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, if a reply is expected,
  16  *      it installs a timer that is run after the packet's timeout has
  17  *      expired.
  18  *  -   When a packet arrives, the data_ready handler walks the list of
  19  *      pending requests for that transport. If a matching XID is found, the
  20  *      caller is woken up, and the timer removed.
  21  *  -   When no reply arrives within the timeout interval, the timer is
  22  *      fired by the kernel and runs xprt_timer(). It either adjusts the
  23  *      timeout values (minor timeout) or wakes up the caller with a status
  24  *      of -ETIMEDOUT.
  25  *  -   When the caller receives a notification from RPC that a reply arrived,
  26  *      it should release the RPC slot, and process the reply.
  27  *      If the call timed out, it may choose to retry the operation by
  28  *      adjusting the initial timeout value, and simply calling rpc_call
  29  *      again.
  30  *
  31  *  Support for async RPC is done through a set of RPC-specific scheduling
  32  *  primitives that `transparently' work for processes as well as async
  33  *  tasks that rely on callbacks.
  34  *
  35  *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
  36  *
  37  *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
  38  */
  39
  40 #include <linux/module.h>
  41
  42 #include <linux/types.h>
  43 #include <linux/interrupt.h>
  44 #include <linux/workqueue.h>
  45 #include <linux/net.h>
  46 #include <linux/ktime.h>
  47
  48 #include <linux/sunrpc/clnt.h>
  49 #include <linux/sunrpc/metrics.h>
  50 #include <linux/sunrpc/bc_xprt.h>
  51
  52 #include "sunrpc.h"
  53
  54 /*
  55  * Local variables
  56  */
  57
  58 #ifdef RPC_DEBUG
  59 # define RPCDBG_FACILITY        RPCDBG_XPRT
  60 #endif
  61
  62 /*
  63  * Local functions
  64  */
  65 static void      xprt_init(struct rpc_xprt *xprt, struct net *net);
  66 static void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
  67 static void     xprt_connect_status(struct rpc_task *task);
  68 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
  69 static void      xprt_destroy(struct rpc_xprt *xprt);
  70
  71 static DEFINE_SPINLOCK(xprt_list_lock);
  72 static LIST_HEAD(xprt_list);
  73
  74 /**
  75  * xprt_register_transport - register a transport implementation
  76  * @transport: transport to register
  77  *
  78  * If a transport implementation is loaded as a kernel module, it can
  79  * call this interface to make itself known to the RPC client.
  80  *
  81  * Returns:
  82  * 0:           transport successfully registered
  83  * -EEXIST:     transport already registered
  84  * -EINVAL:     transport module being unloaded
  85  */
  86 int xprt_register_transport(struct xprt_class *transport)
  87 {
  88         struct xprt_class *t;
  89         int result;
  90
  91         result = -EEXIST;
  92         spin_lock(&xprt_list_lock);
  93         list_for_each_entry(t, &xprt_list, list) {
  94                 /* don't register the same transport class twice */
  95                 if (t->ident == transport->ident)
  96                         goto out;
  97         }
  98
  99         list_add_tail(&transport->list, &xprt_list);
 100         printk(KERN_INFO "RPC: Registered %s transport module.\n",
 101                transport->name);
 102         result = 0;
 103
 104 out:
 105         spin_unlock(&xprt_list_lock);
 106         return result;
 107 }
 108 EXPORT_SYMBOL_GPL(xprt_register_transport);
 109
 110 /**
 111  * xprt_unregister_transport - unregister a transport implementation
 112  * @transport: transport to unregister
 113  *
 114  * Returns:
 115  * 0:           transport successfully unregistered
 116  * -ENOENT:     transport never registered
 117  */
 118 int xprt_unregister_transport(struct xprt_class *transport)
 119 {
 120         struct xprt_class *t;
 121         int result;
 122
 123         result = 0;
 124         spin_lock(&xprt_list_lock);
 125         list_for_each_entry(t, &xprt_list, list) {
 126                 if (t == transport) {
 127                         printk(KERN_INFO
 128                                 "RPC: Unregistered %s transport module.\n",
 129                                 transport->name);
 130                         list_del_init(&transport->list);
 131                         goto out;
 132                 }
 133         }
 134         result = -ENOENT;
 135
 136 out:
 137         spin_unlock(&xprt_list_lock);
 138         return result;
 139 }
 140 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 141
 142 /**
 143  * xprt_load_transport - load a transport implementation
 144  * @transport_name: transport to load
 145  *
 146  * Returns:
 147  * 0:           transport successfully loaded
 148  * -ENOENT:     transport module not available
 149  */
 150 int xprt_load_transport(const char *transport_name)
 151 {
 152         struct xprt_class *t;
 153         int result;
 154
 155         result = 0;
 156         spin_lock(&xprt_list_lock);
 157         list_for_each_entry(t, &xprt_list, list) {
 158                 if (strcmp(t->name, transport_name) == 0) {
 159                         spin_unlock(&xprt_list_lock);
 160                         goto out;
 161                 }
 162         }
 163         spin_unlock(&xprt_list_lock);
 164         result = request_module("xprt%s", transport_name);
 165 out:
 166         return result;
 167 }
 168 EXPORT_SYMBOL_GPL(xprt_load_transport);
 169
 170 /**
 171  * xprt_reserve_xprt - serialize write access to transports
 172  * @task: task that is requesting access to the transport
 173  * @xprt: pointer to the target transport
 174  *
 175  * This prevents mixing the payload of separate requests, and prevents
 176  * transport connects from colliding with writes.  No congestion control
 177  * is provided.
