq_attach_root(rq, &def_root_domain); 6638#ifdef CONFIG_NO_HZ_COMMON 6639 rq->nohz_flags = 0; 6640#endif 6641#ifdef CONFIG_NO_HZ_FULL 6642 rq->last_sched_tick = 0; 6643#endif 6644#endif 6645 init_rq_hrtick(rq); 6646 atomic_set(&rq->nr_iowait, 0); 6647 } 6648 6649 set_load_weight(&init_task); 6650 6651#ifdef CONFIG_PREEMPT_NOTIFIERS 6652 INIT_HLIST_HEAD(&init_task.preempt_notifiers); 6653#endif 6654 6655#ifdef CONFIG_RT_MUTEXES 6656 plist_head_init(&init_task.pi_waiters); 6657#endif 6658 6659 /* 6660 * The boot idle thread does lazy MMU switching as well: 6661 */ 6662 atomic_inc(&init_mm.mm_count); 6663 enter_lazy_tlb(&init_mm, current); 6664 6665 /* 6666 * Make us the idle thread. Technically, schedule() should not be 6667 * called from this thread, however somewhere below it might be, 6668 * but because we are the idle thread, we just pick up running again 6669 * when this runqueue becomes "idle". 6670 */ 6671 init_idle(current, smp_processor_id()); 6672 6673 calc_load_update = jiffies + LOAD_FREQ; 6674 6675 /* 6676 * During early bootup we pretend to be a normal task: 6677 */ 6678 current->sched_class = &fair_sched_class; 6679 6680#ifdef CONFIG_SMP 6681 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT); 6682 /* May be allocated at isolcpus cmdline parse time */ 6683 if (cpu_isolated_map == NULL) 6684 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT); 6685 idle_thread_set_boot_cpu(); 6686#endif 6687 init_sched_fair_class(); 6688 6689 scheduler_running = 1; 6690} 6691 6692#ifdef CONFIG_DEBUG_ATOMIC_SLEEP 6693static inline int preempt_count_equals(int preempt_offset) 6694{ 6695 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth(); 6696 6697 return (nested == preempt_offset); 6698} 6699 6700void __might_sleep(const char *file, int line, int preempt_offset) 6701{ 6702 static unsigned long prev_jiffy; /* ratelimiting */ 6703 6704 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ 6705 if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) || 6706 system_state != SYSTEM_RUNNING || oops_in_progress) 6707 return; 6708 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) 6709 return; 6710 prev_jiffy = jiffies; 6711 6712 printk(KERN_ERR 6713 "BUG: sleeping function called from invalid context at %s:%d\n", 6714 file, line); 6715 printk(KERN_ERR 6716 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", 6717 in_atomic(), irqs_disabled(), 6718 current->pid, current->comm); 6719 6720 debug_show_held_locks(current); 6721 if (irqs_disabled()) 6722 print_irqtrace_events(current); 6723 dump_stack(); 6724} 6725EXPORT_SYMBOL(__might_sleep); 6726#endif 6727 6728#ifdef CONFIG_MAGIC_SYSRQ 6729static void normalize_task(struct rq *rq, struct task_struct *p) 6730{ 6731 const struct sched_class *prev_class = p->sched_class; 6732 int old_prio = p->prio; 6733 int on_rq; 6734 6735 on_rq = p->on_rq; 6736 if (on_rq) 6737 dequeue_task(rq, p, 0); 6738 __setscheduler(rq, p, SCHED_NORMAL, 0); 6739 if (on_rq) { 6740 enqueue_task(rq, p, 0); 6741 resched_task(rq->curr); 6742 } 6743 6744 check_class_changed(rq, p, prev_class, old_prio); 6745} 6746 6747void normalize_rt_tasks(void) 6748{ 6749 struct task_struct *g, *p; 6750 unsigned long flags; 6751 struct rq *rq; 6752 6753 read_lock_irqsave(&tasklist_lock, flags); 6754 do_each_thread(g, p) { 6755 /* 6756 * Only normalize user tasks: 6757 */ 6758 if (!p->mm) 6759 continue; 6760 6761 p->se.exec_start = 0; 6762#ifdef CONFIG_SCHEDSTATS 6763 p->se.statistics.wait_start = 0; 6764 p->se.statistics.sleep_start = 0; 6765 p->se.statistics.block_start = 0; 6766#endif 6767 