core.c revision 4314895165623879937f46d767673654662b570c
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 */ 516#ifdef CONFIG_SMP 517void resched_task(struct task_struct *p) 518{ 519 int cpu; 520 521 assert_raw_spin_locked(&task_rq(p)->lock); 522 523 if (test_tsk_need_resched(p)) 524 return; 525 526 set_tsk_need_resched(p); 527 528 cpu = task_cpu(p); 529 if (cpu == smp_processor_id()) 530 return; 531 532 /* NEED_RESCHED must be visible before we test polling */ 533 smp_mb(); 534 if (!tsk_is_polling(p)) 535 smp_send_reschedule(cpu); 536} 537 538void resched_cpu(int cpu) 539{ 540 struct rq *rq = cpu_rq(cpu); 541 unsigned long flags; 542 543 if (!raw_spin_trylock_irqsave(&rq->lock, flags)) 544 return; 545 resched_task(cpu_curr(cpu)); 546 raw_spin_unlock_irqrestore(&rq->lock, flags); 547} 548 549#ifdef CONFIG_NO_HZ_COMMON 550/* 551 * In the semi idle case, use the nearest busy cpu for migrating timers 552 * from an idle cpu. This is good for power-savings. 553 * 554 * We don't do similar optimization for completely idle system, as 555 * selecting an idle cpu will add more delays to the timers than intended 556 * (as that cpu's timer base may not be uptodate wrt jiffies etc). 557 */ 558int get_nohz_timer_target(void) 559{ 560 int cpu = smp_processor_id(); 561 int i; 562 struct sched_domain *sd; 563 564 rcu_read_lock(); 565 for_each_domain(cpu, sd) { 566 for_each_cpu(i, sched_domain_span(sd)) { 567 if (!idle_cpu(i)) { 568 cpu = i; 569 goto unlock; 570 } 571 } 572 } 573unlock: 574 rcu_read_unlock(); 575 return cpu; 576} 577/* 578 * When add_timer_on() enqueues a timer into the timer wheel of an 579 * idle CPU then this timer might expire before the next timer event 580 * which is scheduled to wake up that CPU. In case of a completely 581 * idle system the next event might even be infinite time into the 582 * future. wake_up_idle_cpu() ensures that the CPU is woken up and 583 * leaves the inner idle loop so the newly added timer is taken into 584 * account when the CPU goes back to idle and evaluates the timer 585 * wheel for the next timer event. 586 */ 587static void wake_up_idle_cpu(int cpu) 588{ 589 struct rq *rq = cpu_rq(cpu); 590 591 if (cpu == smp_processor_id()) 592 return; 593 594 /* 595 * This is safe, as this function is called with the timer 596 * wheel base lock of (cpu) held. When the CPU is on the way 597 * to idle and has not yet set rq->curr to idle then it will 598 * be serialized on the timer wheel base lock and take the new 599 * timer into account automatically. 600 */ 601 if (rq->curr != rq->idle) 602 return; 603 604 /* 605 * We can set TIF_RESCHED on the idle task of the other CPU 606 * lockless. The worst case is that the other CPU runs the 607 * idle task through an additional NOOP schedule() 608 */ 609 set_tsk_need_resched(rq->idle); 610 611 /* NEED_RESCHED must be visible before we test polling */ 612 smp_mb(); 613 if (!tsk_is_polling(rq->idle)) 614 smp_send_reschedule(cpu); 615} 616 617static bool wake_up_full_nohz_cpu(int cpu) 618{ 619 if (tick_nohz_full_cpu(cpu)) { 620 if (cpu != smp_processor_id() || 621 tick_nohz_tick_stopped()) 622 smp_send_reschedule(cpu); 623 return true; 624 } 625 626 return false; 627} 628 629void wake_up_nohz_cpu(int cpu) 630{ 631 if (!wake_up_full_nohz_cpu(cpu)) 632 wake_up_idle_cpu(cpu); 633} 634 635static inline bool got_nohz_idle_kick(void) 636{ 637 int cpu = smp_processor_id(); 638 639 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu))) 640 return false; 641 642 if (idle_cpu(cpu) && !need_resched()) 643 return true; 644 645 /* 646 * We can't run Idle Load Balance on this CPU for this time so we 647 * cancel it and clear NOHZ_BALANCE_KICK 648 */ 649 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); 650 return false; 651} 652 653#else /* CONFIG_NO_HZ_COMMON */ 654 655static inline bool got_nohz_idle_kick(void) 656{ 657 return false; 658} 659 660#endif /* CONFIG_NO_HZ_COMMON */ 661 662#ifdef CONFIG_NO_HZ_FULL 663bool sched_can_stop_tick(void) 664{ 665 struct rq *rq; 666 667 rq = this_rq(); 668 669 /* Make sure rq->nr_running update is visible after the IPI */ 670 smp_rmb(); 671 672 /* More than one running task need preemption */ 673 if (rq->nr_running > 1) 674 return false; 675 676 return true; 677} 678#endif /* CONFIG_NO_HZ_FULL */ 679 680void sched_avg_update(struct rq *rq) 681{ 682 s64 period = sched_avg_period(); 683 684 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) { 685 /* 686 * Inline assembly required to prevent the compiler 687 * optimising this loop into a divmod call. 688 * See __iter_div_u64_rem() for another example of this. 689 */ 690 asm("" : "+rm" (rq->age_stamp)); 691 rq->age_stamp += period; 692 rq->rt_avg /= 2; 693 } 694} 695 696#else /* !CONFIG_SMP */ 697void resched_task(struct task_struct *p) 698{ 699 assert_raw_spin_locked(&task_rq(p)->lock); 700 set_tsk_need_resched(p); 701} 702#endif /* CONFIG_SMP */ 703 704#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ 705 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) 706/* 707 * Iterate task_group tree rooted at *from, calling @down when first entering a 708 * node and @up when leaving it for the final time. 709 * 710 * Caller must hold rcu_lock or sufficient equivalent. 711 */ 712int walk_tg_tree_from(struct task_group *from, 713 tg_visitor down, tg_visitor up, void *data) 714{ 715 struct task_group *parent, *child; 716 int ret; 717 718 parent = from; 719 720down: 721 ret = (*down)(parent, data); 722 if (ret) 723 goto out; 724 list_for_each_entry_rcu(child, &parent->children, siblings) { 725 parent = child; 726 goto down; 727 728up: 729 continue; 730 } 731 ret = (*up)(parent, data); 732 if (ret || parent == from) 733 goto out; 734 735 child = parent; 736 parent = parent->parent; 737 if (parent) 738 goto up; 739out: 740 return ret; 741} 742 743int tg_nop(struct task_group *tg, void *data) 744{ 745 return 0; 746} 747#endif 748 749static void set_load_weight(struct task_struct *p) 750{ 751 int prio = p->static_prio - MAX_RT_PRIO; 752 struct load_weight *load = &p->se.load; 753 754 /* 755 * SCHED_IDLE tasks get minimal weight: 756 */ 757 if (p->policy == SCHED_IDLE) { 758 load->weight = scale_load(WEIGHT_IDLEPRIO); 759 load->inv_weight = WMULT_IDLEPRIO; 760 return; 761 } 762 763 load->weight = scale_load(prio_to_weight[prio]); 764 load->inv_weight = prio_to_wmult[prio]; 765} 766 767static void enqueue_task(struct rq *rq, struct task_struct *p, int flags) 768{ 769 update_rq_clock(rq); 770 sched_info_queued(rq, p); 771 p->sched_class->enqueue_task(rq, p, flags); 772} 773 774static void dequeue_task(struct rq *rq, struct task_struct *p, int flags) 775{ 776 update_rq_clock(rq); 777 sched_info_dequeued(rq, p); 778 p->sched_class->dequeue_task(rq, p, flags); 779} 780 781void activate_task(struct rq *rq, struct task_struct *p, int flags) 782{ 783 if (task_contributes_to_load(p)) 784 rq->nr_uninterruptible--; 785 786 enqueue_task(rq, p, flags); 787} 788 789void deactivate_task(struct rq *rq, struct task_struct *p, int flags) 790{ 791 if (task_contributes_to_load(p)) 792 rq->nr_uninterruptible++; 793 794 dequeue_task(rq, p, flags); 795} 796 797static void update_rq_clock_task(struct rq *rq, s64 delta) 798{ 799/* 800 * In theory, the compile should just see 0 here, and optimize out the call 801 * to sched_rt_avg_update. But I don't trust it... 802 */ 803#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 804 s64 steal = 0, irq_delta = 0; 805#endif 806#ifdef CONFIG_IRQ_TIME_ACCOUNTING 807 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; 808 809 /* 810 * Since irq_time is only updated on {soft,}irq_exit, we might run into 811 * this case when a previous update_rq_clock() happened inside a 812 * {soft,}irq region. 813 * 814 * When this happens, we stop ->clock_task and only update the 815 * prev_irq_time stamp to account for the part that fit, so that a next 816 * update will consume the rest. This ensures ->clock_task is 817 * monotonic. 818 * 819 * It does however cause some slight miss-attribution of {soft,}irq 820 * time, a more accurate solution would be to update the irq_time using 821 * the current rq->clock timestamp, except that would require using 822 * atomic ops. 823 */ 824 if (irq_delta > delta) 825 irq_delta = delta; 826 827 rq->prev_irq_time += irq_delta; 828 delta -= irq_delta; 829#endif 830#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING 831 if (static_key_false((¶virt_steal_rq_enabled))) { 832 u64 st; 833 834 steal = paravirt_steal_clock(cpu_of(rq)); 835 steal -= rq->prev_steal_time_rq; 836 837 if (unlikely(steal > delta)) 838 steal = delta; 839 840 st = steal_ticks(steal); 841 steal = st * TICK_NSEC; 842 843 rq->prev_steal_time_rq += steal; 844 845 delta -= steal; 846 } 847#endif 848 849 rq->clock_task += delta; 850 851#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 852 if ((irq_delta + steal) && sched_feat(NONTASK_POWER)) 853 sched_rt_avg_update(rq, irq_delta + steal); 854#endif 855} 856 857void sched_set_stop_task(int cpu, struct task_struct *stop) 858{ 859 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; 860 struct task_struct *old_stop = cpu_rq(cpu)->stop; 861 862 if (stop) { 863 /* 864 * Make it appear like a SCHED_FIFO task, its something 865 * userspace knows about and won't get confused about. 866 * 867 * Also, it will make PI more or less work without too 868 * much confusion -- but then, stop work should not 869 * rely on PI working anyway. 870 */ 871 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); 872 873 stop->sched_class = &stop_sched_class; 874 } 875 876 cpu_rq(cpu)->stop = stop; 877 878 if (old_stop) { 879 /* 880 * Reset it back to a normal scheduling class so that 881 * it can die in pieces. 882 */ 883 old_stop->sched_class = &rt_sched_class; 884 } 885} 886 887/* 888 * __normal_prio - return the priority that is based on the static prio 889 */ 890static inline int __normal_prio(struct task_struct *p) 891{ 892 return p->static_prio; 893} 894 895/* 896 * Calculate the expected normal priority: i.e. priority 897 * without taking RT-inheritance into account. Might be 898 * boosted by interactivity modifiers. Changes upon fork, 899 * setprio syscalls, and whenever the interactivity 900 * estimator recalculates. 901 */ 902static inline int normal_prio(struct task_struct *p) 903{ 904 int prio; 905 906 if (task_has_rt_policy(p)) 907 prio = MAX_RT_PRIO-1 - p->rt_priority; 908 else 909 prio = __normal_prio(p); 910 return prio; 911} 912 913/* 914 * Calculate the current priority, i.e. the priority 915 * taken into account by the scheduler. This value might 916 * be boosted by RT tasks, or might be boosted by 917 * interactivity modifiers. Will be RT if the task got 918 * RT-boosted. If not then it returns p->normal_prio. 919 */ 920static int effective_prio(struct task_struct *p) 921{ 922 p->normal_prio = normal_prio(p); 923 /* 924 * If we are RT tasks or we were boosted to RT priority, 925 * keep the priority unchanged. Otherwise, update priority 926 * to the normal priority: 927 */ 928 if (!rt_prio(p->prio)) 929 return p->normal_prio; 930 return p->prio; 931} 932 933/** 934 * task_curr - is this task currently executing on a CPU? 935 * @p: the task in question. 936 * 937 * Return: 1 if the task is currently executing. 0 otherwise. 938 */ 939inline int task_curr(const struct task_struct *p) 940{ 941 return cpu_curr(task_cpu(p)) == p; 942} 943 944static inline void check_class_changed(struct rq *rq, struct task_struct *p, 945 const struct sched_class *prev_class, 946 int oldprio) 947{ 948 if (prev_class != p->sched_class) { 949 if (prev_class->switched_from) 950 prev_class->switched_from(rq, p); 951 p->sched_class->switched_to(rq, p); 952 } else if (oldprio != p->prio) 953 p->sched_class->prio_changed(rq, p, oldprio); 954} 955 956void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) 957{ 958 const struct sched_class *class; 959 960 if (p->sched_class == rq->curr->sched_class) { 961 rq->curr->sched_class->check_preempt_curr(rq, p, flags); 962 } else { 963 for_each_class(class) { 964 if (class == rq->curr->sched_class) 965 break; 966 if (class == p->sched_class) { 967 resched_task(rq->curr); 968 break; 969 } 970 } 971 } 972 973 /* 974 * A queue event has occurred, and we're going to schedule. In 975 * this case, we can save a useless back to back clock update. 976 */ 977 if (rq->curr->on_rq && test_tsk_need_resched(rq->curr)) 978 rq->skip_clock_update = 1; 979} 980 981#ifdef CONFIG_SMP 982void set_task_cpu(struct task_struct *p, unsigned int new_cpu) 983{ 984#ifdef CONFIG_SCHED_DEBUG 985 /* 986 * We should never call set_task_cpu() on a blocked task, 987 * ttwu() will sort out the placement. 988 */ 989 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && 990 !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)); 991 992#ifdef CONFIG_LOCKDEP 993 /* 994 * The caller should hold either p->pi_lock or rq->lock, when changing 995 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. 996 * 997 * sched_move_task() holds both and thus holding either pins the cgroup, 998 * see task_group(). 999 * 1000 * Furthermore, all task_rq users should acquire both locks, see 1001 * task_rq_lock(). 1002 */ 1003 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || 1004 lockdep_is_held(&task_rq(p)->lock))); 1005#endif 1006#endif 1007 1008 trace_sched_migrate_task(p, new_cpu); 1009 1010 if (task_cpu(p) != new_cpu) { 1011 if (p->sched_class->migrate_task_rq) 1012 p->sched_class->migrate_task_rq(p, new_cpu); 1013 p->se.nr_migrations++; 1014 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0); 1015 } 1016 1017 __set_task_cpu(p, new_cpu); 1018} 1019 1020struct migration_arg { 1021 struct task_struct *task; 1022 int dest_cpu; 1023}; 1024 1025static int migration_cpu_stop(void *data); 1026 1027/* 1028 * wait_task_inactive - wait for a thread to unschedule. 1029 * 1030 * If @match_state is nonzero, it's the @p->state value just checked and 1031 * not expected to change. If it changes, i.e. @p might have woken up, 1032 * then return zero. When we succeed in waiting for @p to be off its CPU, 1033 * we return a positive number (its total switch count). If a second call 1034 * a short while later returns the same number, the caller can be sure that 1035 * @p has remained unscheduled the whole time. 1036 * 1037 * The caller must ensure that the task *will* unschedule sometime soon, 1038 * else this function might spin for a *long* time. This function can't 1039 * be called with interrupts off, or it may introduce deadlock with 1040 * smp_call_function() if an IPI is sent by the same process we are 1041 * waiting to become inactive. 1042 */ 1043unsigned long wait_task_inactive(struct task_struct *p, long match_state) 1044{ 1045 unsigned long flags; 1046 int running, on_rq; 1047 unsigned long ncsw; 1048 struct rq *rq; 1049 1050 for (;;) { 1051 /* 1052 * We do the initial early heuristics without holding 1053 * any task-queue locks at all. We'll only try to get 1054 * the runqueue lock when things look like they will 1055 * work out! 1056 */ 1057 rq = task_rq(p); 1058 1059 /* 1060 * If the task is actively running on another CPU 1061 * still, just relax and busy-wait without holding 1062 * any locks. 1063 * 1064 * NOTE! Since we don't hold any locks, it's not 1065 * even sure that "rq" stays as the right runqueue! 1066 * But we don't care, since "task_running()" will 1067 * return false if the runqueue has changed and p 1068 * is actually now running somewhere else! 1069 */ 1070 while (task_running(rq, p)) { 1071 if (match_state && unlikely(p->state != match_state)) 1072 return 0; 1073 cpu_relax(); 1074 } 1075 1076 /* 1077 * Ok, time to look more closely! We need the rq 1078 * lock now, to be *sure*. If we're wrong, we'll 1079 * just go back and repeat. 1080 */ 1081 rq = task_rq_lock(p, &flags); 1082 trace_sched_wait_task(p); 1083 running = task_running(rq, p); 1084 on_rq = p->on_rq; 1085 ncsw = 0; 1086 if (!match_state || p->state == match_state) 1087 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ 1088 task_rq_unlock(rq, p, &flags); 1089 1090 /* 1091 * If it changed from the expected state, bail out now. 1092 */ 1093 if (unlikely(!ncsw)) 1094 break; 1095 1096 /* 1097 * Was it really running after all now that we 1098 * checked with the proper locks actually held? 1099 * 1100 * Oops. Go back and try again.. 1101 */ 1102 if (unlikely(running)) { 1103 cpu_relax(); 1104 continue; 1105 } 1106 1107 /* 1108 * It's not enough that it's not actively running, 1109 * it must be off the runqueue _entirely_, and not 1110 * preempted! 1111 * 1112 * So if it was still runnable (but just not actively 1113 * running right now), it's preempted, and we should 1114 * yield - it could be a while. 1115 */ 1116 if (unlikely(on_rq)) { 1117 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ); 1118 1119 set_current_state(TASK_UNINTERRUPTIBLE); 1120 schedule_hrtimeout(&to, HRTIMER_MODE_REL); 1121 continue; 1122 } 1123 1124 /* 1125 * Ahh, all good. It wasn't running, and it wasn't 1126 * runnable, which means that it will never become 1127 * running in the future either. We're all done! 1128 */ 1129 break; 1130 } 1131 1132 return ncsw; 1133} 1134 1135/*** 1136 * kick_process - kick a running thread to enter/exit the kernel 1137 * @p: the to-be-kicked thread 1138 * 1139 * Cause a process which is running on another CPU to enter 1140 * kernel-mode, without any delay. (to get signals handled.) 1141 * 1142 * NOTE: this function doesn't have to take the runqueue lock, 1143 * because all it wants to ensure is that the remote task enters 1144 * the kernel. If the IPI races and the task has been migrated 1145 * to another CPU then no harm is done and the purpose has been 1146 * achieved as well. 1147 */ 1148void kick_process(struct task_struct *p) 1149{ 1150 int cpu; 1151 1152 preempt_disable(); 1153 cpu = task_cpu(p); 1154 if ((cpu != smp_processor_id()) && task_curr(p)) 1155 smp_send_reschedule(cpu); 1156 preempt_enable(); 1157} 1158EXPORT_SYMBOL_GPL(kick_process); 1159#endif /* CONFIG_SMP */ 1160 1161#ifdef CONFIG_SMP 1162/* 1163 * ->cpus_allowed is protected by both rq->lock and p->pi_lock 1164 */ 1165static int select_fallback_rq(int cpu, struct task_struct *p) 1166{ 1167 int nid = cpu_to_node(cpu); 1168 const struct cpumask *nodemask = NULL; 1169 enum { cpuset, possible, fail } state = cpuset; 1170 int dest_cpu; 1171 1172 /* 1173 * If the node that the cpu is on has been offlined, cpu_to_node() 1174 * will return -1. There is no cpu on the node, and we should 1175 * select the cpu on the other node. 1176 */ 1177 if (nid != -1) { 1178 nodemask = cpumask_of_node(nid); 1179 1180 /* Look for allowed, online CPU in same node. */ 1181 for_each_cpu(dest_cpu, nodemask) { 1182 if (!cpu_online(dest_cpu)) 1183 continue; 1184 if (!cpu_active(dest_cpu)) 1185 continue; 1186 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 1187 return dest_cpu; 1188 } 1189 } 1190 1191 for (;;) { 1192 /* Any allowed, online CPU? */ 1193 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { 1194 if (!cpu_online(dest_cpu)) 1195 continue; 1196 if (!cpu_active(dest_cpu)) 1197 continue; 1198 goto out; 1199 } 1200 1201 switch (state) { 1202 case cpuset: 1203 /* No more Mr. Nice Guy. */ 1204 cpuset_cpus_allowed_fallback(p); 1205 state = possible; 1206 break; 1207 1208 case possible: 1209 do_set_cpus_allowed(p, cpu_possible_mask); 1210 state = fail; 1211 break; 1212 1213 case fail: 1214 BUG(); 1215 break; 1216 } 1217 } 1218 1219out: 1220 if (state != cpuset) { 1221 /* 1222 * Don't tell them about moving exiting tasks or 1223 * kernel threads (both mm NULL), since they never 1224 * leave kernel. 1225 */ 1226 if (p->mm && printk_ratelimit()) { 1227 printk_sched("process %d (%s) no longer affine to cpu%d\n", 1228 task_pid_nr(p), p->comm, cpu); 1229 } 1230 } 1231 1232 return dest_cpu; 1233} 1234 1235/* 1236 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. 1237 */ 1238static inline 1239int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags) 1240{ 1241 int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags); 1242 1243 /* 1244 * In order not to call set_task_cpu() on a blocking task we need 1245 * to rely on ttwu() to place the task on a valid ->cpus_allowed 1246 * cpu. 1247 * 1248 * Since this is common to all placement strategies, this lives here. 1249 * 1250 * [ this allows ->select_task() to simply return task_cpu(p) and 1251 * not worry about this generic constraint ] 1252 */ 1253 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) || 1254 !cpu_online(cpu))) 1255 cpu = select_fallback_rq(task_cpu(p), p); 1256 1257 return cpu; 1258} 1259 1260static void update_avg(u64 *avg, u64 sample) 1261{ 1262 s64 diff = sample - *avg; 1263 *avg += diff >> 3; 1264} 1265#endif 1266 1267static void 1268ttwu_stat(struct task_struct *p, int cpu, int wake_flags) 1269{ 1270#ifdef CONFIG_SCHEDSTATS 1271 struct rq *rq = this_rq(); 1272 1273#ifdef CONFIG_SMP 1274 int this_cpu = smp_processor_id(); 1275 1276 if (cpu == this_cpu) { 1277 schedstat_inc(rq, ttwu_local); 1278 schedstat_inc(p, se.statistics.nr_wakeups_local); 1279 } else { 1280 struct sched_domain *sd; 1281 1282 schedstat_inc(p, se.statistics.nr_wakeups_remote); 1283 rcu_read_lock(); 1284 for_each_domain(this_cpu, sd) { 1285 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { 1286 schedstat_inc(sd, ttwu_wake_remote); 1287 break; 1288 } 1289 } 1290 rcu_read_unlock(); 1291 } 1292 1293 if (wake_flags & WF_MIGRATED) 1294 schedstat_inc(p, se.statistics.nr_wakeups_migrate); 1295 1296#endif /* CONFIG_SMP */ 1297 1298 schedstat_inc(rq, ttwu_count); 1299 schedstat_inc(p, se.statistics.nr_wakeups); 1300 1301 if (wake_flags & WF_SYNC) 1302 schedstat_inc(p, se.statistics.nr_wakeups_sync); 1303 1304#endif /* CONFIG_SCHEDSTATS */ 1305} 1306 1307static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) 1308{ 1309 activate_task(rq, p, en_flags); 1310 p->on_rq = 1; 1311 1312 /* if a worker is waking up, notify workqueue */ 1313 if (p->flags & PF_WQ_WORKER) 1314 wq_worker_waking_up(p, cpu_of(rq)); 1315} 1316 1317/* 1318 * Mark the task runnable and perform wakeup-preemption. 1319 */ 1320static void 1321ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) 1322{ 1323 check_preempt_curr(rq, p, wake_flags); 1324 trace_sched_wakeup(p, true); 1325 1326 p->state = TASK_RUNNING; 1327#ifdef CONFIG_SMP 1328 if (p->sched_class->task_woken) 1329 p->sched_class->task_woken(rq, p); 1330 1331 if (rq->idle_stamp) { 1332 u64 delta = rq_clock(rq) - rq->idle_stamp; 1333 u64 max = 2*rq->max_idle_balance_cost; 1334 1335 update_avg(&rq->avg_idle, delta); 1336 1337 if (rq->avg_idle > max) 1338 rq->avg_idle = max; 1339 1340 rq->idle_stamp = 0; 1341 } 1342#endif 1343} 1344 1345static void 1346ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags) 1347{ 1348#ifdef CONFIG_SMP 1349 if (p->sched_contributes_to_load) 1350 rq->nr_uninterruptible--; 1351#endif 1352 1353 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING); 1354 ttwu_do_wakeup(rq, p, wake_flags); 1355} 1356 1357/* 1358 * Called in case the task @p isn't fully descheduled from its runqueue, 1359 * in this case we must do a remote wakeup. Its a 'light' wakeup though, 1360 * since all we need to do is flip p->state to TASK_RUNNING, since 1361 * the task is still ->on_rq. 1362 */ 1363static int ttwu_remote(struct task_struct *p, int wake_flags) 1364{ 1365 struct rq *rq; 1366 int ret = 0; 1367 1368 rq = __task_rq_lock(p); 1369 if (p->on_rq) { 1370 /* check_preempt_curr() may use rq clock */ 1371 update_rq_clock(rq); 1372 ttwu_do_wakeup(rq, p, wake_flags); 1373 ret = 1; 1374 } 1375 __task_rq_unlock(rq); 1376 1377 return ret; 1378} 1379 1380#ifdef CONFIG_SMP 1381static void sched_ttwu_pending(void) 1382{ 1383 struct rq *rq = this_rq(); 1384 struct llist_node *llist = llist_del_all(&rq->wake_list); 1385 struct task_struct *p; 1386 1387 raw_spin_lock(&rq->lock); 1388 1389 while (llist) { 1390 p = llist_entry(llist, struct task_struct, wake_entry); 1391 llist = llist_next(llist); 1392 ttwu_do_activate(rq, p, 0); 1393 } 1394 1395 raw_spin_unlock(&rq->lock); 1396} 1397 1398void scheduler_ipi(void) 1399{ 1400 if (llist_empty(&this_rq()->wake_list) 1401 && !tick_nohz_full_cpu(smp_processor_id()) 1402 && !got_nohz_idle_kick()) 1403 return; 1404 1405 /* 1406 * Not all reschedule IPI handlers call irq_enter/irq_exit, since 1407 * traditionally all their work was done from the interrupt return 1408 * path. Now that we actually do some work, we need to make sure 1409 * we do call them. 1410 * 1411 * Some archs already do call them, luckily irq_enter/exit nest 1412 * properly. 