net/sunrpc/xprt.c

   1 /*
   2  *  linux/net/sunrpc/xprt.c
   3  *
   4  *  This is a generic RPC call interface supporting congestion avoidance,
   5  *  and asynchronous calls.
   6  *
   7  *  The interface works like this:
   8  *
   9  *  -   When a process places a call, it allocates a request slot if
  10  *      one is available. Otherwise, it sleeps on the backlog queue
  11  *      (xprt_reserve).
  12  *  -   Next, the caller puts together the RPC message, stuffs it into
  13  *      the request struct, and calls xprt_transmit().
  14  *  -   xprt_transmit sends the message and installs the caller on the
  15  *      transport's wait list. At the same time, it installs a timer that
  16  *      is run after the packet's timeout has expired.
  17  *  -   When a packet arrives, the data_ready handler walks the list of
  18  *      pending requests for that transport. If a matching XID is found, the
  19  *      caller is woken up, and the timer removed.
  20  *  -   When no reply arrives within the timeout interval, the timer is
  21  *      fired by the kernel and runs xprt_timer(). It either adjusts the
  22  *      timeout values (minor timeout) or wakes up the caller with a status
  23  *      of -ETIMEDOUT.
  24  *  -   When the caller receives a notification from RPC that a reply arrived,
  25  *      it should release the RPC slot, and process the reply.
  26  *      If the call timed out, it may choose to retry the operation by
  27  *      adjusting the initial timeout value, and simply calling rpc_call
  28  *      again.
  29  *
  30  *  Support for async RPC is done through a set of RPC-specific scheduling
  31  *  primitives that `transparently' work for processes as well as async
  32  *  tasks that rely on callbacks.
  33  *
  34  *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
  35  *
  36  *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
  37  */
  38
  39 #include <linux/module.h>
  40
  41 #include <linux/types.h>
  42 #include <linux/interrupt.h>
  43 #include <linux/workqueue.h>
  44 #include <linux/net.h>
  45
  46 #include <linux/sunrpc/clnt.h>
  47 #include <linux/sunrpc/metrics.h>
  48
  49 /*
  50  * Local variables
  51  */
  52
  53 #ifdef RPC_DEBUG
  54 # define RPCDBG_FACILITY        RPCDBG_XPRT
  55 #endif
  56
  57 /*
  58  * Local functions
  59  */
  60 static void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
  61 static inline void      do_xprt_reserve(struct rpc_task *);
  62 static void     xprt_connect_status(struct rpc_task *task);
  63 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
  64
  65 /*
  66  * The transport code maintains an estimate on the maximum number of out-
  67  * standing RPC requests, using a smoothed version of the congestion
  68  * avoidance implemented in 44BSD. This is basically the Van Jacobson
  69  * congestion algorithm: If a retransmit occurs, the congestion window is
  70  * halved; otherwise, it is incremented by 1/cwnd when
  71  *
  72  *      -       a reply is received and
  73  *      -       a full number of requests are outstanding and
  74  *      -       the congestion window hasn't been updated recently.
  75  */
  76 #define RPC_CWNDSHIFT           (8U)
  77 #define RPC_CWNDSCALE           (1U << RPC_CWNDSHIFT)
  78 #define RPC_INITCWND            RPC_CWNDSCALE
  79 #define RPC_MAXCWND(xprt)       ((xprt)->max_reqs << RPC_CWNDSHIFT)
  80
  81 #define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
  82
  83 /**
  84  * xprt_reserve_xprt - serialize write access to transports
  85  * @task: task that is requesting access to the transport
  86  *
  87  * This prevents mixing the payload of separate requests, and prevents
  88  * transport connects from colliding with writes.  No congestion control
  89  * is provided.