6768 if (!rt_task(p)) { 6769 /* 6770 * Renice negative nice level userspace 6771 * tasks back to 0: 6772 */ 6773 if (TASK_NICE(p) < 0 && p->mm) 6774 set_user_nice(p, 0); 6775 continue; 6776 } 6777 6778 raw_spin_lock(&p->pi_lock); 6779 rq = __task_rq_lock(p); 6780 6781 normalize_task(rq, p); 6782 6783 __task_rq_unlock(rq); 6784 raw_spin_unlock(&p->pi_lock); 6785 } while_each_thread(g, p); 6786 6787 read_unlock_irqrestore(&tasklist_lock, flags); 6788} 6789 6790#endif /* CONFIG_MAGIC_SYSRQ */ 6791 6792#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) 6793/* 6794 * These functions are only useful for the IA64 MCA handling, or kdb. 6795 * 6796 * They can only be called when the whole system has been 6797 * stopped - every CPU needs to be quiescent, and no scheduling 6798 * activity can take place. Using them for anything else would 6799 * be a serious bug, and as a result, they aren't even visible 6800 * under any other configuration. 6801 */ 6802 6803/** 6804 * curr_task - return the current task for a given cpu. 6805 * @cpu: the processor in question. 6806 * 6807 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 6808 * 6809 * Return: The current task for @cpu. 6810 */ 6811struct task_struct *curr_task(int cpu) 6812{ 6813 return cpu_curr(cpu); 6814} 6815 6816#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ 6817 6818#ifdef CONFIG_IA64 6819/** 6820 * set_curr_task - set the current task for a given cpu. 6821 * @cpu: the processor in question. 6822 * @p: the task pointer to set. 6823 * 6824 * Description: This function must only be used when non-maskable interrupts 6825 * are serviced on a separate stack. It allows the architecture to switch the 6826 * notion of the current task on a cpu in a non-blocking manner. This function 6827 * must be called with all CPU's synchronized, and interrupts disabled, the 6828 * and caller must save the original value of the current task (see 6829 * curr_task() above) and restore that value before reenabling interrupts and 6830 * re-starting the system. 6831 * 6832 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 6833 */ 6834void set_curr_task(int cpu, struct task_struct *p) 6835{ 6836 cpu_curr(cpu) = p; 6837} 6838 6839#endif 6840 6841#ifdef CONFIG_CGROUP_SCHED 6842/* task_group_lock serializes the addition/removal of task groups */ 6843static DEFINE_SPINLOCK(task_group_lock); 6844 6845static void free_sched_group(struct task_group *tg) 6846{ 6847 free_fair_sched_group(tg); 6848 free_rt_sched_group(tg); 6849 autogroup_free(tg); 6850 kfree(tg); 6851} 6852 6853/* allocate runqueue etc for a new task group */ 6854struct task_group *sched_create_group(struct task_group *parent) 6855{ 6856 struct task_group *tg; 6857 6858 tg = kzalloc(sizeof(*tg), GFP_KERNEL); 6859 if (!tg) 6860 return ERR_PTR(-ENOMEM); 6861 6862 if (!alloc_fair_sched_group(tg, parent)) 6863 goto err; 6864 6865 if (!alloc_rt_sched_group(tg, parent)) 6866 goto err; 6867 6868 return tg; 6869 6870err: 6871 free_sched_group(tg); 6872 return ERR_PTR(-ENOMEM); 6873} 6874 6875void sched_online_group(struct task_group *tg, struct task_group *parent) 6876{ 6877 unsigned long flags; 6878 6879 spin_lock_irqsave(&task_group_lock, flags); 6880 list_add_rcu(&tg->list, &task_groups); 6881 6882 WARN_ON(!parent); /* root should already exist */ 6883 6884 tg->parent = parent; 6885 INIT_LIST_HEAD(&tg->children); 6886 list_add_rcu(&tg->siblings, &parent->children); 6887 spin_unlock_irqrestore(&task_group_lock, flags); 6888} 6889 6890/* rcu callback to free various structures associated with a task group */ 6891static