git.oblomov.eu Git - linux-2.6/blob - 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: %5u 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: %5u 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: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\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 "
 391                                 "xprt %p\n", 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         } else {
 463                 req->rq_timeout = to->to_initval;
 464                 req->rq_retries = 0;
 465                 xprt_reset_majortimeo(req);
 466                 /* Reset the RTT counters == "slow start" */
 467                 spin_lock_bh(&xprt->transport_lock);
 468                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 469                 spin_unlock_bh(&xprt->transport_lock);
 470                 status = -ETIMEDOUT;
 471         }
 472
 473         if (req->rq_timeout == 0) {
 474                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 475                 req->rq_timeout = 5 * HZ;
 476         }
 477         return status;
 478 }
 479
 480 static void xprt_autoclose(struct work_struct *work)
 481 {
 482         struct rpc_xprt *xprt =
 483                 container_of(work, struct rpc_xprt, task_cleanup);
 484
 485         xprt_disconnect(xprt);
 486         xprt->ops->close(xprt);
 487         xprt_release_write(xprt, NULL);
 488 }
 489
 490 /**
 491  * xprt_disconnect - mark a transport as disconnected
 492  * @xprt: transport to flag for disconnect
 493  *
 494  */
 495 void xprt_disconnect(struct rpc_xprt *xprt)
 496 {
 497         dprintk("RPC:       disconnected transport %p\n", xprt);
 498         spin_lock_bh(&xprt->transport_lock);
 499         xprt_clear_connected(xprt);
 500         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 501         spin_unlock_bh(&xprt->transport_lock);
 502 }
 503
 504 static void
 505 xprt_init_autodisconnect(unsigned long data)
 506 {
 507         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 508
 509         spin_lock(&xprt->transport_lock);
 510         if (!list_empty(&xprt->recv) || xprt->shutdown)
 511                 goto out_abort;
 512         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 513                 goto out_abort;
 514         spin_unlock(&xprt->transport_lock);
 515         if (xprt_connecting(xprt))
 516                 xprt_release_write(xprt, NULL);
 517         else
 518                 schedule_work(&xprt->task_cleanup);
 519         return;
 520 out_abort:
 521         spin_unlock(&xprt->transport_lock);
 522 }
 523
 524 /**
 525  * xprt_connect - schedule a transport connect operation
 526  * @task: RPC task that is requesting the connect
 527  *
 528  */
 529 void xprt_connect(struct rpc_task *task)
 530 {
 531         struct rpc_xprt *xprt = task->tk_xprt;
 532
 533         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 534                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 535
 536         if (!xprt_bound(xprt)) {
 537                 task->tk_status = -EIO;
 538                 return;
 539         }
 540         if (!xprt_lock_write(xprt, task))
 541                 return;
 542         if (xprt_connected(xprt))
 543                 xprt_release_write(xprt, task);
 544         else {
 545                 if (task->tk_rqstp)
 546                         task->tk_rqstp->rq_bytes_sent = 0;
 547
 548                 task->tk_timeout = xprt->connect_timeout;
 549                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
 550                 xprt->stat.connect_start = jiffies;
 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                 xprt->stat.connect_count++;
 562                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 563                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 564                                 task->tk_pid);
 565                 return;
 566         }
 567
 568         switch (task->tk_status) {
 569         case -ECONNREFUSED:
 570         case -ECONNRESET:
 571                 dprintk("RPC: %5u xprt_connect_status: server %s refused "
 572                                 "connection\n", task->tk_pid,
 573                                 task->tk_client->cl_server);
 574                 break;
 575         case -ENOTCONN:
 576                 dprintk("RPC: %5u xprt_connect_status: connection broken\n",
 577                                 task->tk_pid);
 578                 break;
 579         case -ETIMEDOUT:
 580                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 581                                 "out\n", task->tk_pid);
 582                 break;
 583         default:
 584                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 585                                 "server %s\n", task->tk_pid, -task->tk_status,
 586                                 task->tk_client->cl_server);
 587                 xprt_release_write(xprt, task);
 588                 task->tk_status = -EIO;
 589         }
 590 }
 591
 592 /**
 593  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 594  * @xprt: transport on which the original request was transmitted
 595  * @xid: RPC XID of incoming reply
 596  *
 597  */
 598 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 599 {
 600         struct list_head *pos;
 601
 602         list_for_each(pos, &xprt->recv) {
 603                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
 604                 if (entry->rq_xid == xid)
 605                         return entry;
 606         }
 607
 608         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 609                         ntohl(xid));
 610         xprt->stat.bad_xids++;
 611         return NULL;
 612 }
 613
 614 /**
 615  * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
 616  * @task: RPC request that recently completed
 617  *
 618  */
 619 void xprt_update_rtt(struct rpc_task *task)
 620 {
 621         struct rpc_rqst *req = task->tk_rqstp;
 622         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 623         unsigned timer = task->tk_msg.rpc_proc->p_timer;
 624
 625         if (timer) {
 626                 if (req->rq_ntrans == 1)
 627                         rpc_update_rtt(rtt, timer,
 628                                         (long)jiffies - req->rq_xtime);
 629                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 630         }
 631 }
 632
 633 /**
 634  * xprt_complete_rqst - called when reply processing is complete
 635  * @task: RPC request that recently completed
 636  * @copied: actual number of bytes received from the transport
 637  *
 638  * Caller holds transport lock.