 178  */
 179 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 180 {
 181         struct rpc_rqst *req = task->tk_rqstp;
 182         int priority;
 183
 184         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 185                 if (task == xprt->snd_task)
 186                         return 1;
 187                 goto out_sleep;
 188         }
 189         xprt->snd_task = task;
 190         if (req != NULL)
 191                 req->rq_ntrans++;
 192
 193         return 1;
 194
 195 out_sleep:
 196         dprintk("RPC: %5u failed to lock transport %p\n",
 197                         task->tk_pid, xprt);
 198         task->tk_timeout = 0;
 199         task->tk_status = -EAGAIN;
 200         if (req == NULL)
 201                 priority = RPC_PRIORITY_LOW;
 202         else if (!req->rq_ntrans)
 203                 priority = RPC_PRIORITY_NORMAL;
 204         else
 205                 priority = RPC_PRIORITY_HIGH;
 206         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
 207         return 0;
 208 }
 209 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 210
 211 static void xprt_clear_locked(struct rpc_xprt *xprt)
 212 {
 213         xprt->snd_task = NULL;
 214         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 215                 smp_mb__before_atomic();
 216                 clear_bit(XPRT_LOCKED, &xprt->state);
 217                 smp_mb__after_atomic();
 218         } else
 219                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 220 }
 221
 222 /*
 223  * xprt_reserve_xprt_cong - serialize write access to transports
 224  * @task: task that is requesting access to the transport
 225  *
 226  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 227  * integrated into the decision of whether a request is allowed to be
 228  * woken up and given access to the transport.
 229  */
 230 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 231 {
 232         struct rpc_rqst *req = task->tk_rqstp;
 233         int priority;
 234
 235         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 236                 if (task == xprt->snd_task)
 237                         return 1;
 238                 goto out_sleep;
 239         }
 240         if (req == NULL) {
 241                 xprt->snd_task = task;
 242                 return 1;
 243         }
 244         if (__xprt_get_cong(xprt, task)) {
 245                 xprt->snd_task = task;
 246                 req->rq_ntrans++;
 247                 return 1;
 248         }
 249         xprt_clear_locked(xprt);
 250 out_sleep:
 251         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
 252         task->tk_timeout = 0;
 253         task->tk_status = -EAGAIN;
 254         if (req == NULL)
 255                 priority = RPC_PRIORITY_LOW;
 256         else if (!req->rq_ntrans)
 257                 priority = RPC_PRIORITY_NORMAL;
 258         else
 259                 priority = RPC_PRIORITY_HIGH;
 260         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
 261         return 0;
 262 }
 263 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 264
 265 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 266 {
 267         int retval;
 268
 269         spin_lock_bh(&xprt->transport_lock);
 270         retval = xprt->ops->reserve_xprt(xprt, task);
 271         spin_unlock_bh(&xprt->transport_lock);
 272         return retval;
 273 }
 274
 275 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
 276 {
 277         struct rpc_xprt *xprt = data;
 278         struct rpc_rqst *req;
 279
 280         req = task->tk_rqstp;
 281         xprt->snd_task = task;
 282         if (req)
 283                 req->rq_ntrans++;
 284         return true;
 285 }
 286
 287 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 288 {
 289         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 290                 return;
 291
 292         if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_func, xprt))
 293                 return;
 294         xprt_clear_locked(xprt);
 295 }
 296
 297 static bool __xprt_lock_write_cong_func(struct rpc_task *task, void *data)
 298 {
 299         struct rpc_xprt *xprt = data;
 300         struct rpc_rqst *req;
 301
 302         req = task->tk_rqstp;
 303         if (req == NULL) {
 304                 xprt->snd_task = task;
 305                 return true;
 306         }
 307         if (__xprt_get_cong(xprt, task)) {
 308                 xprt->snd_task = task;
 309                 req->rq_ntrans++;
 310                 return true;
 311         }
 312         return false;
 313 }
 314
 315 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 316 {
 317         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 318                 return;
 319         if (RPCXPRT_CONGESTED(xprt))
 320                 goto out_unlock;
 321         if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_cong_func, xprt))
 322                 return;
 323 out_unlock:
 324         xprt_clear_locked(xprt);
 325 }
 326
 327 /**
 328  * xprt_release_xprt - allow other requests to use a transport
 329  * @xprt: transport with other tasks potentially waiting
 330  * @task: task that is releasing access to the transport
 331  *
 332  * Note that "task" can be NULL.  No congestion control is provided.
 333  */
 334 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 335 {
 336         if (xprt->snd_task == task) {
 337                 if (task != NULL) {
 338                         struct rpc_rqst *req = task->tk_rqstp;
 339                         if (req != NULL)
 340                                 req->rq_bytes_sent = 0;
 341                 }
 342                 xprt_clear_locked(xprt);
 343                 __xprt_lock_write_next(xprt);
 344         }
 345 }
 346 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 347
 348 /**
 349  * xprt_release_xprt_cong - allow other requests to use a transport
 350  * @xprt: transport with other tasks potentially waiting
 351  * @task: task that is releasing access to the transport
 352  *
 353  * Note that "task" can be NULL.  Another task is awoken to use the
 354  * transport if the transport's congestion window allows it.