void free_sched_group_rcu(struct rcu_head *rhp) 6892{ 6893 /* now it should be safe to free those cfs_rqs */ 6894 free_sched_group(container_of(rhp, struct task_group, rcu)); 6895} 6896 6897/* Destroy runqueue etc associated with a task group */ 6898void sched_destroy_group(struct task_group *tg) 6899{ 6900 /* wait for possible concurrent references to cfs_rqs complete */ 6901 call_rcu(&tg->rcu, free_sched_group_rcu); 6902} 6903 6904void sched_offline_group(struct task_group *tg) 6905{ 6906 unsigned long flags; 6907 int i; 6908 6909 /* end participation in shares distribution */ 6910 for_each_possible_cpu(i) 6911 unregister_fair_sched_group(tg, i); 6912 6913 spin_lock_irqsave(&task_group_lock, flags); 6914 list_del_rcu(&tg->list); 6915 list_del_rcu(&tg->siblings); 6916 spin_unlock_irqrestore(&task_group_lock, flags); 6917} 6918 6919/* change task's runqueue when it moves between groups. 6920 * The caller of this function should have put the task in its new group 6921 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to 6922 * reflect its new group. 6923 */ 6924void sched_move_task(struct task_struct *tsk) 6925{ 6926 struct task_group *tg; 6927 int on_rq, running; 6928 unsigned long flags; 6929 struct rq *rq; 6930 6931 rq = task_rq_lock(tsk, &flags); 6932 6933 running = task_current(rq, tsk); 6934 on_rq = tsk->on_rq; 6935 6936 if (on_rq) 6937 dequeue_task(rq, tsk, 0); 6938 if (unlikely(running)) 6939 tsk->sched_class->put_prev_task(rq, tsk); 6940 6941 tg = container_of(task_css_check(tsk, cpu_cgroup_subsys_id, 6942 lockdep_is_held(&tsk->sighand->siglock)), 6943 struct task_group, css); 6944 tg = autogroup_task_group(tsk, tg); 6945 tsk->sched_task_group = tg; 6946 6947#ifdef CONFIG_FAIR_GROUP_SCHED 6948 if (tsk->sched_class->task_move_group) 6949 tsk->sched_class->task_move_group(tsk, on_rq); 6950 else 6951#endif 6952 set_task_rq(tsk, task_cpu(tsk)); 6953 6954 if (unlikely(running)) 6955 tsk->sched_class->set_curr_task(rq); 6956 if (on_rq) 6957 enqueue_task(rq, tsk, 0); 6958 6959 task_rq_unlock(rq, tsk, &flags); 6960} 6961#endif /* CONFIG_CGROUP_SCHED */ 6962 6963#if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH) 6964static unsigned long to_ratio(u64 period, u64 runtime) 6965{ 6966 if (runtime == RUNTIME_INF) 6967 return 1ULL << 20; 6968 6969 return div64_u64(runtime << 20, period); 6970} 6971#endif 6972 6973#ifdef CONFIG_RT_GROUP_SCHED 6974/* 6975 * Ensure that the real time constraints are schedulable. 6976 */ 6977static DEFINE_MUTEX(rt_constraints_mutex); 6978 6979/* Must be called with tasklist_lock held */ 6980static inline int tg_has_rt_tasks(struct task_group *tg) 6981{ 6982 struct task_struct *g, *p; 6983 6984 do_each_thread(g, p) { 6985 if (rt_task(p) && task_rq(p)->rt.tg == tg) 6986 return 1; 6987 } while_each_thread(g, p); 6988 6989 return 0; 6990} 6991 6992struct rt_schedulable_data { 6993 struct task_group *tg; 6994 u64 rt_period; 6995 u64 rt_runtime; 6996}; 6997 6998static int tg_rt_schedulable(struct task_group *tg, void *data) 6999{ 7000 struct rt_schedulable_data *d = data; 7001 struct task_group *child; 7002 unsigned long total, sum = 0; 7003 u64 period, runtime; 7004 7005 period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7006 runtime = tg->rt_bandwidth.rt_runtime; 7007 7008 if (tg == d->tg) { 7009 period = d->rt_period; 7010 runtime = d->rt_runtime; 7011 } 7012 7013 /* 7014 * Cannot have more runtime than the period. 7015 */ 7016 if (runtime > period && runtime != RUNTIME_INF) 7017 return -EINVAL; 7018 7019 /* 7020 * Ensure we don't starve existing RT tasks. 