1413 * 1414 * Arguably we should visit all archs and update all handlers, 1415 * however a fair share of IPIs are still resched only so this would 1416 * somewhat pessimize the simple resched case. 1417 */ 1418 irq_enter(); 1419 tick_nohz_full_check(); 1420 sched_ttwu_pending(); 1421 1422 /* 1423 * Check if someone kicked us for doing the nohz idle load balance. 1424 */ 1425 if (unlikely(got_nohz_idle_kick())) { 1426 this_rq()->idle_balance = 1; 1427 raise_softirq_irqoff(SCHED_SOFTIRQ); 1428 } 1429 irq_exit(); 1430} 1431 1432static void ttwu_queue_remote(struct task_struct *p, int cpu) 1433{ 1434 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) 1435 smp_send_reschedule(cpu); 1436} 1437 1438bool cpus_share_cache(int this_cpu, int that_cpu) 1439{ 1440 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); 1441} 1442#endif /* CONFIG_SMP */ 1443 1444static void ttwu_queue(struct task_struct *p, int cpu) 1445{ 1446 struct rq *rq = cpu_rq(cpu); 1447 1448#if defined(CONFIG_SMP) 1449 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { 1450 sched_clock_cpu(cpu); /* sync clocks x-cpu */ 1451 ttwu_queue_remote(p, cpu); 1452 return; 1453 } 1454#endif 1455 1456 raw_spin_lock(&rq->lock); 1457 ttwu_do_activate(rq, p, 0); 1458 raw_spin_unlock(&rq->lock); 1459} 1460 1461/** 1462 * try_to_wake_up - wake up a thread 1463 * @p: the thread to be awakened 1464 * @state: the mask of task states that can be woken 1465 * @wake_flags: wake modifier flags (WF_*) 1466 * 1467 * Put it on the run-queue if it's not already there. The "current" 1468 * thread is always on the run-queue (except when the actual 1469 * re-schedule is in progress), and as such you're allowed to do 1470 * the simpler "current->state = TASK_RUNNING" to mark yourself 1471 * runnable without the overhead of this. 1472 * 1473 * Return: %true if @p was woken up, %false if it was already running. 1474 * or @state didn't match @p's state. 1475 */ 1476static int 1477try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) 1478{ 1479 unsigned long flags; 1480 int cpu, success = 0; 1481 1482 /* 1483 * If we are going to wake up a thread waiting for CONDITION we 1484 * need to ensure that CONDITION=1 done by the caller can not be 1485 * reordered with p->state check below. This pairs with mb() in 1486 * set_current_state() the waiting thread does. 1487 */ 1488 smp_mb__before_spinlock(); 1489 raw_spin_lock_irqsave(&p->pi_lock, flags); 1490 if (!(p->state & state)) 1491 goto out; 1492 1493 success = 1; /* we're going to change ->state */ 1494 cpu = task_cpu(p); 1495 1496 if (p->on_rq && ttwu_remote(p, wake_flags)) 1497 goto stat; 1498 1499#ifdef CONFIG_SMP 1500 /* 1501 * If the owning (remote) cpu is still in the middle of schedule() with 1502 * this task as prev, wait until its done referencing the task. 1503 */ 1504 while (p->on_cpu) 1505 cpu_relax(); 1506 /* 1507 * Pairs with the smp_wmb() in finish_lock_switch(). 1508 */ 1509 smp_rmb(); 1510 1511 p->sched_contributes_to_load = !!task_contributes_to_load(p); 1512 p->state = TASK_WAKING; 1513 1514 if (p->sched_class->task_waking) 1515 p->sched_class->task_waking(p); 1516 1517 cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags); 1518 if (task_cpu(p) != cpu) { 1519 wake_flags |= WF_MIGRATED; 1520 set_task_cpu(p, cpu); 1521 } 1522#endif /* CONFIG_SMP */ 1523 1524 ttwu_queue(p, cpu); 1525stat: 1526 ttwu_stat(p, cpu, wake_flags); 1527out: 1528 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1529 1530 return success; 1531} 1532 1533/** 1534 * try_to_wake_up_local - try to wake up a local task with rq lock held 1535 * @p: the thread to be awakened 1536 * 1537 * Put @p on the run-queue if it's not already there. The caller must 1538 * ensure that this_rq() is locked, @p is bound to this_rq() and not 1539 * the current task. 1540 */ 1541static void try_to_wake_up_local(struct task_struct *p) 1542{ 1543 struct rq *rq = task_rq(p); 1544 1545 if (WARN_ON_ONCE(rq != this_rq()) || 1546 WARN_ON_ONCE(p == current)) 1547 return; 1548 1549 lockdep_assert_held(&rq->lock); 1550 1551 if (!raw_spin_trylock(&p->pi_lock)) { 1552 raw_spin_unlock(&rq->lock); 1553 raw_spin_lock(&p->pi_lock); 1554 raw_spin_lock(&rq->lock); 1555 } 1556 1557 if (!(p->state & TASK_NORMAL)) 1558 goto out; 1559 1560 if (!p->on_rq) 1561 ttwu_activate(rq, p, ENQUEUE_WAKEUP); 1562 1563 ttwu_do_wakeup(rq, p, 0); 1564 ttwu_stat(p, smp_processor_id(), 0); 1565out: 1566 raw_spin_unlock(&p->pi_lock); 1567} 1568 1569/** 1570 * wake_up_process - Wake up a specific process 1571 * @p: The process to be woken up. 1572 * 1573 * Attempt to wake up the nominated process and move it to the set of runnable 1574 * processes. 1575 * 1576 * Return: 1 if the process was woken up, 0 if it was already running. 1577 * 1578 * It may be assumed that this function implies a write memory barrier before 1579 * changing the task state if and only if any tasks are woken up. 1580 */ 1581int wake_up_process(struct task_struct *p) 1582{ 1583 WARN_ON(task_is_stopped_or_traced(p)); 1584 return try_to_wake_up(p, TASK_NORMAL, 0); 1585} 1586EXPORT_SYMBOL(wake_up_process); 1587 1588int wake_up_state(struct task_struct *p, unsigned int state) 1589{ 1590 return try_to_wake_up(p, state, 0); 1591} 1592 1593/* 1594 * Perform scheduler related setup for a newly forked process p. 1595 * p is forked by current. 1596 * 1597 * __sched_fork() is basic setup used by init_idle() too: 1598 */ 1599static void __sched_fork(struct task_struct *p) 1600{ 1601 p->on_rq = 0; 1602 1603 p->se.on_rq = 0; 1604 p->se.exec_start = 0; 1605 p->se.sum_exec_runtime = 0; 1606 p->se.prev_sum_exec_runtime = 0; 1607 p->se.nr_migrations = 0; 1608 p->se.vruntime = 0; 1609 INIT_LIST_HEAD(&p->se.group_node); 1610 1611#ifdef CONFIG_SCHEDSTATS 1612 memset(&p->se.statistics, 0, sizeof(p->se.statistics)); 1613#endif 1614 1615 INIT_LIST_HEAD(&p->rt.run_list); 1616 1617#ifdef CONFIG_PREEMPT_NOTIFIERS 1618 INIT_HLIST_HEAD(&p->preempt_notifiers); 1619#endif 1620 1621#ifdef CONFIG_NUMA_BALANCING 1622 if (p->mm && atomic_read(&p->mm->mm_users) == 1) { 1623 p->mm->numa_next_scan = jiffies; 1624 p->mm->numa_next_reset = jiffies; 1625 p->mm->numa_scan_seq = 0; 1626 } 1627 1628 p->node_stamp = 0ULL; 1629 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0; 1630 p->numa_migrate_seq = p->mm ? p->mm->numa_scan_seq - 1 : 0; 1631 p->numa_scan_period = sysctl_numa_balancing_scan_delay; 1632 p->numa_work.next = &p->numa_work; 1633#endif /* CONFIG_NUMA_BALANCING */ 1634} 1635 1636#ifdef CONFIG_NUMA_BALANCING 1637#ifdef CONFIG_SCHED_DEBUG 1638void set_numabalancing_state(bool enabled) 1639{ 1640 if (enabled) 1641 sched_feat_set("NUMA"); 1642 else 1643 sched_feat_set("NO_NUMA"); 1644} 1645#else 1646__read_mostly bool numabalancing_enabled; 1647 1648void set_numabalancing_state(bool enabled) 1649{ 1650 numabalancing_enabled = enabled; 1651} 1652#endif /* CONFIG_SCHED_DEBUG */ 1653#endif /* CONFIG_NUMA_BALANCING */ 1654 1655/* 1656 * fork()/clone()-time setup: 1657 */ 1658void sched_fork(struct task_struct *p) 1659{ 1660 unsigned long flags; 1661 int cpu = get_cpu(); 1662 1663 __sched_fork(p); 1664 /* 1665 * We mark the process as running here. This guarantees that 1666 * nobody will actually run it, and a signal or other external 1667 * event cannot wake it up and insert it on the runqueue either. 1668 */ 1669 p->state = TASK_RUNNING; 1670 1671 /* 1672 * Make sure we do not leak PI boosting priority to the child. 1673 */ 1674 p->prio = current->normal_prio; 1675 1676 /* 1677 * Revert to default priority/policy on fork if requested. 1678 */ 1679 if (unlikely(p->sched_reset_on_fork)) { 1680 if (task_has_rt_policy(p)) { 1681 p->policy = SCHED_NORMAL; 1682 p->static_prio = NICE_TO_PRIO(0); 1683 p->rt_priority = 0; 1684 } else if (PRIO_TO_NICE(p->static_prio) < 0) 1685 p->static_prio = NICE_TO_PRIO(0); 1686 1687 p->prio = p->normal_prio = __normal_prio(p); 1688 set_load_weight(p); 1689 1690 /* 1691 * We don't need the reset flag anymore after the fork. It has 1692 * fulfilled its duty: 1693 */ 1694 p->sched_reset_on_fork = 0; 1695 } 1696 1697 if (!rt_prio(p->prio)) 1698 p->sched_class = &fair_sched_class; 1699 1700 if (p->sched_class->task_fork) 1701 p->sched_class->task_fork(p); 1702 1703 /* 1704 * The child is not yet in the pid-hash so no cgroup attach races, 1705 * and the cgroup is pinned to this child due to cgroup_fork() 1706 * is ran before sched_fork(). 1707 * 1708 * Silence PROVE_RCU. 1709 */ 1710 raw_spin_lock_irqsave(&p->pi_lock, flags); 1711 set_task_cpu(p, cpu); 1712 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1713 1714#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) 1715 if (likely(sched_info_on())) 1716 memset(&p->sched_info, 0, sizeof(p->sched_info)); 1717#endif 1718#if defined(CONFIG_SMP) 1719 p->on_cpu = 0; 1720#endif 1721#ifdef CONFIG_PREEMPT_COUNT 1722 /* Want to start with kernel preemption disabled. */ 1723 task_thread_info(p)->preempt_count = 1; 1724#endif 1725#ifdef CONFIG_SMP 1726 plist_node_init(&p->pushable_tasks, MAX_PRIO); 1727#endif 1728 1729 put_cpu(); 1730} 1731 1732/* 1733 * wake_up_new_task - wake up a newly created task for the first time. 1734 * 1735 * This function will do some initial scheduler statistics housekeeping 1736 * that must be done for every newly created context, then puts the task 1737 * on the runqueue and wakes it. 1738 */ 1739void wake_up_new_task(struct task_struct *p) 1740{ 1741 unsigned long flags; 1742 struct rq *rq; 1743 1744 raw_spin_lock_irqsave(&p->pi_lock, flags); 1745#ifdef CONFIG_SMP 1746 /* 1747 * Fork balancing, do it here and not earlier because: 1748 * - cpus_allowed can change in the fork path 1749 * - any previously selected cpu might disappear through hotplug 1750 */ 1751 set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0)); 1752#endif 1753 1754 /* Initialize new task's runnable average */ 1755 init_task_runnable_average(p); 1756 rq = __task_rq_lock(p); 1757 activate_task(rq, p, 0); 1758 p->on_rq = 1; 1759 trace_sched_wakeup_new(p, true); 1760 check_preempt_curr(rq, p, WF_FORK); 1761#ifdef CONFIG_SMP 1762 if (p->sched_class->task_woken) 1763 p->sched_class->task_woken(rq, p); 1764#endif 1765 task_rq_unlock(rq, p, &flags); 1766} 1767 1768#ifdef CONFIG_PREEMPT_NOTIFIERS 1769 1770/** 1771 * preempt_notifier_register - tell me when current is being preempted & rescheduled 1772 * @notifier: notifier struct to register 1773 */ 1774void preempt_notifier_register(struct preempt_notifier *notifier) 1775{ 1776 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); 1777} 1778EXPORT_SYMBOL_GPL(preempt_notifier_register); 1779 1780/** 1781 * preempt_notifier_unregister - no longer interested in preemption notifications 1782 * @notifier: notifier struct to unregister 1783 * 1784 * This is safe to call from within a preemption notifier. 1785 */ 1786void preempt_notifier_unregister(struct preempt_notifier *notifier) 1787{ 1788 hlist_del(¬ifier->link); 1789} 1790EXPORT_SYMBOL_GPL(preempt_notifier_unregister); 1791 1792static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1793{ 1794 struct preempt_notifier *notifier; 1795 1796 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) 1797 notifier->ops->sched_in(notifier, raw_smp_processor_id()); 1798} 1799 1800static void 1801fire_sched_out_preempt_notifiers(struct task_struct *curr, 1802 struct task_struct *next) 1803{ 1804 struct preempt_notifier *notifier; 1805 1806 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) 1807 notifier->ops->sched_out(notifier, next); 1808} 1809 1810#else /* !CONFIG_PREEMPT_NOTIFIERS */ 1811 1812static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1813{ 1814} 1815 1816static void 1817fire_sched_out_preempt_notifiers(struct task_struct *curr, 1818 struct task_struct *next) 1819{ 1820} 1821 1822#endif /* CONFIG_PREEMPT_NOTIFIERS */ 1823 1824/** 1825 * prepare_task_switch - prepare to switch tasks 1826 * @rq: the runqueue preparing to switch 1827 * @prev: the current task that is being switched out 1828 * @next: the task we are going to switch to. 1829 * 1830 * This is called with the rq lock held and interrupts off. It must 1831 * be paired with a subsequent finish_task_switch after the context 1832 * switch. 1833 * 1834 * prepare_task_switch sets up locking and calls architecture specific 1835 * hooks. 1836 */ 1837static inline void 1838prepare_task_switch(struct rq *rq, struct task_struct *prev, 1839 struct task_struct *next) 1840{ 1841 trace_sched_switch(prev, next); 1842 sched_info_switch(rq, prev, next); 1843 perf_event_task_sched_out(prev, next); 1844 fire_sched_out_preempt_notifiers(prev, next); 1845 prepare_lock_switch(rq, next); 1846 prepare_arch_switch(next); 1847} 1848 1849/** 1850 * finish_task_switch - clean up after a task-switch 1851 * @rq: runqueue associated with task-switch 1852 * @prev: the thread we just switched away from. 1853 * 1854 * finish_task_switch must be called after the context switch, paired 1855 * with a prepare_task_switch call before the context switch. 1856 * finish_task_switch will reconcile locking set up by prepare_task_switch, 1857 * and do any other architecture-specific cleanup actions. 1858 * 1859 * Note that we may have delayed dropping an mm in context_switch(). If 1860 * so, we finish that here outside of the runqueue lock. (Doing it 1861 * with the lock held can cause deadlocks; see schedule() for 1862 * details.) 1863 */ 1864static void finish_task_switch(struct rq *rq, struct task_struct *prev) 1865 __releases(rq->lock) 1866{ 1867 struct mm_struct *mm = rq->prev_mm; 1868 long prev_state; 1869 1870 rq->prev_mm = NULL; 1871 1872 /* 1873 * A task struct has one reference for the use as "current". 1874 * If a task dies, then it sets TASK_DEAD in tsk->state and calls 1875 * schedule one last time. The schedule call will never return, and 1876 * the scheduled task must drop that reference. 1877 * The test for TASK_DEAD must occur while the runqueue locks are 1878 * still held, otherwise prev could be scheduled on another cpu, die 1879 * there before we look at prev->state, and then the reference would 1880 * be dropped twice. 1881 * Manfred Spraul <manfred@colorfullife.com> 1882 */ 1883 prev_state = prev->state; 1884 vtime_task_switch(prev); 1885 finish_arch_switch(prev); 1886 perf_event_task_sched_in(prev, current); 1887 finish_lock_switch(rq, prev); 1888 finish_arch_post_lock_switch(); 1889 1890 fire_sched_in_preempt_notifiers(current); 1891 if (mm) 1892 mmdrop(mm); 1893 if (unlikely(prev_state == TASK_DEAD)) { 1894 /* 1895 * Remove function-return probe instances associated with this 1896 * task and put them back on the free list. 1897 */ 1898 kprobe_flush_task(prev); 1899 put_task_struct(prev); 1900 } 1901 1902 tick_nohz_task_switch(current); 1903} 1904 1905#ifdef CONFIG_SMP 1906 1907/* assumes rq->lock is held */ 1908static inline void pre_schedule(struct rq *rq, struct task_struct *prev) 1909{ 1910 if (prev->sched_class->pre_schedule) 1911 prev->sched_class->pre_schedule(rq, prev); 1912} 1913 1914/* rq->lock is NOT held, but preemption is disabled */ 1915static inline void post_schedule(struct rq *rq) 1916{ 1917 if (rq->post_schedule) { 1918 unsigned long flags; 1919 1920 raw_spin_lock_irqsave(&rq->lock, flags); 1921 if (rq->curr->sched_class->post_schedule) 1922 rq->curr->sched_class->post_schedule(rq); 1923 raw_spin_unlock_irqrestore(&rq->lock, flags); 1924 1925 rq->post_schedule = 0; 1926 } 1927} 1928 1929#else 1930 1931static inline void pre_schedule(struct rq *rq, struct task_struct *p) 1932{ 1933} 1934 1935static inline void post_schedule(struct rq *rq) 1936{ 1937} 1938 1939#endif 1940 1941/** 1942 * schedule_tail - first thing a freshly forked thread must call. 1943 * @prev: the thread we just switched away from. 1944 */ 1945asmlinkage void schedule_tail(struct task_struct *prev) 1946 __releases(rq->lock) 1947{ 1948 struct rq *rq = this_rq(); 1949 1950 finish_task_switch(rq, prev); 1951 1952 /* 1953 * FIXME: do we need to worry about rq being invalidated by the 1954 * task_switch? 1955 */ 1956 post_schedule(rq); 1957 1958#ifdef __ARCH_WANT_UNLOCKED_CTXSW 1959 /* In this case, finish_task_switch does not reenable preemption */ 1960 preempt_enable(); 1961#endif 1962 if (current->set_child_tid) 1963 put_user(task_pid_vnr(current), current->set_child_tid); 1964} 1965 1966/* 1967 * context_switch - switch to the new MM and the new 1968 * thread's register state. 1969 */ 1970static inline void 1971context_switch(struct rq *rq, struct task_struct *prev, 1972 struct task_struct *next) 1973{ 1974 struct mm_struct *mm, *oldmm; 1975 1976 prepare_task_switch(rq, prev, next); 1977 1978 mm = next->mm; 1979 oldmm = prev->active_mm; 1980 /* 1981 * For paravirt, this is coupled with an exit in switch_to to 1982 * combine the page table reload and the switch backend into 1983 * one hypercall. 1984 */ 1985 arch_start_context_switch(prev); 1986 1987 if (!mm) { 1988 next->active_mm = oldmm; 1989 atomic_inc(&oldmm->mm_count); 1990 enter_lazy_tlb(oldmm, next); 1991 } else 1992 switch_mm(oldmm, mm, next); 1993 1994 if (!prev->mm) { 1995 prev->active_mm = NULL; 1996 rq->prev_mm = oldmm; 1997 } 1998 /* 1999 * Since the runqueue lock will be released by the next 2000 * task (which is an invalid locking op but in the case 2001 * of the scheduler it's an obvious special-case), so we 2002 * do an early lockdep release here: 2003 */ 2004#ifndef __ARCH_WANT_UNLOCKED_CTXSW 2005 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 2006#endif 2007 2008 context_tracking_task_switch(prev, next); 2009 /* Here we just switch the register state and the stack. */ 2010 switch_to(prev, next, prev); 2011 2012 barrier(); 2013 /* 2014 * this_rq must be evaluated again because prev may have moved 2015 * CPUs since it called schedule(), thus the 'rq' on its stack 2016 * frame will be invalid. 2017 */ 2018 finish_task_switch(this_rq(), prev); 2019} 2020 2021/* 2022 * nr_running and nr_context_switches: 2023 * 2024 * externally visible scheduler statistics: current number of runnable 2025 * threads, total number of context switches performed since bootup. 2026 */ 2027unsigned long nr_running(void) 2028{ 2029 unsigned long i, sum = 0; 2030 2031 for_each_online_cpu(i) 2032 sum += cpu_rq(i)->nr_running; 2033 2034 return sum; 2035} 2036 2037unsigned long long nr_context_switches(void) 2038{ 2039 int i; 2040 unsigned long long sum = 0; 2041 2042 for_each_possible_cpu(i) 2043 sum += cpu_rq(i)->nr_switches; 2044 2045 return sum; 2046} 2047 2048unsigned long nr_iowait(void) 2049{ 2050 unsigned long i, sum = 0; 2051 2052 for_each_possible_cpu(i) 2053 sum += atomic_read(&cpu_rq(i)->nr_iowait); 2054 2055 return sum; 2056} 2057 2058unsigned long nr_iowait_cpu(int cpu) 2059{ 2060 struct rq *this = cpu_rq(cpu); 2061 return atomic_read(&this->nr_iowait); 2062} 2063 2064#ifdef CONFIG_SMP 2065 2066/* 2067 * sched_exec - execve() is a valuable balancing opportunity, because at 2068 * this point the task has the smallest effective memory and cache footprint. 2069 */ 2070void sched_exec(void) 2071{ 2072 struct task_struct *p = current; 2073 unsigned long flags; 2074 int dest_cpu; 2075 2076 raw_spin_lock_irqsave(&p->pi_lock, flags); 2077 dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0); 2078 if (dest_cpu == smp_processor_id()) 2079 goto unlock; 2080 2081 if (likely(cpu_active(dest_cpu))) { 2082 struct migration_arg arg = { p, dest_cpu }; 2083 2084 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2085 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); 2086 return; 2087 } 2088unlock: 2089 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2090} 2091 2092#endif 2093 2094DEFINE_PER_CPU(struct kernel_stat, kstat); 2095DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); 2096 2097EXPORT_PER_CPU_SYMBOL(kstat); 2098EXPORT_PER_CPU_SYMBOL(kernel_cpustat); 2099 2100/* 2101 * Return any ns on the sched_clock that have not yet been accounted in 2102 * @p in case that task is currently running. 2103 * 2104 * Called with task_rq_lock() held on @rq. 2105 */ 2106static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq) 2107{ 2108 u64 ns = 0; 2109 2110 if (task_current(rq, p)) { 2111 update_rq_clock(rq); 2112 ns = rq_clock_task(rq) - p->se.exec_start; 2113 if ((s64)ns < 0) 2114 ns = 0; 2115 } 2116 2117 return ns; 2118} 2119 2120unsigned long long task_delta_exec(struct task_struct *p) 2121{ 2122 unsigned long flags; 2123 struct rq *rq; 2124 u64 ns = 0; 2125 2126 rq = task_rq_lock(p, &flags); 2127 ns = do_task_delta_exec(p, rq); 2128 task_rq_unlock(rq, p, &flags); 2129 2130 return ns; 2131} 2132 2133/* 2134 * Return accounted runtime for the task. 2135 * In case the task is currently running, return the runtime plus current's 2136 * pending runtime that have not been accounted yet. 2137 */ 2138unsigned long long task_sched_runtime(struct task_struct *p) 2139{ 2140 unsigned long flags; 2141 struct rq *rq; 2142 u64 ns = 0; 2143 2144 rq = task_rq_lock(p, &flags); 2145 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq); 2146 task_rq_unlock(rq, p, &flags); 2147 2148 return ns; 2149} 2150 2151/* 2152 * This function gets called by the timer code, with HZ frequency. 2153 * We call it with interrupts disabled. 2154 */ 2155void scheduler_tick(void) 2156{ 2157 int cpu = smp_processor_id(); 2158 struct rq *rq = cpu_rq(cpu); 2159 struct task_struct *curr = rq->curr; 2160 2161 sched_clock_tick(); 2162 2163 raw_spin_lock(&rq->lock); 2164 update_rq_clock(rq); 2165 curr->sched_class->task_tick(rq, curr, 0); 2166 update_cpu_load_active(rq); 2167 raw_spin_unlock(&rq->lock); 2168 2169 perf_event_task_tick(); 2170 2171#ifdef CONFIG_SMP 2172 rq->idle_balance = idle_cpu(cpu); 2173 trigger_load_balance(rq, cpu); 2174#endif 2175 rq_last_tick_reset(rq); 2176} 2177 2178#ifdef CONFIG_NO_HZ_FULL 2179/** 2180 * scheduler_tick_max_deferment 2181 * 2182 * Keep at least one tick per second when a single 2183 * active task is running because the scheduler doesn't 2184 * yet completely support full dynticks environment. 2185 * 2186 * This makes sure that uptime, CFS vruntime, load 2187 * balancing, etc... continue to move forward, even 2188 * with a very low granularity. 2189 * 2190 * Return: Maximum deferment in nanoseconds. 2191 */ 2192u64 scheduler_tick_max_deferment(void) 2193{ 2194 struct rq *rq = this_rq(); 2195 unsigned long next, now = ACCESS_ONCE(jiffies); 2196 2197 next = rq->last_sched_tick + HZ; 2198 2199 if (time_before_eq(next, now)) 2200 return 0; 2201 2202 return jiffies_to_usecs(next - now) * NSEC_PER_USEC; 2203} 2204#endif 2205 2206notrace unsigned long get_parent_ip(unsigned long addr) 2207{ 2208 if (in_lock_functions(addr)) { 2209 addr = CALLER_ADDR2; 2210 if (in_lock_functions(addr)) 2211 addr = CALLER_ADDR3; 2212 } 2213 return addr; 2214} 2215 2216#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ 2217 defined(CONFIG_PREEMPT_TRACER)) 2218 2219void __kprobes add_preempt_count(int val) 2220{ 2221#ifdef CONFIG_DEBUG_PREEMPT 2222 /* 2223 * Underflow? 2224 */ 2225 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) 2226 return; 2227#endif 2228 preempt_count() += val; 2229#ifdef CONFIG_DEBUG_PREEMPT 2230 /* 2231 * Spinlock count overflowing soon? 2232 */ 2233 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= 2234 PREEMPT_MASK - 10); 2235#endif 2236 if (preempt_count() == val) 2237 trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 2238} 2239EXPORT_SYMBOL(add_preempt_count); 2240 2241void __kprobes sub_preempt_count(int val) 2242{ 2243#ifdef CONFIG_DEBUG_PREEMPT 2244 /* 2245 * Underflow? 2246 */ 2247 if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) 2248 return; 2249 /* 2250 * Is the spinlock portion underflowing? 2251 */ 2252 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && 2253 !