xprt.c revision 11c556b3d8d481829ab5f9933a25d29b00913b5a
1/* 2 * linux/net/sunrpc/xprt.c 3 * 4 * This is a generic RPC call interface supporting congestion avoidance, 5 * and asynchronous calls. 6 * 7 * The interface works like this: 8 * 9 * - When a process places a call, it allocates a request slot if 10 * one is available. Otherwise, it sleeps on the backlog queue 11 * (xprt_reserve). 12 * - Next, the caller puts together the RPC message, stuffs it into 13 * the request struct, and calls xprt_transmit(). 14 * - xprt_transmit sends the message and installs the caller on the 15 * transport's wait list. At the same time, it installs a timer that 16 * is run after the packet's timeout has expired. 17 * - When a packet arrives, the data_ready handler walks the list of 18 * pending requests for that transport. If a matching XID is found, the 19 * caller is woken up, and the timer removed. 20 * - When no reply arrives within the timeout interval, the timer is 21 * fired by the kernel and runs xprt_timer(). It either adjusts the 22 * timeout values (minor timeout) or wakes up the caller with a status 23 * of -ETIMEDOUT. 24 * - When the caller receives a notification from RPC that a reply arrived, 25 * it should release the RPC slot, and process the reply. 26 * If the call timed out, it may choose to retry the operation by 27 * adjusting the initial timeout value, and simply calling rpc_call 28 * again. 29 * 30 * Support for async RPC is done through a set of RPC-specific scheduling 31 * primitives that `transparently' work for processes as well as async 32 * tasks that rely on callbacks. 33 * 34 * Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de> 35 * 36 * Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com> 37 */ 38 39#include <linux/module.h> 40 41#include <linux/types.h> 42#include <linux/interrupt.h> 43#include <linux/workqueue.h> 44#include <linux/random.h> 45 46#include <linux/sunrpc/clnt.h> 47#include <linux/sunrpc/metrics.h> 48 49/* 50 * Local variables 51 */ 52 53#ifdef RPC_DEBUG 54# undef RPC_DEBUG_DATA 55# define RPCDBG_FACILITY RPCDBG_XPRT 56#endif 57 58/* 59 * Local functions 60 */ 61static void xprt_request_init(struct rpc_task *, struct rpc_xprt *); 62static inline void do_xprt_reserve(struct rpc_task *); 63static void xprt_connect_status(struct rpc_task *task); 64static int __xprt_get_cong(struct rpc_xprt *, struct rpc_task *); 65 66/* 67 * The transport code maintains an estimate on the maximum number of out- 68 * standing RPC requests, using a smoothed version of the congestion 69 * avoidance implemented in 44BSD. This is basically the Van Jacobson 70 * congestion algorithm: If a retransmit occurs, the congestion window is 71 * halved; otherwise, it is incremented by 1/cwnd when 72 * 73 * - a reply is received and 74 * - a full number of requests are outstanding and 75 * - the congestion window hasn't been updated recently. 76 */ 77#define RPC_CWNDSHIFT (8U) 78#define RPC_CWNDSCALE (1U << RPC_CWNDSHIFT) 79#define RPC_INITCWND RPC_CWNDSCALE 80#define RPC_MAXCWND(xprt) ((xprt)->max_reqs << RPC_CWNDSHIFT) 81 82#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd) 83 84/** 85 * xprt_reserve_xprt - serialize write access to transports 86 * @task: task that is requesting access to the transport 87 * 88 * This prevents mixing the payload of separate requests, and prevents 89 * transport connects from colliding with writes. No congestion control 90 * is provided. 