7021 */ 7022 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg)) 7023 return -EBUSY; 7024 7025 total = to_ratio(period, runtime); 7026 7027 /* 7028 * Nobody can have more than the global setting allows. 7029 */ 7030 if (total > to_ratio(global_rt_period(), global_rt_runtime())) 7031 return -EINVAL; 7032 7033 /* 7034 * The sum of our children's runtime should not exceed our own. 7035 */ 7036 list_for_each_entry_rcu(child, &tg->children, siblings) { 7037 period = ktime_to_ns(child->rt_bandwidth.rt_period); 7038 runtime = child->rt_bandwidth.rt_runtime; 7039 7040 if (child == d->tg) { 7041 period = d->rt_period; 7042 runtime = d->rt_runtime; 7043 } 7044 7045 sum += to_ratio(period, runtime); 7046 } 7047 7048 if (sum > total) 7049 return -EINVAL; 7050 7051 return 0; 7052} 7053 7054static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime) 7055{ 7056 int ret; 7057 7058 struct rt_schedulable_data data = { 7059 .tg = tg, 7060 .rt_period = period, 7061 .rt_runtime = runtime, 7062 }; 7063 7064 rcu_read_lock(); 7065 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data); 7066 rcu_read_unlock(); 7067 7068 return ret; 7069} 7070 7071static int tg_set_rt_bandwidth(struct task_group *tg, 7072 u64 rt_period, u64 rt_runtime) 7073{ 7074 int i, err = 0; 7075 7076 mutex_lock(&rt_constraints_mutex); 7077 read_lock(&tasklist_lock); 7078 err = __rt_schedulable(tg, rt_period, rt_runtime); 7079 if (err) 7080 goto unlock; 7081 7082 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7083 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period); 7084 tg->rt_bandwidth.rt_runtime = rt_runtime; 7085 7086 for_each_possible_cpu(i) { 7087 struct rt_rq *rt_rq = tg->rt_rq[i]; 7088 7089 raw_spin_lock(&rt_rq->rt_runtime_lock); 7090 rt_rq->rt_runtime = rt_runtime; 7091 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7092 } 7093 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7094unlock: 7095 read_unlock(&tasklist_lock); 7096 mutex_unlock(&rt_constraints_mutex); 7097 7098 return err; 7099} 7100 7101static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) 7102{ 7103 u64 rt_runtime, rt_period; 7104 7105 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7106 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC; 7107 if (rt_runtime_us < 0) 7108 rt_runtime = RUNTIME_INF; 7109 7110 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7111} 7112 7113static long sched_group_rt_runtime(struct task_group *tg) 7114{ 7115 u64 rt_runtime_us; 7116 7117 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF) 7118 return -1; 7119 7120 rt_runtime_us = tg->rt_bandwidth.rt_runtime; 7121 do_div(rt_runtime_us, NSEC_PER_USEC); 7122 return rt_runtime_us; 7123} 7124 7125static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us) 7126{ 7127 u64 rt_runtime, rt_period; 7128 7129 rt_period = (u64)rt_period_us * NSEC_PER_USEC; 7130 rt_runtime = tg->rt_bandwidth.rt_runtime; 7131 7132 if (rt_period == 0) 7133 return -EINVAL; 7134 7135 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7136} 7137 7138static long sched_group_rt_period(struct task_group *tg) 7139{ 7140 u64 rt_period_us; 7141 7142 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period); 7143 do_div(rt_period_us, NSEC_PER_USEC); 7144 return rt_period_us; 7145} 7146 7147static int sched_rt_global_constraints(void) 7148{ 7149 u64 runtime, period; 7150 int ret = 0; 7151 7152 if (sysctl_sched_rt_period <= 0) 7153 return -EINVAL; 7154 7155 runtime = global_rt_runtime(); 7156 period = global_rt_period(); 7157 7158 /* 7159 * Sanity check on the sysctl variables. 