(preempt_count() & PREEMPT_MASK))) 2254 return; 2255#endif 2256 2257 if (preempt_count() == val) 2258 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 2259 preempt_count() -= val; 2260} 2261EXPORT_SYMBOL(sub_preempt_count); 2262 2263#endif 2264 2265/* 2266 * Print scheduling while atomic bug: 2267 */ 2268static noinline void __schedule_bug(struct task_struct *prev) 2269{ 2270 if (oops_in_progress) 2271 return; 2272 2273 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", 2274 prev->comm, prev->pid, preempt_count()); 2275 2276 debug_show_held_locks(prev); 2277 print_modules(); 2278 if (irqs_disabled()) 2279 print_irqtrace_events(prev); 2280 dump_stack(); 2281 add_taint(TAINT_WARN, LOCKDEP_STILL_OK); 2282} 2283 2284/* 2285 * Various schedule()-time debugging checks and statistics: 2286 */ 2287static inline void schedule_debug(struct task_struct *prev) 2288{ 2289 /* 2290 * Test if we are atomic. Since do_exit() needs to call into 2291 * schedule() atomically, we ignore that path for now. 2292 * Otherwise, whine if we are scheduling when we should not be. 2293 */ 2294 if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) 2295 __schedule_bug(prev); 2296 rcu_sleep_check(); 2297 2298 profile_hit(SCHED_PROFILING, __builtin_return_address(0)); 2299 2300 schedstat_inc(this_rq(), sched_count); 2301} 2302 2303static void put_prev_task(struct rq *rq, struct task_struct *prev) 2304{ 2305 if (prev->on_rq || rq->skip_clock_update < 0) 2306 update_rq_clock(rq); 2307 prev->sched_class->put_prev_task(rq, prev); 2308} 2309 2310/* 2311 * Pick up the highest-prio task: 2312 */ 2313static inline struct task_struct * 2314pick_next_task(struct rq *rq) 2315{ 2316 const struct sched_class *class; 2317 struct task_struct *p; 2318 2319 /* 2320 * Optimization: we know that if all tasks are in 2321 * the fair class we can call that function directly: 2322 */ 2323 if (likely(rq->nr_running == rq->cfs.h_nr_running)) { 2324 p = fair_sched_class.pick_next_task(rq); 2325 if (likely(p)) 2326 return p; 2327 } 2328 2329 for_each_class(class) { 2330 p = class->pick_next_task(rq); 2331 if (p) 2332 return p; 2333 } 2334 2335 BUG(); /* the idle class will always have a runnable task */ 2336} 2337 2338/* 2339 * __schedule() is the main scheduler function. 2340 * 2341 * The main means of driving the scheduler and thus entering this function are: 2342 * 2343 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. 2344 * 2345 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return 2346 * paths. For example, see arch/x86/entry_64.S. 2347 * 2348 * To drive preemption between tasks, the scheduler sets the flag in timer 2349 * interrupt handler scheduler_tick(). 2350 * 2351 * 3. Wakeups don't really cause entry into schedule(). They add a 2352 * task to the run-queue and that's it. 2353 * 2354 * Now, if the new task added to the run-queue preempts the current 2355 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets 2356 * called on the nearest possible occasion: 2357 * 2358 * - If the kernel is preemptible (CONFIG_PREEMPT=y): 2359 * 2360 * - in syscall or exception context, at the next outmost 2361 * preempt_enable(). (this might be as soon as the wake_up()'s 2362 * spin_unlock()!) 2363 * 2364 * - in IRQ context, return from interrupt-handler to 2365 * preemptible context 2366 * 2367 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set) 2368 * then at the next: 2369 * 2370 * - cond_resched() call 2371 * - explicit schedule() call 2372 * - return from syscall or exception to user-space 2373 * - return from interrupt-handler to user-space 2374 */ 2375static void __sched __schedule(void) 2376{ 2377 struct task_struct *prev, *next; 2378 unsigned long *switch_count; 2379 struct rq *rq; 2380 int cpu; 2381 2382need_resched: 2383 preempt_disable(); 2384 cpu = smp_processor_id(); 2385 rq = cpu_rq(cpu); 2386 rcu_note_context_switch(cpu); 2387 prev = rq->curr; 2388 2389 schedule_debug(prev); 2390 2391 if (sched_feat(HRTICK)) 2392 hrtick_clear(rq); 2393 2394 /* 2395 * Make sure that signal_pending_state()->signal_pending() below 2396 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE) 2397 * done by the caller to avoid the race with signal_wake_up(). 2398 */ 2399 smp_mb__before_spinlock(); 2400 raw_spin_lock_irq(&rq->lock); 2401 2402 switch_count = &prev->nivcsw; 2403 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { 2404 if (unlikely(signal_pending_state(prev->state, prev))) { 2405 prev->state = TASK_RUNNING; 2406 } else { 2407 deactivate_task(rq, prev, DEQUEUE_SLEEP); 2408 prev->on_rq = 0; 2409 2410 /* 2411 * If a worker went to sleep, notify and ask workqueue 2412 * whether it wants to wake up a task to maintain 2413 * concurrency. 2414 */ 2415 if (prev->flags & PF_WQ_WORKER) { 2416 struct task_struct *to_wakeup; 2417 2418 to_wakeup = wq_worker_sleeping(prev, cpu); 2419 if (to_wakeup) 2420 try_to_wake_up_local(to_wakeup); 2421 } 2422 } 2423 switch_count = &prev->nvcsw; 2424 } 2425 2426 pre_schedule(rq, prev); 2427 2428 if (unlikely(!rq->nr_running)) 2429 idle_balance(cpu, rq); 2430 2431 put_prev_task(rq, prev); 2432 next = pick_next_task(rq); 2433 clear_tsk_need_resched(prev); 2434 rq->skip_clock_update = 0; 2435 2436 if (likely(prev != next)) { 2437 rq->nr_switches++; 2438 rq->curr = next; 2439 ++*switch_count; 2440 2441 context_switch(rq, prev, next); /* unlocks the rq */ 2442 /* 2443 * The context switch have flipped the stack from under us 2444 * and restored the local variables which were saved when 2445 * this task called schedule() in the past. prev == current 2446 * is still correct, but it can be moved to another cpu/rq. 2447 */ 2448 cpu = smp_processor_id(); 2449 rq = cpu_rq(cpu); 2450 } else 2451 raw_spin_unlock_irq(&rq->lock); 2452 2453 post_schedule(rq); 2454 2455 sched_preempt_enable_no_resched(); 2456 if (need_resched()) 2457 goto need_resched; 2458} 2459 2460static inline void sched_submit_work(struct task_struct *tsk) 2461{ 2462 if (!tsk->state || tsk_is_pi_blocked(tsk)) 2463 return; 2464 /* 2465 * If we are going to sleep and we have plugged IO queued, 2466 * make sure to submit it to avoid deadlocks. 2467 */ 2468 if (blk_needs_flush_plug(tsk)) 2469 blk_schedule_flush_plug(tsk); 2470} 2471 2472asmlinkage void __sched schedule(void) 2473{ 2474 struct task_struct *tsk = current; 2475 2476 sched_submit_work(tsk); 2477 __schedule(); 2478} 2479EXPORT_SYMBOL(schedule); 2480 2481#ifdef CONFIG_CONTEXT_TRACKING 2482asmlinkage void __sched schedule_user(void) 2483{ 2484 /* 2485 * If we come here after a random call to set_need_resched(), 2486 * or we have been woken up remotely but the IPI has not yet arrived, 2487 * we haven't yet exited the RCU idle mode. Do it here manually until 2488 * we find a better solution. 2489 */ 2490 user_exit(); 2491 schedule(); 2492 user_enter(); 2493} 2494#endif 2495 2496/** 2497 * schedule_preempt_disabled - called with preemption disabled 2498 * 2499 * Returns with preemption disabled. Note: preempt_count must be 1 2500 */ 2501void __sched schedule_preempt_disabled(void) 2502{ 2503 sched_preempt_enable_no_resched(); 2504 schedule(); 2505 preempt_disable(); 2506} 2507 2508#ifdef CONFIG_PREEMPT 2509/* 2510 * this is the entry point to schedule() from in-kernel preemption 2511 * off of preempt_enable. Kernel preemptions off return from interrupt 2512 * occur there and call schedule directly. 2513 */ 2514asmlinkage void __sched notrace preempt_schedule(void) 2515{ 2516 /* 2517 * If there is a non-zero preempt_count or interrupts are disabled, 2518 * we do not want to preempt the current task. Just return.. 2519 */ 2520 if (likely(!preemptible())) 2521 return; 2522 2523 do { 2524 add_preempt_count_notrace(PREEMPT_ACTIVE); 2525 __schedule(); 2526 sub_preempt_count_notrace(PREEMPT_ACTIVE); 2527 2528 /* 2529 * Check again in case we missed a preemption opportunity 2530 * between schedule and now. 2531 */ 2532 barrier(); 2533 } while (need_resched()); 2534} 2535EXPORT_SYMBOL(preempt_schedule); 2536 2537/* 2538 * this is the entry point to schedule() from kernel preemption 2539 * off of irq context. 2540 * Note, that this is called and return with irqs disabled. This will 2541 * protect us against recursive calling from irq. 2542 */ 2543asmlinkage void __sched preempt_schedule_irq(void) 2544{ 2545 struct thread_info *ti = current_thread_info(); 2546 enum ctx_state prev_state; 2547 2548 /* Catch callers which need to be fixed */ 2549 BUG_ON(ti->preempt_count || !irqs_disabled()); 2550 2551 prev_state = exception_enter(); 2552 2553 do { 2554 add_preempt_count(PREEMPT_ACTIVE); 2555 local_irq_enable(); 2556 __schedule(); 2557 local_irq_disable(); 2558 sub_preempt_count(PREEMPT_ACTIVE); 2559 2560 /* 2561 * Check again in case we missed a preemption opportunity 2562 * between schedule and now. 2563 */ 2564 barrier(); 2565 } while (need_resched()); 2566 2567 exception_exit(prev_state); 2568} 2569 2570#endif /* CONFIG_PREEMPT */ 2571 2572int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags, 2573 void *key) 2574{ 2575 return try_to_wake_up(curr->private, mode, wake_flags); 2576} 2577EXPORT_SYMBOL(default_wake_function); 2578 2579/* 2580 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just 2581 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve 2582 * number) then we wake all the non-exclusive tasks and one exclusive task. 2583 * 2584 * There are circumstances in which we can try to wake a task which has already 2585 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns 2586 * zero in this (rare) case, and we handle it by continuing to scan the queue. 2587 */ 2588static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, 2589 int nr_exclusive, int wake_flags, void *key) 2590{ 2591 wait_queue_t *curr, *next; 2592 2593 list_for_each_entry_safe(curr, next, &q->task_list, task_list) { 2594 unsigned flags = curr->flags; 2595 2596 if (curr->func(curr, mode, wake_flags, key) && 2597 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) 2598 break; 2599 } 2600} 2601 2602/** 2603 * __wake_up - wake up threads blocked on a waitqueue. 2604 * @q: the waitqueue 2605 * @mode: which threads 2606 * @nr_exclusive: how many wake-one or wake-many threads to wake up 2607 * @key: is directly passed to the wakeup function 2608 * 2609 * It may be assumed that this function implies a write memory barrier before 2610 * changing the task state if and only if any tasks are woken up. 2611 */ 2612void __wake_up(wait_queue_head_t *q, unsigned int mode, 2613 int nr_exclusive, void *key) 2614{ 2615 unsigned long flags; 2616 2617 spin_lock_irqsave(&q->lock, flags); 2618 __wake_up_common(q, mode, nr_exclusive, 0, key); 2619 spin_unlock_irqrestore(&q->lock, flags); 2620} 2621EXPORT_SYMBOL(__wake_up); 2622 2623/* 2624 * Same as __wake_up but called with the spinlock in wait_queue_head_t held. 2625 */ 2626void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr) 2627{ 2628 __wake_up_common(q, mode, nr, 0, NULL); 2629} 2630EXPORT_SYMBOL_GPL(__wake_up_locked); 2631 2632void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key) 2633{ 2634 __wake_up_common(q, mode, 1, 0, key); 2635} 2636EXPORT_SYMBOL_GPL(__wake_up_locked_key); 2637 2638/** 2639 * __wake_up_sync_key - wake up threads blocked on a waitqueue. 2640 * @q: the waitqueue 2641 * @mode: which threads 2642 * @nr_exclusive: how many wake-one or wake-many threads to wake up 2643 * @key: opaque value to be passed to wakeup targets 2644 * 2645 * The sync wakeup differs that the waker knows that it will schedule 2646 * away soon, so while the target thread will be woken up, it will not 2647 * be migrated to another CPU - ie. the two threads are 'synchronized' 2648 * with each other. This can prevent needless bouncing between CPUs. 2649 * 2650 * On UP it can prevent extra preemption. 2651 * 2652 * It may be assumed that this function implies a write memory barrier before 2653 * changing the task state if and only if any tasks are woken up. 2654 */ 2655void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, 2656 int nr_exclusive, void *key) 2657{ 2658 unsigned long flags; 2659 int wake_flags = WF_SYNC; 2660 2661 if (unlikely(!q)) 2662 return; 2663 2664 if (unlikely(nr_exclusive != 1)) 2665 wake_flags = 0; 2666 2667 spin_lock_irqsave(&q->lock, flags); 2668 __wake_up_common(q, mode, nr_exclusive, wake_flags, key); 2669 spin_unlock_irqrestore(&q->lock, flags); 2670} 2671EXPORT_SYMBOL_GPL(__wake_up_sync_key); 2672 2673/* 2674 * __wake_up_sync - see __wake_up_sync_key() 2675 */ 2676void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive) 2677{ 2678 __wake_up_sync_key(q, mode, nr_exclusive, NULL); 2679} 2680EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */ 2681 2682/** 2683 * complete: - signals a single thread waiting on this completion 2684 * @x: holds the state of this particular completion 2685 * 2686 * This will wake up a single thread waiting on this completion. Threads will be 2687 * awakened in the same order in which they were queued. 2688 * 2689 * See also complete_all(), wait_for_completion() and related routines. 2690 * 2691 * It may be assumed that this function implies a write memory barrier before 2692 * changing the task state if and only if any tasks are woken up. 2693 */ 2694void complete(struct completion *x) 2695{ 2696 unsigned long flags; 2697 2698 spin_lock_irqsave(&x->wait.lock, flags); 2699 x->done++; 2700 __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL); 2701 spin_unlock_irqrestore(&x->wait.lock, flags); 2702} 2703EXPORT_SYMBOL(complete); 2704 2705/** 2706 * complete_all: - signals all threads waiting on this completion 2707 * @x: holds the state of this particular completion 2708 * 2709 * This will wake up all threads waiting on this particular completion event. 2710 * 2711 * It may be assumed that this function implies a write memory barrier before 2712 * changing the task state if and only if any tasks are woken up. 2713 */ 2714void complete_all(struct completion *x) 2715{ 2716 unsigned long flags; 2717 2718 spin_lock_irqsave(&x->wait.lock, flags); 2719 x->done += UINT_MAX/2; 2720 __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL); 2721 spin_unlock_irqrestore(&x->wait.lock, flags); 2722} 2723EXPORT_SYMBOL(complete_all); 2724 2725static inline long __sched 2726do_wait_for_common(struct completion *x, 2727 long (*action)(long), long timeout, int state) 2728{ 2729 if (!x->done) { 2730 DECLARE_WAITQUEUE(wait, current); 2731 2732 __add_wait_queue_tail_exclusive(&x->wait, &wait); 2733 do { 2734 if (signal_pending_state(state, current)) { 2735 timeout = -ERESTARTSYS; 2736 break; 2737 } 2738 __set_current_state(state); 2739 spin_unlock_irq(&x->wait.lock); 2740 timeout = action(timeout); 2741 spin_lock_irq(&x->wait.lock); 2742 } while (!x->done && timeout); 2743 __remove_wait_queue(&x->wait, &wait); 2744 if (!x->done) 2745 return timeout; 2746 } 2747 x->done--; 2748 return timeout ?: 1; 2749} 2750 2751static inline long __sched 2752__wait_for_common(struct completion *x, 2753 long (*action)(long), long timeout, int state) 2754{ 2755 might_sleep(); 2756 2757 spin_lock_irq(&x->wait.lock); 2758 timeout = do_wait_for_common(x, action, timeout, state); 2759 spin_unlock_irq(&x->wait.lock); 2760 return timeout; 2761} 2762 2763static long __sched 2764wait_for_common(struct completion *x, long timeout, int state) 2765{ 2766 return __wait_for_common(x, schedule_timeout, timeout, state); 2767} 2768 2769static long __sched 2770wait_for_common_io(struct completion *x, long timeout, int state) 2771{ 2772 return __wait_for_common(x, io_schedule_timeout, timeout, state); 2773} 2774 2775/** 2776 * wait_for_completion: - waits for completion of a task 2777 * @x: holds the state of this particular completion 2778 * 2779 * This waits to be signaled for completion of a specific task. It is NOT 2780 * interruptible and there is no timeout. 2781 * 2782 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout 2783 * and interrupt capability. Also see complete(). 2784 */ 2785void __sched wait_for_completion(struct completion *x) 2786{ 2787 wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); 2788} 2789EXPORT_SYMBOL(wait_for_completion); 2790 2791/** 2792 * wait_for_completion_timeout: - waits for completion of a task (w/timeout) 2793 * @x: holds the state of this particular completion 2794 * @timeout: timeout value in jiffies 2795 * 2796 * This waits for either a completion of a specific task to be signaled or for a 2797 * specified timeout to expire. The timeout is in jiffies. It is not 2798 * interruptible. 2799 * 2800 * Return: 0 if timed out, and positive (at least 1, or number of jiffies left 2801 * till timeout) if completed. 2802 */ 2803unsigned long __sched 2804wait_for_completion_timeout(struct completion *x, unsigned long timeout) 2805{ 2806 return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE); 2807} 2808EXPORT_SYMBOL(wait_for_completion_timeout); 2809 2810/** 2811 * wait_for_completion_io: - waits for completion of a task 2812 * @x: holds the state of this particular completion 2813 * 2814 * This waits to be signaled for completion of a specific task. It is NOT 2815 * interruptible and there is no timeout. The caller is accounted as waiting 2816 * for IO. 2817 */ 2818void __sched wait_for_completion_io(struct completion *x) 2819{ 2820 wait_for_common_io(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); 2821} 2822EXPORT_SYMBOL(wait_for_completion_io); 2823 2824/** 2825 * wait_for_completion_io_timeout: - waits for completion of a task (w/timeout) 2826 * @x: holds the state of this particular completion 2827 * @timeout: timeout value in jiffies 2828 * 2829 * This waits for either a completion of a specific task to be signaled or for a 2830 * specified timeout to expire. The timeout is in jiffies. It is not 2831 * interruptible. The caller is accounted as waiting for IO. 2832 * 2833 * Return: 0 if timed out, and positive (at least 1, or number of jiffies left 2834 * till timeout) if completed. 2835 */ 2836unsigned long __sched 2837wait_for_completion_io_timeout(struct completion *x, unsigned long timeout) 2838{ 2839 return wait_for_common_io(x, timeout, TASK_UNINTERRUPTIBLE); 2840} 2841EXPORT_SYMBOL(wait_for_completion_io_timeout); 2842 2843/** 2844 * wait_for_completion_interruptible: - waits for completion of a task (w/intr) 2845 * @x: holds the state of this particular completion 2846 * 2847 * This waits for completion of a specific task to be signaled. It is 2848 * interruptible. 2849 * 2850 * Return: -ERESTARTSYS if interrupted, 0 if completed. 2851 */ 2852int __sched wait_for_completion_interruptible(struct completion *x) 2853{ 2854 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE); 2855 if (t == -ERESTARTSYS) 2856 return t; 2857 return 0; 2858} 2859EXPORT_SYMBOL(wait_for_completion_interruptible); 2860 2861/** 2862 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr)) 2863 * @x: holds the state of this particular completion 2864 * @timeout: timeout value in jiffies 2865 * 2866 * This waits for either a completion of a specific task to be signaled or for a 2867 * specified timeout to expire. It is interruptible. The timeout is in jiffies. 2868 * 2869 * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1, 2870 * or number of jiffies left till timeout) if completed. 2871 */ 2872long __sched 2873wait_for_completion_interruptible_timeout(struct completion *x, 2874 unsigned long timeout) 2875{ 2876 return wait_for_common(x, timeout, TASK_INTERRUPTIBLE); 2877} 2878EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); 2879 2880/** 2881 * wait_for_completion_killable: - waits for completion of a task (killable) 2882 * @x: holds the state of this particular completion 2883 * 2884 * This waits to be signaled for completion of a specific task. It can be 2885 * interrupted by a kill signal. 2886 * 2887 * Return: -ERESTARTSYS if interrupted, 0 if completed. 2888 */ 2889int __sched wait_for_completion_killable(struct completion *x) 2890{ 2891 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE); 2892 if (t == -ERESTARTSYS) 2893 return t; 2894 return 0; 2895} 2896EXPORT_SYMBOL(wait_for_completion_killable); 2897 2898/** 2899 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable)) 2900 * @x: holds the state of this particular completion 2901 * @timeout: timeout value in jiffies 2902 * 2903 * This waits for either a completion of a specific task to be 2904 * signaled or for a specified timeout to expire. It can be 2905 * interrupted by a kill signal. The timeout is in jiffies. 2906 * 2907 * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1, 2908 * or number of jiffies left till timeout) if completed. 2909 */ 2910long __sched 2911wait_for_completion_killable_timeout(struct completion *x, 2912 unsigned long timeout) 2913{ 2914 return wait_for_common(x, timeout, TASK_KILLABLE); 2915} 2916EXPORT_SYMBOL(wait_for_completion_killable_timeout); 2917 2918/** 2919 * try_wait_for_completion - try to decrement a completion without blocking 2920 * @x: completion structure 2921 * 2922 * Return: 0 if a decrement cannot be done without blocking 2923 * 1 if a decrement succeeded. 2924 * 2925 * If a completion is being used as a counting completion, 2926 * attempt to decrement the counter without blocking. This 2927 * enables us to avoid waiting if the resource the completion 2928 * is protecting is not available. 2929 */ 2930bool try_wait_for_completion(struct completion *x) 2931{ 2932 unsigned long flags; 2933 int ret = 1; 2934 2935 spin_lock_irqsave(&x->wait.lock, flags); 2936 if (!x->done) 2937 ret = 0; 2938 else 2939 x->done--; 2940 spin_unlock_irqrestore(&x->wait.lock, flags); 2941 return ret; 2942} 2943EXPORT_SYMBOL(try_wait_for_completion); 2944 2945/** 2946 * completion_done - Test to see if a completion has any waiters 2947 * @x: completion structure 2948 * 2949 * Return: 0 if there are waiters (wait_for_completion() in progress) 2950 * 1 if there are no waiters. 2951 * 2952 */ 2953bool completion_done(struct completion *x) 2954{ 2955 unsigned long flags; 2956 int ret = 1; 2957 2958 spin_lock_irqsave(&x->wait.lock, flags); 2959 if (!x->done) 2960 ret = 0; 2961 spin_unlock_irqrestore(&x->wait.lock, flags); 2962 return ret; 2963} 2964EXPORT_SYMBOL(completion_done); 2965 2966static long __sched 2967sleep_on_common(wait_queue_head_t *q, int state, long timeout) 2968{ 2969 unsigned long flags; 2970 wait_queue_t wait; 2971 2972 init_waitqueue_entry(&wait, current); 2973 2974 __set_current_state(state); 2975 2976 spin_lock_irqsave(&q->lock, flags); 2977 __add_wait_queue(q, &wait); 2978 spin_unlock(&q->lock); 2979 timeout = schedule_timeout(timeout); 2980 spin_lock_irq(&q->lock); 2981 __remove_wait_queue(q, &wait); 2982 spin_unlock_irqrestore(&q->lock, flags); 2983 2984 return timeout; 2985} 2986 2987void __sched interruptible_sleep_on(wait_queue_head_t *q) 2988{ 2989 sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 2990} 2991EXPORT_SYMBOL(interruptible_sleep_on); 2992 2993long __sched 2994interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout) 2995{ 2996 return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout); 2997} 2998EXPORT_SYMBOL(interruptible_sleep_on_timeout); 2999 3000void __sched sleep_on(wait_queue_head_t *q) 3001{ 3002 sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 3003} 3004EXPORT_SYMBOL(sleep_on); 3005 3006long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout) 3007{ 3008 return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout); 3009} 3010EXPORT_SYMBOL(sleep_on_timeout); 3011 3012#ifdef CONFIG_RT_MUTEXES 3013 3014/* 3015 * rt_mutex_setprio - set the current priority of a task 3016 * @p: task 3017 * @prio: prio value (kernel-internal form) 3018 * 3019 * This function changes the 'effective' priority of a task. It does 3020 * not touch ->normal_prio like __setscheduler(). 3021 * 3022 * Used by the rt_mutex code to implement priority inheritance logic. 3023 */ 3024void rt_mutex_setprio(struct task_struct *p, int prio) 3025{ 3026 int oldprio, on_rq, running; 3027 struct rq *rq; 3028 const struct sched_class *prev_class; 3029 3030 BUG_ON(prio < 0 || prio > MAX_PRIO); 3031 3032 rq = __task_rq_lock(p); 3033 3034 /* 3035 * Idle task boosting is a nono in general. There is one 3036 * exception, when PREEMPT_RT and NOHZ is active: 3037 * 3038 * The idle task calls get_next_timer_interrupt() and holds 3039 * the timer wheel base->lock on the CPU and another CPU wants 3040 * to access the timer (probably to cancel it). We can safely 3041 * ignore the boosting request, as the idle CPU runs this code 3042 * with interrupts disabled and will complete the lock 3043 * protected section without being interrupted. So there is no 3044 * real need to boost. 