 355  */
 356 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 357 {
 358         if (xprt->snd_task == task) {
 359                 if (task != NULL) {
 360                         struct rpc_rqst *req = task->tk_rqstp;
 361                         if (req != NULL)
 362                                 req->rq_bytes_sent = 0;
 363                 }
 364                 xprt_clear_locked(xprt);
 365                 __xprt_lock_write_next_cong(xprt);
 366         }
 367 }
 368 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 369
 370 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 371 {
 372         spin_lock_bh(&xprt->transport_lock);
 373         xprt->ops->release_xprt(xprt, task);
 374         spin_unlock_bh(&xprt->transport_lock);
 375 }
 376
 377 /*
 378  * Van Jacobson congestion avoidance. Check if the congestion window
 379  * overflowed. Put the task to sleep if this is the case.
 380  */
 381 static int
 382 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 383 {
 384         struct rpc_rqst *req = task->tk_rqstp;
 385
 386         if (req->rq_cong)
 387                 return 1;
 388         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
 389                         task->tk_pid, xprt->cong, xprt->cwnd);
 390         if (RPCXPRT_CONGESTED(xprt))
 391                 return 0;
 392         req->rq_cong = 1;
 393         xprt->cong += RPC_CWNDSCALE;
 394         return 1;
 395 }
 396
 397 /*
 398  * Adjust the congestion window, and wake up the next task
 399  * that has been sleeping due to congestion
 400  */
 401 static void
 402 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 403 {
 404         if (!req->rq_cong)
 405                 return;
 406         req->rq_cong = 0;
 407         xprt->cong -= RPC_CWNDSCALE;
 408         __xprt_lock_write_next_cong(xprt);
 409 }
 410
 411 /**
 412  * xprt_release_rqst_cong - housekeeping when request is complete
 413  * @task: RPC request that recently completed
 414  *
 415  * Useful for transports that require congestion control.
 416  */
 417 void xprt_release_rqst_cong(struct rpc_task *task)
 418 {
 419         struct rpc_rqst *req = task->tk_rqstp;
 420
 421         __xprt_put_cong(req->rq_xprt, req);
 422 }
 423 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 424
 425 /**
 426  * xprt_adjust_cwnd - adjust transport congestion window
 427  * @xprt: pointer to xprt
 428  * @task: recently completed RPC request used to adjust window
 429  * @result: result code of completed RPC request
 430  *
 431  * The transport code maintains an estimate on the maximum number of out-
 432  * standing RPC requests, using a smoothed version of the congestion
 433  * avoidance implemented in 44BSD. This is basically the Van Jacobson
 434  * congestion algorithm: If a retransmit occurs, the congestion window is
 435  * halved; otherwise, it is incremented by 1/cwnd when
 436  *
 437  *      -       a reply is received and
 438  *      -       a full number of requests are outstanding and
 439  *      -       the congestion window hasn't been updated recently.
 440  */
 441 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
 442 {
 443         struct rpc_rqst *req = task->tk_rqstp;
 444         unsigned long cwnd = xprt->cwnd;
 445
 446         if (result >= 0 && cwnd <= xprt->cong) {
 447                 /* The (cwnd >> 1) term makes sure
 448                  * the result gets rounded properly. */
 449                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 450                 if (cwnd > RPC_MAXCWND(xprt))
 451                         cwnd = RPC_MAXCWND(xprt);
 452                 __xprt_lock_write_next_cong(xprt);
 453         } else if (result == -ETIMEDOUT) {
 454                 cwnd >>= 1;
 455                 if (cwnd < RPC_CWNDSCALE)
 456                         cwnd = RPC_CWNDSCALE;
 457         }
 458         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 459                         xprt->cong, xprt->cwnd, cwnd);
 460         xprt->cwnd = cwnd;
 461         __xprt_put_cong(xprt, req);
 462 }
 463 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 464
 465 /**
 466  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 467  * @xprt: transport with waiting tasks
 468  * @status: result code to plant in each task before waking it
 469  *
 470  */
 471 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 472 {
 473         if (status < 0)
 474                 rpc_wake_up_status(&xprt->pending, status);
 475         else
 476                 rpc_wake_up(&xprt->pending);
 477 }
 478 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 479
 480 /**
 481  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 482  * @task: task to be put to sleep
 483  * @action: function pointer to be executed after wait
 484  *
 485  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
 486  * we don't in general want to force a socket disconnection due to
 487  * an incomplete RPC call transmission.
 488  */
 489 void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
 490 {
 491         struct rpc_rqst *req = task->tk_rqstp;
 492         struct rpc_xprt *xprt = req->rq_xprt;
 493
 494         task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
 495         rpc_sleep_on(&xprt->pending, task, action);
 496 }
 497 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 498
 499 /**
 500  * xprt_write_space - wake the task waiting for transport output buffer space
 501  * @xprt: transport with waiting tasks
 502  *
 503  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 504  */
 505 void xprt_write_space(struct rpc_xprt *xprt)
 506 {
 507         spin_lock_bh(&xprt->transport_lock);
 508         if (xprt->snd_task) {
 509                 dprintk("RPC:       write space: waking waiting task on "
 510                                 "xprt %p\n", xprt);
 511                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
 512         }
 513         spin_unlock_bh(&xprt->transport_lock);
 514 }
 515 EXPORT_SYMBOL_GPL(xprt_write_space);
 516
 517 /**
 518  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 519  * @task: task whose timeout is to be set
 520  *
 521  * Set a request's retransmit timeout based on the transport's
 522  * default timeout parameters.  Used by transports that don't adjust
 523  * the retransmit timeout based on round-trip time estimation.
