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/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 /*
 123  * xprt_reserve_xprt_cong - serialize write access to transports
 124  * @task: task that is requesting access to the transport
 125  *
 126  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 127  * integrated into the decision of whether a request is allowed to be
 128  * woken up and given access to the transport.
 129  */
 130 int xprt_reserve_xprt_cong(struct rpc_task *task)
 131 {
 132         struct rpc_xprt *xprt = task->tk_xprt;
 133         struct rpc_rqst *req = task->tk_rqstp;
 134
 135         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 136                 if (task == xprt->snd_task)
 137                         return 1;
 138                 goto out_sleep;
 139         }
 140         if (__xprt_get_cong(xprt, task)) {
 141                 xprt->snd_task = task;
 142                 if (req) {
 143                         req->rq_bytes_sent = 0;
 144                         req->rq_ntrans++;
 145                 }
 146                 return 1;
 147         }
 148         smp_mb__before_clear_bit();
 149         clear_bit(XPRT_LOCKED, &xprt->state);
 150         smp_mb__after_clear_bit();
 151 out_sleep:
 152         dprintk("RPC: %4d failed to lock transport %p\n", task->tk_pid, xprt);
 153         task->tk_timeout = 0;
 154         task->tk_status = -EAGAIN;
 155         if (req && req->rq_ntrans)
 156                 rpc_sleep_on(&xprt->resend, task, NULL, NULL);
 157         else
 158                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
 159         return 0;
 160 }
 161
 162 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 163 {
 164         int retval;
 165
 166         spin_lock_bh(&xprt->transport_lock);
 167         retval = xprt->ops->reserve_xprt(task);
 168         spin_unlock_bh(&xprt->transport_lock);
 169         return retval;
 170 }
 171
 172 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 173 {
 174         struct rpc_task *task;
 175         struct rpc_rqst *req;
 176
 177         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 178                 return;
 179
 180         task = rpc_wake_up_next(&xprt->resend);
 181         if (!task) {
 182                 task = rpc_wake_up_next(&xprt->sending);
 183                 if (!task)
 184                         goto out_unlock;
 185         }
 186
 187         req = task->tk_rqstp;
 188         xprt->snd_task = task;
 189         if (req) {
 190                 req->rq_bytes_sent = 0;
 191                 req->rq_ntrans++;
 192         }
 193         return;
 194
 195 out_unlock:
 196         smp_mb__before_clear_bit();
 197         clear_bit(XPRT_LOCKED, &xprt->state);
 198         smp_mb__after_clear_bit();
 199 }
 200
 201 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 202 {
 203         struct rpc_task *task;
 204
 205         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 206                 return;
 207         if (RPCXPRT_CONGESTED(xprt))
 208                 goto out_unlock;
 209         task = rpc_wake_up_next(&xprt->resend);
 210         if (!task) {
 211                 task = rpc_wake_up_next(&xprt->sending);
 212                 if (!task)
 213                         goto out_unlock;
 214         }
 215         if (__xprt_get_cong(xprt, task)) {
 216                 struct rpc_rqst *req = task->tk_rqstp;
 217                 xprt->snd_task = task;
 218                 if (req) {
 219                         req->rq_bytes_sent = 0;
 220                         req->rq_ntrans++;
 221                 }
 222                 return;
 223         }
 224 out_unlock:
 225         smp_mb__before_clear_bit();
 226         clear_bit(XPRT_LOCKED, &xprt->state);
 227         smp_mb__after_clear_bit();
 228 }
 229
 230 /**
 231  * xprt_release_xprt - allow other requests to use a transport
 232  * @xprt: transport with other tasks potentially waiting
 233  * @task: task that is releasing access to the transport
 234  *
 235  * Note that "task" can be NULL.  No congestion control is provided.
 236  */
 237 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 238 {
 239         if (xprt->snd_task == task) {
 240                 xprt->snd_task = NULL;
 241                 smp_mb__before_clear_bit();
 242                 clear_bit(XPRT_LOCKED, &xprt->state);
 243                 smp_mb__after_clear_bit();
 244                 __xprt_lock_write_next(xprt);
 245         }
 246 }
 247
 248 /**
 249  * xprt_release_xprt_cong - allow other requests to use a transport
 250  * @xprt: transport with other tasks potentially waiting
 251  * @task: task that is releasing access to the transport
 252  *
 253  * Note that "task" can be NULL.  Another task is awoken to use the
 254  * transport if the transport's congestion window allows it.