3045 */ 3046 if (unlikely(p == rq->idle)) { 3047 WARN_ON(p != rq->curr); 3048 WARN_ON(p->pi_blocked_on); 3049 goto out_unlock; 3050 } 3051 3052 trace_sched_pi_setprio(p, prio); 3053 oldprio = p->prio; 3054 prev_class = p->sched_class; 3055 on_rq = p->on_rq; 3056 running = task_current(rq, p); 3057 if (on_rq) 3058 dequeue_task(rq, p, 0); 3059 if (running) 3060 p->sched_class->put_prev_task(rq, p); 3061 3062 if (rt_prio(prio)) 3063 p->sched_class = &rt_sched_class; 3064 else 3065 p->sched_class = &fair_sched_class; 3066 3067 p->prio = prio; 3068 3069 if (running) 3070 p->sched_class->set_curr_task(rq); 3071 if (on_rq) 3072 enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0); 3073 3074 check_class_changed(rq, p, prev_class, oldprio); 3075out_unlock: 3076 __task_rq_unlock(rq); 3077} 3078#endif 3079void set_user_nice(struct task_struct *p, long nice) 3080{ 3081 int old_prio, delta, on_rq; 3082 unsigned long flags; 3083 struct rq *rq; 3084 3085 if (TASK_NICE(p) == nice || nice < -20 || nice > 19) 3086 return; 3087 /* 3088 * We have to be careful, if called from sys_setpriority(), 3089 * the task might be in the middle of scheduling on another CPU. 3090 */ 3091 rq = task_rq_lock(p, &flags); 3092 /* 3093 * The RT priorities are set via sched_setscheduler(), but we still 3094 * allow the 'normal' nice value to be set - but as expected 3095 * it wont have any effect on scheduling until the task is 3096 * SCHED_FIFO/SCHED_RR: 3097 */ 3098 if (task_has_rt_policy(p)) { 3099 p->static_prio = NICE_TO_PRIO(nice); 3100 goto out_unlock; 3101 } 3102 on_rq = p->on_rq; 3103 if (on_rq) 3104 dequeue_task(rq, p, 0); 3105 3106 p->static_prio = NICE_TO_PRIO(nice); 3107 set_load_weight(p); 3108 old_prio = p->prio; 3109 p->prio = effective_prio(p); 3110 delta = p->prio - old_prio; 3111 3112 if (on_rq) { 3113 enqueue_task(rq, p, 0); 3114 /* 3115 * If the task increased its priority or is running and 3116 * lowered its priority, then reschedule its CPU: 3117 */ 3118 if (delta < 0 || (delta > 0 && task_running(rq, p))) 3119 resched_task(rq->curr); 3120 } 3121out_unlock: 3122 task_rq_unlock(rq, p, &flags); 3123} 3124EXPORT_SYMBOL(set_user_nice); 3125 3126/* 3127 * can_nice - check if a task can reduce its nice value 3128 * @p: task 3129 * @nice: nice value 3130 */ 3131int can_nice(const struct task_struct *p, const int nice) 3132{ 3133 /* convert nice value [19,-20] to rlimit style value [1,40] */ 3134 int nice_rlim = 20 - nice; 3135 3136 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || 3137 capable(CAP_SYS_NICE)); 3138} 3139 3140#ifdef __ARCH_WANT_SYS_NICE 3141 3142/* 3143 * sys_nice - change the priority of the current process. 3144 * @increment: priority increment 3145 * 3146 * sys_setpriority is a more generic, but much slower function that 3147 * does similar things. 3148 */ 3149SYSCALL_DEFINE1(nice, int, increment) 3150{ 3151 long nice, retval; 3152 3153 /* 3154 * Setpriority might change our priority at the same moment. 3155 * We don't have to worry. Conceptually one call occurs first 3156 * and we have a single winner. 3157 */ 3158 if (increment < -40) 3159 increment = -40; 3160 if (increment > 40) 3161 increment = 40; 3162 3163 nice = TASK_NICE(current) + increment; 3164 if (nice < -20) 3165 nice = -20; 3166 if (nice > 19) 3167 nice = 19; 3168 3169 if (increment < 0 && !can_nice(current, nice)) 3170 return -EPERM; 3171 3172 retval = security_task_setnice(current, nice); 3173 if (retval) 3174 return retval; 3175 3176 set_user_nice(current, nice); 3177 return 0; 3178} 3179 3180#endif 3181 3182/** 3183 * task_prio - return the priority value of a given task. 3184 * @p: the task in question. 3185 * 3186 * Return: The priority value as seen by users in /proc. 3187 * RT tasks are offset by -200. Normal tasks are centered 3188 * around 0, value goes from -16 to +15. 3189 */ 3190int task_prio(const struct task_struct *p) 3191{ 3192 return p->prio - MAX_RT_PRIO; 3193} 3194 3195/** 3196 * task_nice - return the nice value of a given task. 3197 * @p: the task in question. 3198 * 3199 * Return: The nice value [ -20 ... 0 ... 19 ]. 3200 */ 3201int task_nice(const struct task_struct *p) 3202{ 3203 return TASK_NICE(p); 3204} 3205EXPORT_SYMBOL(task_nice); 3206 3207/** 3208 * idle_cpu - is a given cpu idle currently? 3209 * @cpu: the processor in question. 3210 * 3211 * Return: 1 if the CPU is currently idle. 0 otherwise. 3212 */ 3213int idle_cpu(int cpu) 3214{ 3215 struct rq *rq = cpu_rq(cpu); 3216 3217 if (rq->curr != rq->idle) 3218 return 0; 3219 3220 if (rq->nr_running) 3221 return 0; 3222 3223#ifdef CONFIG_SMP 3224 if (!llist_empty(&rq->wake_list)) 3225 return 0; 3226#endif 3227 3228 return 1; 3229} 3230 3231/** 3232 * idle_task - return the idle task for a given cpu. 3233 * @cpu: the processor in question. 3234 * 3235 * Return: The idle task for the cpu @cpu. 3236 */ 3237struct task_struct *idle_task(int cpu) 3238{ 3239 return cpu_rq(cpu)->idle; 3240} 3241 3242/** 3243 * find_process_by_pid - find a process with a matching PID value. 3244 * @pid: the pid in question. 3245 * 3246 * The task of @pid, if found. %NULL otherwise. 3247 */ 3248static struct task_struct *find_process_by_pid(pid_t pid) 3249{ 3250 return pid ? find_task_by_vpid(pid) : current; 3251} 3252 3253/* Actually do priority change: must hold rq lock. */ 3254static void 3255__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio) 3256{ 3257 p->policy = policy; 3258 p->rt_priority = prio; 3259 p->normal_prio = normal_prio(p); 3260 /* we are holding p->pi_lock already */ 3261 p->prio = rt_mutex_getprio(p); 3262 if (rt_prio(p->prio)) 3263 p->sched_class = &rt_sched_class; 3264 else 3265 p->sched_class = &fair_sched_class; 3266 set_load_weight(p); 3267} 3268 3269/* 3270 * check the target process has a UID that matches the current process's 3271 */ 3272static bool check_same_owner(struct task_struct *p) 3273{ 3274 const struct cred *cred = current_cred(), *pcred; 3275 bool match; 3276 3277 rcu_read_lock(); 3278 pcred = __task_cred(p); 3279 match = (uid_eq(cred->euid, pcred->euid) || 3280 uid_eq(cred->euid, pcred->uid)); 3281 rcu_read_unlock(); 3282 return match; 3283} 3284 3285static int __sched_setscheduler(struct task_struct *p, int policy, 3286 const struct sched_param *param, bool user) 3287{ 3288 int retval, oldprio, oldpolicy = -1, on_rq, running; 3289 unsigned long flags; 3290 const struct sched_class *prev_class; 3291 struct rq *rq; 3292 int reset_on_fork; 3293 3294 /* may grab non-irq protected spin_locks */ 3295 BUG_ON(in_interrupt()); 3296recheck: 3297 /* double check policy once rq lock held */ 3298 if (policy < 0) { 3299 reset_on_fork = p->sched_reset_on_fork; 3300 policy = oldpolicy = p->policy; 3301 } else { 3302 reset_on_fork = !!(policy & SCHED_RESET_ON_FORK); 3303 policy &= ~SCHED_RESET_ON_FORK; 3304 3305 if (policy != SCHED_FIFO && policy != SCHED_RR && 3306 policy != SCHED_NORMAL && policy != SCHED_BATCH && 3307 policy != SCHED_IDLE) 3308 return -EINVAL; 3309 } 3310 3311 /* 3312 * Valid priorities for SCHED_FIFO and SCHED_RR are 3313 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, 3314 * SCHED_BATCH and SCHED_IDLE is 0. 3315 */ 3316 if (param->sched_priority < 0 || 3317 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) || 3318 (!p->mm && param->sched_priority > MAX_RT_PRIO-1)) 3319 return -EINVAL; 3320 if (rt_policy(policy) != (param->sched_priority != 0)) 3321 return -EINVAL; 3322 3323 /* 3324 * Allow unprivileged RT tasks to decrease priority: 3325 */ 3326 if (user && !capable(CAP_SYS_NICE)) { 3327 if (rt_policy(policy)) { 3328 unsigned long rlim_rtprio = 3329 task_rlimit(p, RLIMIT_RTPRIO); 3330 3331 /* can't set/change the rt policy */ 3332 if (policy != p->policy && !rlim_rtprio) 3333 return -EPERM; 3334 3335 /* can't increase priority */ 3336 if (param->sched_priority > p->rt_priority && 3337 param->sched_priority > rlim_rtprio) 3338 return -EPERM; 3339 } 3340 3341 /* 3342 * Treat SCHED_IDLE as nice 20. Only allow a switch to 3343 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. 3344 */ 3345 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) { 3346 if (!can_nice(p, TASK_NICE(p))) 3347 return -EPERM; 3348 } 3349 3350 /* can't change other user's priorities */ 3351 if (!check_same_owner(p)) 3352 return -EPERM; 3353 3354 /* Normal users shall not reset the sched_reset_on_fork flag */ 3355 if (p->sched_reset_on_fork && !reset_on_fork) 3356 return -EPERM; 3357 } 3358 3359 if (user) { 3360 retval = security_task_setscheduler(p); 3361 if (retval) 3362 return retval; 3363 } 3364 3365 /* 3366 * make sure no PI-waiters arrive (or leave) while we are 3367 * changing the priority of the task: 3368 * 3369 * To be able to change p->policy safely, the appropriate 3370 * runqueue lock must be held. 3371 */ 3372 rq = task_rq_lock(p, &flags); 3373 3374 /* 3375 * Changing the policy of the stop threads its a very bad idea 3376 */ 3377 if (p == rq->stop) { 3378 task_rq_unlock(rq, p, &flags); 3379 return -EINVAL; 3380 } 3381 3382 /* 3383 * If not changing anything there's no need to proceed further: 3384 */ 3385 if (unlikely(policy == p->policy && (!rt_policy(policy) || 3386 param->sched_priority == p->rt_priority))) { 3387 task_rq_unlock(rq, p, &flags); 3388 return 0; 3389 } 3390 3391#ifdef CONFIG_RT_GROUP_SCHED 3392 if (user) { 3393 /* 3394 * Do not allow realtime tasks into groups that have no runtime 3395 * assigned. 3396 */ 3397 if (rt_bandwidth_enabled() && rt_policy(policy) && 3398 task_group(p)->rt_bandwidth.rt_runtime == 0 && 3399 !task_group_is_autogroup(task_group(p))) { 3400 task_rq_unlock(rq, p, &flags); 3401 return -EPERM; 3402 } 3403 } 3404#endif 3405 3406 /* recheck policy now with rq lock held */ 3407 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { 3408 policy = oldpolicy = -1; 3409 task_rq_unlock(rq, p, &flags); 3410 goto recheck; 3411 } 3412 on_rq = p->on_rq; 3413 running = task_current(rq, p); 3414 if (on_rq) 3415 dequeue_task(rq, p, 0); 3416 if (running) 3417 p->sched_class->put_prev_task(rq, p); 3418 3419 p->sched_reset_on_fork = reset_on_fork; 3420 3421 oldprio = p->prio; 3422 prev_class = p->sched_class; 3423 __setscheduler(rq, p, policy, param->sched_priority); 3424 3425 if (running) 3426 p->sched_class->set_curr_task(rq); 3427 if (on_rq) 3428 enqueue_task(rq, p, 0); 3429 3430 check_class_changed(rq, p, prev_class, oldprio); 3431 task_rq_unlock(rq, p, &flags); 3432 3433 rt_mutex_adjust_pi(p); 3434 3435 return 0; 3436} 3437 3438/** 3439 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. 3440 * @p: the task in question. 3441 * @policy: new policy. 3442 * @param: structure containing the new RT priority. 3443 * 3444 * Return: 0 on success. An error code otherwise. 3445 * 3446 * NOTE that the task may be already dead. 3447 */ 3448int sched_setscheduler(struct task_struct *p, int policy, 3449 const struct sched_param *param) 3450{ 3451 return __sched_setscheduler(p, policy, param, true); 3452} 3453EXPORT_SYMBOL_GPL(sched_setscheduler); 3454 3455/** 3456 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. 3457 * @p: the task in question. 3458 * @policy: new policy. 3459 * @param: structure containing the new RT priority. 3460 * 3461 * Just like sched_setscheduler, only don't bother checking if the 3462 * current context has permission. For example, this is needed in 3463 * stop_machine(): we create temporary high priority worker threads, 3464 * but our caller might not have that capability. 3465 * 3466 * Return: 0 on success. An error code otherwise. 3467 */ 3468int sched_setscheduler_nocheck(struct task_struct *p, int policy, 3469 const struct sched_param *param) 3470{ 3471 return __sched_setscheduler(p, policy, param, false); 3472} 3473 3474static int 3475do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) 3476{ 3477 struct sched_param lparam; 3478 struct task_struct *p; 3479 int retval; 3480 3481 if (!param || pid < 0) 3482 return -EINVAL; 3483 if (copy_from_user(&lparam, param, sizeof(struct sched_param))) 3484 return -EFAULT; 3485 3486 rcu_read_lock(); 3487 retval = -ESRCH; 3488 p = find_process_by_pid(pid); 3489 if (p != NULL) 3490 retval = sched_setscheduler(p, policy, &lparam); 3491 rcu_read_unlock(); 3492 3493 return retval; 3494} 3495 3496/** 3497 * sys_sched_setscheduler - set/change the scheduler policy and RT priority 3498 * @pid: the pid in question. 3499 * @policy: new policy. 3500 * @param: structure containing the new RT priority. 3501 * 3502 * Return: 0 on success. An error code otherwise. 3503 */ 3504SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, 3505 struct sched_param __user *, param) 3506{ 3507 /* negative values for policy are not valid */ 3508 if (policy < 0) 3509 return -EINVAL; 3510 3511 return do_sched_setscheduler(pid, policy, param); 3512} 3513 3514/** 3515 * sys_sched_setparam - set/change the RT priority of a thread 3516 * @pid: the pid in question. 3517 * @param: structure containing the new RT priority. 3518 * 3519 * Return: 0 on success. An error code otherwise. 3520 */ 3521SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) 3522{ 3523 return do_sched_setscheduler(pid, -1, param); 3524} 3525 3526/** 3527 * sys_sched_getscheduler - get the policy (scheduling class) of a thread 3528 * @pid: the pid in question. 3529 * 3530 * Return: On success, the policy of the thread. Otherwise, a negative error 3531 * code. 3532 */ 3533SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) 3534{ 3535 struct task_struct *p; 3536 int retval; 3537 3538 if (pid < 0) 3539 return -EINVAL; 3540 3541 retval = -ESRCH; 3542 rcu_read_lock(); 3543 p = find_process_by_pid(pid); 3544 if (p) { 3545 retval = security_task_getscheduler(p); 3546 if (!retval) 3547 retval = p->policy 3548 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); 3549 } 3550 rcu_read_unlock(); 3551 return retval; 3552} 3553 3554/** 3555 * sys_sched_getparam - get the RT priority of a thread 3556 * @pid: the pid in question. 3557 * @param: structure containing the RT priority. 3558 * 3559 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error 3560 * code. 3561 */ 3562SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) 3563{ 3564 struct sched_param lp; 3565 struct task_struct *p; 3566 int retval; 3567 3568 if (!param || pid < 0) 3569 return -EINVAL; 3570 3571 rcu_read_lock(); 3572 p = find_process_by_pid(pid); 3573 retval = -ESRCH; 3574 if (!p) 3575 goto out_unlock; 3576 3577 retval = security_task_getscheduler(p); 3578 if (retval) 3579 goto out_unlock; 3580 3581 lp.sched_priority = p->rt_priority; 3582 rcu_read_unlock(); 3583 3584 /* 3585 * This one might sleep, we cannot do it with a spinlock held ... 3586 */ 3587 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; 3588 3589 return retval; 3590 3591out_unlock: 3592 rcu_read_unlock(); 3593 return retval; 3594} 3595 3596long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) 3597{ 3598 cpumask_var_t cpus_allowed, new_mask; 3599 struct task_struct *p; 3600 int retval; 3601 3602 get_online_cpus(); 3603 rcu_read_lock(); 3604 3605 p = find_process_by_pid(pid); 3606 if (!p) { 3607 rcu_read_unlock(); 3608 put_online_cpus(); 3609 return -ESRCH; 3610 } 3611 3612 /* Prevent p going away */ 3613 get_task_struct(p); 3614 rcu_read_unlock(); 3615 3616 if (p->flags & PF_NO_SETAFFINITY) { 3617 retval = -EINVAL; 3618 goto out_put_task; 3619 } 3620 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { 3621 retval = -ENOMEM; 3622 goto out_put_task; 3623 } 3624 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { 3625 retval = -ENOMEM; 3626 goto out_free_cpus_allowed; 3627 } 3628 retval = -EPERM; 3629 if (!check_same_owner(p)) { 3630 rcu_read_lock(); 3631 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { 3632 rcu_read_unlock(); 3633 goto out_unlock; 3634 } 3635 rcu_read_unlock(); 3636 } 3637 3638 retval = security_task_setscheduler(p); 3639 if (retval) 3640 goto out_unlock; 3641 3642 cpuset_cpus_allowed(p, cpus_allowed); 3643 cpumask_and(new_mask, in_mask, cpus_allowed); 3644again: 3645 retval = set_cpus_allowed_ptr(p, new_mask); 3646 3647 if (!retval) { 3648 cpuset_cpus_allowed(p, cpus_allowed); 3649 if (!cpumask_subset(new_mask, cpus_allowed)) { 3650 /* 3651 * We must have raced with a concurrent cpuset 3652 * update. Just reset the cpus_allowed to the 3653 * cpuset's cpus_allowed 3654 */ 3655 cpumask_copy(new_mask, cpus_allowed); 3656 goto again; 3657 } 3658 } 3659out_unlock: 3660 free_cpumask_var(new_mask); 3661out_free_cpus_allowed: 3662 free_cpumask_var(cpus_allowed); 3663out_put_task: 3664 put_task_struct(p); 3665 put_online_cpus(); 3666 return retval; 3667} 3668 3669static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, 3670 struct cpumask *new_mask) 3671{ 3672 if (len < cpumask_size()) 3673 cpumask_clear(new_mask); 3674 else if (len > cpumask_size()) 3675 len = cpumask_size(); 3676 3677 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; 3678} 3679 3680/** 3681 * sys_sched_setaffinity - set the cpu affinity of a process 3682 * @pid: pid of the process 3683 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 3684 * @user_mask_ptr: user-space pointer to the new cpu mask 3685 * 3686 * Return: 0 on success. An error code otherwise. 3687 */ 3688SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, 3689 unsigned long __user *, user_mask_ptr) 3690{ 3691 cpumask_var_t new_mask; 3692 int retval; 3693 3694 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) 3695 return -ENOMEM; 3696 3697 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); 3698 if (retval == 0) 3699 retval = sched_setaffinity(pid, new_mask); 3700 free_cpumask_var(new_mask); 3701 return retval; 3702} 3703 3704long sched_getaffinity(pid_t pid, struct cpumask *mask) 3705{ 3706 struct task_struct *p; 3707 unsigned long flags; 3708 int retval; 3709 3710 get_online_cpus(); 3711 rcu_read_lock(); 3712 3713 retval = -ESRCH; 3714 p = find_process_by_pid(pid); 3715 if (!p) 3716 goto out_unlock; 3717 3718 retval = security_task_getscheduler(p); 3719 if (retval) 3720 goto out_unlock; 3721 3722 raw_spin_lock_irqsave(&p->pi_lock, flags); 3723 cpumask_and(mask, &p->cpus_allowed, cpu_online_mask); 3724 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 3725 3726out_unlock: 3727 rcu_read_unlock(); 3728 put_online_cpus(); 3729 3730 return retval; 3731} 3732 3733/** 3734 * sys_sched_getaffinity - get the cpu affinity of a process 3735 * @pid: pid of the process 3736 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 3737 * @user_mask_ptr: user-space pointer to hold the current cpu mask 3738 * 3739 * Return: 0 on success. An error code otherwise. 3740 */ 3741SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, 3742 unsigned long __user *, user_mask_ptr) 3743{ 3744 int ret; 3745 cpumask_var_t mask; 3746 3747 if ((len * BITS_PER_BYTE) < nr_cpu_ids) 3748 return -EINVAL; 3749 if (len & (sizeof(unsigned long)-1)) 3750 return -EINVAL; 3751 3752 if (!alloc_cpumask_var(&mask, GFP_KERNEL)) 3753 return -ENOMEM; 3754 3755 ret = sched_getaffinity(pid, mask); 3756 if (ret == 0) { 3757 size_t retlen = min_t(size_t, len, cpumask_size()); 3758 3759 if (copy_to_user(user_mask_ptr, mask, retlen)) 3760 ret = -EFAULT; 3761 else 3762 ret = retlen; 3763 } 3764 free_cpumask_var(mask); 3765 3766 return ret; 3767} 3768 3769/** 3770 * sys_sched_yield - yield the current processor to other threads. 3771 * 3772 * This function yields the current CPU to other tasks. If there are no 3773 * other threads running on this CPU then this function will return. 3774 * 3775 * Return: 0. 3776 */ 3777SYSCALL_DEFINE0(sched_yield) 3778{ 3779 struct rq *rq = this_rq_lock(); 3780 3781 schedstat_inc(rq, yld_count); 3782 current->sched_class->yield_task(rq); 3783 3784 /* 3785 * Since we are going to call schedule() anyway, there's 3786 * no need to preempt or enable interrupts: 3787 */ 3788 __release(rq->lock); 3789 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 3790 do_raw_spin_unlock(&rq->lock); 3791 sched_preempt_enable_no_resched(); 3792 3793 schedule(); 3794 3795 return 0; 3796} 3797 3798static inline int should_resched(void) 3799{ 3800 return need_resched() && !(preempt_count() & PREEMPT_ACTIVE); 3801} 3802 3803static void __cond_resched(void) 3804{ 3805 add_preempt_count(PREEMPT_ACTIVE); 3806 __schedule(); 3807 sub_preempt_count(PREEMPT_ACTIVE); 3808} 3809 3810int __sched _cond_resched(void) 3811{ 3812 if (should_resched()) { 3813 __cond_resched(); 3814 return 1; 3815 } 3816 return 0; 3817} 3818EXPORT_SYMBOL(_cond_resched); 3819 3820/* 3821 * __cond_resched_lock() - if a reschedule is pending, drop the given lock, 3822 * call schedule, and on return reacquire the lock. 3823 * 3824 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level 3825 * operations here to prevent schedule() from being called twice (once via 3826 * spin_unlock(), once by hand). 3827 */ 3828int __cond_resched_lock(spinlock_t *lock) 3829{ 3830 int resched = should_resched(); 3831 int ret = 0; 3832 3833 lockdep_assert_held(lock); 3834 3835 if (spin_needbreak(lock) || resched) { 3836 spin_unlock(lock); 3837 if (resched) 3838 __cond_resched(); 3839 else 3840 cpu_relax(); 3841 ret = 1; 3842 spin_lock(lock); 3843 } 3844 return ret; 3845} 3846EXPORT_SYMBOL(__cond_resched_lock); 3847 3848int __sched __cond_resched_softirq(void) 3849{ 3850 BUG_ON(!in_softirq()); 3851 3852 if (should_resched()) { 3853 local_bh_enable(); 3854 __cond_resched(); 3855 local_bh_disable(); 3856 return 1; 3857 } 3858 return 0; 3859} 3860EXPORT_SYMBOL(__cond_resched_softirq); 3861 3862/** 3863 * yield - yield the current processor to other threads. 3864 * 3865 * Do not ever use this function, there's a 99% chance you're doing it wrong. 3866 * 3867 * The scheduler is at all times free to pick the calling task as the most 3868 * eligible task to run, if removing the yield() call from your code breaks 3869 * it, its already broken. 3870 * 3871 * Typical broken usage is: 3872 * 3873 * while (!event) 3874 * yield(); 3875 * 3876 * where one assumes that yield() will let 'the other' process run that will 3877 * make event true. If the current task is a SCHED_FIFO task that will never 3878 * happen. Never use yield() as a progress guarantee!! 3879 * 3880 * If you want to use yield() to wait for something, use wait_event(). 3881 * If you want to use yield() to be 'nice' for others, use cond_resched(). 3882 * If you still want to use yield(), do not! 3883 */ 3884void __sched yield(void) 3885{ 3886 set_current_state(TASK_RUNNING); 3887 sys_sched_yield(); 3888} 3889EXPORT_SYMBOL(yield); 3890 3891/** 3892 * yield_to - yield the current processor to another thread in 3893 * your thread group, or accelerate that thread toward the 3894 * processor it's on. 3895 * @p: target task 3896 * @preempt: whether task preemption is allowed or not 3897 * 3898 * It's the caller's job to ensure that the target task struct 3899 * can't go away on us before we can do any checks. 3900 * 3901 * Return: 3902 * true (>0) if we indeed boosted the target task. 3903 * false (0) if we failed to boost the target. 3904 * -ESRCH if there's no task to yield to. 3905 */ 3906bool __sched yield_to(struct task_struct *p, bool preempt) 3907{ 3908 struct task_struct *curr = current; 3909 struct rq *rq, *p_rq; 3910 unsigned long flags; 3911 int yielded = 0; 3912 3913 local_irq_save(flags); 3914 rq = this_rq(); 3915 3916again: 3917 p_rq = task_rq(p); 3918 /* 3919 * If we're the only runnable task on the rq and target rq also 3920 * has only one task, there's absolutely no point in yielding. 3921 */ 3922 if (rq->nr_running == 1 && p_rq->nr_running == 1) { 3923 yielded = -ESRCH; 3924 goto out_irq; 3925 } 3926 3927 double_rq_lock(rq, p_rq); 3928 while (task_rq(p) != p_rq) { 3929 double_rq_unlock(rq, p_rq); 3930 goto again; 3931 } 3932 3933 if (!curr->sched_class->yield_to_task) 3934 goto out_unlock; 3935 3936 if (curr->sched_class != p->sched_class) 3937 goto out_unlock; 3938 3939 if (task_running(p_rq, p) || p->state) 3940 goto out_unlock; 3941 3942 yielded = curr->sched_class->yield_to_task(rq, p, preempt); 3943 if (yielded) { 3944 schedstat_inc(rq, yld_count); 3945 /* 3946 * Make p's CPU reschedule; pick_next_entity takes care of 3947 * fairness. 3948 */ 3949 if (preempt && rq != p_rq) 3950 resched_task(p_rq->curr); 3951 } 3952 3953out_unlock: 3954 double_rq_unlock(rq, p_rq); 3955out_irq: 3956 local_irq_restore(flags); 3957 3958 if (yielded > 0) 3959 schedule(); 3960 3961 return yielded; 3962} 3963EXPORT_SYMBOL_GPL(yield_to); 3964 3965/* 3966 * This task is about to go to sleep on IO. Increment rq->nr_iowait so 3967 * that process accounting knows that this is a task in IO wait state. 3968 */ 3969void __sched io_schedule(void) 3970{ 3971 struct rq *rq = raw_rq(); 3972 3973 delayacct_blkio_start(); 3974 atomic_inc(&rq->nr_iowait); 3975 blk_flush_plug(current); 3976 current->in_iowait = 1; 3977 schedule(); 3978 current->in_iowait = 0; 3979 atomic_dec(&rq->nr_iowait); 3980 delayacct_blkio_end(); 3981} 3982EXPORT_SYMBOL(io_schedule); 3983 3984long __sched io_schedule_timeout(long timeout) 3985{ 3986 struct rq *rq = raw_rq(); 3987 long ret; 3988 3989 delayacct_blkio_start(); 3990 atomic_inc(&rq->nr_iowait); 3991 blk_flush_plug(current); 3992 current->in_iowait = 1; 3993 ret = schedule_timeout(timeout); 3994 current->in_iowait = 0; 3995 atomic_dec(&rq->nr_iowait); 3996 delayacct_blkio_end(); 3997 return ret; 3998} 3999 4000/** 4001 * sys_sched_get_priority_max - return maximum RT priority. 