 639  */
 640 void xprt_complete_rqst(struct rpc_task *task, int copied)
 641 {
 642         struct rpc_rqst *req = task->tk_rqstp;
 643
 644         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 645                         task->tk_pid, ntohl(req->rq_xid), copied);
 646
 647         task->tk_xprt->stat.recvs++;
 648         task->tk_rtt = (long)jiffies - req->rq_xtime;
 649
 650         list_del_init(&req->rq_list);
 651         /* Ensure all writes are done before we update req->rq_received */
 652         smp_wmb();
 653         req->rq_received = req->rq_private_buf.len = copied;
 654         rpc_wake_up_task(task);
 655 }
 656
 657 static void xprt_timer(struct rpc_task *task)
 658 {
 659         struct rpc_rqst *req = task->tk_rqstp;
 660         struct rpc_xprt *xprt = req->rq_xprt;
 661
 662         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
 663
 664         spin_lock(&xprt->transport_lock);
 665         if (!req->rq_received) {
 666                 if (xprt->ops->timer)
 667                         xprt->ops->timer(task);
 668                 task->tk_status = -ETIMEDOUT;
 669         }
 670         task->tk_timeout = 0;
 671         rpc_wake_up_task(task);
 672         spin_unlock(&xprt->transport_lock);
 673 }
 674
 675 /**
 676  * xprt_prepare_transmit - reserve the transport before sending a request
 677  * @task: RPC task about to send a request
 678  *
 679  */
 680 int xprt_prepare_transmit(struct rpc_task *task)
 681 {
 682         struct rpc_rqst *req = task->tk_rqstp;
 683         struct rpc_xprt *xprt = req->rq_xprt;
 684         int err = 0;
 685
 686         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 687
 688         spin_lock_bh(&xprt->transport_lock);
 689         if (req->rq_received && !req->rq_bytes_sent) {
 690                 err = req->rq_received;
 691                 goto out_unlock;
 692         }
 693         if (!xprt->ops->reserve_xprt(task)) {
 694                 err = -EAGAIN;
 695                 goto out_unlock;
 696         }
 697
 698         if (!xprt_connected(xprt)) {
 699                 err = -ENOTCONN;
 700                 goto out_unlock;
 701         }
 702 out_unlock:
 703         spin_unlock_bh(&xprt->transport_lock);
 704         return err;
 705 }
 706
 707 void xprt_end_transmit(struct rpc_task *task)
 708 {
 709         xprt_release_write(task->tk_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: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 725
 726         if (!req->rq_received) {
 727                 if (list_empty(&req->rq_list)) {
 728                         spin_lock_bh(&xprt->transport_lock);
 729                         /* Update the softirq receive buffer */
 730                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 731                                         sizeof(req->rq_private_buf));
 732                         /* Add request to the receive list */
 733                         list_add_tail(&req->rq_list, &xprt->recv);
 734                         spin_unlock_bh(&xprt->transport_lock);
 735                         xprt_reset_majortimeo(req);
 736                         /* Turn off autodisconnect */
 737                         del_singleshot_timer_sync(&xprt->timer);
 738                 }
 739         } else if (!req->rq_bytes_sent)
 740                 return;
 741
 742         status = xprt->ops->send_request(task);
 743         if (status == 0) {
 744                 dprintk("RPC: %5u xmit complete\n", task->tk_pid);
 745                 spin_lock_bh(&xprt->transport_lock);
 746
 747                 xprt->ops->set_retrans_timeout(task);
 748
 749                 xprt->stat.sends++;
 750                 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
 751                 xprt->stat.bklog_u += xprt->backlog.qlen;
 752
 753                 /* Don't race with disconnect */
 754                 if (!xprt_connected(xprt))
 755                         task->tk_status = -ENOTCONN;
 756                 else if (!req->rq_received)
 757                         rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
 758                 spin_unlock_bh(&xprt->transport_lock);
 759                 return;
 760         }
 761
 762         /* Note: at this point, task->tk_sleeping has not yet been set,
 763          *       hence there is no danger of the waking up task being put on
 764          *       schedq, and being picked up by a parallel run of rpciod().