7160 */ 7161 if (runtime > period && runtime != RUNTIME_INF) 7162 return -EINVAL; 7163 7164 mutex_lock(&rt_constraints_mutex); 7165 read_lock(&tasklist_lock); 7166 ret = __rt_schedulable(NULL, 0, 0); 7167 read_unlock(&tasklist_lock); 7168 mutex_unlock(&rt_constraints_mutex); 7169 7170 return ret; 7171} 7172 7173static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk) 7174{ 7175 /* Don't accept realtime tasks when there is no way for them to run */ 7176 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0) 7177 return 0; 7178 7179 return 1; 7180} 7181 7182#else /* !CONFIG_RT_GROUP_SCHED */ 7183static int sched_rt_global_constraints(void) 7184{ 7185 unsigned long flags; 7186 int i; 7187 7188 if (sysctl_sched_rt_period <= 0) 7189 return -EINVAL; 7190 7191 /* 7192 * There's always some RT tasks in the root group 7193 * -- migration, kstopmachine etc.. 7194 */ 7195 if (sysctl_sched_rt_runtime == 0) 7196 return -EBUSY; 7197 7198 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags); 7199 for_each_possible_cpu(i) { 7200 struct rt_rq *rt_rq = &cpu_rq(i)->rt; 7201 7202 raw_spin_lock(&rt_rq->rt_runtime_lock); 7203 rt_rq->rt_runtime = global_rt_runtime(); 7204 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7205 } 7206 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags); 7207 7208 return 0; 7209} 7210#endif /* CONFIG_RT_GROUP_SCHED */ 7211 7212int sched_rr_handler(struct ctl_table *table, int write, 7213 void __user *buffer, size_t *lenp, 7214 loff_t *ppos) 7215{ 7216 int ret; 7217 static DEFINE_MUTEX(mutex); 7218 7219 mutex_lock(&mutex); 7220 ret = proc_dointvec(table, write, buffer, lenp, ppos); 7221 /* make sure that internally we keep jiffies */ 7222 /* also, writing zero resets timeslice to default */ 7223 if (!ret && write) { 7224 sched_rr_timeslice = sched_rr_timeslice <= 0 ? 7225 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice); 7226 } 7227 mutex_unlock(&mutex); 7228 return ret; 7229} 7230 7231int sched_rt_handler(struct ctl_table *table, int write, 7232 void __user *buffer, size_t *lenp, 7233 loff_t *ppos) 7234{ 7235 int ret; 7236 int old_period, old_runtime; 7237 static DEFINE_MUTEX(mutex); 7238 7239 mutex_lock(&mutex); 7240 old_period = sysctl_sched_rt_period; 7241 old_runtime = sysctl_sched_rt_runtime; 7242 7243 ret = proc_dointvec(table, write, buffer, lenp, ppos); 7244 7245 if (!ret && write) { 7246 ret = sched_rt_global_constraints(); 7247 if (ret) { 7248 sysctl_sched_rt_period = old_period; 7249 sysctl_sched_rt_runtime = old_runtime; 7250 } else { 7251 def_rt_bandwidth.rt_runtime = global_rt_runtime(); 7252 def_rt_bandwidth.rt_period = 7253 ns_to_ktime(global_rt_period()); 7254 } 7255 } 7256 mutex_unlock(&mutex); 7257 7258 return ret; 7259} 7260 7261#ifdef CONFIG_CGROUP_SCHED 7262 7263static inline struct task_group *css_tg(struct cgroup_subsys_state *css) 7264{ 7265 return css ? container_of(css, struct task_group, css) : NULL; 7266} 7267 7268static struct cgroup_subsys_state * 7269cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) 7270{ 7271 struct task_group *parent = css_tg(parent_css); 7272 struct task_group *tg; 7273 7274 if (!parent) { 7275 /* This is early initialization for the top cgroup */ 7276 return &root_task_group.css; 7277 } 7278 7279 tg = sched_create_group(parent); 7280 if (IS_ERR(tg)) 7281 return ERR_PTR(-ENOMEM); 7282 7283 return &tg->css; 7284} 7285 7286static int cpu_cgroup_css_online(struct cgroup_subsys_state *css) 7287{ 7288 struct task_group *tg = css_tg(css); 7289 struct task_group *parent = css_tg(css_parent(css)); 7290 7291 if (parent) 