91 */ 92int xprt_reserve_xprt(struct rpc_task *task) 93{ 94 struct rpc_xprt *xprt = task->tk_xprt; 95 struct rpc_rqst *req = task->tk_rqstp; 96 97 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) { 98 if (task == xprt->snd_task) 99 return 1; 100 if (task == NULL) 101 return 0; 102 goto out_sleep; 103 } 104 xprt->snd_task = task; 105 if (req) { 106 req->rq_bytes_sent = 0; 107 req->rq_ntrans++; 108 } 109 return 1; 110 111out_sleep: 112 dprintk("RPC: %4d failed to lock transport %p\n", 113 task->tk_pid, xprt); 114 task->tk_timeout = 0; 115 task->tk_status = -EAGAIN; 116 if (req && req->rq_ntrans) 117 rpc_sleep_on(&xprt->resend, task, NULL, NULL); 118 else 119 rpc_sleep_on(&xprt->sending, task, NULL, NULL); 120 return 0; 121} 122 123static void xprt_clear_locked(struct rpc_xprt *xprt) 124{ 125 xprt->snd_task = NULL; 126 if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) { 127 smp_mb__before_clear_bit(); 128 clear_bit(XPRT_LOCKED, &xprt->state); 129 smp_mb__after_clear_bit(); 130 } else 131 schedule_work(&xprt->task_cleanup); 132} 133 134/* 135 * xprt_reserve_xprt_cong - serialize write access to transports 136 * @task: task that is requesting access to the transport 137 * 138 * Same as xprt_reserve_xprt, but Van Jacobson congestion control is 139 * integrated into the decision of whether a request is allowed to be 140 * woken up and given access to the transport. 141 */ 142int xprt_reserve_xprt_cong(struct rpc_task *task) 143{ 144 struct rpc_xprt *xprt = task->tk_xprt; 145 struct rpc_rqst *req = task->tk_rqstp; 146 147 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) { 148 if (task == xprt->snd_task) 149 return 1; 150 goto out_sleep; 151 } 152 if (__xprt_get_cong(xprt, task)) { 153 xprt->snd_task = task; 154 if (req) { 155 req->rq_bytes_sent = 0; 156 req->rq_ntrans++; 157 } 158 return 1; 159 } 160 xprt_clear_locked(xprt); 161out_sleep: 162 dprintk("RPC: %4d failed to lock transport %p\n", task->tk_pid, xprt); 163 task->tk_timeout = 0; 164 task->tk_status = -EAGAIN; 165 if (req && req->rq_ntrans) 166 rpc_sleep_on(&xprt->resend, task, NULL, NULL); 167 else 168 rpc_sleep_on(&xprt->sending, task, NULL, NULL); 169 return 0; 170} 171 172static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task) 173{ 174 int retval; 175 176 spin_lock_bh(&xprt->transport_lock); 177 retval = xprt->ops->reserve_xprt(task); 178 spin_unlock_bh(&xprt->transport_lock); 179 return retval; 180} 181 182static void __xprt_lock_write_next(struct rpc_xprt *xprt) 183{ 184 struct rpc_task *task; 185 struct rpc_rqst *req; 186 187 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) 188 return; 189 190 task = rpc_wake_up_next(&xprt->resend); 191 if (!task) { 192 task = rpc_wake_up_next(&xprt->sending); 193 if (!task) 194 goto out_unlock; 195 } 196 197 req = task->tk_rqstp; 198 xprt->snd_task = task; 199 if (req) { 200 req->rq_bytes_sent = 0; 201 req->rq_ntrans++; 202 } 203 return; 204 205out_unlock: 206 xprt_clear_locked(xprt); 207} 208 209static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt) 210{ 211 struct rpc_task *task; 212 213 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) 214 return; 215 if (RPCXPRT_CONGESTED(xprt)) 216 goto out_unlock; 217 task = rpc_wake_up_next(&xprt->resend); 218 if (!task) { 219 task = rpc_wake_up_next(&xprt->sending); 220 if (!task) 221 goto out_unlock; 222 } 223 if (__xprt_get_cong(xprt, task)) { 224 struct rpc_rqst *req = task->tk_rqstp; 225 xprt->snd_task = task; 226 if (req) { 227 req->rq_bytes_sent = 0; 228 req->rq_ntrans++; 229 } 230 return; 231 } 232out_unlock: 233 xprt_clear_locked(xprt); 234} 235 236/** 237 * xprt_release_xprt - allow other requests to use a transport 238 * @xprt: transport with other tasks potentially waiting 239 * @task: task that is releasing access to the transport 240 * 241 * Note that "task" can be NULL. No congestion control is provided. 