  90  */
  91 int xprt_reserve_xprt(struct rpc_task *task)
  92 {
  93         struct rpc_xprt *xprt = task->tk_xprt;
  94         struct rpc_rqst *req = task->tk_rqstp;
  95
  96         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
  97                 if (task == xprt->snd_task)
  98                         return 1;
  99                 if (task == NULL)
 100                         return 0;
 101                 goto out_sleep;
 102         }
 103         xprt->snd_task = task;
 104         if (req) {
 105                 req->rq_bytes_sent = 0;
 106                 req->rq_ntrans++;
 107         }
 108         return 1;
 109
 110 out_sleep:
 111         dprintk("RPC: %4d failed to lock transport %p\n",
 112                         task->tk_pid, xprt);
 113         task->tk_timeout = 0;
 114         task->tk_status = -EAGAIN;
 115         if (req && req->rq_ntrans)
 116                 rpc_sleep_on(&xprt->resend, task, NULL, NULL);
 117         else
 118                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
 119         return 0;
 120 }
 121
 122 static void xprt_clear_locked(struct rpc_xprt *xprt)
 123 {
 124         xprt->snd_task = NULL;
 125         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
 126                 smp_mb__before_clear_bit();
 127                 clear_bit(XPRT_LOCKED, &xprt->state);
 128                 smp_mb__after_clear_bit();
 129         } else
 130                 schedule_work(&xprt->task_cleanup);
 131 }
 132
 133 /*
 134  * xprt_reserve_xprt_cong - serialize write access to transports
 135  * @task: task that is requesting access to the transport
 136  *
 137  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 138  * integrated into the decision of whether a request is allowed to be
 139  * woken up and given access to the transport.
 140  */
 141 int xprt_reserve_xprt_cong(struct rpc_task *task)
 142 {
 143         struct rpc_xprt *xprt = task->tk_xprt;
 144         struct rpc_rqst *req = task->tk_rqstp;
 145
 146         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 147                 if (task == xprt->snd_task)
 148                         return 1;
 149                 goto out_sleep;
 150         }
 151         if (__xprt_get_cong(xprt, task)) {
 152                 xprt->snd_task = task;
 153                 if (req) {
 154                         req->rq_bytes_sent = 0;
 155                         req->rq_ntrans++;
 156                 }
 157                 return 1;
 158         }
 159         xprt_clear_locked(xprt);
 160 out_sleep:
 161         dprintk("RPC: %4d failed to lock transport %p\n", task->tk_pid, xprt);
 162         task->tk_timeout = 0;
 163         task->tk_status = -EAGAIN;
 164         if (req && req->rq_ntrans)
 165                 rpc_sleep_on(&xprt->resend, task, NULL, NULL);
 166         else
 167                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
 168         return 0;
 169 }
 170
 171 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 172 {
 173         int retval;
 174
 175         spin_lock_bh(&xprt->transport_lock);
 176         retval = xprt->ops->reserve_xprt(task);
 177         spin_unlock_bh(&xprt->transport_lock);
 178         return retval;
 179 }
 180
 181 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 182 {
 183         struct rpc_task *task;
 184         struct rpc_rqst *req;
 185
 186         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 187                 return;
 188
 189         task = rpc_wake_up_next(&xprt->resend);
 190         if (!task) {
 191                 task = rpc_wake_up_next(&xprt->sending);
 192                 if (!task)
 193                         goto out_unlock;
 194         }
 195
 196         req = task->tk_rqstp;
 197         xprt->snd_task = task;
 198         if (req) {
 199                 req->rq_bytes_sent = 0;
 200                 req->rq_ntrans++;
 201         }
 202         return;
 203
 204 out_unlock:
 205         xprt_clear_locked(xprt);
 206 }
 207
 208 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 209 {
 210         struct rpc_task *task;
 211
 212         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 213                 return;
 214         if (RPCXPRT_CONGESTED(xprt))
 215                 goto out_unlock;
 216         task = rpc_wake_up_next(&xprt->resend);
 217         if (!task) {
 218                 task = rpc_wake_up_next(&xprt->sending);
 219                 if (!task)
 220                         goto out_unlock;
 221         }
 222         if (__xprt_get_cong(xprt, task)) {
 223                 struct rpc_rqst *req = task->tk_rqstp;
 224                 xprt->snd_task = task;
 225                 if (req) {
 226                         req->rq_bytes_sent = 0;
 227                         req->rq_ntrans++;
 228                 }
 229                 return;
 230         }
 231 out_unlock:
 232         xprt_clear_locked(xprt);
 233 }
 234
 235 /**
 236  * xprt_release_xprt - allow other requests to use a transport
 237  * @xprt: transport with other tasks potentially waiting
 238  * @task: task that is releasing access to the transport
 239  *
 240  * Note that "task" can be NULL.  No congestion control is provided.