7292 sched_online_group(tg, parent); 7293 return 0; 7294} 7295 7296static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) 7297{ 7298 struct task_group *tg = css_tg(css); 7299 7300 sched_destroy_group(tg); 7301} 7302 7303static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css) 7304{ 7305 struct task_group *tg = css_tg(css); 7306 7307 sched_offline_group(tg); 7308} 7309 7310static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css, 7311 struct cgroup_taskset *tset) 7312{ 7313 struct task_struct *task; 7314 7315 cgroup_taskset_for_each(task, css, tset) { 7316#ifdef CONFIG_RT_GROUP_SCHED 7317 if (!sched_rt_can_attach(css_tg(css), task)) 7318 return -EINVAL; 7319#else 7320 /* We don't support RT-tasks being in separate groups */ 7321 if (task->sched_class != &fair_sched_class) 7322 return -EINVAL; 7323#endif 7324 } 7325 return 0; 7326} 7327 7328static void cpu_cgroup_attach(struct cgroup_subsys_state *css, 7329 struct cgroup_taskset *tset) 7330{ 7331 struct task_struct *task; 7332 7333 cgroup_taskset_for_each(task, css, tset) 7334 sched_move_task(task); 7335} 7336 7337static void cpu_cgroup_exit(struct cgroup_subsys_state *css, 7338 struct cgroup_subsys_state *old_css, 7339 struct task_struct *task) 7340{ 7341 /* 7342 * cgroup_exit() is called in the copy_process() failure path. 7343 * Ignore this case since the task hasn't ran yet, this avoids 7344 * trying to poke a half freed task state from generic code. 7345 */ 7346 if (!(task->flags & PF_EXITING)) 7347 return; 7348 7349 sched_move_task(task); 7350} 7351 7352#ifdef CONFIG_FAIR_GROUP_SCHED 7353static int cpu_shares_write_u64(struct cgroup_subsys_state *css, 7354 struct cftype *cftype, u64 shareval) 7355{ 7356 return sched_group_set_shares(css_tg(css), scale_load(shareval)); 7357} 7358 7359static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, 7360 struct cftype *cft) 7361{ 7362 struct task_group *tg = css_tg(css); 7363 7364 return (u64) scale_load_down(tg->shares); 7365} 7366 7367#ifdef CONFIG_CFS_BANDWIDTH 7368static DEFINE_MUTEX(cfs_constraints_mutex); 7369 7370const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ 7371const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ 7372 7373static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); 7374 7375static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) 7376{ 7377 int i, ret = 0, runtime_enabled, runtime_was_enabled; 7378 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7379 7380 if (tg == &root_task_group) 7381 return -EINVAL; 7382 7383 /* 7384 * Ensure we have at some amount of bandwidth every period. This is 7385 * to prevent reaching a state of large arrears when throttled via 7386 * entity_tick() resulting in prolonged exit starvation. 7387 */ 7388 if (quota < min_cfs_quota_period || period < min_cfs_quota_period) 7389 return -EINVAL; 7390 7391 /* 7392 * Likewise, bound things on the otherside by preventing insane quota 7393 * periods. This also allows us to normalize in computing quota 7394 * feasibility. 7395 */ 7396 if (period > max_cfs_quota_period) 7397 return -EINVAL; 7398 7399 mutex_lock(&cfs_constraints_mutex); 7400 ret = __cfs_schedulable(tg, period, quota); 7401 if (ret) 7402 goto out_unlock; 7403 7404 runtime_enabled = quota != RUNTIME_INF; 7405 runtime_was_enabled = cfs_b->quota != RUNTIME_INF; 7406 account_cfs_bandwidth_used(runtime_enabled, runtime_was_enabled); 7407 raw_spin_lock_irq(&cfs_b->lock); 7408 cfs_b->period = ns_to_ktime(period); 7409 cfs_b->quota = quota; 7410 7411 __refill_cfs_bandwidth_runtime(cfs_b); 7412 /* restart the period