 765          */
 766         task->tk_status = status;
 767         if (status == -ECONNREFUSED)
 768                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
 769 }
 770
 771 static inline void do_xprt_reserve(struct rpc_task *task)
 772 {
 773         struct rpc_xprt *xprt = task->tk_xprt;
 774
 775         task->tk_status = 0;
 776         if (task->tk_rqstp)
 777                 return;
 778         if (!list_empty(&xprt->free)) {
 779                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 780                 list_del_init(&req->rq_list);
 781                 task->tk_rqstp = req;
 782                 xprt_request_init(task, xprt);
 783                 return;
 784         }
 785         dprintk("RPC:       waiting for request slot\n");
 786         task->tk_status = -EAGAIN;
 787         task->tk_timeout = 0;
 788         rpc_sleep_on(&xprt->backlog, task, NULL, NULL);
 789 }
 790
 791 /**
 792  * xprt_reserve - allocate an RPC request slot
 793  * @task: RPC task requesting a slot allocation
 794  *
 795  * If no more slots are available, place the task on the transport's
 796  * backlog queue.
 797  */
 798 void xprt_reserve(struct rpc_task *task)
 799 {
 800         struct rpc_xprt *xprt = task->tk_xprt;
 801
 802         task->tk_status = -EIO;
 803         spin_lock(&xprt->reserve_lock);
 804         do_xprt_reserve(task);
 805         spin_unlock(&xprt->reserve_lock);
 806 }
 807
 808 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
 809 {
 810         return xprt->xid++;
 811 }
 812
 813 static inline void xprt_init_xid(struct rpc_xprt *xprt)
 814 {
 815         xprt->xid = net_random();
 816 }
 817
 818 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
 819 {
 820         struct rpc_rqst *req = task->tk_rqstp;
 821
 822         req->rq_timeout = xprt->timeout.to_initval;
 823         req->rq_task    = task;
 824         req->rq_xprt    = xprt;
 825         req->rq_buffer  = NULL;
 826         req->rq_xid     = xprt_alloc_xid(xprt);
 827         req->rq_release_snd_buf = NULL;
 828         xprt_reset_majortimeo(req);
 829         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
 830                         req, ntohl(req->rq_xid));
 831 }
 832
 833 /**
 834  * xprt_release - release an RPC request slot
 835  * @task: task which is finished with the slot
 836  *
 837  */
 838 void xprt_release(struct rpc_task *task)
 839 {
 840         struct rpc_xprt *xprt = task->tk_xprt;
 841         struct rpc_rqst *req;
 842
 843         if (!(req = task->tk_rqstp))
 844                 return;
 845         rpc_count_iostats(task);
 846         spin_lock_bh(&xprt->transport_lock);
 847         xprt->ops->release_xprt(xprt, task);
 848         if (xprt->ops->release_request)
 849                 xprt->ops->release_request(task);
 850         if (!list_empty(&req->rq_list))
 851                 list_del(&req->rq_list);
 852         xprt->last_used = jiffies;
 853         if (list_empty(&xprt->recv))
 854                 mod_timer(&xprt->timer,
 855                                 xprt->last_used + xprt->idle_timeout);
 856         spin_unlock_bh(&xprt->transport_lock);
 857         xprt->ops->buf_free(req->rq_buffer);
 858         task->tk_rqstp = NULL;
 859         if (req->rq_release_snd_buf)
 860                 req->rq_release_snd_buf(req);
 861         memset(req, 0, sizeof(*req));   /* mark unused */
 862
 863         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
 864
 865         spin_lock(&xprt->reserve_lock);
 866         list_add(&req->rq_list, &xprt->free);
 867         rpc_wake_up_next(&xprt->backlog);
 868         spin_unlock(&xprt->reserve_lock);
 869 }
 870
 871 /**
 872  * xprt_set_timeout - set constant RPC timeout
 873  * @to: RPC timeout parameters to set up
 874  * @retr: number of retries