 255  */
 256 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 257 {
 258         if (xprt->snd_task == task) {
 259                 xprt->snd_task = NULL;
 260                 smp_mb__before_clear_bit();
 261                 clear_bit(XPRT_LOCKED, &xprt->state);
 262                 smp_mb__after_clear_bit();
 263                 __xprt_lock_write_next_cong(xprt);
 264         }
 265 }
 266
 267 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 268 {
 269         spin_lock_bh(&xprt->transport_lock);
 270         xprt->ops->release_xprt(xprt, task);
 271         spin_unlock_bh(&xprt->transport_lock);
 272 }
 273
 274 /*
 275  * Van Jacobson congestion avoidance. Check if the congestion window
 276  * overflowed. Put the task to sleep if this is the case.
 277  */
 278 static int
 279 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 280 {
 281         struct rpc_rqst *req = task->tk_rqstp;
 282
 283         if (req->rq_cong)
 284                 return 1;
 285         dprintk("RPC: %4d xprt_cwnd_limited cong = %ld cwnd = %ld\n",
 286                         task->tk_pid, xprt->cong, xprt->cwnd);
 287         if (RPCXPRT_CONGESTED(xprt))
 288                 return 0;
 289         req->rq_cong = 1;
 290         xprt->cong += RPC_CWNDSCALE;
 291         return 1;
 292 }
 293
 294 /*
 295  * Adjust the congestion window, and wake up the next task
 296  * that has been sleeping due to congestion
 297  */
 298 static void
 299 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 300 {
 301         if (!req->rq_cong)
 302                 return;
 303         req->rq_cong = 0;
 304         xprt->cong -= RPC_CWNDSCALE;
 305         __xprt_lock_write_next_cong(xprt);
 306 }
 307
 308 /**
 309  * xprt_release_rqst_cong - housekeeping when request is complete
 310  * @task: RPC request that recently completed
 311  *
 312  * Useful for transports that require congestion control.
 313  */
 314 void xprt_release_rqst_cong(struct rpc_task *task)
 315 {
 316         __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
 317 }
 318
 319 /**
 320  * xprt_adjust_cwnd - adjust transport congestion window
 321  * @task: recently completed RPC request used to adjust window
 322  * @result: result code of completed RPC request
 323  *
 324  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
 325  */
 326 void xprt_adjust_cwnd(struct rpc_task *task, int result)
 327 {
 328         struct rpc_rqst *req = task->tk_rqstp;
 329         struct rpc_xprt *xprt = task->tk_xprt;
 330         unsigned long cwnd = xprt->cwnd;
 331
 332         if (result >= 0 && cwnd <= xprt->cong) {
 333                 /* The (cwnd >> 1) term makes sure
 334                  * the result gets rounded properly. */
 335                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 336                 if (cwnd > RPC_MAXCWND(xprt))
 337                         cwnd = RPC_MAXCWND(xprt);
 338                 __xprt_lock_write_next_cong(xprt);
 339         } else if (result == -ETIMEDOUT) {
 340                 cwnd >>= 1;
 341                 if (cwnd < RPC_CWNDSCALE)
 342                         cwnd = RPC_CWNDSCALE;
 343         }
 344         dprintk("RPC:      cong %ld, cwnd was %ld, now %ld\n",
 345                         xprt->cong, xprt->cwnd, cwnd);
 346         xprt->cwnd = cwnd;
 347         __xprt_put_cong(xprt, req);
 348 }
 349
 350 /**
 351  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 352  * @xprt: transport with waiting tasks
 353  * @status: result code to plant in each task before waking it
 354  *
 355  */
 356 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 357 {
 358         if (status < 0)
 359                 rpc_wake_up_status(&xprt->pending, status);
 360         else
 361                 rpc_wake_up(&xprt->pending);
 362 }
 363
 364 /**
 365  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 366  * @task: task to be put to sleep
 367  *
 368  */
 369 void xprt_wait_for_buffer_space(struct rpc_task *task)
 370 {
 371         struct rpc_rqst *req = task->tk_rqstp;
 372         struct rpc_xprt *xprt = req->rq_xprt;
 373
 374         task->tk_timeout = req->rq_timeout;
 375         rpc_sleep_on(&xprt->pending, task, NULL, NULL);
 376 }
 377
 378 /**
 379  * xprt_write_space - wake the task waiting for transport output buffer space
 380  * @xprt: transport with waiting tasks
 381  *
 382  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 383  */
 384 void xprt_write_space(struct rpc_xprt *xprt)
 385 {
 386         if (unlikely(xprt->shutdown))
 387                 return;
 388
 389         spin_lock_bh(&xprt->transport_lock);
 390         if (xprt->snd_task) {
 391                 dprintk("RPC:      write space: waking waiting task on xprt %p\n",
 392                                 xprt);
 393                 rpc_wake_up_task(xprt->snd_task);
 394         }
 395         spin_unlock_bh(&xprt->transport_lock);
 396 }
 397
 398 /**
 399  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 400  * @task: task whose timeout is to be set
 401  *
 402  * Set a request's retransmit timeout based on the transport's
 403  * default timeout parameters.  Used by transports that don't adjust
 404  * the retransmit timeout based on round-trip time estimation.