 524  */
 525 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 526 {
 527         task->tk_timeout = task->tk_rqstp->rq_timeout;
 528 }
 529 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
 530
 531 /**
 532  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 533  * @task: task whose timeout is to be set
 534  *
 535  * Set a request's retransmit timeout using the RTT estimator.
 536  */
 537 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 538 {
 539         int timer = task->tk_msg.rpc_proc->p_timer;
 540         struct rpc_clnt *clnt = task->tk_client;
 541         struct rpc_rtt *rtt = clnt->cl_rtt;
 542         struct rpc_rqst *req = task->tk_rqstp;
 543         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
 544
 545         task->tk_timeout = rpc_calc_rto(rtt, timer);
 546         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 547         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 548                 task->tk_timeout = max_timeout;
 549 }
 550 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 551
 552 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 553 {
 554         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 555
 556         req->rq_majortimeo = req->rq_timeout;
 557         if (to->to_exponential)
 558                 req->rq_majortimeo <<= to->to_retries;
 559         else
 560                 req->rq_majortimeo += to->to_increment * to->to_retries;
 561         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 562                 req->rq_majortimeo = to->to_maxval;
 563         req->rq_majortimeo += jiffies;
 564 }
 565
 566 /**
 567  * xprt_adjust_timeout - adjust timeout values for next retransmit
 568  * @req: RPC request containing parameters to use for the adjustment
 569  *
 570  */
 571 int xprt_adjust_timeout(struct rpc_rqst *req)
 572 {
 573         struct rpc_xprt *xprt = req->rq_xprt;
 574         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 575         int status = 0;
 576
 577         if (time_before(jiffies, req->rq_majortimeo)) {
 578                 if (to->to_exponential)
 579                         req->rq_timeout <<= 1;
 580                 else
 581                         req->rq_timeout += to->to_increment;
 582                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 583                         req->rq_timeout = to->to_maxval;
 584                 req->rq_retries++;
 585         } else {
 586                 req->rq_timeout = to->to_initval;
 587                 req->rq_retries = 0;
 588                 xprt_reset_majortimeo(req);
 589                 /* Reset the RTT counters == "slow start" */
 590                 spin_lock_bh(&xprt->transport_lock);
 591                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 592                 spin_unlock_bh(&xprt->transport_lock);
 593                 status = -ETIMEDOUT;
 594         }
 595
 596         if (req->rq_timeout == 0) {
 597                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 598                 req->rq_timeout = 5 * HZ;
 599         }
 600         return status;
 601 }
 602
 603 static void xprt_autoclose(struct work_struct *work)
 604 {
 605         struct rpc_xprt *xprt =
 606                 container_of(work, struct rpc_xprt, task_cleanup);
 607
 608         xprt->ops->close(xprt);
 609         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 610         xprt_release_write(xprt, NULL);
 611 }
 612
 613 /**
 614  * xprt_disconnect_done - mark a transport as disconnected
 615  * @xprt: transport to flag for disconnect
 616  *
 617  */
 618 void xprt_disconnect_done(struct rpc_xprt *xprt)
 619 {
 620         dprintk("RPC:       disconnected transport %p\n", xprt);
 621         spin_lock_bh(&xprt->transport_lock);
 622         xprt_clear_connected(xprt);
 623         xprt_wake_pending_tasks(xprt, -EAGAIN);
 624         spin_unlock_bh(&xprt->transport_lock);
 625 }
 626 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 627
 628 /**
 629  * xprt_force_disconnect - force a transport to disconnect
 630  * @xprt: transport to disconnect
 631  *
 632  */
 633 void xprt_force_disconnect(struct rpc_xprt *xprt)
 634 {
 635         /* Don't race with the test_bit() in xprt_clear_locked() */
 636         spin_lock_bh(&xprt->transport_lock);
 637         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 638         /* Try to schedule an autoclose RPC call */
 639         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 640                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 641         xprt_wake_pending_tasks(xprt, -EAGAIN);
 642         spin_unlock_bh(&xprt->transport_lock);
 643 }
 644
 645 /**
 646  * xprt_conditional_disconnect - force a transport to disconnect
 647  * @xprt: transport to disconnect
 648  * @cookie: 'connection cookie'
 649  *
 650  * This attempts to break the connection if and only if 'cookie' matches
 651  * the current transport 'connection cookie'. It ensures that we don't
 652  * try to break the connection more than once when we need to retransmit
 653  * a batch of RPC requests.