4002 * @policy: scheduling class. 4003 * 4004 * Return: On success, this syscall returns the maximum 4005 * rt_priority that can be used by a given scheduling class. 4006 * On failure, a negative error code is returned. 4007 */ 4008SYSCALL_DEFINE1(sched_get_priority_max, int, policy) 4009{ 4010 int ret = -EINVAL; 4011 4012 switch (policy) { 4013 case SCHED_FIFO: 4014 case SCHED_RR: 4015 ret = MAX_USER_RT_PRIO-1; 4016 break; 4017 case SCHED_NORMAL: 4018 case SCHED_BATCH: 4019 case SCHED_IDLE: 4020 ret = 0; 4021 break; 4022 } 4023 return ret; 4024} 4025 4026/** 4027 * sys_sched_get_priority_min - return minimum RT priority. 4028 * @policy: scheduling class. 4029 * 4030 * Return: On success, this syscall returns the minimum 4031 * rt_priority that can be used by a given scheduling class. 4032 * On failure, a negative error code is returned. 4033 */ 4034SYSCALL_DEFINE1(sched_get_priority_min, int, policy) 4035{ 4036 int ret = -EINVAL; 4037 4038 switch (policy) { 4039 case SCHED_FIFO: 4040 case SCHED_RR: 4041 ret = 1; 4042 break; 4043 case SCHED_NORMAL: 4044 case SCHED_BATCH: 4045 case SCHED_IDLE: 4046 ret = 0; 4047 } 4048 return ret; 4049} 4050 4051/** 4052 * sys_sched_rr_get_interval - return the default timeslice of a process. 4053 * @pid: pid of the process. 4054 * @interval: userspace pointer to the timeslice value. 4055 * 4056 * this syscall writes the default timeslice value of a given process 4057 * into the user-space timespec buffer. A value of '0' means infinity. 4058 * 4059 * Return: On success, 0 and the timeslice is in @interval. Otherwise, 4060 * an error code. 4061 */ 4062SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, 4063 struct timespec __user *, interval) 4064{ 4065 struct task_struct *p; 4066 unsigned int time_slice; 4067 unsigned long flags; 4068 struct rq *rq; 4069 int retval; 4070 struct timespec t; 4071 4072 if (pid < 0) 4073 return -EINVAL; 4074 4075 retval = -ESRCH; 4076 rcu_read_lock(); 4077 p = find_process_by_pid(pid); 4078 if (!p) 4079 goto out_unlock; 4080 4081 retval = security_task_getscheduler(p); 4082 if (retval) 4083 goto out_unlock; 4084 4085 rq = task_rq_lock(p, &flags); 4086 time_slice = p->sched_class->get_rr_interval(rq, p); 4087 task_rq_unlock(rq, p, &flags); 4088 4089 rcu_read_unlock(); 4090 jiffies_to_timespec(time_slice, &t); 4091 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; 4092 return retval; 4093 4094out_unlock: 4095 rcu_read_unlock(); 4096 return retval; 4097} 4098 4099static const char stat_nam[] = TASK_STATE_TO_CHAR_STR; 4100 4101void sched_show_task(struct task_struct *p) 4102{ 4103 unsigned long free = 0; 4104 int ppid; 4105 unsigned state; 4106 4107 state = p->state ? __ffs(p->state) + 1 : 0; 4108 printk(KERN_INFO "%-15.15s %c", p->comm, 4109 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); 4110#if BITS_PER_LONG == 32 4111 if (state == TASK_RUNNING) 4112 printk(KERN_CONT " running "); 4113 else 4114 printk(KERN_CONT " %08lx ", thread_saved_pc(p)); 4115#else 4116 if (state == TASK_RUNNING) 4117 printk(KERN_CONT " running task "); 4118 else 4119 printk(KERN_CONT " %016lx ", thread_saved_pc(p)); 4120#endif 4121#ifdef CONFIG_DEBUG_STACK_USAGE 4122 free = stack_not_used(p); 4123#endif 4124 rcu_read_lock(); 4125 ppid = task_pid_nr(rcu_dereference(p->real_parent)); 4126 rcu_read_unlock(); 4127 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, 4128 task_pid_nr(p), ppid, 4129 (unsigned long)task_thread_info(p)->flags); 4130 4131 print_worker_info(KERN_INFO, p); 4132 show_stack(p, NULL); 4133} 4134 4135void show_state_filter(unsigned long state_filter) 4136{ 4137 struct task_struct *g, *p; 4138 4139#if BITS_PER_LONG == 32 4140 printk(KERN_INFO 4141 " task PC stack pid father\n"); 4142#else 4143 printk(KERN_INFO 4144 " task PC stack pid father\n"); 4145#endif 4146 rcu_read_lock(); 4147 do_each_thread(g, p) { 4148 /* 4149 * reset the NMI-timeout, listing all files on a slow 4150 * console might take a lot of time: 4151 */ 4152 touch_nmi_watchdog(); 4153 if (!state_filter || (p->state & state_filter)) 4154 sched_show_task(p); 4155 } while_each_thread(g, p); 4156 4157 touch_all_softlockup_watchdogs(); 4158 4159#ifdef CONFIG_SCHED_DEBUG 4160 sysrq_sched_debug_show(); 4161#endif 4162 rcu_read_unlock(); 4163 /* 4164 * Only show locks if all tasks are dumped: 4165 */ 4166 if (!state_filter) 4167 debug_show_all_locks(); 4168} 4169 4170void init_idle_bootup_task(struct task_struct *idle) 4171{ 4172 idle->sched_class = &idle_sched_class; 4173} 4174 4175/** 4176 * init_idle - set up an idle thread for a given CPU 4177 * @idle: task in question 4178 * @cpu: cpu the idle task belongs to 4179 * 4180 * NOTE: this function does not set the idle thread's NEED_RESCHED 4181 * flag, to make booting more robust. 4182 */ 4183void init_idle(struct task_struct *idle, int cpu) 4184{ 4185 struct rq *rq = cpu_rq(cpu); 4186 unsigned long flags; 4187 4188 raw_spin_lock_irqsave(&rq->lock, flags); 4189 4190 __sched_fork(idle); 4191 idle->state = TASK_RUNNING; 4192 idle->se.exec_start = sched_clock(); 4193 4194 do_set_cpus_allowed(idle, cpumask_of(cpu)); 4195 /* 4196 * We're having a chicken and egg problem, even though we are 4197 * holding rq->lock, the cpu isn't yet set to this cpu so the 4198 * lockdep check in task_group() will fail. 4199 * 4200 * Similar case to sched_fork(). / Alternatively we could 4201 * use task_rq_lock() here and obtain the other rq->lock. 4202 * 4203 * Silence PROVE_RCU 4204 */ 4205 rcu_read_lock(); 4206 __set_task_cpu(idle, cpu); 4207 rcu_read_unlock(); 4208 4209 rq->curr = rq->idle = idle; 4210#if defined(CONFIG_SMP) 4211 idle->on_cpu = 1; 4212#endif 4213 raw_spin_unlock_irqrestore(&rq->lock, flags); 4214 4215 /* Set the preempt count _outside_ the spinlocks! */ 4216 task_thread_info(idle)->preempt_count = 0; 4217 4218 /* 4219 * The idle tasks have their own, simple scheduling class: 4220 */ 4221 idle->sched_class = &idle_sched_class; 4222 ftrace_graph_init_idle_task(idle, cpu); 4223 vtime_init_idle(idle, cpu); 4224#if defined(CONFIG_SMP) 4225 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); 4226#endif 4227} 4228 4229#ifdef CONFIG_SMP 4230void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) 4231{ 4232 if (p->sched_class && p->sched_class->set_cpus_allowed) 4233 p->sched_class->set_cpus_allowed(p, new_mask); 4234 4235 cpumask_copy(&p->cpus_allowed, new_mask); 4236 p->nr_cpus_allowed = cpumask_weight(new_mask); 4237} 4238 4239/* 4240 * This is how migration works: 4241 * 4242 * 1) we invoke migration_cpu_stop() on the target CPU using 4243 * stop_one_cpu(). 4244 * 2) stopper starts to run (implicitly forcing the migrated thread 4245 * off the CPU) 4246 * 3) it checks whether the migrated task is still in the wrong runqueue. 4247 * 4) if it's in the wrong runqueue then the migration thread removes 4248 * it and puts it into the right queue. 4249 * 5) stopper completes and stop_one_cpu() returns and the migration 4250 * is done. 4251 */ 4252 4253/* 4254 * Change a given task's CPU affinity. Migrate the thread to a 4255 * proper CPU and schedule it away if the CPU it's executing on 4256 * is removed from the allowed bitmask. 4257 * 4258 * NOTE: the caller must have a valid reference to the task, the 4259 * task must not exit() & deallocate itself prematurely. The 4260 * call is not atomic; no spinlocks may be held. 4261 */ 4262int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) 4263{ 4264 unsigned long flags; 4265 struct rq *rq; 4266 unsigned int dest_cpu; 4267 int ret = 0; 4268 4269 rq = task_rq_lock(p, &flags); 4270 4271 if (cpumask_equal(&p->cpus_allowed, new_mask)) 4272 goto out; 4273 4274 if (!cpumask_intersects(new_mask, cpu_active_mask)) { 4275 ret = -EINVAL; 4276 goto out; 4277 } 4278 4279 do_set_cpus_allowed(p, new_mask); 4280 4281 /* Can the task run on the task's current CPU? If so, we're done */ 4282 if (cpumask_test_cpu(task_cpu(p), new_mask)) 4283 goto out; 4284 4285 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); 4286 if (p->on_rq) { 4287 struct migration_arg arg = { p, dest_cpu }; 4288 /* Need help from migration thread: drop lock and wait. */ 4289 task_rq_unlock(rq, p, &flags); 4290 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); 4291 tlb_migrate_finish(p->mm); 4292 return 0; 4293 } 4294out: 4295 task_rq_unlock(rq, p, &flags); 4296 4297 return ret; 4298} 4299EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); 4300 4301/* 4302 * Move (not current) task off this cpu, onto dest cpu. We're doing 4303 * this because either it can't run here any more (set_cpus_allowed() 4304 * away from this CPU, or CPU going down), or because we're 4305 * attempting to rebalance this task on exec (sched_exec). 4306 * 4307 * So we race with normal scheduler movements, but that's OK, as long 4308 * as the task is no longer on this CPU. 4309 * 4310 * Returns non-zero if task was successfully migrated. 4311 */ 4312static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) 4313{ 4314 struct rq *rq_dest, *rq_src; 4315 int ret = 0; 4316 4317 if (unlikely(!cpu_active(dest_cpu))) 4318 return ret; 4319 4320 rq_src = cpu_rq(src_cpu); 4321 rq_dest = cpu_rq(dest_cpu); 4322 4323 raw_spin_lock(&p->pi_lock); 4324 double_rq_lock(rq_src, rq_dest); 4325 /* Already moved. */ 4326 if (task_cpu(p) != src_cpu) 4327 goto done; 4328 /* Affinity changed (again). */ 4329 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 4330 goto fail; 4331 4332 /* 4333 * If we're not on a rq, the next wake-up will ensure we're 4334 * placed properly. 4335 */ 4336 if (p->on_rq) { 4337 dequeue_task(rq_src, p, 0); 4338 set_task_cpu(p, dest_cpu); 4339 enqueue_task(rq_dest, p, 0); 4340 check_preempt_curr(rq_dest, p, 0); 4341 } 4342done: 4343 ret = 1; 4344fail: 4345 double_rq_unlock(rq_src, rq_dest); 4346 raw_spin_unlock(&p->pi_lock); 4347 return ret; 4348} 4349 4350/* 4351 * migration_cpu_stop - this will be executed by a highprio stopper thread 4352 * and performs thread migration by bumping thread off CPU then 4353 * 'pushing' onto another runqueue. 4354 */ 4355static int migration_cpu_stop(void *data) 4356{ 4357 struct migration_arg *arg = data; 4358 4359 /* 4360 * The original target cpu might have gone down and we might 4361 * be on another cpu but it doesn't matter. 4362 */ 4363 local_irq_disable(); 4364 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu); 4365 local_irq_enable(); 4366 return 0; 4367} 4368 4369#ifdef CONFIG_HOTPLUG_CPU 4370 4371/* 4372 * Ensures that the idle task is using init_mm right before its cpu goes 4373 * offline. 4374 */ 4375void idle_task_exit(void) 4376{ 4377 struct mm_struct *mm = current->active_mm; 4378 4379 BUG_ON(cpu_online(smp_processor_id())); 4380 4381 if (mm != &init_mm) 4382 switch_mm(mm, &init_mm, current); 4383 mmdrop(mm); 4384} 4385 4386/* 4387 * Since this CPU is going 'away' for a while, fold any nr_active delta 4388 * we might have. Assumes we're called after migrate_tasks() so that the 4389 * nr_active count is stable. 4390 * 4391 * Also see the comment "Global load-average calculations". 4392 */ 4393static void calc_load_migrate(struct rq *rq) 4394{ 4395 long delta = calc_load_fold_active(rq); 4396 if (delta) 4397 atomic_long_add(delta, &calc_load_tasks); 4398} 4399 4400/* 4401 * Migrate all tasks from the rq, sleeping tasks will be migrated by 4402 * try_to_wake_up()->select_task_rq(). 4403 * 4404 * Called with rq->lock held even though we'er in stop_machine() and 4405 * there's no concurrency possible, we hold the required locks anyway 4406 * because of lock validation efforts. 4407 */ 4408static void migrate_tasks(unsigned int dead_cpu) 4409{ 4410 struct rq *rq = cpu_rq(dead_cpu); 4411 struct task_struct *next, *stop = rq->stop; 4412 int dest_cpu; 4413 4414 /* 4415 * Fudge the rq selection such that the below task selection loop 4416 * doesn't get stuck on the currently eligible stop task. 4417 * 4418 * We're currently inside stop_machine() and the rq is either stuck 4419 * in the stop_machine_cpu_stop() loop, or we're executing this code, 4420 * either way we should never end up calling schedule() until we're 4421 * done here. 4422 */ 4423 rq->stop = NULL; 4424 4425 /* 4426 * put_prev_task() and pick_next_task() sched 4427 * class method both need to have an up-to-date 4428 * value of rq->clock[_task] 4429 */ 4430 update_rq_clock(rq); 4431 4432 for ( ; ; ) { 4433 /* 4434 * There's this thread running, bail when that's the only 4435 * remaining thread. 4436 */ 4437 if (rq->nr_running == 1) 4438 break; 4439 4440 next = pick_next_task(rq); 4441 BUG_ON(!next); 4442 next->sched_class->put_prev_task(rq, next); 4443 4444 /* Find suitable destination for @next, with force if needed. */ 4445 dest_cpu = select_fallback_rq(dead_cpu, next); 4446 raw_spin_unlock(&rq->lock); 4447 4448 __migrate_task(next, dead_cpu, dest_cpu); 4449 4450 raw_spin_lock(&rq->lock); 4451 } 4452 4453 rq->stop = stop; 4454} 4455 4456#endif /* CONFIG_HOTPLUG_CPU */ 4457 4458#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) 4459 4460static struct ctl_table sd_ctl_dir[] = { 4461 { 4462 .procname = "sched_domain", 4463 .mode = 0555, 4464 }, 4465 {} 4466}; 4467 4468static struct ctl_table sd_ctl_root[] = { 4469 { 4470 .procname = "kernel", 4471 .mode = 0555, 4472 .child = sd_ctl_dir, 4473 }, 4474 {} 4475}; 4476 4477static struct ctl_table *sd_alloc_ctl_entry(int n) 4478{ 4479 struct ctl_table *entry = 4480 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL); 4481 4482 return entry; 4483} 4484 4485static void sd_free_ctl_entry(struct ctl_table **tablep) 4486{ 4487 struct ctl_table *entry; 4488 4489 /* 4490 * In the intermediate directories, both the child directory and 4491 * procname are dynamically allocated and could fail but the mode 4492 * will always be set. In the lowest directory the names are 4493 * static strings and all have proc handlers. 4494 */ 4495 for (entry = *tablep; entry->mode; entry++) { 4496 if (entry->child) 4497 sd_free_ctl_entry(&entry->child); 4498 if (entry->proc_handler == NULL) 4499 kfree(entry->procname); 4500 } 4501 4502 kfree(*tablep); 4503 *tablep = NULL; 4504} 4505 4506static int min_load_idx = 0; 4507static int max_load_idx = CPU_LOAD_IDX_MAX-1; 4508 4509static void 4510set_table_entry(struct ctl_table *entry, 4511 const char *procname, void *data, int maxlen, 4512 umode_t mode, proc_handler *proc_handler, 4513 bool load_idx) 4514{ 4515 entry->procname = procname; 4516 entry->data = data; 4517 entry->maxlen = maxlen; 4518 entry->mode = mode; 4519 entry->proc_handler = proc_handler; 4520 4521 if (load_idx) { 4522 entry->extra1 = &min_load_idx; 4523 entry->extra2 = &max_load_idx; 4524 } 4525} 4526 4527static struct ctl_table * 4528sd_alloc_ctl_domain_table(struct sched_domain *sd) 4529{ 4530 struct ctl_table *table = sd_alloc_ctl_entry(13); 4531 4532 if (table == NULL) 4533 return NULL; 4534 4535 set_table_entry(&table[0], "min_interval", &sd->min_interval, 4536 sizeof(long), 0644, proc_doulongvec_minmax, false); 4537 set_table_entry(&table[1], "max_interval", &sd->max_interval, 4538 sizeof(long), 0644, proc_doulongvec_minmax, false); 4539 set_table_entry(&table[2], "busy_idx", &sd->busy_idx, 4540 sizeof(int), 0644, proc_dointvec_minmax, true); 4541 set_table_entry(&table[3], "idle_idx", &sd->idle_idx, 4542 sizeof(int), 0644, proc_dointvec_minmax, true); 4543 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx, 4544 sizeof(int), 0644, proc_dointvec_minmax, true); 4545 set_table_entry(&table[5], "wake_idx", &sd->wake_idx, 4546 sizeof(int), 0644, proc_dointvec_minmax, true); 4547 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx, 4548 sizeof(int), 0644, proc_dointvec_minmax, true); 4549 set_table_entry(&table[7], "busy_factor", &sd->busy_factor, 4550 sizeof(int), 0644, proc_dointvec_minmax, false); 4551 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct, 4552 sizeof(int), 0644, proc_dointvec_minmax, false); 4553 set_table_entry(&table[9], "cache_nice_tries", 4554 &sd->cache_nice_tries, 4555 sizeof(int), 0644, proc_dointvec_minmax, false); 4556 set_table_entry(&table[10], "flags", &sd->flags, 4557 sizeof(int), 0644, proc_dointvec_minmax, false); 4558 set_table_entry(&table[11], "name", sd->name, 4559 CORENAME_MAX_SIZE, 0444, proc_dostring, false); 4560 /* &table[12] is terminator */ 4561 4562 return table; 4563} 4564 4565static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu) 4566{ 4567 struct ctl_table *entry, *table; 4568 struct sched_domain *sd; 4569 int domain_num = 0, i; 4570 char buf[32]; 4571 4572 for_each_domain(cpu, sd) 4573 domain_num++; 4574 entry = table = sd_alloc_ctl_entry(domain_num + 1); 4575 if (table == NULL) 4576 return NULL; 4577 4578 i = 0; 4579 for_each_domain(cpu, sd) { 4580 snprintf(buf, 32, "domain%d", i); 4581 entry->procname = kstrdup(buf, GFP_KERNEL); 4582 entry->mode = 0555; 4583 entry->child = sd_alloc_ctl_domain_table(sd); 4584 entry++; 4585 i++; 4586 } 4587 return table; 4588} 4589 4590static struct ctl_table_header *sd_sysctl_header; 4591static void register_sched_domain_sysctl(void) 4592{ 4593 int i, cpu_num = num_possible_cpus(); 4594 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1); 4595 char buf[32]; 4596 4597 WARN_ON(sd_ctl_dir[0].child); 4598 sd_ctl_dir[0].child = entry; 4599 4600 if (entry == NULL) 4601 return; 4602 4603 for_each_possible_cpu(i) { 4604 snprintf(buf, 32, "cpu%d", i); 4605 entry->procname = kstrdup(buf, GFP_KERNEL); 4606 entry->mode = 0555; 4607 entry->child = sd_alloc_ctl_cpu_table(i); 4608 entry++; 4609 } 4610 4611 WARN_ON(sd_sysctl_header); 4612 sd_sysctl_header = register_sysctl_table(sd_ctl_root); 4613} 4614 4615/* may be called multiple times per register */ 4616static void unregister_sched_domain_sysctl(void) 4617{ 4618 if (sd_sysctl_header) 4619 unregister_sysctl_table(sd_sysctl_header); 4620 sd_sysctl_header = NULL; 4621 if (sd_ctl_dir[0].child) 4622 sd_free_ctl_entry(&sd_ctl_dir[0].child); 4623} 4624#else 4625static void register_sched_domain_sysctl(void) 4626{ 4627} 4628static void unregister_sched_domain_sysctl(void) 4629{ 4630} 4631#endif 4632 4633static void set_rq_online(struct rq *rq) 4634{ 4635 if (!rq->online) { 4636 const struct sched_class *class; 4637 4638 cpumask_set_cpu(rq->cpu, rq->rd->online); 4639 rq->online = 1; 4640 4641 for_each_class(class) { 4642 if (class->rq_online) 4643 class->rq_online(rq); 4644 } 4645 } 4646} 4647 4648static void set_rq_offline(struct rq *rq) 4649{ 4650 if (rq->online) { 4651 const struct sched_class *class; 4652 4653 for_each_class(class) { 4654 if (class->rq_offline) 4655 class->rq_offline(rq); 4656 } 4657 4658 cpumask_clear_cpu(rq->cpu, rq->rd->online); 4659 rq->online = 0; 4660 } 4661} 4662 4663/* 4664 * migration_call - callback that gets triggered when a CPU is added. 4665 * Here we can start up the necessary migration thread for the new CPU. 4666 */ 4667static int 4668migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) 4669{ 4670 int cpu = (long)hcpu; 4671 unsigned long flags; 4672 struct rq *rq = cpu_rq(cpu); 4673 4674 switch (action & ~CPU_TASKS_FROZEN) { 4675 4676 case CPU_UP_PREPARE: 4677 rq->calc_load_update = calc_load_update; 4678 break; 4679 4680 case CPU_ONLINE: 4681 /* Update our root-domain */ 4682 raw_spin_lock_irqsave(&rq->lock, flags); 4683 if (rq->rd) { 4684 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 4685 4686 set_rq_online(rq); 4687 } 4688 raw_spin_unlock_irqrestore(&rq->lock, flags); 4689 break; 4690 4691#ifdef CONFIG_HOTPLUG_CPU 4692 case CPU_DYING: 4693 sched_ttwu_pending(); 4694 /* Update our root-domain */ 4695 raw_spin_lock_irqsave(&rq->lock, flags); 4696 if (rq->rd) { 4697 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 4698 set_rq_offline(rq); 4699 } 4700 migrate_tasks(cpu); 4701 BUG_ON(rq->nr_running != 1); /* the migration thread */ 4702 raw_spin_unlock_irqrestore(&rq->lock, flags); 4703 break; 4704 4705 case CPU_DEAD: 4706 calc_load_migrate(rq); 4707 break; 4708#endif 4709 } 4710 4711 update_max_interval(); 4712 4713 return NOTIFY_OK; 4714} 4715 4716/* 4717 * Register at high priority so that task migration (migrate_all_tasks) 4718 * happens before everything else. This has to be lower priority than 4719 * the notifier in the perf_event subsystem, though. 4720 */ 4721static struct notifier_block migration_notifier = { 4722 .notifier_call = migration_call, 4723 .priority = CPU_PRI_MIGRATION, 4724}; 4725 4726static int sched_cpu_active(struct notifier_block *nfb, 4727 unsigned long action, void *hcpu) 4728{ 4729 switch (action & ~CPU_TASKS_FROZEN) { 4730 case CPU_STARTING: 4731 case CPU_DOWN_FAILED: 4732 set_cpu_active((long)hcpu, true); 4733 return NOTIFY_OK; 4734 default: 4735 return NOTIFY_DONE; 4736 } 4737} 4738 4739static int sched_cpu_inactive(struct notifier_block *nfb, 4740 unsigned long action, void *hcpu) 4741{ 4742 switch (action & ~CPU_TASKS_FROZEN) { 4743 case CPU_DOWN_PREPARE: 4744 set_cpu_active((long)hcpu, false); 4745 return NOTIFY_OK; 4746 default: 4747 return NOTIFY_DONE; 4748 } 4749} 4750 4751static int __init migration_init(void) 4752{ 4753 void *cpu = (void *)(long)smp_processor_id(); 4754 int err; 4755 4756 /* Initialize migration for the boot CPU */ 4757 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu); 4758 BUG_ON(err == NOTIFY_BAD); 4759 migration_call(&migration_notifier, CPU_ONLINE, cpu); 4760 register_cpu_notifier(&migration_notifier); 4761 4762 /* Register cpu active notifiers */ 4763 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE); 4764 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE); 4765 4766 return 0; 4767} 4768early_initcall(migration_init); 4769#endif 4770 4771#ifdef CONFIG_SMP 4772 4773static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */ 4774 4775#ifdef CONFIG_SCHED_DEBUG 4776 4777static __read_mostly int sched_debug_enabled; 4778 4779static int __init sched_debug_setup(char *str) 4780{ 4781 sched_debug_enabled = 1; 4782 4783 return 0; 4784} 4785early_param("sched_debug", sched_debug_setup); 4786 4787static inline bool sched_debug(void) 4788{ 4789 return sched_debug_enabled; 4790} 4791 4792static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, 4793 struct cpumask *groupmask) 4794{ 4795 struct sched_group *group = sd->groups; 4796 char str[256]; 4797 4798 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd)); 4799 cpumask_clear(groupmask); 4800 4801 printk(KERN_DEBUG "%*s domain %d: ", level, "", level); 4802 4803 if (!(sd->flags & SD_LOAD_BALANCE)) { 4804 printk("does not load-balance\n"); 4805 if (sd->parent) 4806 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" 4807 " has parent"); 4808 return -1; 4809 } 4810 4811 printk(KERN_CONT "span %s level %s\n", str, sd->name); 4812 4813 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { 4814 printk(KERN_ERR "ERROR: domain->span does not contain " 4815 "CPU%d\n", cpu); 4816 } 4817 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) { 4818 printk(KERN_ERR "ERROR: domain->groups does not contain" 4819 " CPU%d\n", cpu); 4820 } 4821 4822 printk(KERN_DEBUG "%*s groups:", level + 1, ""); 4823 do { 4824 if (!group) { 4825 printk("\n"); 4826 printk(KERN_ERR "ERROR: group is NULL\n"); 4827 break; 4828 } 4829 4830 /* 4831 * Even though we initialize ->power to something semi-sane, 4832 * we leave power_orig unset. This allows us to detect if 4833 * domain iteration is still funny without causing /0 traps. 4834 */ 4835 if (!group->sgp->power_orig) { 4836 printk(KERN_CONT "\n"); 4837 printk(KERN_ERR "ERROR: domain->cpu_power not " 4838 "set\n"); 4839 break; 4840 } 4841 4842 if (!cpumask_weight(sched_group_cpus(group))) { 4843 printk(KERN_CONT "\n"); 4844 printk(KERN_ERR "ERROR: empty group\n"); 4845 break; 4846 } 4847 4848 if (!