timer (if active) to handle new period expiry */ 7413 if (runtime_enabled && cfs_b->timer_active) { 7414 /* force a reprogram */ 7415 cfs_b->timer_active = 0; 7416 __start_cfs_bandwidth(cfs_b); 7417 } 7418 raw_spin_unlock_irq(&cfs_b->lock); 7419 7420 for_each_possible_cpu(i) { 7421 struct cfs_rq *cfs_rq = tg->cfs_rq[i]; 7422 struct rq *rq = cfs_rq->rq; 7423 7424 raw_spin_lock_irq(&rq->lock); 7425 cfs_rq->runtime_enabled = runtime_enabled; 7426 cfs_rq->runtime_remaining = 0; 7427 7428 if (cfs_rq->throttled) 7429 unthrottle_cfs_rq(cfs_rq); 7430 raw_spin_unlock_irq(&rq->lock); 7431 } 7432out_unlock: 7433 mutex_unlock(&cfs_constraints_mutex); 7434 7435 return ret; 7436} 7437 7438int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) 7439{ 7440 u64 quota, period; 7441 7442 period = ktime_to_ns(tg->cfs_bandwidth.period); 7443 if (cfs_quota_us < 0) 7444 quota = RUNTIME_INF; 7445 else 7446 quota = (u64)cfs_quota_us * NSEC_PER_USEC; 7447 7448 return tg_set_cfs_bandwidth(tg, period, quota); 7449} 7450 7451long tg_get_cfs_quota(struct task_group *tg) 7452{ 7453 u64 quota_us; 7454 7455 if (tg->cfs_bandwidth.quota == RUNTIME_INF) 7456 return -1; 7457 7458 quota_us = tg->cfs_bandwidth.quota; 7459 do_div(quota_us, NSEC_PER_USEC); 7460 7461 return quota_us; 7462} 7463 7464int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) 7465{ 7466 u64 quota, period; 7467 7468 period = (u64)cfs_period_us * NSEC_PER_USEC; 7469 quota = tg->cfs_bandwidth.quota; 7470 7471 return tg_set_cfs_bandwidth(tg, period, quota); 7472} 7473 7474long tg_get_cfs_period(struct task_group *tg) 7475{ 7476 u64 cfs_period_us; 7477 7478 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); 7479 do_div(cfs_period_us, NSEC_PER_USEC); 7480 7481 return cfs_period_us; 7482} 7483 7484static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, 7485 struct cftype *cft) 7486{ 7487 return tg_get_cfs_quota(css_tg(css)); 7488} 7489 7490static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, 7491 struct cftype *cftype, s64 cfs_quota_us) 7492{ 7493 return tg_set_cfs_quota(css_tg(css), cfs_quota_us); 7494} 7495 7496static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, 7497 struct cftype *cft) 7498{ 7499 return tg_get_cfs_period(css_tg(css)); 7500} 7501 7502static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, 7503 struct cftype *cftype, u64 cfs_period_us) 7504{ 7505 return tg_set_cfs_period(css_tg(css), cfs_period_us); 7506} 7507 7508struct cfs_schedulable_data { 7509 struct task_group *tg; 7510 u64 period, quota; 7511}; 7512 7513/* 7514 * normalize group quota/period to be quota/max_period 7515 * note: units are usecs 7516 */ 7517static u64 normalize_cfs_quota(struct task_group *tg, 7518 struct cfs_schedulable_data *d) 7519{ 7520 u64 quota, period; 7521 7522 if (tg == d->tg) { 7523 period = d->period; 7524 quota = d->quota; 7525 } else { 7526 period = tg_get_cfs_period(tg); 7527 quota = tg_get_cfs_quota(tg); 7528 } 7529 7530 /* note: these should typically be equivalent */ 7531 if (quota == RUNTIME_INF || quota == -1) 7532 return RUNTIME_INF; 7533 7534 return to_ratio(period, quota); 7535} 7536 7537static int tg_cfs_schedulable_down(struct task_group *tg, void *data) 7538{ 7539 struct cfs_schedulable_data *d = data; 7540 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7541 s64 quota = 0, parent_quota = -1; 7542 7543 if (!tg->parent) { 7544 quota = RUNTIME_INF; 7545 } else { 7546 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; 7547 7548 quota = normalize_cfs_quota(tg, d); 7549 parent_quota = parent_b->hierarchal_quota; 7550 