 654  *
 655  */
 656 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 657 {
 658         /* Don't race with the test_bit() in xprt_clear_locked() */
 659         spin_lock_bh(&xprt->transport_lock);
 660         if (cookie != xprt->connect_cookie)
 661                 goto out;
 662         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
 663                 goto out;
 664         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 665         /* Try to schedule an autoclose RPC call */
 666         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 667                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 668         xprt_wake_pending_tasks(xprt, -EAGAIN);
 669 out:
 670         spin_unlock_bh(&xprt->transport_lock);
 671 }
 672
 673 static void
 674 xprt_init_autodisconnect(unsigned long data)
 675 {
 676         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 677
 678         spin_lock(&xprt->transport_lock);
 679         if (!list_empty(&xprt->recv))
 680                 goto out_abort;
 681         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 682                 goto out_abort;
 683         spin_unlock(&xprt->transport_lock);
 684         set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
 685         queue_work(rpciod_workqueue, &xprt->task_cleanup);
 686         return;
 687 out_abort:
 688         spin_unlock(&xprt->transport_lock);
 689 }
 690
 691 /**
 692  * xprt_connect - schedule a transport connect operation
 693  * @task: RPC task that is requesting the connect
 694  *
 695  */
 696 void xprt_connect(struct rpc_task *task)
 697 {
 698         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 699
 700         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 701                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 702
 703         if (!xprt_bound(xprt)) {
 704                 task->tk_status = -EAGAIN;
 705                 return;
 706         }
 707         if (!xprt_lock_write(xprt, task))
 708                 return;
 709
 710         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
 711                 xprt->ops->close(xprt);
 712
 713         if (xprt_connected(xprt))
 714                 xprt_release_write(xprt, task);
 715         else {
 716                 task->tk_rqstp->rq_bytes_sent = 0;
 717                 task->tk_timeout = task->tk_rqstp->rq_timeout;
 718                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
 719
 720                 if (test_bit(XPRT_CLOSING, &xprt->state))
 721                         return;
 722                 if (xprt_test_and_set_connecting(xprt))
 723                         return;
 724                 xprt->stat.connect_start = jiffies;
 725                 xprt->ops->connect(xprt, task);
 726         }
 727 }
 728
 729 static void xprt_connect_status(struct rpc_task *task)
 730 {
 731         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 732
 733         if (task->tk_status == 0) {
 734                 xprt->stat.connect_count++;
 735                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 736                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 737                                 task->tk_pid);
 738                 return;
 739         }
 740
 741         switch (task->tk_status) {
 742         case -ECONNREFUSED:
 743         case -ECONNRESET:
 744         case -ECONNABORTED:
 745         case -ENETUNREACH:
 746         case -EHOSTUNREACH:
 747         case -EPIPE:
 748         case -EAGAIN:
 749                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
 750                 break;
 751         case -ETIMEDOUT:
 752                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 753                                 "out\n", task->tk_pid);
 754                 break;
 755         default:
 756                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 757                                 "server %s\n", task->tk_pid, -task->tk_status,
 758                                 xprt->servername);
 759                 xprt_release_write(xprt, task);
 760                 task->tk_status = -EIO;
 761         }
 762 }
 763
 764 /**
 765  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 766  * @xprt: transport on which the original request was transmitted
 767  * @xid: RPC XID of incoming reply
 768  *
 769  */
 770 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 771 {
 772         struct rpc_rqst *entry;
 773
 774         list_for_each_entry(entry, &xprt->recv, rq_list)
 775                 if (entry->rq_xid == xid)
 776                         return entry;
 777
 778         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 779                         ntohl(xid));
 780         xprt->stat.bad_xids++;
 781         return NULL;
 782 }
 783 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 784
 785 static void xprt_update_rtt(struct rpc_task *task)
 786 {
 787         struct rpc_rqst *req = task->tk_rqstp;
 788         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 789         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
 790         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
 791
 792         if (timer) {
 793                 if (req->rq_ntrans == 1)
 794                         rpc_update_rtt(rtt, timer, m);
 795                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 796         }
 797 }
 798
 799 /**
 800  * xprt_complete_rqst - called when reply processing is complete
 801  * @task: RPC request that recently completed
 802  * @copied: actual number of bytes received from the transport
 803  *
 804  * Caller holds transport lock.
 805  */
 806 void xprt_complete_rqst(struct rpc_task *task, int copied)
 807 {
 808         struct rpc_rqst *req = task->tk_rqstp;
 809         struct rpc_xprt *xprt = req->rq_xprt;
 810
 811         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 812                         task->tk_pid, ntohl(req->rq_xid), copied);
 813
 814         xprt->stat.recvs++;
 815         req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
 816         if (xprt->ops->timer != NULL)
 817                 xprt_update_rtt(task);
 818
 819         list_del_init(&req->rq_list);
 820         req->rq_private_buf.len = copied;
 821         /* Ensure all writes are done before we update */
 822         /* req->rq_reply_bytes_recvd */
 823         smp_wmb();
 824         req->rq_reply_bytes_recvd = copied;
 825         rpc_wake_up_queued_task(&xprt->pending, task);
 826 }
 827 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
 828
 829 static void xprt_timer(struct rpc_task *task)
 830 {
 831         struct rpc_rqst *req = task->tk_rqstp;
 832         struct rpc_xprt *xprt = req->rq_xprt;
 833
 834         if (task->tk_status != -ETIMEDOUT)
 835                 return;
 836         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
 837
 838         spin_lock_bh(&xprt->transport_lock);
 839         if (!req->rq_reply_bytes_recvd) {
 840                 if (xprt->ops->timer)
 841                         xprt->ops->timer(xprt, task);
 842         } else
 843                 task->tk_status = 0;
 844         spin_unlock_bh(&xprt->transport_lock);
 845 }
 846
 847 static inline int xprt_has_timer(struct rpc_xprt *xprt)
 848 {
 849         return xprt->idle_timeout != 0;
 850 }
 851
 852 /**
 853  * xprt_prepare_transmit - reserve the transport before sending a request
 854  * @task: RPC task about to send a request
 855  *
 856  */
 857 bool xprt_prepare_transmit(struct rpc_task *task)
 858 {
 859         struct rpc_rqst *req = task->tk_rqstp;
 860         struct rpc_xprt *xprt = req->rq_xprt;
 861         bool ret = false;
 862
 863         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 864
 865         spin_lock_bh(&xprt->transport_lock);
 866         if (!req->rq_bytes_sent) {
 867                 if (req->rq_reply_bytes_recvd) {
 868                         task->tk_status = req->rq_reply_bytes_recvd;
 869                         goto out_unlock;
 870                 }
 871                 if ((task->tk_flags & RPC_TASK_NO_RETRANS_TIMEOUT)
 872                     && xprt_connected(xprt)
 873                     && req->rq_connect_cookie == xprt->connect_cookie) {
 874                         xprt->ops->set_retrans_timeout(task);
 875                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
 876                         goto out_unlock;
 877                 }
 878         }
 879         if (!xprt->ops->reserve_xprt(xprt, task)) {
 880                 task->tk_status = -EAGAIN;
 881                 goto out_unlock;
 882         }
 883         ret = true;
 884 out_unlock:
 885         spin_unlock_bh(&xprt->transport_lock);
 886         return ret;
 887 }
 888
 889 void xprt_end_transmit(struct rpc_task *task)
 890 {
 891         xprt_release_write(task->tk_rqstp->rq_xprt, task);
 892 }
 893
 894 /**
 895  * xprt_transmit - send an RPC request on a transport
 896  * @task: controlling RPC task
 897  *
 898  * We have to copy the iovec because sendmsg fiddles with its contents.