 241  */
 242 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 243 {
 244         if (xprt->snd_task == task) {
 245                 xprt_clear_locked(xprt);
 246                 __xprt_lock_write_next(xprt);
 247         }
 248 }
 249
 250 /**
 251  * xprt_release_xprt_cong - allow other requests to use a transport
 252  * @xprt: transport with other tasks potentially waiting
 253  * @task: task that is releasing access to the transport
 254  *
 255  * Note that "task" can be NULL.  Another task is awoken to use the
 256  * transport if the transport's congestion window allows it.
 257  */
 258 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 259 {
 260         if (xprt->snd_task == task) {
 261                 xprt_clear_locked(xprt);
 262                 __xprt_lock_write_next_cong(xprt);
 263         }
 264 }
 265
 266 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 267 {
 268         spin_lock_bh(&xprt->transport_lock);
 269         xprt->ops->release_xprt(xprt, task);
 270         spin_unlock_bh(&xprt->transport_lock);
 271 }
 272
 273 /*
 274  * Van Jacobson congestion avoidance. Check if the congestion window
 275  * overflowed. Put the task to sleep if this is the case.
 276  */
 277 static int
 278 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 279 {
 280         struct rpc_rqst *req = task->tk_rqstp;
 281
 282         if (req->rq_cong)
 283                 return 1;
 284         dprintk("RPC: %4d xprt_cwnd_limited cong = %ld cwnd = %ld\n",
 285                         task->tk_pid, xprt->cong, xprt->cwnd);
 286         if (RPCXPRT_CONGESTED(xprt))
 287                 return 0;
 288         req->rq_cong = 1;
 289         xprt->cong += RPC_CWNDSCALE;
 290         return 1;
 291 }
 292
 293 /*
 294  * Adjust the congestion window, and wake up the next task
 295  * that has been sleeping due to congestion
 296  */
 297 static void
 298 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 299 {
 300         if (!req->rq_cong)
 301                 return;
 302         req->rq_cong = 0;
 303         xprt->cong -= RPC_CWNDSCALE;
 304         __xprt_lock_write_next_cong(xprt);
 305 }
 306
 307 /**
 308  * xprt_release_rqst_cong - housekeeping when request is complete
 309  * @task: RPC request that recently completed
 310  *
 311  * Useful for transports that require congestion control.
 312  */
 313 void xprt_release_rqst_cong(struct rpc_task *task)
 314 {
 315         __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
 316 }
 317
 318 /**
 319  * xprt_adjust_cwnd - adjust transport congestion window
 320  * @task: recently completed RPC request used to adjust window
 321  * @result: result code of completed RPC request
 322  *
 323  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
 324  */
 325 void xprt_adjust_cwnd(struct rpc_task *task, int result)
 326 {
 327         struct rpc_rqst *req = task->tk_rqstp;
 328         struct rpc_xprt *xprt = task->tk_xprt;
 329         unsigned long cwnd = xprt->cwnd;
 330
 331         if (result >= 0 && cwnd <= xprt->cong) {
 332                 /* The (cwnd >> 1) term makes sure
 333                  * the result gets rounded properly. */
 334                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 335                 if (cwnd > RPC_MAXCWND(xprt))
 336                         cwnd = RPC_MAXCWND(xprt);
 337                 __xprt_lock_write_next_cong(xprt);
 338         } else if (result == -ETIMEDOUT) {
 339                 cwnd >>= 1;
 340                 if (cwnd < RPC_CWNDSCALE)
 341                         cwnd = RPC_CWNDSCALE;
 342         }
 343         dprintk("RPC:      cong %ld, cwnd was %ld, now %ld\n",
 344                         xprt->cong, xprt->cwnd, cwnd);
 345         xprt->cwnd = cwnd;
 346         __xprt_put_cong(xprt, req);
 347 }
 348
 349 /**
 350  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 351  * @xprt: transport with waiting tasks
 352  * @status: result code to plant in each task before waking it
 353  *
 354  */
 355 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 356 {
 357         if (status < 0)
 358                 rpc_wake_up_status(&xprt->pending, status);
 359         else
 360                 rpc_wake_up(&xprt->pending);
 361 }
 362
 363 /**
 364  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 365  * @task: task to be put to sleep
 366  *
 367  */
 368 void xprt_wait_for_buffer_space(struct rpc_task *task)
 369 {
 370         struct rpc_rqst *req = task->tk_rqstp;
 371         struct rpc_xprt *xprt = req->rq_xprt;