(sd->flags & SD_OVERLAP) && 4849 cpumask_intersects(groupmask, sched_group_cpus(group))) { 4850 printk(KERN_CONT "\n"); 4851 printk(KERN_ERR "ERROR: repeated CPUs\n"); 4852 break; 4853 } 4854 4855 cpumask_or(groupmask, groupmask, sched_group_cpus(group)); 4856 4857 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group)); 4858 4859 printk(KERN_CONT " %s", str); 4860 if (group->sgp->power != SCHED_POWER_SCALE) { 4861 printk(KERN_CONT " (cpu_power = %d)", 4862 group->sgp->power); 4863 } 4864 4865 group = group->next; 4866 } while (group != sd->groups); 4867 printk(KERN_CONT "\n"); 4868 4869 if (!cpumask_equal(sched_domain_span(sd), groupmask)) 4870 printk(KERN_ERR "ERROR: groups don't span domain->span\n"); 4871 4872 if (sd->parent && 4873 !cpumask_subset(groupmask, sched_domain_span(sd->parent))) 4874 printk(KERN_ERR "ERROR: parent span is not a superset " 4875 "of domain->span\n"); 4876 return 0; 4877} 4878 4879static void sched_domain_debug(struct sched_domain *sd, int cpu) 4880{ 4881 int level = 0; 4882 4883 if (!sched_debug_enabled) 4884 return; 4885 4886 if (!sd) { 4887 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); 4888 return; 4889 } 4890 4891 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); 4892 4893 for (;;) { 4894 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) 4895 break; 4896 level++; 4897 sd = sd->parent; 4898 if (!sd) 4899 break; 4900 } 4901} 4902#else /* !CONFIG_SCHED_DEBUG */ 4903# define sched_domain_debug(sd, cpu) do { } while (0) 4904static inline bool sched_debug(void) 4905{ 4906 return false; 4907} 4908#endif /* CONFIG_SCHED_DEBUG */ 4909 4910static int sd_degenerate(struct sched_domain *sd) 4911{ 4912 if (cpumask_weight(sched_domain_span(sd)) == 1) 4913 return 1; 4914 4915 /* Following flags need at least 2 groups */ 4916 if (sd->flags & (SD_LOAD_BALANCE | 4917 SD_BALANCE_NEWIDLE | 4918 SD_BALANCE_FORK | 4919 SD_BALANCE_EXEC | 4920 SD_SHARE_CPUPOWER | 4921 SD_SHARE_PKG_RESOURCES)) { 4922 if (sd->groups != sd->groups->next) 4923 return 0; 4924 } 4925 4926 /* Following flags don't use groups */ 4927 if (sd->flags & (SD_WAKE_AFFINE)) 4928 return 0; 4929 4930 return 1; 4931} 4932 4933static int 4934sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) 4935{ 4936 unsigned long cflags = sd->flags, pflags = parent->flags; 4937 4938 if (sd_degenerate(parent)) 4939 return 1; 4940 4941 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) 4942 return 0; 4943 4944 /* Flags needing groups don't count if only 1 group in parent */ 4945 if (parent->groups == parent->groups->next) { 4946 pflags &= ~(SD_LOAD_BALANCE | 4947 SD_BALANCE_NEWIDLE | 4948 SD_BALANCE_FORK | 4949 SD_BALANCE_EXEC | 4950 SD_SHARE_CPUPOWER | 4951 SD_SHARE_PKG_RESOURCES | 4952 SD_PREFER_SIBLING); 4953 if (nr_node_ids == 1) 4954 pflags &= ~SD_SERIALIZE; 4955 } 4956 if (~cflags & pflags) 4957 return 0; 4958 4959 return 1; 4960} 4961 4962static void free_rootdomain(struct rcu_head *rcu) 4963{ 4964 struct root_domain *rd = container_of(rcu, struct root_domain, rcu); 4965 4966 cpupri_cleanup(&rd->cpupri); 4967 free_cpumask_var(rd->rto_mask); 4968 free_cpumask_var(rd->online); 4969 free_cpumask_var(rd->span); 4970 kfree(rd); 4971} 4972 4973static void rq_attach_root(struct rq *rq, struct root_domain *rd) 4974{ 4975 struct root_domain *old_rd = NULL; 4976 unsigned long flags; 4977 4978 raw_spin_lock_irqsave(&rq->lock, flags); 4979 4980 if (rq->rd) { 4981 old_rd = rq->rd; 4982 4983 if (cpumask_test_cpu(rq->cpu, old_rd->online)) 4984 set_rq_offline(rq); 4985 4986 cpumask_clear_cpu(rq->cpu, old_rd->span); 4987 4988 /* 4989 * If we dont want to free the old_rt yet then 4990 * set old_rd to NULL to skip the freeing later 4991 * in this function: 4992 */ 4993 if (!atomic_dec_and_test(&old_rd->refcount)) 4994 old_rd = NULL; 4995 } 4996 4997 atomic_inc(&rd->refcount); 4998 rq->rd = rd; 4999 5000 cpumask_set_cpu(rq->cpu, rd->span); 5001 if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) 5002 set_rq_online(rq); 5003 5004 raw_spin_unlock_irqrestore(&rq->lock, flags); 5005 5006 if (old_rd) 5007 call_rcu_sched(&old_rd->rcu, free_rootdomain); 5008} 5009 5010static int init_rootdomain(struct root_domain *rd) 5011{ 5012 memset(rd, 0, sizeof(*rd)); 5013 5014 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL)) 5015 goto out; 5016 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL)) 5017 goto free_span; 5018 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) 5019 goto free_online; 5020 5021 if (cpupri_init(&rd->cpupri) != 0) 5022 goto free_rto_mask; 5023 return 0; 5024 5025free_rto_mask: 5026 free_cpumask_var(rd->rto_mask); 5027free_online: 5028 free_cpumask_var(rd->online); 5029free_span: 5030 free_cpumask_var(rd->span); 5031out: 5032 return -ENOMEM; 5033} 5034 5035/* 5036 * By default the system creates a single root-domain with all cpus as 5037 * members (mimicking the global state we have today). 5038 */ 5039struct root_domain def_root_domain; 5040 5041static void init_defrootdomain(void) 5042{ 5043 init_rootdomain(&def_root_domain); 5044 5045 atomic_set(&def_root_domain.refcount, 1); 5046} 5047 5048static struct root_domain *alloc_rootdomain(void) 5049{ 5050 struct root_domain *rd; 5051 5052 rd = kmalloc(sizeof(*rd), GFP_KERNEL); 5053 if (!rd) 5054 return NULL; 5055 5056 if (init_rootdomain(rd) != 0) { 5057 kfree(rd); 5058 return NULL; 5059 } 5060 5061 return rd; 5062} 5063 5064static void free_sched_groups(struct sched_group *sg, int free_sgp) 5065{ 5066 struct sched_group *tmp, *first; 5067 5068 if (!sg) 5069 return; 5070 5071 first = sg; 5072 do { 5073 tmp = sg->next; 5074 5075 if (free_sgp && atomic_dec_and_test(&sg->sgp->ref)) 5076 kfree(sg->sgp); 5077 5078 kfree(sg); 5079 sg = tmp; 5080 } while (sg != first); 5081} 5082 5083static void free_sched_domain(struct rcu_head *rcu) 5084{ 5085 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); 5086 5087 /* 5088 * If its an overlapping domain it has private groups, iterate and 5089 * nuke them all. 5090 */ 5091 if (sd->flags & SD_OVERLAP) { 5092 free_sched_groups(sd->groups, 1); 5093 } else if (atomic_dec_and_test(&sd->groups->ref)) { 5094 kfree(sd->groups->sgp); 5095 kfree(sd->groups); 5096 } 5097 kfree(sd); 5098} 5099 5100static void destroy_sched_domain(struct sched_domain *sd, int cpu) 5101{ 5102 call_rcu(&sd->rcu, free_sched_domain); 5103} 5104 5105static void destroy_sched_domains(struct sched_domain *sd, int cpu) 5106{ 5107 for (; sd; sd = sd->parent) 5108 destroy_sched_domain(sd, cpu); 5109} 5110 5111/* 5112 * Keep a special pointer to the highest sched_domain that has 5113 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this 5114 * allows us to avoid some pointer chasing select_idle_sibling(). 5115 * 5116 * Also keep a unique ID per domain (we use the first cpu number in 5117 * the cpumask of the domain), this allows us to quickly tell if 5118 * two cpus are in the same cache domain, see cpus_share_cache(). 5119 */ 5120DEFINE_PER_CPU(struct sched_domain *, sd_llc); 5121DEFINE_PER_CPU(int, sd_llc_size); 5122DEFINE_PER_CPU(int, sd_llc_id); 5123 5124static void update_top_cache_domain(int cpu) 5125{ 5126 struct sched_domain *sd; 5127 int id = cpu; 5128 int size = 1; 5129 5130 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); 5131 if (sd) { 5132 id = cpumask_first(sched_domain_span(sd)); 5133 size = cpumask_weight(sched_domain_span(sd)); 5134 } 5135 5136 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); 5137 per_cpu(sd_llc_size, cpu) = size; 5138 per_cpu(sd_llc_id, cpu) = id; 5139} 5140 5141/* 5142 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must 5143 * hold the hotplug lock. 5144 */ 5145static void 5146cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) 5147{ 5148 struct rq *rq = cpu_rq(cpu); 5149 struct sched_domain *tmp; 5150 5151 /* Remove the sched domains which do not contribute to scheduling. */ 5152 for (tmp = sd; tmp; ) { 5153 struct sched_domain *parent = tmp->parent; 5154 if (!parent) 5155 break; 5156 5157 if (sd_parent_degenerate(tmp, parent)) { 5158 tmp->parent = parent->parent; 5159 if (parent->parent) 5160 parent->parent->child = tmp; 5161 /* 5162 * Transfer SD_PREFER_SIBLING down in case of a 5163 * degenerate parent; the spans match for this 5164 * so the property transfers. 5165 */ 5166 if (parent->flags & SD_PREFER_SIBLING) 5167 tmp->flags |= SD_PREFER_SIBLING; 5168 destroy_sched_domain(parent, cpu); 5169 } else 5170 tmp = tmp->parent; 5171 } 5172 5173 if (sd && sd_degenerate(sd)) { 5174 tmp = sd; 5175 sd = sd->parent; 5176 destroy_sched_domain(tmp, cpu); 5177 if (sd) 5178 sd->child = NULL; 5179 } 5180 5181 sched_domain_debug(sd, cpu); 5182 5183 rq_attach_root(rq, rd); 5184 tmp = rq->sd; 5185 rcu_assign_pointer(rq->sd, sd); 5186 destroy_sched_domains(tmp, cpu); 5187 5188 update_top_cache_domain(cpu); 5189} 5190 5191/* cpus with isolated domains */ 5192static cpumask_var_t cpu_isolated_map; 5193 5194/* Setup the mask of cpus configured for isolated domains */ 5195static int __init isolated_cpu_setup(char *str) 5196{ 5197 alloc_bootmem_cpumask_var(&cpu_isolated_map); 5198 cpulist_parse(str, cpu_isolated_map); 5199 return 1; 5200} 5201 5202__setup("isolcpus=", isolated_cpu_setup); 5203 5204static const struct cpumask *cpu_cpu_mask(int cpu) 5205{ 5206 return cpumask_of_node(cpu_to_node(cpu)); 5207} 5208 5209struct sd_data { 5210 struct sched_domain **__percpu sd; 5211 struct sched_group **__percpu sg; 5212 struct sched_group_power **__percpu sgp; 5213}; 5214 5215struct s_data { 5216 struct sched_domain ** __percpu sd; 5217 struct root_domain *rd; 5218}; 5219 5220enum s_alloc { 5221 sa_rootdomain, 5222 sa_sd, 5223 sa_sd_storage, 5224 sa_none, 5225}; 5226 5227struct sched_domain_topology_level; 5228 5229typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu); 5230typedef const struct cpumask *(*sched_domain_mask_f)(int cpu); 5231 5232#define SDTL_OVERLAP 0x01 5233 5234struct sched_domain_topology_level { 5235 sched_domain_init_f init; 5236 sched_domain_mask_f mask; 5237 int flags; 5238 int numa_level; 5239 struct sd_data data; 5240}; 5241 5242/* 5243 * Build an iteration mask that can exclude certain CPUs from the upwards 5244 * domain traversal. 5245 * 5246 * Asymmetric node setups can result in situations where the domain tree is of 5247 * unequal depth, make sure to skip domains that already cover the entire 5248 * range. 5249 * 5250 * In that case build_sched_domains() will have terminated the iteration early 5251 * and our sibling sd spans will be empty. Domains should always include the 5252 * cpu they're built on, so check that. 5253 * 5254 */ 5255static void build_group_mask(struct sched_domain *sd, struct sched_group *sg) 5256{ 5257 const struct cpumask *span = sched_domain_span(sd); 5258 struct sd_data *sdd = sd->private; 5259 struct sched_domain *sibling; 5260 int i; 5261 5262 for_each_cpu(i, span) { 5263 sibling = *per_cpu_ptr(sdd->sd, i); 5264 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 5265 continue; 5266 5267 cpumask_set_cpu(i, sched_group_mask(sg)); 5268 } 5269} 5270 5271/* 5272 * Return the canonical balance cpu for this group, this is the first cpu 5273 * of this group that's also in the iteration mask. 5274 */ 5275int group_balance_cpu(struct sched_group *sg) 5276{ 5277 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg)); 5278} 5279 5280static int 5281build_overlap_sched_groups(struct sched_domain *sd, int cpu) 5282{ 5283 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg; 5284 const struct cpumask *span = sched_domain_span(sd); 5285 struct cpumask *covered = sched_domains_tmpmask; 5286 struct sd_data *sdd = sd->private; 5287 struct sched_domain *child; 5288 int i; 5289 5290 cpumask_clear(covered); 5291 5292 for_each_cpu(i, span) { 5293 struct cpumask *sg_span; 5294 5295 if (cpumask_test_cpu(i, covered)) 5296 continue; 5297 5298 child = *per_cpu_ptr(sdd->sd, i); 5299 5300 /* See the comment near build_group_mask(). */ 5301 if (!cpumask_test_cpu(i, sched_domain_span(child))) 5302 continue; 5303 5304 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 5305 GFP_KERNEL, cpu_to_node(cpu)); 5306 5307 if (!sg) 5308 goto fail; 5309 5310 sg_span = sched_group_cpus(sg); 5311 if (child->child) { 5312 child = child->child; 5313 cpumask_copy(sg_span, sched_domain_span(child)); 5314 } else 5315 cpumask_set_cpu(i, sg_span); 5316 5317 cpumask_or(covered, covered, sg_span); 5318 5319 sg->sgp = *per_cpu_ptr(sdd->sgp, i); 5320 if (atomic_inc_return(&sg->sgp->ref) == 1) 5321 build_group_mask(sd, sg); 5322 5323 /* 5324 * Initialize sgp->power such that even if we mess up the 5325 * domains and no possible iteration will get us here, we won't 5326 * die on a /0 trap. 5327 */ 5328 sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span); 5329 5330 /* 5331 * Make sure the first group of this domain contains the 5332 * canonical balance cpu. Otherwise the sched_domain iteration 5333 * breaks. See update_sg_lb_stats(). 5334 */ 5335 if ((!groups && cpumask_test_cpu(cpu, sg_span)) || 5336 group_balance_cpu(sg) == cpu) 5337 groups = sg; 5338 5339 if (!first) 5340 first = sg; 5341 if (last) 5342 last->next = sg; 5343 last = sg; 5344 last->next = first; 5345 } 5346 sd->groups = groups; 5347 5348 return 0; 5349 5350fail: 5351 free_sched_groups(first, 0); 5352 5353 return -ENOMEM; 5354} 5355 5356static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg) 5357{ 5358 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 5359 struct sched_domain *child = sd->child; 5360 5361 if (child) 5362 cpu = cpumask_first(sched_domain_span(child)); 5363 5364 if (sg) { 5365 *sg = *per_cpu_ptr(sdd->sg, cpu); 5366 (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu); 5367 atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */ 5368 } 5369 5370 return cpu; 5371} 5372 5373/* 5374 * build_sched_groups will build a circular linked list of the groups 5375 * covered by the given span, and will set each group's ->cpumask correctly, 5376 * and ->cpu_power to 0. 5377 * 5378 * Assumes the sched_domain tree is fully constructed 5379 */ 5380static int 5381build_sched_groups(struct sched_domain *sd, int cpu) 5382{ 5383 struct sched_group *first = NULL, *last = NULL; 5384 struct sd_data *sdd = sd->private; 5385 const struct cpumask *span = sched_domain_span(sd); 5386 struct cpumask *covered; 5387 int i; 5388 5389 get_group(cpu, sdd, &sd->groups); 5390 atomic_inc(&sd->groups->ref); 5391 5392 if (cpu != cpumask_first(span)) 5393 return 0; 5394 5395 lockdep_assert_held(&sched_domains_mutex); 5396 covered = sched_domains_tmpmask; 5397 5398 cpumask_clear(covered); 5399 5400 for_each_cpu(i, span) { 5401 struct sched_group *sg; 5402 int group, j; 5403 5404 if (cpumask_test_cpu(i, covered)) 5405 continue; 5406 5407 group = get_group(i, sdd, &sg); 5408 cpumask_clear(sched_group_cpus(sg)); 5409 sg->sgp->power = 0; 5410 cpumask_setall(sched_group_mask(sg)); 5411 5412 for_each_cpu(j, span) { 5413 if (get_group(j, sdd, NULL) != group) 5414 continue; 5415 5416 cpumask_set_cpu(j, covered); 5417 cpumask_set_cpu(j, sched_group_cpus(sg)); 5418 } 5419 5420 if (!first) 5421 first = sg; 5422 if (last) 5423 last->next = sg; 5424 last = sg; 5425 } 5426 last->next = first; 5427 5428 return 0; 5429} 5430 5431/* 5432 * Initialize sched groups cpu_power. 5433 * 5434 * cpu_power indicates the capacity of sched group, which is used while 5435 * distributing the load between different sched groups in a sched domain. 5436 * Typically cpu_power for all the groups in a sched domain will be same unless 5437 * there are asymmetries in the topology. If there are asymmetries, group 5438 * having more cpu_power will pickup more load compared to the group having 5439 * less cpu_power. 5440 */ 5441static void init_sched_groups_power(int cpu, struct sched_domain *sd) 5442{ 5443 struct sched_group *sg = sd->groups; 5444 5445 WARN_ON(!sg); 5446 5447 do { 5448 sg->group_weight = cpumask_weight(sched_group_cpus(sg)); 5449 sg = sg->next; 5450 } while (sg != sd->groups); 5451 5452 if (cpu != group_balance_cpu(sg)) 5453 return; 5454 5455 update_group_power(sd, cpu); 5456 atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight); 5457} 5458 5459int __weak arch_sd_sibling_asym_packing(void) 5460{ 5461 return 0*SD_ASYM_PACKING; 5462} 5463 5464/* 5465 * Initializers for schedule domains 5466 * Non-inlined to reduce accumulated stack pressure in build_sched_domains() 5467 */ 5468 5469#ifdef CONFIG_SCHED_DEBUG 5470# define SD_INIT_NAME(sd, type) sd->name = #type 5471#else 5472# define SD_INIT_NAME(sd, type) do { } while (0) 5473#endif 5474 5475#define SD_INIT_FUNC(type) \ 5476static noinline struct sched_domain * \ 5477sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \ 5478{ \ 5479 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \ 5480 *sd = SD_##type##_INIT; \ 5481 SD_INIT_NAME(sd, type); \ 5482 sd->private = &tl->data; \ 5483 return sd; \ 5484} 5485 5486SD_INIT_FUNC(CPU) 5487#ifdef CONFIG_SCHED_SMT 5488 SD_INIT_FUNC(SIBLING) 5489#endif 5490#ifdef CONFIG_SCHED_MC 5491 SD_INIT_FUNC(MC) 5492#endif 5493#ifdef CONFIG_SCHED_BOOK 5494 SD_INIT_FUNC(BOOK) 5495#endif 5496 5497static int default_relax_domain_level = -1; 5498int sched_domain_level_max; 5499 5500static int __init setup_relax_domain_level(char *str) 5501{ 5502 if (kstrtoint(str, 0, &default_relax_domain_level)) 5503 pr_warn("Unable to set relax_domain_level\n"); 5504 5505 return 1; 5506} 5507__setup("relax_domain_level=", setup_relax_domain_level); 5508 5509static void set_domain_attribute(struct sched_domain *sd, 5510 struct sched_domain_attr *attr) 5511{ 5512 int request; 5513 5514 if (!attr || attr->relax_domain_level < 0) { 5515 if (default_relax_domain_level < 0) 5516 return; 5517 else 5518 request = default_relax_domain_level; 5519 } else 5520 request = attr->relax_domain_level; 5521 if (request < sd->level) { 5522 /* turn off idle balance on this domain */ 5523 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 5524 } else { 5525 /* turn on idle balance on this domain */ 5526 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 5527 } 5528} 5529 5530static void __sdt_free(const struct cpumask *cpu_map); 5531static int __sdt_alloc(const struct cpumask *cpu_map); 5532 5533static void __free_domain_allocs(struct s_data *d, enum s_alloc what, 5534 const struct cpumask *cpu_map) 5535{ 5536 switch (what) { 5537 case sa_rootdomain: 5538 if (!atomic_read(&d->rd->refcount)) 5539 free_rootdomain(&d->rd->rcu); /* fall through */ 5540 case sa_sd: 5541 free_percpu(d->sd); /* fall through */ 5542 case sa_sd_storage: 5543 __sdt_free(cpu_map); /* fall through */ 5544 case sa_none: 5545 break; 5546 } 5547} 5548 5549static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, 5550 const struct cpumask *cpu_map) 5551{ 5552 memset(d, 0, sizeof(*d)); 5553 5554 if (__sdt_alloc(cpu_map)) 5555 return sa_sd_storage; 5556 d->sd = alloc_percpu(struct sched_domain *); 5557 if (!d->sd) 5558 return sa_sd_storage; 5559 d->rd = alloc_rootdomain(); 5560 if (!d->rd) 5561 return sa_sd; 5562 return sa_rootdomain; 5563} 5564 5565/* 5566 * NULL the sd_data elements we've used to build the sched_domain and 5567 * sched_group structure so that the subsequent __free_domain_allocs() 5568 * will not free the data we're using. 5569 */ 5570static void claim_allocations(int cpu, struct sched_domain *sd) 5571{ 5572 struct sd_data *sdd = sd->private; 5573 5574 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); 5575 *per_cpu_ptr(sdd->sd, cpu) = NULL; 5576 5577 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) 5578 *per_cpu_ptr(sdd->sg, cpu) = NULL; 5579 5580 if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref)) 5581 *per_cpu_ptr(sdd->sgp, cpu) = NULL; 5582} 5583 5584#ifdef CONFIG_SCHED_SMT 5585static const struct cpumask *cpu_smt_mask(int cpu) 5586{ 5587 return topology_thread_cpumask(cpu); 5588} 5589#endif 5590 5591/* 5592 * Topology list, bottom-up. 5593 */ 5594static struct sched_domain_topology_level default_topology[] = { 5595#ifdef CONFIG_SCHED_SMT 5596 { sd_init_SIBLING, cpu_smt_mask, }, 5597#endif 5598#ifdef CONFIG_SCHED_MC 5599 { sd_init_MC, cpu_coregroup_mask, }, 5600#endif 5601#ifdef CONFIG_SCHED_BOOK 5602 { sd_init_BOOK, cpu_book_mask, }, 5603#endif 5604 { sd_init_CPU, cpu_cpu_mask, }, 5605 { NULL, }, 5606}; 5607 5608static struct sched_domain_topology_level *sched_domain_topology = default_topology; 5609 5610#define for_each_sd_topology(tl) \ 5611 for (tl = sched_domain_topology; tl->init; tl++) 5612 5613#ifdef CONFIG_NUMA 5614 5615static int sched_domains_numa_levels; 5616static int *sched_domains_numa_distance; 5617static struct cpumask ***sched_domains_numa_masks; 5618static int sched_domains_curr_level; 5619 5620static inline int sd_local_flags(int level) 5621{ 5622 if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE) 5623 return 0; 5624 5625 return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE; 5626} 5627 5628static struct sched_domain * 5629sd_numa_init(struct sched_domain_topology_level *tl, int cpu) 5630{ 5631 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); 5632 int level = tl->numa_level; 5633 int sd_weight = cpumask_weight( 5634 sched_domains_numa_masks[level][cpu_to_node(cpu)]); 5635 5636 *sd = (struct sched_domain){ 5637 .min_interval = sd_weight, 5638 .max_interval = 2*sd_weight, 5639 .busy_factor = 32, 5640 .imbalance_pct = 125, 5641 .cache_nice_tries = 2, 5642 .busy_idx = 3, 5643 .idle_idx = 2, 5644 .newidle_idx = 0, 5645 .wake_idx = 0, 5646 .forkexec_idx = 0, 5647 5648 .flags = 1*SD_LOAD_BALANCE 5649 | 1*SD_BALANCE_NEWIDLE 5650 | 0*SD_BALANCE_EXEC 5651 | 0*SD_BALANCE_FORK 5652 | 0*SD_BALANCE_WAKE 5653 | 0*SD_WAKE_AFFINE 5654 | 0*SD_SHARE_CPUPOWER 5655 | 0*SD_SHARE_PKG_RESOURCES 5656 | 1*SD_SERIALIZE 5657 | 0*SD_PREFER_SIBLING 5658 | sd_local_flags(level) 5659 , 5660 .last_balance = jiffies, 5661 .balance_interval = sd_weight, 5662 }; 5663 SD_INIT_NAME(sd, NUMA); 5664 sd->private = &tl->data; 5665 5666 /* 5667 * Ugly hack to pass state to sd_numa_mask()... 5668 */ 5669 sched_domains_curr_level = tl->numa_level; 5670 5671 return sd; 5672} 5673 5674static const struct cpumask *sd_numa_mask(int cpu) 5675{ 5676 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; 5677} 5678 5679static void sched_numa_warn(const char *str) 5680{ 5681 static int done = false; 5682 int i,j; 5683 5684 if (done) 5685 return; 5686 5687 done = true; 5688 5689 printk(KERN_WARNING "ERROR: %s\n\n", str); 5690 5691 for (i = 0; i < nr_node_ids; i++) { 5692 printk(KERN_WARNING " "); 5693 for (j = 0; j < nr_node_ids; j++) 5694 printk(KERN_CONT "%02d ", node_distance(i,j)); 5695 printk(KERN_CONT "\n"); 5696 } 5697 printk(KERN_WARNING "\n"); 5698} 5699 5700static bool find_numa_distance(int distance) 5701{ 5702 int i; 5703 5704 if (distance == node_distance(0, 0)) 5705 return true; 5706 5707 for (i = 0; i < sched_domains_numa_levels; i++) { 5708 if (sched_domains_numa_distance[i] == distance) 5709 return true; 5710 } 5711 5712 return false; 5713} 5714 5715static void sched_init_numa(void) 5716{ 5717 int next_distance, curr_distance = node_distance(0, 0); 5718 struct sched_domain_topology_level *tl; 5719 int level = 0; 5720 int i, j, k; 5721 5722 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL); 5723 if (!sched_domains_numa_distance) 5724 return; 5725 5726 /* 5727 * O(nr_nodes^2) deduplicating selection sort -- in order to find the 5728 * unique distances in the node_distance() table. 5729 * 5730 * Assumes node_distance(0,j) includes all distances in 5731 * node_distance(i,j) in order to avoid cubic time. 5732 */ 5733 next_distance = curr_distance; 5734 for (i = 0; i < nr_node_ids; i++) { 5735 for (j = 0; j < nr_node_ids; j++) { 5736 for (k = 0; k < nr_node_ids; k++) { 5737 int distance = node_distance(i, k); 5738 5739 if (distance > curr_distance && 5740 (distance < next_distance || 5741 next_distance == curr_distance)) 5742 next_distance = distance; 5743 5744 /* 5745 * While not a strong assumption it would be nice to know 5746 * about cases where if node A is connected to B, B is not 5747 * equally connected to A. 5748 */ 5749 if (sched_debug() && node_distance(k, i) != distance) 5750 sched_numa_warn("Node-distance not symmetric"); 5751 5752 if (sched_debug() && i && !find_numa_distance(distance)) 5753 sched_numa_warn("Node-0 not representative"); 5754 } 5755 if (next_distance != curr_distance) { 5756 sched_domains_numa_distance[level++] = next_distance; 5757 sched_domains_numa_levels = level; 5758 curr_distance = next_distance; 5759 } else break; 5760 } 5761 5762 /* 5763 * In case of sched_debug() we verify the above assumption. 5764 */ 5765 if (!sched_debug()) 5766 break; 5767 } 5768 /* 5769 * 'level' contains the number of unique distances, excluding the 5770 * identity distance node_distance(i,i). 5771 * 5772 * The sched_domains_numa_distance[] array includes the actual distance 5773 * numbers. 5774 */ 5775 5776 /* 5777 * Here, we should temporarily reset sched_domains_numa_levels to 0. 5778 * If it fails to allocate memory for array sched_domains_numa_masks[][], 5779 * the array will contain less then 'level' members. This could be 5780 * dangerous when we use it to iterate array sched_domains_numa_masks[][] 5781 * in other functions. 5782 * 5783 * We reset it to 'level' at the end of this function. 