 899  */
 900 void xprt_transmit(struct rpc_task *task)
 901 {
 902         struct rpc_rqst *req = task->tk_rqstp;
 903         struct rpc_xprt *xprt = req->rq_xprt;
 904         int status, numreqs;
 905
 906         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 907
 908         if (!req->rq_reply_bytes_recvd) {
 909                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
 910                         /*
 911                          * Add to the list only if we're expecting a reply
 912                          */
 913                         spin_lock_bh(&xprt->transport_lock);
 914                         /* Update the softirq receive buffer */
 915                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 916                                         sizeof(req->rq_private_buf));
 917                         /* Add request to the receive list */
 918                         list_add_tail(&req->rq_list, &xprt->recv);
 919                         spin_unlock_bh(&xprt->transport_lock);
 920                         xprt_reset_majortimeo(req);
 921                         /* Turn off autodisconnect */
 922                         del_singleshot_timer_sync(&xprt->timer);
 923                 }
 924         } else if (!req->rq_bytes_sent)
 925                 return;
 926
 927         req->rq_xtime = ktime_get();
 928         status = xprt->ops->send_request(task);
 929         if (status != 0) {
 930                 task->tk_status = status;
 931                 return;
 932         }
 933
 934         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
 935         task->tk_flags |= RPC_TASK_SENT;
 936         spin_lock_bh(&xprt->transport_lock);
 937
 938         xprt->ops->set_retrans_timeout(task);
 939
 940         numreqs = atomic_read(&xprt->num_reqs);
 941         if (numreqs > xprt->stat.max_slots)
 942                 xprt->stat.max_slots = numreqs;
 943         xprt->stat.sends++;
 944         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
 945         xprt->stat.bklog_u += xprt->backlog.qlen;
 946         xprt->stat.sending_u += xprt->sending.qlen;
 947         xprt->stat.pending_u += xprt->pending.qlen;
 948
 949         /* Don't race with disconnect */
 950         if (!xprt_connected(xprt))
 951                 task->tk_status = -ENOTCONN;
 952         else {
 953                 /*
 954                  * Sleep on the pending queue since
 955                  * we're expecting a reply.
 956                  */
 957                 if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task))
 958                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
 959                 req->rq_connect_cookie = xprt->connect_cookie;
 960         }
 961         spin_unlock_bh(&xprt->transport_lock);
 962 }
 963
 964 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
 965 {
 966         set_bit(XPRT_CONGESTED, &xprt->state);
 967         rpc_sleep_on(&xprt->backlog, task, NULL);
 968 }
 969
 970 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
 971 {
 972         if (rpc_wake_up_next(&xprt->backlog) == NULL)
 973                 clear_bit(XPRT_CONGESTED, &xprt->state);
 974 }
 975
 976 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
 977 {
 978         bool ret = false;
 979
 980         if (!test_bit(XPRT_CONGESTED, &xprt->state))
 981                 goto out;
 982         spin_lock(&xprt->reserve_lock);
 983         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
 984                 rpc_sleep_on(&xprt->backlog, task, NULL);
 985                 ret = true;
 986         }
 987         spin_unlock(&xprt->reserve_lock);
 988 out:
 989         return ret;
 990 }
 991
 992 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
 993 {
 994         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
 995
 996         if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
 997                 goto out;
 998         req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
 999         if (req != NULL)
1000                 goto out;
1001         atomic_dec(&xprt->num_reqs);
1002         req = ERR_PTR(-ENOMEM);
1003 out:
1004         return req;
1005 }
1006
1007 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1008 {
1009         if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
1010                 kfree(req);
1011                 return true;
1012         }
1013         return false;
1014 }
1015
1016 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1017 {
1018         struct rpc_rqst *req;
1019
1020         spin_lock(&xprt->reserve_lock);
1021         if (!list_empty(&xprt->free)) {
1022                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1023                 list_del(&req->rq_list);
1024                 goto out_init_req;
1025         }
1026         req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
1027         if (!IS_ERR(req))
1028                 goto out_init_req;
1029         switch (PTR_ERR(req)) {
1030         case -ENOMEM:
1031                 dprintk("RPC:       dynamic allocation of request slot "
1032                                 "failed! Retrying\n");
1033                 task->tk_status = -ENOMEM;
1034                 break;
1035         case -EAGAIN:
1036                 xprt_add_backlog(xprt, task);
1037                 dprintk("RPC:       waiting for request slot\n");
1038         default:
1039                 task->tk_status = -EAGAIN;
1040         }
1041         spin_unlock(&xprt->reserve_lock);
1042         return;
1043 out_init_req:
1044         task->tk_status = 0;
1045         task->tk_rqstp = req;
1046         xprt_request_init(task, xprt);
1047         spin_unlock(&xprt->reserve_lock);
1048 }
1049 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1050
1051 void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1052 {
1053         /* Note: grabbing the xprt_lock_write() ensures that we throttle
1054          * new slot allocation if the transport is congested (i.e. when
1055          * reconnecting a stream transport or when out of socket write
1056          * buffer space).