 372
 373         task->tk_timeout = req->rq_timeout;
 374         rpc_sleep_on(&xprt->pending, task, NULL, NULL);
 375 }
 376
 377 /**
 378  * xprt_write_space - wake the task waiting for transport output buffer space
 379  * @xprt: transport with waiting tasks
 380  *
 381  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 382  */
 383 void xprt_write_space(struct rpc_xprt *xprt)
 384 {
 385         if (unlikely(xprt->shutdown))
 386                 return;
 387
 388         spin_lock_bh(&xprt->transport_lock);
 389         if (xprt->snd_task) {
 390                 dprintk("RPC:      write space: waking waiting task on xprt %p\n",
 391                                 xprt);
 392                 rpc_wake_up_task(xprt->snd_task);
 393         }
 394         spin_unlock_bh(&xprt->transport_lock);
 395 }
 396
 397 /**
 398  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 399  * @task: task whose timeout is to be set
 400  *
 401  * Set a request's retransmit timeout based on the transport's
 402  * default timeout parameters.  Used by transports that don't adjust
 403  * the retransmit timeout based on round-trip time estimation.
 404  */
 405 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 406 {
 407         task->tk_timeout = task->tk_rqstp->rq_timeout;
 408 }
 409
 410 /*
 411  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 412  * @task: task whose timeout is to be set
 413  *
 414  * Set a request's retransmit timeout using the RTT estimator.
 415  */
 416 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 417 {
 418         int timer = task->tk_msg.rpc_proc->p_timer;
 419         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 420         struct rpc_rqst *req = task->tk_rqstp;
 421         unsigned long max_timeout = req->rq_xprt->timeout.to_maxval;
 422
 423         task->tk_timeout = rpc_calc_rto(rtt, timer);
 424         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 425         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 426                 task->tk_timeout = max_timeout;
 427 }
 428
 429 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 430 {
 431         struct rpc_timeout *to = &req->rq_xprt->timeout;
 432
 433         req->rq_majortimeo = req->rq_timeout;
 434         if (to->to_exponential)
 435                 req->rq_majortimeo <<= to->to_retries;
 436         else
 437                 req->rq_majortimeo += to->to_increment * to->to_retries;
 438         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 439                 req->rq_majortimeo = to->to_maxval;
 440         req->rq_majortimeo += jiffies;
 441 }
 442
 443 /**
 444  * xprt_adjust_timeout - adjust timeout values for next retransmit
 445  * @req: RPC request containing parameters to use for the adjustment
 446  *
 447  */
 448 int xprt_adjust_timeout(struct rpc_rqst *req)
 449 {
 450         struct rpc_xprt *xprt = req->rq_xprt;
 451         struct rpc_timeout *to = &xprt->timeout;
 452         int status = 0;
 453
 454         if (time_before(jiffies, req->rq_majortimeo)) {
 455                 if (to->to_exponential)
 456                         req->rq_timeout <<= 1;
 457                 else
 458                         req->rq_timeout += to->to_increment;
 459                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 460                         req->rq_timeout = to->to_maxval;
 461                 req->rq_retries++;
 462         } 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(void *args)
 481 {
 482         struct rpc_xprt *xprt = (struct rpc_xprt *)args;
 483
 484         xprt_disconnect(xprt);
 485         xprt->ops->close(xprt);
 486         xprt_release_write(xprt, NULL);
 487 }
 488
 489 /**
 490  * xprt_disconnect - mark a transport as disconnected
 491  * @xprt: transport to flag for disconnect
 492  *
 493  */
 494 void xprt_disconnect(struct rpc_xprt *xprt)
 495 {
 496         dprintk("RPC:      disconnected transport %p\n", xprt);
 497         spin_lock_bh(&xprt->transport_lock);
 498         xprt_clear_connected(xprt);
 499         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 500         spin_unlock_bh(&xprt->transport_lock);
 501 }
 502
 503 static void
 504 xprt_init_autodisconnect(unsigned long data)
 505 {
 506         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 507
 508         spin_lock(&xprt->transport_lock);
 509         if (!list_empty(&xprt->recv) || xprt->shutdown)
 510                 goto out_abort;