 875  * @incr: amount of increase after each retry
 876  *
 877  */
 878 void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
 879 {
 880         to->to_initval   =
 881         to->to_increment = incr;
 882         to->to_maxval    = to->to_initval + (incr * retr);
 883         to->to_retries   = retr;
 884         to->to_exponential = 0;
 885 }
 886
 887 /**
 888  * xprt_create_transport - create an RPC transport
 889  * @proto: requested transport protocol
 890  * @ap: remote peer address
 891  * @size: length of address
 892  * @to: timeout parameters
 893  *
 894  */
 895 struct rpc_xprt *xprt_create_transport(int proto, struct sockaddr *ap, size_t size, struct rpc_timeout *to)
 896 {
 897         struct rpc_xprt *xprt;
 898         struct rpc_rqst *req;
 899
 900         switch (proto) {
 901         case IPPROTO_UDP:
 902                 xprt = xs_setup_udp(ap, size, to);
 903                 break;
 904         case IPPROTO_TCP:
 905                 xprt = xs_setup_tcp(ap, size, to);
 906                 break;
 907         default:
 908                 printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n",
 909                                 proto);
 910                 return ERR_PTR(-EIO);
 911         }
 912         if (IS_ERR(xprt)) {
 913                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
 914                                 -PTR_ERR(xprt));
 915                 return xprt;
 916         }
 917
 918         kref_init(&xprt->kref);
 919         spin_lock_init(&xprt->transport_lock);
 920         spin_lock_init(&xprt->reserve_lock);
 921
 922         INIT_LIST_HEAD(&xprt->free);
 923         INIT_LIST_HEAD(&xprt->recv);
 924         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
 925         init_timer(&xprt->timer);
 926         xprt->timer.function = xprt_init_autodisconnect;
 927         xprt->timer.data = (unsigned long) xprt;
 928         xprt->last_used = jiffies;
 929         xprt->cwnd = RPC_INITCWND;
 930         xprt->bind_index = 0;
 931
 932         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
 933         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
 934         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
 935         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
 936         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
 937
 938         /* initialize free list */
 939         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
 940                 list_add(&req->rq_list, &xprt->free);
 941
 942         xprt_init_xid(xprt);
 943
 944         dprintk("RPC:       created transport %p with %u slots\n", xprt,
 945                         xprt->max_reqs);
 946
 947         return xprt;
 948 }
 949
 950 /**
 951  * xprt_destroy - destroy an RPC transport, killing off all requests.
 952  * @kref: kref for the transport to destroy
 953  *
 954  */
 955 static void xprt_destroy(struct kref *kref)
 956 {
 957         struct rpc_xprt *xprt = container_of(kref, struct rpc_xprt, kref);
 958
 959         dprintk("RPC:       destroying transport %p\n", xprt);
 960         xprt->shutdown = 1;
 961         del_timer_sync(&xprt->timer);
 962
 963         /*
 964          * Tear down transport state and free the rpc_xprt
 965          */
 966         xprt->ops->destroy(xprt);
 967 }
 968
 969 /**
 970  * xprt_put - release a reference to an RPC transport.
 971  * @xprt: pointer to the transport
 972  *
 973  */
 974 void xprt_put(struct rpc_xprt *xprt)
 975 {
 976         kref_put(&xprt->kref, xprt_destroy);
 977 }
 978
 979 /**
 980  * xprt_get - return a reference to an RPC transport.
 981  * @xprt: pointer to the transport
 982  *
 983  */
 984 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
 985 {
 986         kref_get(&xprt->kref);
 987         return xprt;
 988 }