1057          */
1058         if (xprt_lock_write(xprt, task)) {
1059                 xprt_alloc_slot(xprt, task);
1060                 xprt_release_write(xprt, task);
1061         }
1062 }
1063 EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1064
1065 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1066 {
1067         spin_lock(&xprt->reserve_lock);
1068         if (!xprt_dynamic_free_slot(xprt, req)) {
1069                 memset(req, 0, sizeof(*req));   /* mark unused */
1070                 list_add(&req->rq_list, &xprt->free);
1071         }
1072         xprt_wake_up_backlog(xprt);
1073         spin_unlock(&xprt->reserve_lock);
1074 }
1075
1076 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1077 {
1078         struct rpc_rqst *req;
1079         while (!list_empty(&xprt->free)) {
1080                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1081                 list_del(&req->rq_list);
1082                 kfree(req);
1083         }
1084 }
1085
1086 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1087                 unsigned int num_prealloc,
1088                 unsigned int max_alloc)
1089 {
1090         struct rpc_xprt *xprt;
1091         struct rpc_rqst *req;
1092         int i;
1093
1094         xprt = kzalloc(size, GFP_KERNEL);
1095         if (xprt == NULL)
1096                 goto out;
1097
1098         xprt_init(xprt, net);
1099
1100         for (i = 0; i < num_prealloc; i++) {
1101                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1102                 if (!req)
1103                         goto out_free;
1104                 list_add(&req->rq_list, &xprt->free);
1105         }
1106         if (max_alloc > num_prealloc)
1107                 xprt->max_reqs = max_alloc;
1108         else
1109                 xprt->max_reqs = num_prealloc;
1110         xprt->min_reqs = num_prealloc;
1111         atomic_set(&xprt->num_reqs, num_prealloc);
1112
1113         return xprt;
1114
1115 out_free:
1116         xprt_free(xprt);
1117 out:
1118         return NULL;
1119 }
1120 EXPORT_SYMBOL_GPL(xprt_alloc);
1121
1122 void xprt_free(struct rpc_xprt *xprt)
1123 {
1124         put_net(xprt->xprt_net);
1125         xprt_free_all_slots(xprt);
1126         kfree(xprt);
1127 }
1128 EXPORT_SYMBOL_GPL(xprt_free);
1129
1130 /**
1131  * xprt_reserve - allocate an RPC request slot
1132  * @task: RPC task requesting a slot allocation
1133  *
1134  * If the transport is marked as being congested, or if no more
1135  * slots are available, place the task on the transport's
1136  * backlog queue.
1137  */
1138 void xprt_reserve(struct rpc_task *task)
1139 {
1140         struct rpc_xprt *xprt;
1141
1142         task->tk_status = 0;
1143         if (task->tk_rqstp != NULL)
1144                 return;
1145
1146         task->tk_timeout = 0;
1147         task->tk_status = -EAGAIN;
1148         rcu_read_lock();
1149         xprt = rcu_dereference(task->tk_client->cl_xprt);
1150         if (!xprt_throttle_congested(xprt, task))
1151                 xprt->ops->alloc_slot(xprt, task);
1152         rcu_read_unlock();
1153 }
1154
1155 /**
1156  * xprt_retry_reserve - allocate an RPC request slot
1157  * @task: RPC task requesting a slot allocation
1158  *
1159  * If no more slots are available, place the task on the transport's
1160  * backlog queue.
1161  * Note that the only difference with xprt_reserve is that we now
1162  * ignore the value of the XPRT_CONGESTED flag.