242 */ 243void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task) 244{ 245 if (xprt->snd_task == task) { 246 xprt_clear_locked(xprt); 247 __xprt_lock_write_next(xprt); 248 } 249} 250 251/** 252 * xprt_release_xprt_cong - allow other requests to use a transport 253 * @xprt: transport with other tasks potentially waiting 254 * @task: task that is releasing access to the transport 255 * 256 * Note that "task" can be NULL. Another task is awoken to use the 257 * transport if the transport's congestion window allows it. 258 */ 259void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task) 260{ 261 if (xprt->snd_task == task) { 262 xprt_clear_locked(xprt); 263 __xprt_lock_write_next_cong(xprt); 264 } 265} 266 267static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task) 268{ 269 spin_lock_bh(&xprt->transport_lock); 270 xprt->ops->release_xprt(xprt, task); 271 spin_unlock_bh(&xprt->transport_lock); 272} 273 274/* 275 * Van Jacobson congestion avoidance. Check if the congestion window 276 * overflowed. Put the task to sleep if this is the case. 277 */ 278static int 279__xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task) 280{ 281 struct rpc_rqst *req = task->tk_rqstp; 282 283 if (req->rq_cong) 284 return 1; 285 dprintk("RPC: %4d xprt_cwnd_limited cong = %ld cwnd = %ld\n", 286 task->tk_pid, xprt->cong, xprt->cwnd); 287 if (RPCXPRT_CONGESTED(xprt)) 288 return 0; 289 req->rq_cong = 1; 290 xprt->cong += RPC_CWNDSCALE; 291 return 1; 292} 293 294/* 295 * Adjust the congestion window, and wake up the next task 296 * that has been sleeping due to congestion 297 */ 298static void 299__xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req) 300{ 301 if (!req->rq_cong) 302 return; 303 req->rq_cong = 0; 304 xprt->cong -= RPC_CWNDSCALE; 305 __xprt_lock_write_next_cong(xprt); 306} 307 308/** 309 * xprt_release_rqst_cong - housekeeping when request is complete 310 * @task: RPC request that recently completed 311 * 312 * Useful for transports that require congestion control. 313 */ 314void xprt_release_rqst_cong(struct rpc_task *task) 315{ 316 __xprt_put_cong(task->tk_xprt, task->tk_rqstp); 317} 318 319/** 320 * xprt_adjust_cwnd - adjust transport congestion window 321 * @task: recently completed RPC request used to adjust window 322 * @result: result code of completed RPC request 323 * 324 * We use a time-smoothed congestion estimator to avoid heavy oscillation. 325 */ 326void xprt_adjust_cwnd(struct rpc_task *task, int result) 327{ 328 struct rpc_rqst *req = task->tk_rqstp; 329 struct rpc_xprt *xprt = task->tk_xprt; 330 unsigned long cwnd = xprt->cwnd; 331 332 if (result >= 0 && cwnd <= xprt->cong) { 333 /* The (cwnd >> 1) term makes sure 334 * the result gets rounded properly. */ 335 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd; 336 if (cwnd > RPC_MAXCWND(xprt)) 337 cwnd = RPC_MAXCWND(xprt); 338 __xprt_lock_write_next_cong(xprt); 339 } else if (result == -ETIMEDOUT) { 340 cwnd >>= 1; 341 if (cwnd < RPC_CWNDSCALE) 342 cwnd = RPC_CWNDSCALE; 343 } 344 dprintk("RPC: cong %ld, cwnd was %ld, now %ld\n", 345 xprt->cong, xprt->cwnd, cwnd); 346 xprt->cwnd = cwnd; 347 __xprt_put_cong(xprt, req); 348} 349 350/** 351 * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue 352 * @xprt: transport with waiting tasks 353 * @status: result code to plant in each task before waking it 354 * 355 */ 356void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status) 357{ 358 if (status < 0) 359 rpc_wake_up_status(&xprt->pending, status); 