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