 405  */
 406 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 407 {
 408         task->tk_timeout = task->tk_rqstp->rq_timeout;
 409 }
 410
 411 /*
 412  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 413  * @task: task whose timeout is to be set
 414  *
 415  * Set a request's retransmit timeout using the RTT estimator.
 416  */
 417 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 418 {
 419         int timer = task->tk_msg.rpc_proc->p_timer;
 420         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 421         struct rpc_rqst *req = task->tk_rqstp;
 422         unsigned long max_timeout = req->rq_xprt->timeout.to_maxval;
 423
 424         task->tk_timeout = rpc_calc_rto(rtt, timer);
 425         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 426         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 427                 task->tk_timeout = max_timeout;
 428 }
 429
 430 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 431 {
 432         struct rpc_timeout *to = &req->rq_xprt->timeout;
 433
 434         req->rq_majortimeo = req->rq_timeout;
 435         if (to->to_exponential)
 436                 req->rq_majortimeo <<= to->to_retries;
 437         else
 438                 req->rq_majortimeo += to->to_increment * to->to_retries;
 439         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 440                 req->rq_majortimeo = to->to_maxval;
 441         req->rq_majortimeo += jiffies;
 442 }
 443
 444 /**
 445  * xprt_adjust_timeout - adjust timeout values for next retransmit
 446  * @req: RPC request containing parameters to use for the adjustment
 447  *
 448  */
 449 int xprt_adjust_timeout(struct rpc_rqst *req)
 450 {
 451         struct rpc_xprt *xprt = req->rq_xprt;
 452         struct rpc_timeout *to = &xprt->timeout;
 453         int status = 0;
 454
 455         if (time_before(jiffies, req->rq_majortimeo)) {
 456                 if (to->to_exponential)
 457                         req->rq_timeout <<= 1;
 458                 else
 459                         req->rq_timeout += to->to_increment;
 460                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 461                         req->rq_timeout = to->to_maxval;
 462                 req->rq_retries++;
 463                 pprintk("RPC: %lu retrans\n", jiffies);
 464         } else {
 465                 req->rq_timeout = to->to_initval;
 466                 req->rq_retries = 0;
 467                 xprt_reset_majortimeo(req);
 468                 /* Reset the RTT counters == "slow start" */
 469                 spin_lock_bh(&xprt->transport_lock);
 470                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 471                 spin_unlock_bh(&xprt->transport_lock);
 472                 pprintk("RPC: %lu timeout\n", jiffies);
 473                 status = -ETIMEDOUT;
 474         }
 475
 476         if (req->rq_timeout == 0) {
 477                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 478                 req->rq_timeout = 5 * HZ;
 479         }
 480         return status;
 481 }
 482
 483 static void xprt_autoclose(void *args)
 484 {
 485         struct rpc_xprt *xprt = (struct rpc_xprt *)args;
 486
 487         xprt_disconnect(xprt);
 488         xprt->ops->close(xprt);
 489         xprt_release_write(xprt, NULL);
 490 }
 491
 492 /**
 493  * xprt_disconnect - mark a transport as disconnected
 494  * @xprt: transport to flag for disconnect
 495  *
 496  */
 497 void xprt_disconnect(struct rpc_xprt *xprt)
 498 {
 499         dprintk("RPC:      disconnected transport %p\n", xprt);
 500         spin_lock_bh(&xprt->transport_lock);
 501         xprt_clear_connected(xprt);
 502         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 503         spin_unlock_bh(&xprt->transport_lock);
 504 }
 505
 506 static void
 507 xprt_init_autodisconnect(unsigned long data)
 508 {
 509         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 510
 511         spin_lock(&xprt->transport_lock);
 512         if (!list_empty(&xprt->recv) || xprt->shutdown)
 513                 goto out_abort;
 514         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 515                 goto out_abort;
 516         spin_unlock(&xprt->transport_lock);
 517         if (xprt_connecting(xprt))
 518                 xprt_release_write(xprt, NULL);
 519         else
 520                 schedule_work(&xprt->task_cleanup);
 521         return;
 522 out_abort:
