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