 511         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 512                 goto out_abort;
 513         spin_unlock(&xprt->transport_lock);
 514         if (xprt_connecting(xprt))
 515                 xprt_release_write(xprt, NULL);
 516         else
 517                 schedule_work(&xprt->task_cleanup);
 518         return;
 519 out_abort:
 520         spin_unlock(&xprt->transport_lock);
 521 }
 522
 523 /**
 524  * xprt_connect - schedule a transport connect operation
 525  * @task: RPC task that is requesting the connect
 526  *
 527  */
 528 void xprt_connect(struct rpc_task *task)
 529 {
 530         struct rpc_xprt *xprt = task->tk_xprt;
 531
 532         dprintk("RPC: %4d xprt_connect xprt %p %s connected\n", task->tk_pid,
 533                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 534
 535         if (!xprt_bound(xprt)) {
 536                 task->tk_status = -EIO;
 537                 return;
 538         }
 539         if (!xprt_lock_write(xprt, task))
 540                 return;
 541         if (xprt_connected(xprt))
 542                 xprt_release_write(xprt, task);
 543         else {
 544                 if (task->tk_rqstp)
 545                         task->tk_rqstp->rq_bytes_sent = 0;
 546
 547                 task->tk_timeout = xprt->connect_timeout;
 548                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
 549                 xprt->stat.connect_start = jiffies;
 550                 xprt->ops->connect(task);
 551         }
 552         return;
 553 }
 554
 555 static void xprt_connect_status(struct rpc_task *task)
 556 {
 557         struct rpc_xprt *xprt = task->tk_xprt;
 558
 559         if (task->tk_status >= 0) {
 560                 xprt->stat.connect_count++;
 561                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 562                 dprintk("RPC: %4d xprt_connect_status: connection established\n",
 563                                 task->tk_pid);
 564                 return;
 565         }
 566
 567         switch (task->tk_status) {
 568         case -ECONNREFUSED:
 569         case -ECONNRESET:
 570                 dprintk("RPC: %4d xprt_connect_status: server %s refused connection\n",
 571                                 task->tk_pid, task->tk_client->cl_server);
 572                 break;
 573         case -ENOTCONN:
 574                 dprintk("RPC: %4d xprt_connect_status: connection broken\n",
 575                                 task->tk_pid);
 576                 break;
 577         case -ETIMEDOUT:
 578                 dprintk("RPC: %4d xprt_connect_status: connect attempt timed out\n",
 579                                 task->tk_pid);
 580                 break;
 581         default:
 582                 dprintk("RPC: %4d xprt_connect_status: error %d connecting to server %s\n",
 583                                 task->tk_pid, -task->tk_status, task->tk_client->cl_server);
 584                 xprt_release_write(xprt, task);
 585                 task->tk_status = -EIO;
 586         }
 587 }
 588
 589 /**
 590  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 591  * @xprt: transport on which the original request was transmitted
 592  * @xid: RPC XID of incoming reply
 593  *
 594  */
 595 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 596 {
 597         struct list_head *pos;
 598
 599         list_for_each(pos, &xprt->recv) {
 600                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
 601                 if (entry->rq_xid == xid)
 602                         return entry;
 603         }
 604         xprt->stat.bad_xids++;
 605         return NULL;
 606 }
 607
 608 /**
 609  * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
 610  * @task: RPC request that recently completed
 611  *
 612  */
 613 void xprt_update_rtt(struct rpc_task *task)
 614 {
 615         struct rpc_rqst *req = task->tk_rqstp;
 616         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 617         unsigned timer = task->tk_msg.rpc_proc->p_timer;
 618
 619         if (timer) {
 620                 if (req->rq_ntrans == 1)
 621                         rpc_update_rtt(rtt, timer,
 622                                         (long)jiffies - req->rq_xtime);
 623                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 624         }
 625 }
 626
 627 /**
 628  * xprt_complete_rqst - called when reply processing is complete
 629  * @task: RPC request that recently completed
 630  * @copied: actual number of bytes received from the transport
 631  *
 632  * Caller holds transport lock.