 523         spin_unlock(&xprt->transport_lock);
 524 }
 525
 526 /**
 527  * xprt_connect - schedule a transport connect operation
 528  * @task: RPC task that is requesting the connect
 529  *
 530  */
 531 void xprt_connect(struct rpc_task *task)
 532 {
 533         struct rpc_xprt *xprt = task->tk_xprt;
 534
 535         dprintk("RPC: %4d xprt_connect xprt %p %s connected\n", task->tk_pid,
 536                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 537
 538         if (xprt->shutdown) {
 539                 task->tk_status = -EIO;
 540                 return;
 541         }
 542         if (!xprt->addr.sin_port) {
 543                 task->tk_status = -EIO;
 544                 return;
 545         }
 546         if (!xprt_lock_write(xprt, task))
 547                 return;
 548         if (xprt_connected(xprt))
 549                 xprt_release_write(xprt, task);
 550         else {
 551                 if (task->tk_rqstp)
 552                         task->tk_rqstp->rq_bytes_sent = 0;
 553
 554                 task->tk_timeout = xprt->connect_timeout;
 555                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
 556                 xprt->ops->connect(task);
 557         }
 558         return;
 559 }
 560
 561 static void xprt_connect_status(struct rpc_task *task)
 562 {
 563         struct rpc_xprt *xprt = task->tk_xprt;
 564
 565         if (task->tk_status >= 0) {
 566                 dprintk("RPC: %4d xprt_connect_status: connection established\n",
 567                                 task->tk_pid);
 568                 return;
 569         }
 570
 571         switch (task->tk_status) {
 572         case -ECONNREFUSED:
 573         case -ECONNRESET:
 574                 dprintk("RPC: %4d xprt_connect_status: server %s refused connection\n",
 575                                 task->tk_pid, task->tk_client->cl_server);
 576                 break;
 577         case -ENOTCONN:
 578                 dprintk("RPC: %4d xprt_connect_status: connection broken\n",
 579                                 task->tk_pid);
 580                 break;
 581         case -ETIMEDOUT:
 582                 dprintk("RPC: %4d xprt_connect_status: connect attempt timed out\n",
 583                                 task->tk_pid);
 584                 break;
 585         default:
 586                 dprintk("RPC: %4d xprt_connect_status: error %d connecting to server %s\n",
 587                                 task->tk_pid, -task->tk_status, task->tk_client->cl_server);
 588                 xprt_release_write(xprt, task);
 589                 task->tk_status = -EIO;
 590                 return;
 591         }
 592
 593         /* if soft mounted, just cause this RPC to fail */
 594         if (RPC_IS_SOFT(task)) {
 595                 xprt_release_write(xprt, task);
 596                 task->tk_status = -EIO;
 597         }
 598 }
 599
 600 /**
 601  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 602  * @xprt: transport on which the original request was transmitted
 603  * @xid: RPC XID of incoming reply
 604  *
 605  */
 606 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid)
 607 {
 608         struct list_head *pos;
 609         struct rpc_rqst *req = NULL;
 610
 611         list_for_each(pos, &xprt->recv) {
 612                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
 613                 if (entry->rq_xid == xid) {
 614                         req = entry;
 615                         break;
 616                 }
 617         }
 618         return req;
 619 }
 620
 621 /**
 622  * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
 623  * @task: RPC request that recently completed
 624  *
 625  */
 626 void xprt_update_rtt(struct rpc_task *task)
 627 {
 628         struct rpc_rqst *req = task->tk_rqstp;
 629         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 630         unsigned timer = task->tk_msg.rpc_proc->p_timer;
 631
 632         if (timer) {
 633                 if (req->rq_ntrans == 1)
 634                         rpc_update_rtt(rtt, timer,
 635                                         (long)jiffies - req->rq_xtime);
 636                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 637         }
 638 }
 639
 640 /**
 641  * xprt_complete_rqst - called when reply processing is complete
 642  * @task: RPC request that recently completed
 643  * @copied: actual number of bytes received from the transport
 644  *
 645  * Caller holds transport lock.