5784 */ 5785 sched_domains_numa_levels = 0; 5786 5787 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); 5788 if (!sched_domains_numa_masks) 5789 return; 5790 5791 /* 5792 * Now for each level, construct a mask per node which contains all 5793 * cpus of nodes that are that many hops away from us. 5794 */ 5795 for (i = 0; i < level; i++) { 5796 sched_domains_numa_masks[i] = 5797 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); 5798 if (!sched_domains_numa_masks[i]) 5799 return; 5800 5801 for (j = 0; j < nr_node_ids; j++) { 5802 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); 5803 if (!mask) 5804 return; 5805 5806 sched_domains_numa_masks[i][j] = mask; 5807 5808 for (k = 0; k < nr_node_ids; k++) { 5809 if (node_distance(j, k) > sched_domains_numa_distance[i]) 5810 continue; 5811 5812 cpumask_or(mask, mask, cpumask_of_node(k)); 5813 } 5814 } 5815 } 5816 5817 tl = kzalloc((ARRAY_SIZE(default_topology) + level) * 5818 sizeof(struct sched_domain_topology_level), GFP_KERNEL); 5819 if (!tl) 5820 return; 5821 5822 /* 5823 * Copy the default topology bits.. 5824 */ 5825 for (i = 0; default_topology[i].init; i++) 5826 tl[i] = default_topology[i]; 5827 5828 /* 5829 * .. and append 'j' levels of NUMA goodness. 5830 */ 5831 for (j = 0; j < level; i++, j++) { 5832 tl[i] = (struct sched_domain_topology_level){ 5833 .init = sd_numa_init, 5834 .mask = sd_numa_mask, 5835 .flags = SDTL_OVERLAP, 5836 .numa_level = j, 5837 }; 5838 } 5839 5840 sched_domain_topology = tl; 5841 5842 sched_domains_numa_levels = level; 5843} 5844 5845static void sched_domains_numa_masks_set(int cpu) 5846{ 5847 int i, j; 5848 int node = cpu_to_node(cpu); 5849 5850 for (i = 0; i < sched_domains_numa_levels; i++) { 5851 for (j = 0; j < nr_node_ids; j++) { 5852 if (node_distance(j, node) <= sched_domains_numa_distance[i]) 5853 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]); 5854 } 5855 } 5856} 5857 5858static void sched_domains_numa_masks_clear(int cpu) 5859{ 5860 int i, j; 5861 for (i = 0; i < sched_domains_numa_levels; i++) { 5862 for (j = 0; j < nr_node_ids; j++) 5863 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]); 5864 } 5865} 5866 5867/* 5868 * Update sched_domains_numa_masks[level][node] array when new cpus 5869 * are onlined. 5870 */ 5871static int sched_domains_numa_masks_update(struct notifier_block *nfb, 5872 unsigned long action, 5873 void *hcpu) 5874{ 5875 int cpu = (long)hcpu; 5876 5877 switch (action & ~CPU_TASKS_FROZEN) { 5878 case CPU_ONLINE: 5879 sched_domains_numa_masks_set(cpu); 5880 break; 5881 5882 case CPU_DEAD: 5883 sched_domains_numa_masks_clear(cpu); 5884 break; 5885 5886 default: 5887 return NOTIFY_DONE; 5888 } 5889 5890 return NOTIFY_OK; 5891} 5892#else 5893static inline void sched_init_numa(void) 5894{ 5895} 5896 5897static int sched_domains_numa_masks_update(struct notifier_block *nfb, 5898 unsigned long action, 5899 void *hcpu) 5900{ 5901 return 0; 5902} 5903#endif /* CONFIG_NUMA */ 5904 5905static int __sdt_alloc(const struct cpumask *cpu_map) 5906{ 5907 struct sched_domain_topology_level *tl; 5908 int j; 5909 5910 for_each_sd_topology(tl) { 5911 struct sd_data *sdd = &tl->data; 5912 5913 sdd->sd = alloc_percpu(struct sched_domain *); 5914 if (!sdd->sd) 5915 return -ENOMEM; 5916 5917 sdd->sg = alloc_percpu(struct sched_group *); 5918 if (!sdd->sg) 5919 return -ENOMEM; 5920 5921 sdd->sgp = alloc_percpu(struct sched_group_power *); 5922 if (!sdd->sgp) 5923 return -ENOMEM; 5924 5925 for_each_cpu(j, cpu_map) { 5926 struct sched_domain *sd; 5927 struct sched_group *sg; 5928 struct sched_group_power *sgp; 5929 5930 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), 5931 GFP_KERNEL, cpu_to_node(j)); 5932 if (!sd) 5933 return -ENOMEM; 5934 5935 *per_cpu_ptr(sdd->sd, j) = sd; 5936 5937 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 5938 GFP_KERNEL, cpu_to_node(j)); 5939 if (!sg) 5940 return -ENOMEM; 5941 5942 sg->next = sg; 5943 5944 *per_cpu_ptr(sdd->sg, j) = sg; 5945 5946 sgp = kzalloc_node(sizeof(struct sched_group_power) + cpumask_size(), 5947 GFP_KERNEL, cpu_to_node(j)); 5948 if (!sgp) 5949 return -ENOMEM; 5950 5951 *per_cpu_ptr(sdd->sgp, j) = sgp; 5952 } 5953 } 5954 5955 return 0; 5956} 5957 5958static void __sdt_free(const struct cpumask *cpu_map) 5959{ 5960 struct sched_domain_topology_level *tl; 5961 int j; 5962 5963 for_each_sd_topology(tl) { 5964 struct sd_data *sdd = &tl->data; 5965 5966 for_each_cpu(j, cpu_map) { 5967 struct sched_domain *sd; 5968 5969 if (sdd->sd) { 5970 sd = *per_cpu_ptr(sdd->sd, j); 5971 if (sd && (sd->flags & SD_OVERLAP)) 5972 free_sched_groups(sd->groups, 0); 5973 kfree(*per_cpu_ptr(sdd->sd, j)); 5974 } 5975 5976 if (sdd->sg) 5977 kfree(*per_cpu_ptr(sdd->sg, j)); 5978 if (sdd->sgp) 5979 kfree(*per_cpu_ptr(sdd->sgp, j)); 5980 } 5981 free_percpu(sdd->sd); 5982 sdd->sd = NULL; 5983 free_percpu(sdd->sg); 5984 sdd->sg = NULL; 5985 free_percpu(sdd->sgp); 5986 sdd->sgp = NULL; 5987 } 5988} 5989 5990struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, 5991 const struct cpumask *cpu_map, struct sched_domain_attr *attr, 5992 struct sched_domain *child, int cpu) 5993{ 5994 struct sched_domain *sd = tl->init(tl, cpu); 5995 if (!sd) 5996 return child; 5997 5998 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); 5999 if (child) { 6000 sd->level = child->level + 1; 6001 sched_domain_level_max = max(sched_domain_level_max, sd->level); 6002 child->parent = sd; 6003 sd->child = child; 6004 } 6005 set_domain_attribute(sd, attr); 6006 6007 return sd; 6008} 6009 6010/* 6011 * Build sched domains for a given set of cpus and attach the sched domains 6012 * to the individual cpus 6013 */ 6014static int build_sched_domains(const struct cpumask *cpu_map, 6015 struct sched_domain_attr *attr) 6016{ 6017 enum s_alloc alloc_state; 6018 struct sched_domain *sd; 6019 struct s_data d; 6020 int i, ret = -ENOMEM; 6021 6022 alloc_state = __visit_domain_allocation_hell(&d, cpu_map); 6023 if (alloc_state != sa_rootdomain) 6024 goto error; 6025 6026 /* Set up domains for cpus specified by the cpu_map. */ 6027 for_each_cpu(i, cpu_map) { 6028 struct sched_domain_topology_level *tl; 6029 6030 sd = NULL; 6031 for_each_sd_topology(tl) { 6032 sd = build_sched_domain(tl, cpu_map, attr, sd, i); 6033 if (tl == sched_domain_topology) 6034 *per_cpu_ptr(d.sd, i) = sd; 6035 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) 6036 sd->flags |= SD_OVERLAP; 6037 if (cpumask_equal(cpu_map, sched_domain_span(sd))) 6038 break; 6039 } 6040 } 6041 6042 /* Build the groups for the domains */ 6043 for_each_cpu(i, cpu_map) { 6044 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6045 sd->span_weight = cpumask_weight(sched_domain_span(sd)); 6046 if (sd->flags & SD_OVERLAP) { 6047 if (build_overlap_sched_groups(sd, i)) 6048 goto error; 6049 } else { 6050 if (build_sched_groups(sd, i)) 6051 goto error; 6052 } 6053 } 6054 } 6055 6056 /* Calculate CPU power for physical packages and nodes */ 6057 for (i = nr_cpumask_bits-1; i >= 0; i--) { 6058 if (!cpumask_test_cpu(i, cpu_map)) 6059 continue; 6060 6061 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6062 claim_allocations(i, sd); 6063 init_sched_groups_power(i, sd); 6064 } 6065 } 6066 6067 /* Attach the domains */ 6068 rcu_read_lock(); 6069 for_each_cpu(i, cpu_map) { 6070 sd = *per_cpu_ptr(d.sd, i); 6071 cpu_attach_domain(sd, d.rd, i); 6072 } 6073 rcu_read_unlock(); 6074 6075 ret = 0; 6076error: 6077 __free_domain_allocs(&d, alloc_state, cpu_map); 6078 return ret; 6079} 6080 6081static cpumask_var_t *doms_cur; /* current sched domains */ 6082static int ndoms_cur; /* number of sched domains in 'doms_cur' */ 6083static struct sched_domain_attr *dattr_cur; 6084 /* attribues of custom domains in 'doms_cur' */ 6085 6086/* 6087 * Special case: If a kmalloc of a doms_cur partition (array of 6088 * cpumask) fails, then fallback to a single sched domain, 6089 * as determined by the single cpumask fallback_doms. 6090 */ 6091static cpumask_var_t fallback_doms; 6092 6093/* 6094 * arch_update_cpu_topology lets virtualized architectures update the 6095 * cpu core maps. It is supposed to return 1 if the topology changed 6096 * or 0 if it stayed the same. 6097 */ 6098int __attribute__((weak)) arch_update_cpu_topology(void) 6099{ 6100 return 0; 6101} 6102 6103cpumask_var_t *alloc_sched_domains(unsigned int ndoms) 6104{ 6105 int i; 6106 cpumask_var_t *doms; 6107 6108 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL); 6109 if (!doms) 6110 return NULL; 6111 for (i = 0; i < ndoms; i++) { 6112 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { 6113 free_sched_domains(doms, i); 6114 return NULL; 6115 } 6116 } 6117 return doms; 6118} 6119 6120void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) 6121{ 6122 unsigned int i; 6123 for (i = 0; i < ndoms; i++) 6124 free_cpumask_var(doms[i]); 6125 kfree(doms); 6126} 6127 6128/* 6129 * Set up scheduler domains and groups. Callers must hold the hotplug lock. 6130 * For now this just excludes isolated cpus, but could be used to 6131 * exclude other special cases in the future. 6132 */ 6133static int init_sched_domains(const struct cpumask *cpu_map) 6134{ 6135 int err; 6136 6137 arch_update_cpu_topology(); 6138 ndoms_cur = 1; 6139 doms_cur = alloc_sched_domains(ndoms_cur); 6140 if (!doms_cur) 6141 doms_cur = &fallback_doms; 6142 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map); 6143 err = build_sched_domains(doms_cur[0], NULL); 6144 register_sched_domain_sysctl(); 6145 6146 return err; 6147} 6148 6149/* 6150 * Detach sched domains from a group of cpus specified in cpu_map 6151 * These cpus will now be attached to the NULL domain 6152 */ 6153static void detach_destroy_domains(const struct cpumask *cpu_map) 6154{ 6155 int i; 6156 6157 rcu_read_lock(); 6158 for_each_cpu(i, cpu_map) 6159 cpu_attach_domain(NULL, &def_root_domain, i); 6160 rcu_read_unlock(); 6161} 6162 6163/* handle null as "default" */ 6164static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 6165 struct sched_domain_attr *new, int idx_new) 6166{ 6167 struct sched_domain_attr tmp; 6168 6169 /* fast path */ 6170 if (!new && !cur) 6171 return 1; 6172 6173 tmp = SD_ATTR_INIT; 6174 return !memcmp(cur ? (cur + idx_cur) : &tmp, 6175 new ? (new + idx_new) : &tmp, 6176 sizeof(struct sched_domain_attr)); 6177} 6178 6179/* 6180 * Partition sched domains as specified by the 'ndoms_new' 6181 * cpumasks in the array doms_new[] of cpumasks. This compares 6182 * doms_new[] to the current sched domain partitioning, doms_cur[]. 6183 * It destroys each deleted domain and builds each new domain. 6184 * 6185 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. 6186 * The masks don't intersect (don't overlap.) We should setup one 6187 * sched domain for each mask. CPUs not in any of the cpumasks will 6188 * not be load balanced. If the same cpumask appears both in the 6189 * current 'doms_cur' domains and in the new 'doms_new', we can leave 6190 * it as it is. 6191 * 6192 * The passed in 'doms_new' should be allocated using 6193 * alloc_sched_domains. This routine takes ownership of it and will 6194 * free_sched_domains it when done with it. If the caller failed the 6195 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, 6196 * and partition_sched_domains() will fallback to the single partition 6197 * 'fallback_doms', it also forces the domains to be rebuilt. 6198 * 6199 * If doms_new == NULL it will be replaced with cpu_online_mask. 6200 * ndoms_new == 0 is a special case for destroying existing domains, 6201 * and it will not create the default domain. 6202 * 6203 * Call with hotplug lock held 6204 */ 6205void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], 6206 struct sched_domain_attr *dattr_new) 6207{ 6208 int i, j, n; 6209 int new_topology; 6210 6211 mutex_lock(&sched_domains_mutex); 6212 6213 /* always unregister in case we don't destroy any domains */ 6214 unregister_sched_domain_sysctl(); 6215 6216 /* Let architecture update cpu core mappings. */ 6217 new_topology = arch_update_cpu_topology(); 6218 6219 n = doms_new ? ndoms_new : 0; 6220 6221 /* Destroy deleted domains */ 6222 for (i = 0; i < ndoms_cur; i++) { 6223 for (j = 0; j < n && !new_topology; j++) { 6224 if (cpumask_equal(doms_cur[i], doms_new[j]) 6225 && dattrs_equal(dattr_cur, i, dattr_new, j)) 6226 goto match1; 6227 } 6228 /* no match - a current sched domain not in new doms_new[] */ 6229 detach_destroy_domains(doms_cur[i]); 6230match1: 6231 ; 6232 } 6233 6234 n = ndoms_cur; 6235 if (doms_new == NULL) { 6236 n = 0; 6237 doms_new = &fallback_doms; 6238 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); 6239 WARN_ON_ONCE(dattr_new); 6240 } 6241 6242 /* Build new domains */ 6243 for (i = 0; i < ndoms_new; i++) { 6244 for (j = 0; j < n && !new_topology; j++) { 6245 if (cpumask_equal(doms_new[i], doms_cur[j]) 6246 && dattrs_equal(dattr_new, i, dattr_cur, j)) 6247 goto match2; 6248 } 6249 /* no match - add a new doms_new */ 6250 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); 6251match2: 6252 ; 6253 } 6254 6255 /* Remember the new sched domains */ 6256 if (doms_cur != &fallback_doms) 6257 free_sched_domains(doms_cur, ndoms_cur); 6258 kfree(dattr_cur); /* kfree(NULL) is safe */ 6259 doms_cur = doms_new; 6260 dattr_cur = dattr_new; 6261 ndoms_cur = ndoms_new; 6262 6263 register_sched_domain_sysctl(); 6264 6265 mutex_unlock(&sched_domains_mutex); 6266} 6267 6268static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */ 6269 6270/* 6271 * Update cpusets according to cpu_active mask. If cpusets are 6272 * disabled, cpuset_update_active_cpus() becomes a simple wrapper 6273 * around partition_sched_domains(). 6274 * 6275 * If we come here as part of a suspend/resume, don't touch cpusets because we 6276 * want to restore it back to its original state upon resume anyway. 6277 */ 6278static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, 6279 void *hcpu) 6280{ 6281 switch (action) { 6282 case CPU_ONLINE_FROZEN: 6283 case CPU_DOWN_FAILED_FROZEN: 6284 6285 /* 6286 * num_cpus_frozen tracks how many CPUs are involved in suspend 6287 * resume sequence. As long as this is not the last online 6288 * operation in the resume sequence, just build a single sched 6289 * domain, ignoring cpusets. 6290 */ 6291 num_cpus_frozen--; 6292 if (likely(num_cpus_frozen)) { 6293 partition_sched_domains(1, NULL, NULL); 6294 break; 6295 } 6296 6297 /* 6298 * This is the last CPU online operation. So fall through and 6299 * restore the original sched domains by considering the 6300 * cpuset configurations. 6301 */ 6302 6303 case CPU_ONLINE: 6304 case CPU_DOWN_FAILED: 6305 cpuset_update_active_cpus(true); 6306 break; 6307 default: 6308 return NOTIFY_DONE; 6309 } 6310 return NOTIFY_OK; 6311} 6312 6313static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, 6314 void *hcpu) 6315{ 6316 switch (action) { 6317 case CPU_DOWN_PREPARE: 6318 cpuset_update_active_cpus(false); 6319 break; 6320 case CPU_DOWN_PREPARE_FROZEN: 6321 num_cpus_frozen++; 6322 partition_sched_domains(1, NULL, NULL); 6323 break; 6324 default: 6325 return NOTIFY_DONE; 6326 } 6327 return NOTIFY_OK; 6328} 6329 6330void __init sched_init_smp(void) 6331{ 6332 cpumask_var_t non_isolated_cpus; 6333 6334 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); 6335 alloc_cpumask_var(&fallback_doms, GFP_KERNEL); 6336 6337 sched_init_numa(); 6338 6339 get_online_cpus(); 6340 mutex_lock(&sched_domains_mutex); 6341 init_sched_domains(cpu_active_mask); 6342 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); 6343 if (cpumask_empty(non_isolated_cpus)) 6344 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus); 6345 mutex_unlock(&sched_domains_mutex); 6346 put_online_cpus(); 6347 6348 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE); 6349 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE); 6350 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE); 6351 6352 init_hrtick(); 6353 6354 /* Move init over to a non-isolated CPU */ 6355 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) 6356 BUG(); 6357 sched_init_granularity(); 6358 free_cpumask_var(non_isolated_cpus); 6359 6360 init_sched_rt_class(); 6361} 6362#else 6363void __init sched_init_smp(void) 6364{ 6365 sched_init_granularity(); 6366} 6367#endif /* CONFIG_SMP */ 6368 6369const_debug unsigned int sysctl_timer_migration = 1; 6370 6371int in_sched_functions(unsigned long addr) 6372{ 6373 return in_lock_functions(addr) || 6374 (addr >= (unsigned long)__sched_text_start 6375 && addr < (unsigned long)__sched_text_end); 6376} 6377 6378#ifdef CONFIG_CGROUP_SCHED 6379/* 6380 * Default task group. 6381 * Every task in system belongs to this group at bootup. 6382 */ 6383struct task_group root_task_group; 6384LIST_HEAD(task_groups); 6385#endif 6386 6387DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); 6388 6389void __init sched_init(void) 6390{ 6391 int i, j; 6392 unsigned long alloc_size = 0, ptr; 6393 6394#ifdef CONFIG_FAIR_GROUP_SCHED 6395 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 6396#endif 6397#ifdef CONFIG_RT_GROUP_SCHED 6398 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 6399#endif 6400#ifdef CONFIG_CPUMASK_OFFSTACK 6401 alloc_size += num_possible_cpus() * cpumask_size(); 6402#endif 6403 if (alloc_size) { 6404 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); 6405 6406#ifdef CONFIG_FAIR_GROUP_SCHED 6407 root_task_group.se = (struct sched_entity **)ptr; 6408 ptr += nr_cpu_ids * sizeof(void **); 6409 6410 root_task_group.cfs_rq = (struct cfs_rq **)ptr; 6411 ptr += nr_cpu_ids * sizeof(void **); 6412 6413#endif /* CONFIG_FAIR_GROUP_SCHED */ 6414#ifdef CONFIG_RT_GROUP_SCHED 6415 root_task_group.rt_se = (struct sched_rt_entity **)ptr; 6416 ptr += nr_cpu_ids * sizeof(void **); 6417 6418 root_task_group.rt_rq = (struct rt_rq **)ptr; 6419 ptr += nr_cpu_ids * sizeof(void **); 6420 6421#endif /* CONFIG_RT_GROUP_SCHED */ 6422#ifdef CONFIG_CPUMASK_OFFSTACK 6423 for_each_possible_cpu(i) { 6424 per_cpu(load_balance_mask, i) = (void *)ptr; 6425 ptr += cpumask_size(); 6426 } 6427#endif /* CONFIG_CPUMASK_OFFSTACK */ 6428 } 6429 6430#ifdef CONFIG_SMP 6431 init_defrootdomain(); 6432#endif 6433 6434 init_rt_bandwidth(&def_rt_bandwidth, 6435 global_rt_period(), global_rt_runtime()); 6436 6437#ifdef CONFIG_RT_GROUP_SCHED 6438 init_rt_bandwidth(&root_task_group.rt_bandwidth, 6439 global_rt_period(), global_rt_runtime()); 6440#endif /* CONFIG_RT_GROUP_SCHED */ 6441 6442#ifdef CONFIG_CGROUP_SCHED 6443 list_add(&root_task_group.list, &task_groups); 6444 INIT_LIST_HEAD(&root_task_group.children); 6445 INIT_LIST_HEAD(&root_task_group.siblings); 6446 autogroup_init(&init_task); 6447 6448#endif /* CONFIG_CGROUP_SCHED */ 6449 6450 for_each_possible_cpu(i) { 6451 struct rq *rq; 6452 6453 rq = cpu_rq(i); 6454 raw_spin_lock_init(&rq->lock); 6455 rq->nr_running = 0; 6456 rq->calc_load_active = 0; 6457 rq->calc_load_update = jiffies + LOAD_FREQ; 6458 init_cfs_rq(&rq->cfs); 6459 init_rt_rq(&rq->rt, rq); 6460#ifdef CONFIG_FAIR_GROUP_SCHED 6461 root_task_group.shares = ROOT_TASK_GROUP_LOAD; 6462 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); 6463 /* 6464 * How much cpu bandwidth does root_task_group get? 6465 * 6466 * In case of task-groups formed thr' the cgroup filesystem, it 6467 * gets 100% of the cpu resources in the system. This overall 6468 * system cpu resource is divided among the tasks of 6469 * root_task_group and its child task-groups in a fair manner, 6470 * based on each entity's (task or task-group's) weight 6471 * (se->load.weight). 6472 * 6473 * In other words, if root_task_group has 10 tasks of weight 6474 * 1024) and two child groups A0 and A1 (of weight 1024 each), 6475 * then A0's share of the cpu resource is: 6476 * 6477 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% 6478 * 6479 * We achieve this by letting root_task_group's tasks sit 6480 * directly in rq->cfs (i.e root_task_group->se[] = NULL). 6481 */ 6482 init_cfs_bandwidth(&root_task_group.cfs_bandwidth); 6483 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); 6484#endif /* CONFIG_FAIR_GROUP_SCHED */ 6485 6486 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; 6487#ifdef CONFIG_RT_GROUP_SCHED 6488 INIT_LIST_HEAD(&rq->leaf_rt_rq_list); 6489 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); 6490#endif 6491 6492 for (j = 0; j < CPU_LOAD_IDX_MAX; j++) 6493 rq->cpu_load[j] = 0; 6494 6495 rq->last_load_update_tick = jiffies; 6496 6497#ifdef CONFIG_SMP 6498 rq->sd = NULL; 6499 rq->rd = NULL; 6500 rq->cpu_power = SCHED_POWER_SCALE; 6501 rq->post_schedule = 0; 6502 rq->active_balance = 0; 6503 rq->next_balance = jiffies; 6504 rq->push_cpu = 0; 6505 rq->cpu = i; 6506 rq->online = 0; 6507 rq->idle_stamp = 0; 6508 rq->avg_idle = 2*sysctl_sched_migration_cost; 6509 rq->max_idle_balance_cost = sysctl_sched_migration_cost; 6510 6511 INIT_LIST_HEAD(&rq->cfs_tasks); 6512 6513 rq_attach_root(rq, &def_root_domain); 6514#ifdef CONFIG_NO_HZ_COMMON 6515 rq->nohz_flags = 0; 6516#endif 6517#ifdef CONFIG_NO_HZ_FULL 6518 rq->last_sched_tick = 0; 6519#endif 6520#endif 6521 init_rq_hrtick(rq); 6522 atomic_set(&rq->nr_iowait, 0); 6523 } 6524 6525 set_load_weight(&init_task); 6526 6527#ifdef CONFIG_PREEMPT_NOTIFIERS 6528 INIT_HLIST_HEAD(&init_task.preempt_notifiers); 6529#endif 6530 6531#ifdef CONFIG_RT_MUTEXES 6532 plist_head_init(&init_task.pi_waiters); 6533#endif 6534 6535 /* 6536 * The boot idle thread does lazy MMU switching as well: 6537 */ 6538 atomic_inc(&init_mm.mm_count); 6539 enter_lazy_tlb(&init_mm, current); 6540 6541 /* 6542 * Make us the idle thread. Technically, schedule() should not be 6543 * called from this thread, however somewhere below it might be, 6544 * but because we are the idle thread, we just pick up running again 6545 * when this runqueue becomes "idle". 6546 */ 6547 init_idle(current, smp_processor_id()); 6548 6549 calc_load_update = jiffies + LOAD_FREQ; 6550 6551 /* 6552 * During early bootup we pretend to be a normal task: 6553 */ 6554 current->sched_class = &fair_sched_class; 6555 6556#ifdef CONFIG_SMP 6557 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT); 6558 /* May be allocated at isolcpus cmdline parse time */ 6559 if (cpu_isolated_map == NULL) 6560 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT); 6561 idle_thread_set_boot_cpu(); 6562#endif 6563 init_sched_fair_class(); 6564 6565 scheduler_running = 1; 6566} 6567 6568#ifdef CONFIG_DEBUG_ATOMIC_SLEEP 6569static inline int preempt_count_equals(int preempt_offset) 6570{ 6571 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth(); 6572 6573 return (nested == preempt_offset); 6574} 6575 6576void __might_sleep(const char *file, int line, int preempt_offset) 6577{ 6578 static unsigned long prev_jiffy; /* ratelimiting */ 6579 6580 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ 6581 if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) || 6582 system_state != SYSTEM_RUNNING || oops_in_progress) 6583 return; 6584 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) 6585 return; 6586 prev_jiffy = jiffies; 6587 6588 printk(KERN_ERR 6589 "BUG: sleeping function called from invalid context at %s:%d\n", 6590 file, line); 6591 printk(KERN_ERR 6592 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", 6593 in_atomic(), irqs_disabled(), 6594 current->pid, current->comm); 6595 6596 debug_show_held_locks(current); 6597 if (irqs_disabled()) 6598 print_irqtrace_events(current); 6599 dump_stack(); 6600} 6601EXPORT_SYMBOL(__might_sleep); 6602#endif 6603 6604#ifdef CONFIG_MAGIC_SYSRQ 6605static void normalize_task(struct rq *rq, struct task_struct *p) 6606{ 6607 const struct sched_class *prev_class = p->sched_class; 6608 int old_prio = p->prio; 6609 int on_rq; 6610 6611 on_rq = p->on_rq; 6612 if (on_rq) 6613 dequeue_task(rq, p, 0); 6614 __setscheduler(rq, p, SCHED_NORMAL, 0); 6615 if (on_rq) { 6616 enqueue_task(rq, p, 0); 6617 resched_task(rq->curr); 6618 } 6619 6620 check_class_changed(rq, p, prev_class, old_prio); 6621} 6622 6623void normalize_rt_tasks(void) 6624{ 6625 struct task_struct *g, *p; 6626 unsigned long flags; 6627 struct rq *rq; 6628 6629 read_lock_irqsave(&tasklist_lock, flags); 6630 do_each_thread(g, p) { 6631 /* 6632 * Only normalize user tasks: 6633 */ 6634 if (!p->mm) 6635 continue; 6636 6637 p->se.exec_start = 0; 6638#ifdef CONFIG_SCHEDSTATS 6639 p->se.statistics.wait_start = 0; 6640 p->se.statistics.sleep_start = 0; 6641 p->se.statistics.block_start = 0; 6642#endif 6643 6644 if (!rt_task(p)) { 6645 /* 6646 * Renice negative nice level userspace 6647 * tasks back to 0: 6648 */ 6649 if (TASK_NICE(p) < 0 && p->mm) 6650 set_user_nice(p, 0); 6651 continue; 6652 } 6653 6654 raw_spin_lock(&p->pi_lock); 6655 rq = __task_rq_lock(p); 6656 6657 normalize_task(rq, p); 6658 6659 __task_rq_unlock(rq); 6660 raw_spin_unlock(&p->pi_lock); 6661 } while_each_thread(g, p); 6662 6663 read_unlock_irqrestore(&tasklist_lock, flags); 6664} 6665 6666#endif /* CONFIG_MAGIC_SYSRQ */ 6667 6668#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) 6669/* 6670 * These functions are only useful for the IA64 MCA handling, or kdb. 6671 * 6672 * They can only be called when the whole system has been 6673 * stopped - every CPU needs to be quiescent, and no scheduling 6674 * activity can take place. Using them for anything else would 6675 * be a serious bug, and as a result, they aren't even visible 6676 * under any other configuration. 