 633  */
 634 void xprt_complete_rqst(struct rpc_task *task, int copied)
 635 {
 636         struct rpc_rqst *req = task->tk_rqstp;
 637
 638         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 639                         task->tk_pid, ntohl(req->rq_xid), copied);
 640
 641         task->tk_xprt->stat.recvs++;
 642         task->tk_rtt = (long)jiffies - req->rq_xtime;
 643
 644         list_del_init(&req->rq_list);
 645         /* Ensure all writes are done before we update req->rq_received */
 646         smp_wmb();
 647         req->rq_received = req->rq_private_buf.len = copied;
 648         rpc_wake_up_task(task);
 649 }
 650
 651 static void xprt_timer(struct rpc_task *task)
 652 {
 653         struct rpc_rqst *req = task->tk_rqstp;
 654         struct rpc_xprt *xprt = req->rq_xprt;
 655
 656         dprintk("RPC: %4d xprt_timer\n", task->tk_pid);
 657
 658         spin_lock(&xprt->transport_lock);
 659         if (!req->rq_received) {
 660                 if (xprt->ops->timer)
 661                         xprt->ops->timer(task);
 662                 task->tk_status = -ETIMEDOUT;
 663         }
 664         task->tk_timeout = 0;
 665         rpc_wake_up_task(task);
 666         spin_unlock(&xprt->transport_lock);
 667 }
 668
 669 /**
 670  * xprt_prepare_transmit - reserve the transport before sending a request
 671  * @task: RPC task about to send a request
 672  *
 673  */
 674 int xprt_prepare_transmit(struct rpc_task *task)
 675 {
 676         struct rpc_rqst *req = task->tk_rqstp;
 677         struct rpc_xprt *xprt = req->rq_xprt;
 678         int err = 0;
 679
 680         dprintk("RPC: %4d xprt_prepare_transmit\n", task->tk_pid);
 681
 682         spin_lock_bh(&xprt->transport_lock);
 683         if (req->rq_received && !req->rq_bytes_sent) {
 684                 err = req->rq_received;
 685                 goto out_unlock;
 686         }
 687         if (!xprt->ops->reserve_xprt(task)) {
 688                 err = -EAGAIN;
 689                 goto out_unlock;
 690         }
 691
 692         if (!xprt_connected(xprt)) {
 693                 err = -ENOTCONN;
 694                 goto out_unlock;
 695         }
 696 out_unlock:
 697         spin_unlock_bh(&xprt->transport_lock);
 698         return err;
 699 }
 700
 701 void xprt_end_transmit(struct rpc_task *task)
 702 {
 703         xprt_release_write(task->tk_xprt, task);
 704 }
 705
 706 /**
 707  * xprt_transmit - send an RPC request on a transport
 708  * @task: controlling RPC task
 709  *
 710  * We have to copy the iovec because sendmsg fiddles with its contents.
 711  */
 712 void xprt_transmit(struct rpc_task *task)
 713 {
 714         struct rpc_rqst *req = task->tk_rqstp;
 715         struct rpc_xprt *xprt = req->rq_xprt;
 716         int status;
 717
 718         dprintk("RPC: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 719
 720         if (!req->rq_received) {
 721                 if (list_empty(&req->rq_list)) {
 722                         spin_lock_bh(&xprt->transport_lock);
 723                         /* Update the softirq receive buffer */
 724                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 725                                         sizeof(req->rq_private_buf));
 726                         /* Add request to the receive list */
 727                         list_add_tail(&req->rq_list, &xprt->recv);
 728                         spin_unlock_bh(&xprt->transport_lock);
 729                         xprt_reset_majortimeo(req);
 730                         /* Turn off autodisconnect */
 731                         del_singleshot_timer_sync(&xprt->timer);
 732                 }
 733         } else if (!req->rq_bytes_sent)
 734                 return;
 735
 736         status = xprt->ops->send_request(task);
 737         if (status == 0) {
 738                 dprintk("RPC: %4d xmit complete\n", task->tk_pid);
 739                 spin_lock_bh(&xprt->transport_lock);
 740
 741                 xprt->ops->set_retrans_timeout(task);
 742
 743                 xprt->stat.sends++;
 744                 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
 745                 xprt->stat.bklog_u += xprt->backlog.qlen;
 746
 747                 /* Don't race with disconnect */
 748                 if (!xprt_connected(xprt))
 749                         task->tk_status = -ENOTCONN;
 750                 else if (!req->rq_received)
 751                         rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
 752                 spin_unlock_bh(&xprt->transport_lock);
 753                 return;
 754         }
 755
 756         /* Note: at this point, task->tk_sleeping has not yet been set,
 757          *       hence there is no danger of the waking up task being put on
 758          *       schedq, and being picked up by a parallel run of rpciod().