 646  */
 647 void xprt_complete_rqst(struct rpc_task *task, int copied)
 648 {
 649         struct rpc_rqst *req = task->tk_rqstp;
 650
 651         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 652                         task->tk_pid, ntohl(req->rq_xid), copied);
 653
 654         list_del_init(&req->rq_list);
 655         req->rq_received = req->rq_private_buf.len = copied;
 656         rpc_wake_up_task(task);
 657 }
 658
 659 static void xprt_timer(struct rpc_task *task)
 660 {
 661         struct rpc_rqst *req = task->tk_rqstp;
 662         struct rpc_xprt *xprt = req->rq_xprt;
 663
 664         dprintk("RPC: %4d xprt_timer\n", task->tk_pid);
 665
 666         spin_lock(&xprt->transport_lock);
 667         if (!req->rq_received) {
 668                 if (xprt->ops->timer)
 669                         xprt->ops->timer(task);
 670                 task->tk_status = -ETIMEDOUT;
 671         }
 672         task->tk_timeout = 0;
 673         rpc_wake_up_task(task);
 674         spin_unlock(&xprt->transport_lock);
 675 }
 676
 677 /**
 678  * xprt_prepare_transmit - reserve the transport before sending a request
 679  * @task: RPC task about to send a request
 680  *
 681  */
 682 int xprt_prepare_transmit(struct rpc_task *task)
 683 {
 684         struct rpc_rqst *req = task->tk_rqstp;
 685         struct rpc_xprt *xprt = req->rq_xprt;
 686         int err = 0;
 687
 688         dprintk("RPC: %4d xprt_prepare_transmit\n", task->tk_pid);
 689
 690         if (xprt->shutdown)
 691                 return -EIO;
 692
 693         spin_lock_bh(&xprt->transport_lock);
 694         if (req->rq_received && !req->rq_bytes_sent) {
 695                 err = req->rq_received;
 696                 goto out_unlock;
 697         }
 698         if (!xprt->ops->reserve_xprt(task)) {
 699                 err = -EAGAIN;
 700                 goto out_unlock;
 701         }
 702
 703         if (!xprt_connected(xprt)) {
 704                 err = -ENOTCONN;
 705                 goto out_unlock;
 706         }
 707 out_unlock:
 708         spin_unlock_bh(&xprt->transport_lock);
 709         return err;
 710 }
 711
 712 void
 713 xprt_abort_transmit(struct rpc_task *task)
 714 {
 715         struct rpc_xprt *xprt = task->tk_xprt;
 716
 717         xprt_release_write(xprt, task);
 718 }
 719
 720 /**
 721  * xprt_transmit - send an RPC request on a transport
 722  * @task: controlling RPC task
 723  *
 724  * We have to copy the iovec because sendmsg fiddles with its contents.
 725  */
 726 void xprt_transmit(struct rpc_task *task)
 727 {
 728         struct rpc_rqst *req = task->tk_rqstp;
 729         struct rpc_xprt *xprt = req->rq_xprt;
 730         int status;
 731
 732         dprintk("RPC: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 733
 734         smp_rmb();
 735         if (!req->rq_received) {
 736                 if (list_empty(&req->rq_list)) {
 737                         spin_lock_bh(&xprt->transport_lock);
 738                         /* Update the softirq receive buffer */
 739                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 740                                         sizeof(req->rq_private_buf));
 741                         /* Add request to the receive list */
 742                         list_add_tail(&req->rq_list, &xprt->recv);
 743                         spin_unlock_bh(&xprt->transport_lock);
 744                         xprt_reset_majortimeo(req);
 745                         /* Turn off autodisconnect */
 746                         del_singleshot_timer_sync(&xprt->timer);
 747                 }
 748         } else if (!req->rq_bytes_sent)
 749                 return;
 750
 751         status = xprt->ops->send_request(task);
 752         if (status == 0) {
 753                 dprintk("RPC: %4d xmit complete\n", task->tk_pid);
 754                 spin_lock_bh(&xprt->transport_lock);
 755                 xprt->ops->set_retrans_timeout(task);
 756                 /* Don't race with disconnect */
 757                 if (!xprt_connected(xprt))
 758                         task->tk_status = -ENOTCONN;
 759                 else if (!req->rq_received)
 760                         rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
 761                 xprt->ops->release_xprt(xprt, task);
 762                 spin_unlock_bh(&xprt->transport_lock);
 763                 return;
 764         }
 765
 766         /* Note: at this point, task->tk_sleeping has not yet been set,
 767          *       hence there is no danger of the waking up task being put on
 768          *       schedq, and being picked up by a parallel run of rpciod().