7551 /* 7552 * ensure max(child_quota) <= parent_quota, inherit when no 7553 * limit is set 7554 */ 7555 if (quota == RUNTIME_INF) 7556 quota = parent_quota; 7557 else if (parent_quota != RUNTIME_INF && quota > parent_quota) 7558 return -EINVAL; 7559 } 7560 cfs_b->hierarchal_quota = quota; 7561 7562 return 0; 7563} 7564 7565static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) 7566{ 7567 int ret; 7568 struct cfs_schedulable_data data = { 7569 .tg = tg, 7570 .period = period, 7571 .quota = quota, 7572 }; 7573 7574 if (quota != RUNTIME_INF) { 7575 do_div(data.period, NSEC_PER_USEC); 7576 do_div(data.quota, NSEC_PER_USEC); 7577 } 7578 7579 rcu_read_lock(); 7580 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); 7581 rcu_read_unlock(); 7582 7583 return ret; 7584} 7585 7586static int cpu_stats_show(struct cgroup_subsys_state *css, struct cftype *cft, 7587 struct cgroup_map_cb *cb) 7588{ 7589 struct task_group *tg = css_tg(css); 7590 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7591 7592 cb->fill(cb, "nr_periods", cfs_b->nr_periods); 7593 cb->fill(cb, "nr_throttled", cfs_b->nr_throttled); 7594 cb->fill(cb, "throttled_time", cfs_b->throttled_time); 7595 7596 return 0; 7597} 7598#endif /* CONFIG_CFS_BANDWIDTH */ 7599#endif /* CONFIG_FAIR_GROUP_SCHED */ 7600 7601#ifdef CONFIG_RT_GROUP_SCHED 7602static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, 7603 struct cftype *cft, s64 val) 7604{ 7605 return sched_group_set_rt_runtime(css_tg(css), val); 7606} 7607 7608static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, 7609 struct cftype *cft) 7610{ 7611 return sched_group_rt_runtime(css_tg(css)); 7612} 7613 7614static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, 7615 struct cftype *cftype, u64 rt_period_us) 7616{ 7617 return sched_group_set_rt_period(css_tg(css), rt_period_us); 7618} 7619 7620static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, 7621 struct cftype *cft) 7622{ 7623 return sched_group_rt_period(css_tg(css)); 7624} 7625#endif /* CONFIG_RT_GROUP_SCHED */ 7626 7627static struct cftype cpu_files[] = { 7628#ifdef CONFIG_FAIR_GROUP_SCHED 7629 { 7630 .name = "shares", 7631 .read_u64 = cpu_shares_read_u64, 7632 .write_u64 = cpu_shares_write_u64, 7633 }, 7634#endif 7635#ifdef CONFIG_CFS_BANDWIDTH 7636 { 7637 .name = "cfs_quota_us", 7638 .read_s64 = cpu_cfs_quota_read_s64, 7639 .write_s64 = cpu_cfs_quota_write_s64, 7640 }, 7641 { 7642 .name = "cfs_period_us", 7643 .read_u64 = cpu_cfs_period_read_u64, 7644 .write_u64 = cpu_cfs_period_write_u64, 7645 }, 7646 { 7647 .name = "stat", 7648 .read_map = cpu_stats_show, 7649 }, 7650#endif 7651#ifdef CONFIG_RT_GROUP_SCHED 7652 { 7653 .name = "rt_runtime_us", 7654 .read_s64 = cpu_rt_runtime_read, 7655 .write_s64 = cpu_rt_runtime_write, 7656 }, 7657 { 7658 .name = "rt_period_us", 7659 .read_u64 = cpu_rt_period_read_uint, 7660 .write_u64 = cpu_rt_period_write_uint, 7661 }, 7662#endif 7663 { } /* terminate */ 7664}; 7665 7666struct cgroup_subsys cpu_cgroup_subsys = { 7667 .name = "cpu", 7668 .css_alloc = cpu_cgroup_css_alloc, 7669 .css_free = cpu_cgroup_css_free, 7670 .css_online = cpu_cgroup_css_online, 7671 .css_offline = cpu_cgroup_css_offline, 7672 .can_attach = cpu_cgroup_can_attach, 7673 .attach = cpu_cgroup_attach, 7674 .exit = cpu_cgroup_exit, 7675 .subsys_id = cpu_cgroup_subsys_id, 7676 .base_cftypes = cpu_files, 7677 .early_init = 1, 7678}; 7679 7680#endif /* CONFIG_CGROUP_SCHED */ 7681 7682void dump_cpu_task(int cpu) 7683{ 7684 pr_info("Task dump for CPU %d:\n", cpu); 7685 sched_show_task(cpu_curr(cpu)); 7686} 7687