 759          */
 760         task->tk_status = status;
 761         if (status == -ECONNREFUSED)
 762                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
 763 }
 764
 765 static inline void do_xprt_reserve(struct rpc_task *task)
 766 {
 767         struct rpc_xprt *xprt = task->tk_xprt;
 768
 769         task->tk_status = 0;
 770         if (task->tk_rqstp)
 771                 return;
 772         if (!list_empty(&xprt->free)) {
 773                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 774                 list_del_init(&req->rq_list);
 775                 task->tk_rqstp = req;
 776                 xprt_request_init(task, xprt);
 777                 return;
 778         }
 779         dprintk("RPC:      waiting for request slot\n");
 780         task->tk_status = -EAGAIN;
 781         task->tk_timeout = 0;
 782         rpc_sleep_on(&xprt->backlog, task, NULL, NULL);
 783 }
 784
 785 /**
 786  * xprt_reserve - allocate an RPC request slot
 787  * @task: RPC task requesting a slot allocation
 788  *
 789  * If no more slots are available, place the task on the transport's
 790  * backlog queue.
 791  */
 792 void xprt_reserve(struct rpc_task *task)
 793 {
 794         struct rpc_xprt *xprt = task->tk_xprt;
 795
 796         task->tk_status = -EIO;
 797         spin_lock(&xprt->reserve_lock);
 798         do_xprt_reserve(task);
 799         spin_unlock(&xprt->reserve_lock);
 800 }
 801
 802 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
 803 {
 804         return xprt->xid++;
 805 }
 806
 807 static inline void xprt_init_xid(struct rpc_xprt *xprt)
 808 {
 809         xprt->xid = net_random();
 810 }
 811
 812 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
 813 {
 814         struct rpc_rqst *req = task->tk_rqstp;
 815
 816         req->rq_timeout = xprt->timeout.to_initval;
 817         req->rq_task    = task;
 818         req->rq_xprt    = xprt;
 819         req->rq_buffer  = NULL;
 820         req->rq_bufsize = 0;
 821         req->rq_xid     = xprt_alloc_xid(xprt);
 822         req->rq_release_snd_buf = NULL;
 823         xprt_reset_majortimeo(req);
 824         dprintk("RPC: %4d reserved req %p xid %08x\n", task->tk_pid,
 825                         req, ntohl(req->rq_xid));
 826 }
 827
 828 /**
 829  * xprt_release - release an RPC request slot
 830  * @task: task which is finished with the slot
 831  *
 832  */
 833 void xprt_release(struct rpc_task *task)
 834 {
 835         struct rpc_xprt *xprt = task->tk_xprt;
 836         struct rpc_rqst *req;
 837
 838         if (!(req = task->tk_rqstp))
 839                 return;
 840         rpc_count_iostats(task);
 841         spin_lock_bh(&xprt->transport_lock);
 842         xprt->ops->release_xprt(xprt, task);
 843         if (xprt->ops->release_request)
 844                 xprt->ops->release_request(task);
 845         if (!list_empty(&req->rq_list))
 846                 list_del(&req->rq_list);
 847         xprt->last_used = jiffies;
 848         if (list_empty(&xprt->recv))
 849                 mod_timer(&xprt->timer,
 850                                 xprt->last_used + xprt->idle_timeout);
 851         spin_unlock_bh(&xprt->transport_lock);
 852         xprt->ops->buf_free(task);
 853         task->tk_rqstp = NULL;
 854         if (req->rq_release_snd_buf)
 855                 req->rq_release_snd_buf(req);
 856         memset(req, 0, sizeof(*req));   /* mark unused */
 857
 858         dprintk("RPC: %4d release request %p\n", task->tk_pid, req);
 859
 860         spin_lock(&xprt->reserve_lock);
 861         list_add(&req->rq_list, &xprt->free);
 862         rpc_wake_up_next(&xprt->backlog);
 863         spin_unlock(&xprt->reserve_lock);
 864 }
 865
 866 /**
 867  * xprt_set_timeout - set constant RPC timeout
 868  * @to: RPC timeout parameters to set up