 769          */
 770         task->tk_status = status;
 771
 772         switch (status) {
 773         case -ECONNREFUSED:
 774                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
 775         case -EAGAIN:
 776         case -ENOTCONN:
 777                 return;
 778         default:
 779                 break;
 780         }
 781         xprt_release_write(xprt, task);
 782         return;
 783 }
 784
 785 static inline void do_xprt_reserve(struct rpc_task *task)
 786 {
 787         struct rpc_xprt *xprt = task->tk_xprt;
 788
 789         task->tk_status = 0;
 790         if (task->tk_rqstp)
 791                 return;
 792         if (!list_empty(&xprt->free)) {
 793                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 794                 list_del_init(&req->rq_list);
 795                 task->tk_rqstp = req;
 796                 xprt_request_init(task, xprt);
 797                 return;
 798         }
 799         dprintk("RPC:      waiting for request slot\n");
 800         task->tk_status = -EAGAIN;
 801         task->tk_timeout = 0;
 802         rpc_sleep_on(&xprt->backlog, task, NULL, NULL);
 803 }
 804
 805 /**
 806  * xprt_reserve - allocate an RPC request slot
 807  * @task: RPC task requesting a slot allocation
 808  *
 809  * If no more slots are available, place the task on the transport's
 810  * backlog queue.
 811  */
 812 void xprt_reserve(struct rpc_task *task)
 813 {
 814         struct rpc_xprt *xprt = task->tk_xprt;
 815
 816         task->tk_status = -EIO;
 817         if (!xprt->shutdown) {
 818                 spin_lock(&xprt->reserve_lock);
 819                 do_xprt_reserve(task);
 820                 spin_unlock(&xprt->reserve_lock);
 821         }
 822 }
 823
 824 static inline u32 xprt_alloc_xid(struct rpc_xprt *xprt)
 825 {
 826         return xprt->xid++;
 827 }
 828
 829 static inline void xprt_init_xid(struct rpc_xprt *xprt)
 830 {
 831         get_random_bytes(&xprt->xid, sizeof(xprt->xid));
 832 }
 833
 834 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
 835 {
 836         struct rpc_rqst *req = task->tk_rqstp;
 837
 838         req->rq_timeout = xprt->timeout.to_initval;
 839         req->rq_task    = task;
 840         req->rq_xprt    = xprt;
 841         req->rq_xid     = xprt_alloc_xid(xprt);
 842         req->rq_release_snd_buf = NULL;
 843         dprintk("RPC: %4d reserved req %p xid %08x\n", task->tk_pid,
 844                         req, ntohl(req->rq_xid));
 845 }
 846
 847 /**
 848  * xprt_release - release an RPC request slot
 849  * @task: task which is finished with the slot
 850  *
 851  */
 852 void xprt_release(struct rpc_task *task)
 853 {
 854         struct rpc_xprt *xprt = task->tk_xprt;
 855         struct rpc_rqst *req;
 856
 857         if (!(req = task->tk_rqstp))
 858                 return;
 859         spin_lock_bh(&xprt->transport_lock);
 860         xprt->ops->release_xprt(xprt, task);
 861         if (xprt->ops->release_request)
 862                 xprt->ops->release_request(task);
 863         if (!list_empty(&req->rq_list))
 864                 list_del(&req->rq_list);
 865         xprt->last_used = jiffies;
 866         if (list_empty(&xprt->recv) && !xprt->shutdown)
 867                 mod_timer(&xprt->timer,
 868                                 xprt->last_used + xprt->idle_timeout);
 869         spin_unlock_bh(&xprt->transport_lock);
 870         task->tk_rqstp = NULL;
 871         if (req->rq_release_snd_buf)
 872                 req->rq_release_snd_buf(req);
 873         memset(req, 0, sizeof(*req));   /* mark unused */
 874
 875         dprintk("RPC: %4d release request %p\n", task->tk_pid, req);
 876
 877         spin_lock(&xprt->reserve_lock);
 878         list_add(&req->rq_list, &xprt->free);
 879         rpc_wake_up_next(&xprt->backlog);
 880         spin_unlock(&xprt->reserve_lock);
 881 }
 882
 883 /**
 884  * xprt_set_timeout - set constant RPC timeout
