net/sunrpc/xprt.c

   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/net.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 # 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->stat.connect_start = jiffies;
 552                 xprt->ops->connect(task);
 553         }
 554         return;
 555 }
 556
 557 static void xprt_connect_status(struct rpc_task *task)
 558 {
 559         struct rpc_xprt *xprt = task->tk_xprt;
 560
 561         if (task->tk_status >= 0) {
 562                 xprt->stat.connect_count++;
 563                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 564                 dprintk("RPC: %4d xprt_connect_status: connection established\n",
 565                                 task->tk_pid);
 566                 return;
 567         }
 568
 569         switch (task->tk_status) {
 570         case -ECONNREFUSED:
 571         case -ECONNRESET:
 572                 dprintk("RPC: %4d xprt_connect_status: server %s refused connection\n",
 573                                 task->tk_pid, task->tk_client->cl_server);
 574                 break;
 575         case -ENOTCONN:
 576                 dprintk("RPC: %4d xprt_connect_status: connection broken\n",
 577                                 task->tk_pid);
 578                 break;
 579         case -ETIMEDOUT:
 580                 dprintk("RPC: %4d xprt_connect_status: connect attempt timed out\n",
 581                                 task->tk_pid);
 582                 break;
 583         default:
 584                 dprintk("RPC: %4d xprt_connect_status: error %d connecting to server %s\n",
 585                                 task->tk_pid, -task->tk_status, task->tk_client->cl_server);
 586                 xprt_release_write(xprt, task);
 587                 task->tk_status = -EIO;
 588                 return;
 589         }
 590
 591         /* if soft mounted, just cause this RPC to fail */
 592         if (RPC_IS_SOFT(task)) {
 593                 xprt_release_write(xprt, task);
 594                 task->tk_status = -EIO;
 595         }
 596 }
 597
 598 /**
 599  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 600  * @xprt: transport on which the original request was transmitted
 601  * @xid: RPC XID of incoming reply
 602  *
 603  */
 604 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid)
 605 {
 606         struct list_head *pos;
 607
 608         list_for_each(pos, &xprt->recv) {
 609                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
 610                 if (entry->rq_xid == xid)
 611                         return entry;
 612         }
 613         xprt->stat.bad_xids++;
 614         return NULL;
 615 }
 616
 617 /**
 618  * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
 619  * @task: RPC request that recently completed
 620  *
 621  */
 622 void xprt_update_rtt(struct rpc_task *task)
 623 {
 624         struct rpc_rqst *req = task->tk_rqstp;
 625         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 626         unsigned timer = task->tk_msg.rpc_proc->p_timer;
 627
 628         if (timer) {
 629                 if (req->rq_ntrans == 1)
 630                         rpc_update_rtt(rtt, timer,
 631                                         (long)jiffies - req->rq_xtime);
 632                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 633         }
 634 }
 635
 636 /**
 637  * xprt_complete_rqst - called when reply processing is complete
 638  * @task: RPC request that recently completed
 639  * @copied: actual number of bytes received from the transport
 640  *
 641  * Caller holds transport lock.
 642  */
 643 void xprt_complete_rqst(struct rpc_task *task, int copied)
 644 {
 645         struct rpc_rqst *req = task->tk_rqstp;
 646
 647         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 648                         task->tk_pid, ntohl(req->rq_xid), copied);
 649
 650         task->tk_xprt->stat.recvs++;
 651         task->tk_rtt = (long)jiffies - req->rq_xtime;
 652
 653         list_del_init(&req->rq_list);
 654         /* Ensure all writes are done before we update req->rq_received */
 655         smp_wmb();
 656         req->rq_received = req->rq_private_buf.len = copied;
 657         rpc_wake_up_task(task);
 658 }
 659
 660 static void xprt_timer(struct rpc_task *task)
 661 {
 662         struct rpc_rqst *req = task->tk_rqstp;
 663         struct rpc_xprt *xprt = req->rq_xprt;
 664
 665         dprintk("RPC: %4d xprt_timer\n", task->tk_pid);
 666
 667         spin_lock(&xprt->transport_lock);
 668         if (!req->rq_received) {
 669                 if (xprt->ops->timer)
 670                         xprt->ops->timer(task);
 671                 task->tk_status = -ETIMEDOUT;
 672         }
 673         task->tk_timeout = 0;
 674         rpc_wake_up_task(task);
 675         spin_unlock(&xprt->transport_lock);
 676 }
 677
 678 /**
 679  * xprt_prepare_transmit - reserve the transport before sending a request
 680  * @task: RPC task about to send a request
 681  *
 682  */
 683 int xprt_prepare_transmit(struct rpc_task *task)
 684 {
 685         struct rpc_rqst *req = task->tk_rqstp;
 686         struct rpc_xprt *xprt = req->rq_xprt;
 687         int err = 0;
 688
 689         dprintk("RPC: %4d xprt_prepare_transmit\n", task->tk_pid);
 690
 691         spin_lock_bh(&xprt->transport_lock);
 692         if (req->rq_received && !req->rq_bytes_sent) {
 693                 err = req->rq_received;
 694                 goto out_unlock;
 695         }
 696         if (!xprt->ops->reserve_xprt(task)) {
 697                 err = -EAGAIN;
 698                 goto out_unlock;
 699         }
 700
 701         if (!xprt_connected(xprt)) {
 702                 err = -ENOTCONN;
 703                 goto out_unlock;
 704         }
 705 out_unlock:
 706         spin_unlock_bh(&xprt->transport_lock);
 707         return err;
 708 }
 709
 710 void
 711 xprt_abort_transmit(struct rpc_task *task)
 712 {
 713         struct rpc_xprt *xprt = task->tk_xprt;
 714
 715         xprt_release_write(xprt, task);
 716 }
 717
 718 /**
 719  * xprt_transmit - send an RPC request on a transport
 720  * @task: controlling RPC task
 721  *
 722  * We have to copy the iovec because sendmsg fiddles with its contents.