 869  * @retr: number of retries
 870  * @incr: amount of increase after each retry
 871  *
 872  */
 873 void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
 874 {
 875         to->to_initval   =
 876         to->to_increment = incr;
 877         to->to_maxval    = to->to_initval + (incr * retr);
 878         to->to_retries   = retr;
 879         to->to_exponential = 0;
 880 }
 881
 882 /**
 883  * xprt_create_transport - create an RPC transport
 884  * @proto: requested transport protocol
 885  * @ap: remote peer address
 886  * @size: length of address
 887  * @to: timeout parameters
 888  *
 889  */
 890 struct rpc_xprt *xprt_create_transport(int proto, struct sockaddr *ap, size_t size, struct rpc_timeout *to)
 891 {
 892         struct rpc_xprt *xprt;
 893         struct rpc_rqst *req;
 894
 895         switch (proto) {
 896         case IPPROTO_UDP:
 897                 xprt = xs_setup_udp(ap, size, to);
 898                 break;
 899         case IPPROTO_TCP:
 900                 xprt = xs_setup_tcp(ap, size, to);
 901                 break;
 902         default:
 903                 printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n",
 904                                 proto);
 905                 return ERR_PTR(-EIO);
 906         }
 907         if (IS_ERR(xprt)) {
 908                 dprintk("RPC:      xprt_create_transport: failed, %ld\n",
 909                                 -PTR_ERR(xprt));
 910                 return xprt;
 911         }
 912
 913         kref_init(&xprt->kref);
 914         spin_lock_init(&xprt->transport_lock);
 915         spin_lock_init(&xprt->reserve_lock);
 916
 917         INIT_LIST_HEAD(&xprt->free);
 918         INIT_LIST_HEAD(&xprt->recv);
 919         INIT_WORK(&xprt->task_cleanup, xprt_autoclose, xprt);
 920         init_timer(&xprt->timer);
 921         xprt->timer.function = xprt_init_autodisconnect;
 922         xprt->timer.data = (unsigned long) xprt;
 923         xprt->last_used = jiffies;
 924         xprt->cwnd = RPC_INITCWND;
 925
 926         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
 927         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
 928         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
 929         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
 930         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
 931
 932         /* initialize free list */
 933         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
 934                 list_add(&req->rq_list, &xprt->free);
 935
 936         xprt_init_xid(xprt);
 937
 938         dprintk("RPC:      created transport %p with %u slots\n", xprt,
 939                         xprt->max_reqs);
 940
 941         return xprt;
 942 }
 943
 944 /**
 945  * xprt_destroy - destroy an RPC transport, killing off all requests.
 946  * @kref: kref for the transport to destroy
 947  *
 948  */
 949 static void xprt_destroy(struct kref *kref)
 950 {
 951         struct rpc_xprt *xprt = container_of(kref, struct rpc_xprt, kref);
 952
 953         dprintk("RPC:      destroying transport %p\n", xprt);
 954         xprt->shutdown = 1;
 955         del_timer_sync(&xprt->timer);
 956
 957         /*
 958          * Tear down transport state and free the rpc_xprt
 959          */
 960         xprt->ops->destroy(xprt);
 961 }
 962
 963 /**
 964  * xprt_put - release a reference to an RPC transport.
 965  * @xprt: pointer to the transport
 966  *
 967  */
 968 void xprt_put(struct rpc_xprt *xprt)
 969 {
 970         kref_put(&xprt->kref, xprt_destroy);
 971 }
 972
 973 /**
 974  * xprt_get - return a reference to an RPC transport.
 975  * @xprt: pointer to the transport
 976  *
 977  */
 978 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
 979 {
 980         kref_get(&xprt->kref);
 981         return xprt;
 982 }