360 else 361 rpc_wake_up(&xprt->pending); 362} 363 364/** 365 * xprt_wait_for_buffer_space - wait for transport output buffer to clear 366 * @task: task to be put to sleep 367 * 368 */ 369void xprt_wait_for_buffer_space(struct rpc_task *task) 370{ 371 struct rpc_rqst *req = task->tk_rqstp; 372 struct rpc_xprt *xprt = req->rq_xprt; 373 374 task->tk_timeout = req->rq_timeout; 375 rpc_sleep_on(&xprt->pending, task, NULL, NULL); 376} 377 378/** 379 * xprt_write_space - wake the task waiting for transport output buffer space 380 * @xprt: transport with waiting tasks 381 * 382 * Can be called in a soft IRQ context, so xprt_write_space never sleeps. 383 */ 384void xprt_write_space(struct rpc_xprt *xprt) 385{ 386 if (unlikely(xprt->shutdown)) 387 return; 388 389 spin_lock_bh(&xprt->transport_lock); 390 if (xprt->snd_task) { 391 dprintk("RPC: write space: waking waiting task on xprt %p\n", 392 xprt); 393 rpc_wake_up_task(xprt->snd_task); 394 } 395 spin_unlock_bh(&xprt->transport_lock); 396} 397 398/** 399 * xprt_set_retrans_timeout_def - set a request's retransmit timeout 400 * @task: task whose timeout is to be set 401 * 402 * Set a request's retransmit timeout based on the transport's 403 * default timeout parameters. Used by transports that don't adjust 404 * the retransmit timeout based on round-trip time estimation. 405 */ 406void xprt_set_retrans_timeout_def(struct rpc_task *task) 407{ 408 task->tk_timeout = task->tk_rqstp->rq_timeout; 409} 410 411/* 412 * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout 413 * @task: task whose timeout is to be set 414 * 415 * Set a request's retransmit timeout using the RTT estimator. 416 */ 417void xprt_set_retrans_timeout_rtt(struct rpc_task *task) 418{ 419 int timer = task->tk_msg.rpc_proc->p_timer; 420 struct rpc_rtt *rtt = task->tk_client->cl_rtt; 421 struct rpc_rqst *req = task->tk_rqstp; 422 unsigned long max_timeout = req->rq_xprt->timeout.to_maxval; 423 424 task->tk_timeout = rpc_calc_rto(rtt, timer); 425 task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries; 426 if (task->tk_timeout > max_timeout || task->tk_timeout == 0) 427 task->tk_timeout = max_timeout; 428} 429 430static void xprt_reset_majortimeo(struct rpc_rqst *req) 431{ 432 struct rpc_timeout *to = &req->rq_xprt->timeout; 433 434 req->rq_majortimeo = req->rq_timeout; 435 if (to->to_exponential) 436 req->rq_majortimeo <<= to->to_retries; 437 else 438 req->rq_majortimeo += to->to_increment * to->to_retries; 439 if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0) 440 req->rq_majortimeo = to->to_maxval; 441 req->rq_majortimeo += jiffies; 442} 443 444/** 445 * xprt_adjust_timeout - adjust timeout values for next retransmit 446 * @req: RPC request containing parameters to use for the adjustment 447 * 448 */ 449int xprt_adjust_timeout(struct rpc_rqst *req) 450{ 451 struct rpc_xprt *xprt = req->rq_xprt; 452 struct rpc_timeout *to = &xprt->timeout; 453 int status = 0; 454 455 if (time_before(jiffies, req->rq_majortimeo)) { 456 if (to->to_exponential) 457 req->rq_timeout <<= 1; 458 else 459 req->rq_timeout += to->to_increment; 460 if (to->to_maxval && req->rq_timeout >= to->to_maxval) 461 req->rq_timeout = to->to_maxval; 462 req->rq_retries++; 463 pprintk("RPC: %lu retrans\n", jiffies); 464 } else { 465 req->rq_timeout = to->to_initval; 466 req->rq_retries = 0; 467 xprt_reset_majortimeo(req); 468 /* Reset the RTT counters == "slow start" */ 469 spin_lock_bh(&xprt->transport_lock); 470 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval); 471 spin_unlock_bh(&xprt->transport_lock); 472 pprintk("RPC: %lu timeout\n", jiffies); 473 status = -ETIMEDOUT; 474 } 475 476 if (req->rq_timeout == 0) { 477 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n"); 478 req->rq_timeout = 5 * HZ; 479 } 480 return status; 481} 482 483static void xprt_autoclose(void *args) 484{ 485 struct rpc_xprt *xprt = (struct rpc_xprt *)args; 486 487 xprt_disconnect(xprt); 488 xprt->ops->close(xprt); 489 xprt_release_write(xprt, NULL); 490} 491 492/** 493 * xprt_disconnect - mark a transport as disconnected 494 * @xprt: transport to flag for disconnect 495 * 496 */ 497void xprt_disconnect(struct rpc_xprt *xprt) 498{ 499 dprintk("RPC: disconnected transport %p\n", xprt); 500 spin_lock_bh(&xprt->transport_lock); 501 xprt_clear_connected(xprt); 502 xprt_wake_pending_tasks(xprt, -ENOTCONN); 503 spin_unlock_bh(&xprt->transport_lock); 504} 505 506static void 507xprt_init_autodisconnect(unsigned long data) 508{ 509 struct rpc_xprt *xprt = (struct rpc_xprt *)data; 510 511 spin_lock(&xprt->transport_lock); 512 if (!list_empty(&xprt->recv) || xprt->shutdown) 513 goto out_abort; 514 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) 515 goto out_abort; 516 spin_unlock(&xprt->transport_lock); 517 if (xprt_connecting(xprt)) 518 xprt_release_write(xprt, NULL); 519 else 520 schedule_work(&xprt->task_cleanup); 521 return; 522out_abort: 523 spin_unlock(&xprt->transport_lock); 524} 525 526/** 527 * xprt_connect - schedule a transport connect operation 528 * @task: RPC task that is requesting the connect 529 * 530 */ 531void xprt_connect(struct rpc_task *task) 532{ 533 struct rpc_xprt *xprt = task->tk_xprt; 534 535 dprintk("RPC: %4d xprt_connect xprt %p %s connected\n", task->tk_pid, 536 xprt, (xprt_connected(xprt) ? "is" : "is not")); 537 538 if (!xprt->addr.sin_port) { 539 task->tk_status = -EIO; 540 return; 541 } 542 if (!xprt_lock_write(xprt, task)) 543 return; 544 if (xprt_connected(xprt)) 545 xprt_release_write(xprt, task); 546 else { 547 if (task->tk_rqstp) 548 task->tk_rqstp->rq_bytes_sent = 0; 549 550 task->tk_timeout = xprt->connect_timeout; 551 rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL); 552 xprt->stat.connect_start = jiffies; 553 xprt->ops->connect(task); 554 } 555 return; 556} 557 558static void xprt_connect_status(struct rpc_task *task) 559{ 560 struct rpc_xprt *xprt = task->tk_xprt; 561 562 if (task->tk_status >= 0) { 563 xprt->stat.connect_count++; 564 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start; 565 dprintk("RPC: %4d xprt_connect_status: connection established\n", 566 task->tk_pid); 567 return; 568 } 569 570 switch (task->tk_status) { 571 case -ECONNREFUSED: 572 case -ECONNRESET: 573 dprintk("RPC: %4d xprt_connect_status: server %s refused connection\n", 574 task->tk_pid, task->tk_client->cl_server); 575 break; 576 case -ENOTCONN: 577 dprintk("RPC: %4d xprt_connect_status: connection broken\n", 578 task->tk_pid); 579 break; 580 case -ETIMEDOUT: 581 dprintk("RPC: %4d xprt_connect_status: connect attempt timed out\n", 582 task->tk_pid); 583 break; 584 default: 585 dprintk("RPC: %4d xprt_connect_status: error %d connecting to server %s\n", 586 task->tk_pid, -task->tk_status, task->tk_client->cl_server); 587 xprt_release_write(xprt, task); 588 task->tk_status = -EIO; 589 return; 590 } 591 592 /* if soft mounted, just cause this RPC to fail */ 593 if (RPC_IS_SOFT(task)) { 594 xprt_release_write(xprt, task); 595 task->tk_status = -EIO; 596 } 597} 598 599/** 600 * xprt_lookup_rqst - find an RPC request corresponding to an XID 601 * @xprt: transport on which the original request was transmitted 602 * @xid: RPC XID of incoming reply 603 * 604 */ 605struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid) 606{ 607 struct list_head *pos; 608 609 list_for_each(pos, &xprt->recv) { 610 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list); 611 if (entry->rq_xid == xid) 612 return entry; 613 } 614 xprt->stat.bad_xids++; 615 return NULL; 616} 617 618/** 619 * xprt_update_rtt - update an RPC client's RTT state after receiving a reply 620 * @task: RPC request that recently completed 621 * 622 */ 623void xprt_update_rtt(struct rpc_task *task) 624{ 625 struct rpc_rqst *req = task->tk_rqstp; 626 struct rpc_rtt *rtt = task->tk_client->cl_rtt; 627 unsigned timer = task->tk_msg.rpc_proc->p_timer; 628 629 if (timer) { 630 if (req->rq_ntrans == 1) 631 rpc_update_rtt(rtt, timer, 632 (long)jiffies - req->rq_xtime); 633 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1); 634 } 635} 636 637/** 638 * xprt_complete_rqst - called when reply processing is complete 639 * @task: RPC request that recently completed 640 * @copied: actual number of bytes received from the transport 641 * 642 * Caller holds transport lock. 643 */ 644void xprt_complete_rqst(struct rpc_task *task, int copied) 645{ 646 struct rpc_rqst *req = task->tk_rqstp; 647 648 dprintk("RPC: %5u xid %08x complete (%d bytes received)\n", 649 task->tk_pid, ntohl(req->rq_xid), copied); 650 651 task->tk_xprt->stat.recvs++; 652 task->tk_rtt = (long)jiffies - req->rq_xtime; 653 654 list_del_init(&req->rq_list); 655 req->rq_received = req->rq_private_buf.len = copied; 656 rpc_wake_up_task(task); 657} 658 659static void xprt_timer(struct rpc_task *task) 660{ 661 struct rpc_rqst *req = task->tk_rqstp; 662 struct rpc_xprt *xprt = req->rq_xprt; 663 664 dprintk("RPC: %4d xprt_timer\n", task->tk_pid); 665 666 spin_lock(&xprt->transport_lock); 667 if (!req->rq_received) { 668 if (xprt->ops->timer) 669 xprt->ops->timer(task); 670 task->tk_status = -ETIMEDOUT; 671 } 672 task->tk_timeout = 0; 673 rpc_wake_up_task(task); 674 spin_unlock(&xprt->transport_lock); 675} 676 677/** 678 * xprt_prepare_transmit - reserve the transport before sending a request 679 * @task: RPC task about to send a request 680 * 681 */ 682int xprt_prepare_transmit(struct rpc_task *task) 683{ 684 struct rpc_rqst *req = task->tk_rqstp; 685 struct rpc_xprt *xprt = req->rq_xprt; 686 int err = 0; 687 688 dprintk("RPC: %4d xprt_prepare_transmit\n", task->tk_pid); 689 690 spin_lock_bh(&xprt->transport_lock); 691 if (req->rq_received && !req->rq_bytes_sent) { 692 err = req->rq_received; 693 goto out_unlock; 694 } 695 if (!xprt->ops->reserve_xprt(task)) { 696 err = -EAGAIN; 697 goto out_unlock; 698 } 699 700 if (!xprt_connected(xprt)) { 701 err = -ENOTCONN; 702 goto out_unlock; 703 } 704out_unlock: 705 spin_unlock_bh(&xprt->transport_lock); 706 return err; 707} 708 709void 710xprt_abort_transmit(struct rpc_task *task) 711{ 712 struct rpc_xprt *xprt = task->tk_xprt; 713 714 xprt_release_write(xprt, task); 715} 716 717/** 718 * xprt_transmit - send an RPC request on a transport 719 * @task: controlling RPC task 720 * 721 * We have to copy the iovec because sendmsg fiddles with its contents. 