6677 */ 6678 6679/** 6680 * curr_task - return the current task for a given cpu. 6681 * @cpu: the processor in question. 6682 * 6683 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 6684 * 6685 * Return: The current task for @cpu. 6686 */ 6687struct task_struct *curr_task(int cpu) 6688{ 6689 return cpu_curr(cpu); 6690} 6691 6692#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ 6693 6694#ifdef CONFIG_IA64 6695/** 6696 * set_curr_task - set the current task for a given cpu. 6697 * @cpu: the processor in question. 6698 * @p: the task pointer to set. 6699 * 6700 * Description: This function must only be used when non-maskable interrupts 6701 * are serviced on a separate stack. It allows the architecture to switch the 6702 * notion of the current task on a cpu in a non-blocking manner. This function 6703 * must be called with all CPU's synchronized, and interrupts disabled, the 6704 * and caller must save the original value of the current task (see 6705 * curr_task() above) and restore that value before reenabling interrupts and 6706 * re-starting the system. 6707 * 6708 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 6709 */ 6710void set_curr_task(int cpu, struct task_struct *p) 6711{ 6712 cpu_curr(cpu) = p; 6713} 6714 6715#endif 6716 6717#ifdef CONFIG_CGROUP_SCHED 6718/* task_group_lock serializes the addition/removal of task groups */ 6719static DEFINE_SPINLOCK(task_group_lock); 6720 6721static void free_sched_group(struct task_group *tg) 6722{ 6723 free_fair_sched_group(tg); 6724 free_rt_sched_group(tg); 6725 autogroup_free(tg); 6726 kfree(tg); 6727} 6728 6729/* allocate runqueue etc for a new task group */ 6730struct task_group *sched_create_group(struct task_group *parent) 6731{ 6732 struct task_group *tg; 6733 6734 tg = kzalloc(sizeof(*tg), GFP_KERNEL); 6735 if (!tg) 6736 return ERR_PTR(-ENOMEM); 6737 6738 if (!alloc_fair_sched_group(tg, parent)) 6739 goto err; 6740 6741 if (!alloc_rt_sched_group(tg, parent)) 6742 goto err; 6743 6744 return tg; 6745 6746err: 6747 free_sched_group(tg); 6748 return ERR_PTR(-ENOMEM); 6749} 6750 6751void sched_online_group(struct task_group *tg, struct task_group *parent) 6752{ 6753 unsigned long flags; 6754 6755 spin_lock_irqsave(&task_group_lock, flags); 6756 list_add_rcu(&tg->list, &task_groups); 6757 6758 WARN_ON(!parent); /* root should already exist */ 6759 6760 tg->parent = parent; 6761 INIT_LIST_HEAD(&tg->children); 6762 list_add_rcu(&tg->siblings, &parent->children); 6763 spin_unlock_irqrestore(&task_group_lock, flags); 6764} 6765 6766/* rcu callback to free various structures associated with a task group */ 6767static void free_sched_group_rcu(struct rcu_head *rhp) 6768{ 6769 /* now it should be safe to free those cfs_rqs */ 6770 free_sched_group(container_of(rhp, struct task_group, rcu)); 6771} 6772 6773/* Destroy runqueue etc associated with a task group */ 6774void sched_destroy_group(struct task_group *tg) 6775{ 6776 /* wait for possible concurrent references to cfs_rqs complete */ 6777 call_rcu(&tg->rcu, free_sched_group_rcu); 6778} 6779 6780void sched_offline_group(struct task_group *tg) 6781{ 6782 unsigned long flags; 6783 int i; 6784 6785 /* end participation in shares distribution */ 6786 for_each_possible_cpu(i) 6787 unregister_fair_sched_group(tg, i); 6788 6789 spin_lock_irqsave(&task_group_lock, flags); 6790 list_del_rcu(&tg->list); 6791 list_del_rcu(&tg->siblings); 6792 spin_unlock_irqrestore(&task_group_lock, flags); 6793} 6794 6795/* change task's runqueue when it moves between groups. 6796 * The caller of this function should have put the task in its new group 6797 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to 6798 * reflect its new group. 6799 */ 6800void sched_move_task(struct task_struct *tsk) 6801{ 6802 struct task_group *tg; 6803 int on_rq, running; 6804 unsigned long flags; 6805 struct rq *rq; 6806 6807 rq = task_rq_lock(tsk, &flags); 6808 6809 running = task_current(rq, tsk); 6810 on_rq = tsk->on_rq; 6811 6812 if (on_rq) 6813 dequeue_task(rq, tsk, 0); 6814 if (unlikely(running)) 6815 tsk->sched_class->put_prev_task(rq, tsk); 6816 6817 tg = container_of(task_css_check(tsk, cpu_cgroup_subsys_id, 6818 lockdep_is_held(&tsk->sighand->siglock)), 6819 struct task_group, css); 6820 tg = autogroup_task_group(tsk, tg); 6821 tsk->sched_task_group = tg; 6822 6823#ifdef CONFIG_FAIR_GROUP_SCHED 6824 if (tsk->sched_class->task_move_group) 6825 tsk->sched_class->task_move_group(tsk, on_rq); 6826 else 6827#endif 6828 set_task_rq(tsk, task_cpu(tsk)); 6829 6830 if (unlikely(running)) 6831 tsk->sched_class->set_curr_task(rq); 6832 if (on_rq) 6833 enqueue_task(rq, tsk, 0); 6834 6835 task_rq_unlock(rq, tsk, &flags); 6836} 6837#endif /* CONFIG_CGROUP_SCHED */ 6838 6839#if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH) 6840static unsigned long to_ratio(u64 period, u64 runtime) 6841{ 6842 if (runtime == RUNTIME_INF) 6843 return 1ULL << 20; 6844 6845 return div64_u64(runtime << 20, period); 6846} 6847#endif 6848 6849#ifdef CONFIG_RT_GROUP_SCHED 6850/* 6851 * Ensure that the real time constraints are schedulable. 6852 */ 6853static DEFINE_MUTEX(rt_constraints_mutex); 6854 6855/* Must be called with tasklist_lock held */ 6856static inline int tg_has_rt_tasks(struct task_group *tg) 6857{ 6858 struct task_struct *g, *p; 6859 6860 do_each_thread(g, p) { 6861 if (rt_task(p) && task_rq(p)->rt.tg == tg) 6862 return 1; 6863 } while_each_thread(g, p); 6864 6865 return 0; 6866} 6867 6868struct rt_schedulable_data { 6869 struct task_group *tg; 6870 u64 rt_period; 6871 u64 rt_runtime; 6872}; 6873 6874static int tg_rt_schedulable(struct task_group *tg, void *data) 6875{ 6876 struct rt_schedulable_data *d = data; 6877 struct task_group *child; 6878 unsigned long total, sum = 0; 6879 u64 period, runtime; 6880 6881 period = ktime_to_ns(tg->rt_bandwidth.rt_period); 6882 runtime = tg->rt_bandwidth.rt_runtime; 6883 6884 if (tg == d->tg) { 6885 period = d->rt_period; 6886 runtime = d->rt_runtime; 6887 } 6888 6889 /* 6890 * Cannot have more runtime than the period. 6891 */ 6892 if (runtime > period && runtime != RUNTIME_INF) 6893 return -EINVAL; 6894 6895 /* 6896 * Ensure we don't starve existing RT tasks. 6897 */ 6898 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg)) 6899 return -EBUSY; 6900 6901 total = to_ratio(period, runtime); 6902 6903 /* 6904 * Nobody can have more than the global setting allows. 6905 */ 6906 if (total > to_ratio(global_rt_period(), global_rt_runtime())) 6907 return -EINVAL; 6908 6909 /* 6910 * The sum of our children's runtime should not exceed our own. 6911 */ 6912 list_for_each_entry_rcu(child, &tg->children, siblings) { 6913 period = ktime_to_ns(child->rt_bandwidth.rt_period); 6914 runtime = child->rt_bandwidth.rt_runtime; 6915 6916 if (child == d->tg) { 6917 period = d->rt_period; 6918 runtime = d->rt_runtime; 6919 } 6920 6921 sum += to_ratio(period, runtime); 6922 } 6923 6924 if (sum > total) 6925 return -EINVAL; 6926 6927 return 0; 6928} 6929 6930static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime) 6931{ 6932 int ret; 6933 6934 struct rt_schedulable_data data = { 6935 .tg = tg, 6936 .rt_period = period, 6937 .rt_runtime = runtime, 6938 }; 6939 6940 rcu_read_lock(); 6941 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data); 6942 rcu_read_unlock(); 6943 6944 return ret; 6945} 6946 6947static int tg_set_rt_bandwidth(struct task_group *tg, 6948 u64 rt_period, u64 rt_runtime) 6949{ 6950 int i, err = 0; 6951 6952 mutex_lock(&rt_constraints_mutex); 6953 read_lock(&tasklist_lock); 6954 err = __rt_schedulable(tg, rt_period, rt_runtime); 6955 if (err) 6956 goto unlock; 6957 6958 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock); 6959 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period); 6960 tg->rt_bandwidth.rt_runtime = rt_runtime; 6961 6962 for_each_possible_cpu(i) { 6963 struct rt_rq *rt_rq = tg->rt_rq[i]; 6964 6965 raw_spin_lock(&rt_rq->rt_runtime_lock); 6966 rt_rq->rt_runtime = rt_runtime; 6967 raw_spin_unlock(&rt_rq->rt_runtime_lock); 6968 } 6969 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock); 6970unlock: 6971 read_unlock(&tasklist_lock); 6972 mutex_unlock(&rt_constraints_mutex); 6973 6974 return err; 6975} 6976 6977static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) 6978{ 6979 u64 rt_runtime, rt_period; 6980 6981 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period); 6982 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC; 6983 if (rt_runtime_us < 0) 6984 rt_runtime = RUNTIME_INF; 6985 6986 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 6987} 6988 6989static long sched_group_rt_runtime(struct task_group *tg) 6990{ 6991 u64 rt_runtime_us; 6992 6993 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF) 6994 return -1; 6995 6996 rt_runtime_us = tg->rt_bandwidth.rt_runtime; 6997 do_div(rt_runtime_us, NSEC_PER_USEC); 6998 return rt_runtime_us; 6999} 7000 7001static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us) 7002{ 7003 u64 rt_runtime, rt_period; 7004 7005 rt_period = (u64)rt_period_us * NSEC_PER_USEC; 7006 rt_runtime = tg->rt_bandwidth.rt_runtime; 7007 7008 if (rt_period == 0) 7009 return -EINVAL; 7010 7011 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7012} 7013 7014static long sched_group_rt_period(struct task_group *tg) 7015{ 7016 u64 rt_period_us; 7017 7018 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period); 7019 do_div(rt_period_us, NSEC_PER_USEC); 7020 return rt_period_us; 7021} 7022 7023static int sched_rt_global_constraints(void) 7024{ 7025 u64 runtime, period; 7026 int ret = 0; 7027 7028 if (sysctl_sched_rt_period <= 0) 7029 return -EINVAL; 7030 7031 runtime = global_rt_runtime(); 7032 period = global_rt_period(); 7033 7034 /* 7035 * Sanity check on the sysctl variables. 7036 */ 7037 if (runtime > period && runtime != RUNTIME_INF) 7038 return -EINVAL; 7039 7040 mutex_lock(&rt_constraints_mutex); 7041 read_lock(&tasklist_lock); 7042 ret = __rt_schedulable(NULL, 0, 0); 7043 read_unlock(&tasklist_lock); 7044 mutex_unlock(&rt_constraints_mutex); 7045 7046 return ret; 7047} 7048 7049static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk) 7050{ 7051 /* Don't accept realtime tasks when there is no way for them to run */ 7052 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0) 7053 return 0; 7054 7055 return 1; 7056} 7057 7058#else /* !CONFIG_RT_GROUP_SCHED */ 7059static int sched_rt_global_constraints(void) 7060{ 7061 unsigned long flags; 7062 int i; 7063 7064 if (sysctl_sched_rt_period <= 0) 7065 return -EINVAL; 7066 7067 /* 7068 * There's always some RT tasks in the root group 7069 * -- migration, kstopmachine etc.. 7070 */ 7071 if (sysctl_sched_rt_runtime == 0) 7072 return -EBUSY; 7073 7074 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags); 7075 for_each_possible_cpu(i) { 7076 struct rt_rq *rt_rq = &cpu_rq(i)->rt; 7077 7078 raw_spin_lock(&rt_rq->rt_runtime_lock); 7079 rt_rq->rt_runtime = global_rt_runtime(); 7080 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7081 } 7082 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags); 7083 7084 return 0; 7085} 7086#endif /* CONFIG_RT_GROUP_SCHED */ 7087 7088int sched_rr_handler(struct ctl_table *table, int write, 7089 void __user *buffer, size_t *lenp, 7090 loff_t *ppos) 7091{ 7092 int ret; 7093 static DEFINE_MUTEX(mutex); 7094 7095 mutex_lock(&mutex); 7096 ret = proc_dointvec(table, write, buffer, lenp, ppos); 7097 /* make sure that internally we keep jiffies */ 7098 /* also, writing zero resets timeslice to default */ 7099 if (!ret && write) { 7100 sched_rr_timeslice = sched_rr_timeslice <= 0 ? 7101 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice); 7102 } 7103 mutex_unlock(&mutex); 7104 return ret; 7105} 7106 7107int sched_rt_handler(struct ctl_table *table, int write, 7108 void __user *buffer, size_t *lenp, 7109 loff_t *ppos) 7110{ 7111 int ret; 7112 int old_period, old_runtime; 7113 static DEFINE_MUTEX(mutex); 7114 7115 mutex_lock(&mutex); 7116 old_period = sysctl_sched_rt_period; 7117 old_runtime = sysctl_sched_rt_runtime; 7118 7119 ret = proc_dointvec(table, write, buffer, lenp, ppos); 7120 7121 if (!ret && write) { 7122 ret = sched_rt_global_constraints(); 7123 if (ret) { 7124 sysctl_sched_rt_period = old_period; 7125 sysctl_sched_rt_runtime = old_runtime; 7126 } else { 7127 def_rt_bandwidth.rt_runtime = global_rt_runtime(); 7128 def_rt_bandwidth.rt_period = 7129 ns_to_ktime(global_rt_period()); 7130 } 7131 } 7132 mutex_unlock(&mutex); 7133 7134 return ret; 7135} 7136 7137#ifdef CONFIG_CGROUP_SCHED 7138 7139static inline struct task_group *css_tg(struct cgroup_subsys_state *css) 7140{ 7141 return css ? container_of(css, struct task_group, css) : NULL; 7142} 7143 7144static struct cgroup_subsys_state * 7145cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) 7146{ 7147 struct task_group *parent = css_tg(parent_css); 7148 struct task_group *tg; 7149 7150 if (!parent) { 7151 /* This is early initialization for the top cgroup */ 7152 return &root_task_group.css; 7153 } 7154 7155 tg = sched_create_group(parent); 7156 if (IS_ERR(tg)) 7157 return ERR_PTR(-ENOMEM); 7158 7159 return &tg->css; 7160} 7161 7162static int cpu_cgroup_css_online(struct cgroup_subsys_state *css) 7163{ 7164 struct task_group *tg = css_tg(css); 7165 struct task_group *parent = css_tg(css_parent(css)); 7166 7167 if (parent) 7168 sched_online_group(tg, parent); 7169 return 0; 7170} 7171 7172static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) 7173{ 7174 struct task_group *tg = css_tg(css); 7175 7176 sched_destroy_group(tg); 7177} 7178 7179static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css) 7180{ 7181 struct task_group *tg = css_tg(css); 7182 7183 sched_offline_group(tg); 7184} 7185 7186static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css, 7187 struct cgroup_taskset *tset) 7188{ 7189 struct task_struct *task; 7190 7191 cgroup_taskset_for_each(task, css, tset) { 7192#ifdef CONFIG_RT_GROUP_SCHED 7193 if (!sched_rt_can_attach(css_tg(css), task)) 7194 return -EINVAL; 7195#else 7196 /* We don't support RT-tasks being in separate groups */ 7197 if (task->sched_class != &fair_sched_class) 7198 return -EINVAL; 7199#endif 7200 } 7201 return 0; 7202} 7203 7204static void cpu_cgroup_attach(struct cgroup_subsys_state *css, 7205 struct cgroup_taskset *tset) 7206{ 7207 struct task_struct *task; 7208 7209 cgroup_taskset_for_each(task, css, tset) 7210 sched_move_task(task); 7211} 7212 7213static void cpu_cgroup_exit(struct cgroup_subsys_state *css, 7214 struct cgroup_subsys_state *old_css, 7215 struct task_struct *task) 7216{ 7217 /* 7218 * cgroup_exit() is called in the copy_process() failure path. 7219 * Ignore this case since the task hasn't ran yet, this avoids 7220 * trying to poke a half freed task state from generic code. 7221 */ 7222 if (!(task->flags & PF_EXITING)) 7223 return; 7224 7225 sched_move_task(task); 7226} 7227 7228#ifdef CONFIG_FAIR_GROUP_SCHED 7229static int cpu_shares_write_u64(struct cgroup_subsys_state *css, 7230 struct cftype *cftype, u64 shareval) 7231{ 7232 return sched_group_set_shares(css_tg(css), scale_load(shareval)); 7233} 7234 7235static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, 7236 struct cftype *cft) 7237{ 7238 struct task_group *tg = css_tg(css); 7239 7240 return (u64) scale_load_down(tg->shares); 7241} 7242 7243#ifdef CONFIG_CFS_BANDWIDTH 7244static DEFINE_MUTEX(cfs_constraints_mutex); 7245 7246const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ 7247const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ 7248 7249static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); 7250 7251static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) 7252{ 7253 int i, ret = 0, runtime_enabled, runtime_was_enabled; 7254 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7255 7256 if (tg == &root_task_group) 7257 return -EINVAL; 7258 7259 /* 7260 * Ensure we have at some amount of bandwidth every period. This is 7261 * to prevent reaching a state of large arrears when throttled via 7262 * entity_tick() resulting in prolonged exit starvation. 7263 */ 7264 if (quota < min_cfs_quota_period || period < min_cfs_quota_period) 7265 return -EINVAL; 7266 7267 /* 7268 * Likewise, bound things on the otherside by preventing insane quota 7269 * periods. This also allows us to normalize in computing quota 7270 * feasibility. 7271 */ 7272 if (period > max_cfs_quota_period) 7273 return -EINVAL; 7274 7275 mutex_lock(&cfs_constraints_mutex); 7276 ret = __cfs_schedulable(tg, period, quota); 7277 if (ret) 7278 goto out_unlock; 7279 7280 runtime_enabled = quota != RUNTIME_INF; 7281 runtime_was_enabled = cfs_b->quota != RUNTIME_INF; 7282 account_cfs_bandwidth_used(runtime_enabled, runtime_was_enabled); 7283 raw_spin_lock_irq(&cfs_b->lock); 7284 cfs_b->period = ns_to_ktime(period); 7285 cfs_b->quota = quota; 7286 7287 __refill_cfs_bandwidth_runtime(cfs_b); 7288 /* restart the period timer (if active) to handle new period expiry */ 7289 if (runtime_enabled && cfs_b->timer_active) { 7290 /* force a reprogram */ 7291 cfs_b->timer_active = 0; 7292 __start_cfs_bandwidth(cfs_b); 7293 } 7294 raw_spin_unlock_irq(&cfs_b->lock); 7295 7296 for_each_possible_cpu(i) { 7297 struct cfs_rq *cfs_rq = tg->cfs_rq[i]; 7298 struct rq *rq = cfs_rq->rq; 7299 7300 raw_spin_lock_irq(&rq->lock); 7301 cfs_rq->runtime_enabled = runtime_enabled; 7302 cfs_rq->runtime_remaining = 0; 7303 7304 if (cfs_rq->throttled) 7305 unthrottle_cfs_rq(cfs_rq); 7306 raw_spin_unlock_irq(&rq->lock); 7307 } 7308out_unlock: 7309 mutex_unlock(&cfs_constraints_mutex); 7310 7311 return ret; 7312} 7313 7314int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) 7315{ 7316 u64 quota, period; 7317 7318 period = ktime_to_ns(tg->cfs_bandwidth.period); 7319 if (cfs_quota_us < 0) 7320 quota = RUNTIME_INF; 7321 else 7322 quota = (u64)cfs_quota_us * NSEC_PER_USEC; 7323 7324 return tg_set_cfs_bandwidth(tg, period, quota); 7325} 7326 7327long tg_get_cfs_quota(struct task_group *tg) 7328{ 7329 u64 quota_us; 7330 7331 if (tg->cfs_bandwidth.quota == RUNTIME_INF) 7332 return -1; 7333 7334 quota_us = tg->cfs_bandwidth.quota; 7335 do_div(quota_us, NSEC_PER_USEC); 7336 7337 return quota_us; 7338} 7339 7340int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) 7341{ 7342 u64 quota, period; 7343 7344 period = (u64)cfs_period_us * NSEC_PER_USEC; 7345 quota = tg->cfs_bandwidth.quota; 7346 7347 return tg_set_cfs_bandwidth(tg, period, quota); 7348} 7349 7350long tg_get_cfs_period(struct task_group *tg) 7351{ 7352 u64 cfs_period_us; 7353 7354 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); 7355 do_div(cfs_period_us, NSEC_PER_USEC); 7356 7357 return cfs_period_us; 7358} 7359 7360static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, 7361 struct cftype *cft) 7362{ 7363 return tg_get_cfs_quota(css_tg(css)); 7364} 7365 7366static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, 7367 struct cftype *cftype, s64 cfs_quota_us) 7368{ 7369 return tg_set_cfs_quota(css_tg(css), cfs_quota_us); 7370} 7371 7372static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, 7373 struct cftype *cft) 7374{ 7375 return tg_get_cfs_period(css_tg(css)); 7376} 7377 7378static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, 7379 struct cftype *cftype, u64 cfs_period_us) 7380{ 7381 return tg_set_cfs_period(css_tg(css), cfs_period_us); 7382} 7383 7384struct cfs_schedulable_data { 7385 struct task_group *tg; 7386 u64 period, quota; 7387}; 7388 7389/* 7390 * normalize group quota/period to be quota/max_period 7391 * note: units are usecs 7392 */ 7393static u64 normalize_cfs_quota(struct task_group *tg, 7394 struct cfs_schedulable_data *d) 7395{ 7396 u64 quota, period; 7397 7398 if (tg == d->tg) { 7399 period = d->period; 7400 quota = d->quota; 7401 } else { 7402 period = tg_get_cfs_period(tg); 7403 quota = tg_get_cfs_quota(tg); 7404 } 7405 7406 /* note: these should typically be equivalent */ 7407 if (quota == RUNTIME_INF || quota == -1) 7408 return RUNTIME_INF; 7409 7410 return to_ratio(period, quota); 7411} 7412 7413static int tg_cfs_schedulable_down(struct task_group *tg, void *data) 7414{ 7415 struct cfs_schedulable_data *d = data; 7416 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7417 s64 quota = 0, parent_quota = -1; 7418 7419 if (!tg->parent) { 7420 quota = RUNTIME_INF; 7421 } else { 7422 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; 7423 7424 quota = normalize_cfs_quota(tg, d); 7425 parent_quota = parent_b->hierarchal_quota; 7426 7427 /* 7428 * ensure max(child_quota) <= parent_quota, inherit when no 7429 * limit is set 7430 */ 7431 if (quota == RUNTIME_INF) 7432 quota = parent_quota; 7433 else if (parent_quota != RUNTIME_INF && quota > parent_quota) 7434 return -EINVAL; 7435 } 7436 cfs_b->hierarchal_quota = quota; 7437 7438 return 0; 7439} 7440 7441static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) 7442{ 7443 int ret; 7444 struct cfs_schedulable_data data = { 7445 .tg = tg, 7446 .period = period, 7447 .quota = quota, 7448 }; 7449 7450 if (quota != RUNTIME_INF) { 7451 do_div(data.period, NSEC_PER_USEC); 7452 do_div(data.quota, NSEC_PER_USEC); 7453 } 7454 7455 rcu_read_lock(); 7456 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); 7457 rcu_read_unlock(); 7458 7459 return ret; 7460} 7461 7462static int cpu_stats_show(struct cgroup_subsys_state *css, struct cftype *cft, 7463 struct cgroup_map_cb *cb) 7464{ 7465 struct task_group *tg = css_tg(css); 7466 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7467 7468 cb->fill(cb, "nr_periods", cfs_b->nr_periods); 7469 cb->fill(cb, "nr_throttled", cfs_b->nr_throttled); 7470 cb->fill(cb, "throttled_time", cfs_b->throttled_time); 7471 7472 return 0; 7473} 7474#endif /* CONFIG_CFS_BANDWIDTH */ 7475#endif /* CONFIG_FAIR_GROUP_SCHED */ 7476 7477#ifdef CONFIG_RT_GROUP_SCHED 7478static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, 7479 struct cftype *cft, s64 val) 7480{ 7481 return sched_group_set_rt_runtime(css_tg(css), val); 7482} 7483 7484static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, 7485 struct cftype *cft) 7486{ 7487 return sched_group_rt_runtime(css_tg(css)); 7488} 7489 7490static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, 7491 struct cftype *cftype, u64 rt_period_us) 7492{ 7493 return sched_group_set_rt_period(css_tg(css), rt_period_us); 7494} 7495 7496static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, 7497 struct cftype *cft) 7498{ 7499 return sched_group_rt_period(css_tg(css)); 7500} 7501#endif /* CONFIG_RT_GROUP_SCHED */ 7502 7503static struct cftype cpu_files[] = { 7504#ifdef CONFIG_FAIR_GROUP_SCHED 7505 { 7506 .name = "shares", 7507 .read_u64 = cpu_shares_read_u64, 7508 .write_u64 = cpu_shares_write_u64, 7509 }, 7510#endif 7511#ifdef CONFIG_CFS_BANDWIDTH 7512 { 7513 .name = "cfs_quota_us", 7514 .read_s64 = cpu_cfs_quota_read_s64, 7515 .write_s64 = cpu_cfs_quota_write_s64, 7516 }, 7517 { 7518 .name = "cfs_period_us", 7519 .read_u64 = cpu_cfs_period_read_u64, 7520 .write_u64 = cpu_cfs_period_write_u64, 7521 }, 7522 { 7523 .name = "stat", 7524 .read_map = cpu_stats_show, 7525 }, 7526#endif 7527#ifdef CONFIG_RT_GROUP_SCHED 7528 { 7529 .name = "rt_runtime_us", 7530 .read_s64 = cpu_rt_runtime_read, 7531 .write_s64 = cpu_rt_runtime_write, 7532 }, 7533 { 7534 .name = "rt_period_us", 7535 .read_u64 = cpu_rt_period_read_uint, 7536 .write_u64 = cpu_rt_period_write_uint, 7537 }, 7538#endif 7539 { } /* terminate */ 7540}; 7541 7542struct cgroup_subsys cpu_cgroup_subsys = { 7543 .name = "cpu", 7544 .css_alloc = cpu_cgroup_css_alloc, 7545 .css_free = cpu_cgroup_css_free, 7546 .css_online = cpu_cgroup_css_online, 7547 .css_offline = cpu_cgroup_css_offline, 7548 .can_attach = cpu_cgroup_can_attach, 7549 .attach = cpu_cgroup_attach, 7550 .exit = cpu_cgroup_exit, 7551 .subsys_id = cpu_cgroup_subsys_id, 7552 .base_cftypes = cpu_files, 7553 .early_init = 1, 7554}; 7555 7556#endif /* CONFIG_CGROUP_SCHED */ 7557 7558void dump_cpu_task(int cpu) 7559{ 7560 pr_info("Task dump for CPU %d:\n", cpu); 7561 sched_show_task(cpu_curr(cpu)); 7562} 7563