 885  * @to: RPC timeout parameters to set up
 886  * @retr: number of retries
 887  * @incr: amount of increase after each retry
 888  *
 889  */
 890 void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
 891 {
 892         to->to_initval   =
 893         to->to_increment = incr;
 894         to->to_maxval    = to->to_initval + (incr * retr);
 895         to->to_retries   = retr;
 896         to->to_exponential = 0;
 897 }
 898
 899 static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc_timeout *to)
 900 {
 901         int result;
 902         struct rpc_xprt *xprt;
 903         struct rpc_rqst *req;
 904
 905         if ((xprt = kmalloc(sizeof(struct rpc_xprt), GFP_KERNEL)) == NULL)
 906                 return ERR_PTR(-ENOMEM);
 907         memset(xprt, 0, sizeof(*xprt)); /* Nnnngh! */
 908
 909         xprt->addr = *ap;
 910
 911         switch (proto) {
 912         case IPPROTO_UDP:
 913                 result = xs_setup_udp(xprt, to);
 914                 break;
 915         case IPPROTO_TCP:
 916                 result = xs_setup_tcp(xprt, to);
 917                 break;
 918         default:
 919                 printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n",
 920                                 proto);
 921                 result = -EIO;
 922                 break;
 923         }
 924         if (result) {
 925                 kfree(xprt);
 926                 return ERR_PTR(result);
 927         }
 928
 929         spin_lock_init(&xprt->transport_lock);
 930         spin_lock_init(&xprt->reserve_lock);
 931
 932         INIT_LIST_HEAD(&xprt->free);
 933         INIT_LIST_HEAD(&xprt->recv);
 934         INIT_WORK(&xprt->task_cleanup, xprt_autoclose, xprt);
 935         init_timer(&xprt->timer);
 936         xprt->timer.function = xprt_init_autodisconnect;
 937         xprt->timer.data = (unsigned long) xprt;
 938         xprt->last_used = jiffies;
 939         xprt->cwnd = RPC_INITCWND;
 940
 941         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
 942         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
 943         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
 944         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
 945
 946         /* initialize free list */
 947         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
 948                 list_add(&req->rq_list, &xprt->free);
 949
 950         xprt_init_xid(xprt);
 951
 952         dprintk("RPC:      created transport %p with %u slots\n", xprt,
 953                         xprt->max_reqs);
 954
 955         return xprt;
 956 }
 957
 958 /**
 959  * xprt_create_proto - create an RPC client transport
 960  * @proto: requested transport protocol
 961  * @sap: remote peer's address
 962  * @to: timeout parameters for new transport
 963  *
 964  */
 965 struct rpc_xprt *xprt_create_proto(int proto, struct sockaddr_in *sap, struct rpc_timeout *to)
 966 {
 967         struct rpc_xprt *xprt;
 968
 969         xprt = xprt_setup(proto, sap, to);
 970         if (IS_ERR(xprt))
 971                 dprintk("RPC:      xprt_create_proto failed\n");
 972         else
 973                 dprintk("RPC:      xprt_create_proto created xprt %p\n", xprt);
 974         return xprt;
 975 }
 976
 977 static void xprt_shutdown(struct rpc_xprt *xprt)
 978 {
 979         xprt->shutdown = 1;
 980         rpc_wake_up(&xprt->sending);
 981         rpc_wake_up(&xprt->resend);
 982         xprt_wake_pending_tasks(xprt, -EIO);
 983         rpc_wake_up(&xprt->backlog);
 984         del_timer_sync(&xprt->timer);
 985 }
 986
 987 /**
 988  * xprt_destroy - destroy an RPC transport, killing off all requests.
 989  * @xprt: transport to destroy
 990  *
 991  */
 992 int xprt_destroy(struct rpc_xprt *xprt)
 993 {
 994         dprintk("RPC:      destroying transport %p\n", xprt);
 995         xprt_shutdown(xprt);
 996         xprt->ops->destroy(xprt);
 997         kfree(xprt);
 998
 999         return 0;
1000 }