722 */ 723void xprt_transmit(struct rpc_task *task) 724{ 725 struct rpc_rqst *req = task->tk_rqstp; 726 struct rpc_xprt *xprt = req->rq_xprt; 727 int status; 728 729 dprintk("RPC: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen); 730 731 smp_rmb(); 732 if (!req->rq_received) { 733 if (list_empty(&req->rq_list)) { 734 spin_lock_bh(&xprt->transport_lock); 735 /* Update the softirq receive buffer */ 736 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, 737 sizeof(req->rq_private_buf)); 738 /* Add request to the receive list */ 739 list_add_tail(&req->rq_list, &xprt->recv); 740 spin_unlock_bh(&xprt->transport_lock); 741 xprt_reset_majortimeo(req); 742 /* Turn off autodisconnect */ 743 del_singleshot_timer_sync(&xprt->timer); 744 } 745 } else if (!req->rq_bytes_sent) 746 return; 747 748 status = xprt->ops->send_request(task); 749 if (status == 0) { 750 dprintk("RPC: %4d xmit complete\n", task->tk_pid); 751 spin_lock_bh(&xprt->transport_lock); 752 753 xprt->ops->set_retrans_timeout(task); 754 755 xprt->stat.sends++; 756 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs; 757 xprt->stat.bklog_u += xprt->backlog.qlen; 758 759 /* Don't race with disconnect */ 760 if (!xprt_connected(xprt)) 761 task->tk_status = -ENOTCONN; 762 else if (!req->rq_received) 763 rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer); 764 765 xprt->ops->release_xprt(xprt, task); 766 spin_unlock_bh(&xprt->transport_lock); 767 return; 768 } 769 770 /* Note: at this point, task->tk_sleeping has not yet been set, 771 * hence there is no danger of the waking up task being put on 772 * schedq, and being picked up by a parallel run of rpciod(). 773 */ 774 task->tk_status = status; 775 776 switch (status) { 777 case -ECONNREFUSED: 778 rpc_sleep_on(&xprt->sending, task, NULL, NULL); 779 case -EAGAIN: 780 case -ENOTCONN: 781 return; 782 default: 783 break; 784 } 785 xprt_release_write(xprt, task); 786 return; 787} 788 789static inline void do_xprt_reserve(struct rpc_task *task) 790{ 791 struct rpc_xprt *xprt = task->tk_xprt; 792 793 task->tk_status = 0; 794 if (task->tk_rqstp) 795 return; 796 if (!list_empty(&xprt->free)) { 797 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list); 798 list_del_init(&req->rq_list); 799 task->tk_rqstp = req; 800 xprt_request_init(task, xprt); 801 return; 802 } 803 dprintk("RPC: waiting for request slot\n"); 804 task->tk_status = -EAGAIN; 805 task->tk_timeout = 0; 806 rpc_sleep_on(&xprt->backlog, task, NULL, NULL); 807} 808 809/** 810 * xprt_reserve - allocate an RPC request slot 811 * @task: RPC task requesting a slot allocation 812 * 813 * If no more slots are available, place the task on the transport's 814 * backlog queue. 815 */ 816void xprt_reserve(struct rpc_task *task) 817{ 818 struct rpc_xprt *xprt = task->tk_xprt; 819 820 task->tk_status = -EIO; 821 spin_lock(&xprt->reserve_lock); 822 do_xprt_reserve(task); 823 spin_unlock(&xprt->reserve_lock); 824} 825 826static inline u32 xprt_alloc_xid(struct rpc_xprt *xprt) 827{ 828 return xprt->xid++; 829} 830 831static inline void xprt_init_xid(struct rpc_xprt *xprt) 832{ 833 get_random_bytes(&xprt->xid, sizeof(xprt->xid)); 834} 835 836static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt) 837{ 838 struct rpc_rqst *req = task->tk_rqstp; 839 840 req->rq_timeout = xprt->timeout.to_initval; 841 req->rq_task = task; 842 req->rq_xprt = xprt; 843 req->rq_buffer = NULL; 844 req->rq_bufsize = 0; 845 req->rq_xid = xprt_alloc_xid(xprt); 846 req->rq_release_snd_buf = NULL; 847 dprintk("RPC: %4d reserved req %p xid %08x\n", task->tk_pid, 848 req, ntohl(req->rq_xid)); 849} 850 851/** 852 * xprt_release - release an RPC request slot 853 * @task: task which is finished with the slot 854 * 855 */ 856void xprt_release(struct rpc_task *task) 857{ 858 struct rpc_xprt *xprt = task->tk_xprt; 859 struct rpc_rqst *req; 860 861 if (!