 723  */
 724 void xprt_transmit(struct rpc_task *task)
 725 {
 726         struct rpc_rqst *req = task->tk_rqstp;
 727         struct rpc_xprt *xprt = req->rq_xprt;
 728         int status;
 729
 730         dprintk("RPC: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 731
 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
 789 static 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  */
 816 void 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
 826 static inline u32 xprt_alloc_xid(struct rpc_xprt *xprt)
 827 {
 828         return xprt->xid++;
 829 }
 830
 831 static inline void xprt_init_xid(struct rpc_xprt *xprt)
 832 {
 833         xprt->xid = net_random();
 834 }
 835
 836 static 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  */
 856 void 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  */
 896 void 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
 905 static 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 = kzalloc(sizeof(struct rpc_xprt), GFP_KERNEL)) == NULL)
 912                 return ERR_PTR(-ENOMEM);
 913
 914         xprt->addr = *ap;
 915
 916         switch (proto) {
 917         case IPPROTO_UDP:
 918                 result = xs_setup_udp(xprt, to);
 919                 break;
 920         case IPPROTO_TCP:
 921                 result = xs_setup_tcp(xprt, to);
 922                 break;
 923         default:
 924                 printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n",
 925                                 proto);
 926                 result = -EIO;
 927                 break;
 928         }
 929         if (result) {
 930                 kfree(xprt);
 931                 return ERR_PTR(result);
 932         }
 933
 934         spin_lock_init(&xprt->transport_lock);
 935         spin_lock_init(&xprt->reserve_lock);
 936
 937         INIT_LIST_HEAD(&xprt->free);
 938         INIT_LIST_HEAD(&xprt->recv);
 939         INIT_WORK(&xprt->task_cleanup, xprt_autoclose, xprt);
 940         init_timer(&xprt->timer);
 941         xprt->timer.function = xprt_init_autodisconnect;
 942         xprt->timer.data = (unsigned long) xprt;
 943         xprt->last_used = jiffies;
 944         xprt->cwnd = RPC_INITCWND;
 945
 946         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
 947         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
 948         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
 949         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
 950
 951         /* initialize free list */
 952         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
 953                 list_add(&req->rq_list, &xprt->free);
 954
 955         xprt_init_xid(xprt);
 956
 957         dprintk("RPC:      created transport %p with %u slots\n", xprt,
 958                         xprt->max_reqs);
 959
 960         return xprt;
 961 }
 962
 963 /**
 964  * xprt_create_proto - create an RPC client transport
 965  * @proto: requested transport protocol
 966  * @sap: remote peer's address
 967  * @to: timeout parameters for new transport
 968  *
 969  */
 970 struct rpc_xprt *xprt_create_proto(int proto, struct sockaddr_in *sap, struct rpc_timeout *to)
 971 {
 972         struct rpc_xprt *xprt;
 973
 974         xprt = xprt_setup(proto, sap, to);
 975         if (IS_ERR(xprt))
 976                 dprintk("RPC:      xprt_create_proto failed\n");
 977         else
 978                 dprintk("RPC:      xprt_create_proto created xprt %p\n", xprt);
 979         return xprt;
 980 }
 981
 982 /**
 983  * xprt_destroy - destroy an RPC transport, killing off all requests.
 984  * @xprt: transport to destroy
 985  *
 986  */
 987 int xprt_destroy(struct rpc_xprt *xprt)
 988 {
 989         dprintk("RPC:      destroying transport %p\n", xprt);
 990         xprt->shutdown = 1;
 991         del_timer_sync(&xprt->timer);
 992         xprt->ops->destroy(xprt);
 993         kfree(xprt);
 994
 995         return 0;
 996 }