(req = task->tk_rqstp)) 862 return; 863 rpc_count_iostats(task); 864 spin_lock_bh(&xprt->transport_lock); 865 xprt->ops->release_xprt(xprt, task); 866 if (xprt->ops->release_request) 867 xprt->ops->release_request(task); 868 if (!list_empty(&req->rq_list)) 869 list_del(&req->rq_list); 870 xprt->last_used = jiffies; 871 if (list_empty(&xprt->recv)) 872 mod_timer(&xprt->timer, 873 xprt->last_used + xprt->idle_timeout); 874 spin_unlock_bh(&xprt->transport_lock); 875 xprt->ops->buf_free(task); 876 task->tk_rqstp = NULL; 877 if (req->rq_release_snd_buf) 878 req->rq_release_snd_buf(req); 879 memset(req, 0, sizeof(*req)); /* mark unused */ 880 881 dprintk("RPC: %4d release request %p\n", task->tk_pid, req); 882 883 spin_lock(&xprt->reserve_lock); 884 list_add(&req->rq_list, &xprt->free); 885 rpc_wake_up_next(&xprt->backlog); 886 spin_unlock(&xprt->reserve_lock); 887} 888 889/** 890 * xprt_set_timeout - set constant RPC timeout 891 * @to: RPC timeout parameters to set up 892 * @retr: number of retries 893 * @incr: amount of increase after each retry 894 * 895 */ 896void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr) 897{ 898 to->to_initval = 899 to->to_increment = incr; 900 to->to_maxval = to->to_initval + (incr * retr); 901 to->to_retries = retr; 902 to->to_exponential = 0; 903} 904 905static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc_timeout *to) 906{ 907 int result; 908 struct rpc_xprt *xprt; 909 struct rpc_rqst *req; 910 911 if ((xprt = kmalloc(sizeof(struct rpc_xprt), GFP_KERNEL)) == NULL) 912 return ERR_PTR(-ENOMEM); 913 memset(xprt, 0, sizeof(*xprt)); /* Nnnngh! */ 914 915 xprt->addr = *ap; 916 917 switch (proto) { 918 case IPPROTO_UDP: 919 result = xs_setup_udp(xprt, to); 920 break; 921 case IPPROTO_TCP: 922 result = xs_setup_tcp(xprt, to); 923 break; 924 default: 925 printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n", 926 proto); 927 result = -EIO; 928 break; 929 } 930 if (result) { 931 kfree(xprt); 932 return ERR_PTR(result); 933 } 934 935 spin_lock_init(&xprt->transport_lock); 936 spin_lock_init(&xprt->reserve_lock); 937 938 INIT_LIST_HEAD(&xprt->free); 939 INIT_LIST_HEAD(&xprt->recv); 940 INIT_WORK(&xprt->task_cleanup, xprt_autoclose, xprt); 941 init_timer(&xprt->timer); 942 xprt->timer.function = xprt_init_autodisconnect; 943 xprt->timer.data = (unsigned long) xprt; 944 xprt->last_used = jiffies; 945 xprt->cwnd = RPC_INITCWND; 946 947 rpc_init_wait_queue(&xprt->pending, "xprt_pending"); 948 rpc_init_wait_queue(&xprt->sending, "xprt_sending"); 949 rpc_init_wait_queue(&xprt->resend, "xprt_resend"); 950 rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog"); 951 952 /* initialize free list */ 953 for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--) 954 list_add(&req->rq_list, &xprt->free); 955 956 xprt_init_xid(xprt); 957 958 dprintk("RPC: created transport %p with %u slots\n", xprt, 959 xprt->max_reqs); 960 961 return xprt; 962} 963 964/** 965 * xprt_create_proto - create an RPC client transport 966 * @proto: requested transport protocol 967 * @sap: remote peer's address 968 * @to: timeout parameters for new transport 969 * 970 */ 971struct rpc_xprt *xprt_create_proto(int proto, struct sockaddr_in *sap, struct rpc_timeout *to) 972{ 973 struct rpc_xprt *xprt; 974 975 xprt = xprt_setup(proto, sap, to); 976 if (IS_ERR(xprt)) 977 dprintk("RPC: xprt_create_proto failed\n"); 978 else 979 dprintk("RPC: xprt_create_proto created xprt %p\n", xprt); 980 return xprt; 981} 982 983/** 984 * xprt_destroy - destroy an RPC transport, killing off all requests. 985 * @xprt: transport to destroy 986 * 987 */ 988int xprt_destroy(struct rpc_xprt *xprt) 989{ 990 dprintk("RPC: destroying transport %p\n", xprt); 991 xprt->shutdown = 1; 992 del_timer_sync(&xprt->timer); 993 xprt->ops->destroy(xprt); 994 kfree(xprt); 995 996 return 0; 997} 998