1163  */
1164 void xprt_retry_reserve(struct rpc_task *task)
1165 {
1166         struct rpc_xprt *xprt;
1167
1168         task->tk_status = 0;
1169         if (task->tk_rqstp != NULL)
1170                 return;
1171
1172         task->tk_timeout = 0;
1173         task->tk_status = -EAGAIN;
1174         rcu_read_lock();
1175         xprt = rcu_dereference(task->tk_client->cl_xprt);
1176         xprt->ops->alloc_slot(xprt, task);
1177         rcu_read_unlock();
1178 }
1179
1180 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1181 {
1182         return (__force __be32)xprt->xid++;
1183 }
1184
1185 static inline void xprt_init_xid(struct rpc_xprt *xprt)
1186 {
1187         xprt->xid = prandom_u32();
1188 }
1189
1190 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1191 {
1192         struct rpc_rqst *req = task->tk_rqstp;
1193
1194         INIT_LIST_HEAD(&req->rq_list);
1195         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1196         req->rq_task    = task;
1197         req->rq_xprt    = xprt;
1198         req->rq_buffer  = NULL;
1199         req->rq_xid     = xprt_alloc_xid(xprt);
1200         req->rq_connect_cookie = xprt->connect_cookie - 1;
1201         req->rq_bytes_sent = 0;
1202         req->rq_snd_buf.len = 0;
1203         req->rq_snd_buf.buflen = 0;
1204         req->rq_rcv_buf.len = 0;
1205         req->rq_rcv_buf.buflen = 0;
1206         req->rq_release_snd_buf = NULL;
1207         xprt_reset_majortimeo(req);
1208         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1209                         req, ntohl(req->rq_xid));
1210 }
1211
1212 /**
1213  * xprt_release - release an RPC request slot
1214  * @task: task which is finished with the slot
1215  *
1216  */
1217 void xprt_release(struct rpc_task *task)
1218 {
1219         struct rpc_xprt *xprt;
1220         struct rpc_rqst *req = task->tk_rqstp;
1221
1222         if (req == NULL) {
1223                 if (task->tk_client) {
1224                         rcu_read_lock();
1225                         xprt = rcu_dereference(task->tk_client->cl_xprt);
1226                         if (xprt->snd_task == task)
1227                                 xprt_release_write(xprt, task);
1228                         rcu_read_unlock();
1229                 }
1230                 return;
1231         }
1232
1233         xprt = req->rq_xprt;
1234         if (task->tk_ops->rpc_count_stats != NULL)
1235                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1236         else if (task->tk_client)
1237                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1238         spin_lock_bh(&xprt->transport_lock);
1239         xprt->ops->release_xprt(xprt, task);
1240         if (xprt->ops->release_request)
1241                 xprt->ops->release_request(task);
1242         if (!list_empty(&req->rq_list))
1243                 list_del(&req->rq_list);
1244         xprt->last_used = jiffies;
1245         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1246                 mod_timer(&xprt->timer,
1247                                 xprt->last_used + xprt->idle_timeout);
1248         spin_unlock_bh(&xprt->transport_lock);
1249         if (req->rq_buffer)
1250                 xprt->ops->buf_free(req->rq_buffer);
1251         if (req->rq_cred != NULL)
1252                 put_rpccred(req->rq_cred);
1253         task->tk_rqstp = NULL;
1254         if (req->rq_release_snd_buf)
1255                 req->rq_release_snd_buf(req);
1256
1257         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1258         if (likely(!bc_prealloc(req)))
1259                 xprt_free_slot(xprt, req);
1260         else
1261                 xprt_free_bc_request(req);
1262 }
1263
1264 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1265 {
1266         atomic_set(&xprt->count, 1);
1267
1268         spin_lock_init(&xprt->transport_lock);
1269         spin_lock_init(&xprt->reserve_lock);
1270
1271         INIT_LIST_HEAD(&xprt->free);
1272         INIT_LIST_HEAD(&xprt->recv);
1273 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1274         spin_lock_init(&xprt->bc_pa_lock);
1275         INIT_LIST_HEAD(&xprt->bc_pa_list);
1276 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1277
1278         xprt->last_used = jiffies;
1279         xprt->cwnd = RPC_INITCWND;
1280         xprt->bind_index = 0;
1281
1282         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1283         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1284         rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1285         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1286
1287         xprt_init_xid(xprt);
1288
1289         xprt->xprt_net = get_net(net);
1290 }
1291
1292 /**
1293  * xprt_create_transport - create an RPC transport
1294  * @args: rpc transport creation arguments
1295  *
1296  */
1297 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1298 {
1299         struct rpc_xprt *xprt;
1300         struct xprt_class *t;
1301
1302         spin_lock(&xprt_list_lock);
1303         list_for_each_entry(t, &xprt_list, list) {
1304                 if (t->ident == args->ident) {
1305                         spin_unlock(&xprt_list_lock);
1306                         goto found;
1307                 }
1308         }
1309         spin_unlock(&xprt_list_lock);
1310         dprintk("RPC: transport (%d) not supported\n", args->ident);
1311         return ERR_PTR(-EIO);
1312
1313 found:
1314         xprt = t->setup(args);
1315         if (IS_ERR(xprt)) {
1316                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1317                                 -PTR_ERR(xprt));
1318                 goto out;
1319         }
1320         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1321                 xprt->idle_timeout = 0;
1322         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1323         if (xprt_has_timer(xprt))
1324                 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1325                             (unsigned long)xprt);
1326         else
1327                 init_timer(&xprt->timer);
1328
1329         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1330                 xprt_destroy(xprt);
1331                 return ERR_PTR(-EINVAL);
1332         }
1333         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1334         if (xprt->servername == NULL) {
1335                 xprt_destroy(xprt);
1336                 return ERR_PTR(-ENOMEM);
1337         }
1338
1339         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1340                         xprt->max_reqs);
1341 out:
1342         return xprt;
1343 }
1344
1345 /**
1346  * xprt_destroy - destroy an RPC transport, killing off all requests.
1347  * @xprt: transport to destroy
1348  *
1349  */
1350 static void xprt_destroy(struct rpc_xprt *xprt)
1351 {
1352         dprintk("RPC:       destroying transport %p\n", xprt);
1353         del_timer_sync(&xprt->timer);
1354
1355         rpc_destroy_wait_queue(&xprt->binding);
1356         rpc_destroy_wait_queue(&xprt->pending);
1357         rpc_destroy_wait_queue(&xprt->sending);
1358         rpc_destroy_wait_queue(&xprt->backlog);
1359         cancel_work_sync(&xprt->task_cleanup);
1360         kfree(xprt->servername);
1361         /*
1362          * Tear down transport state and free the rpc_xprt
1363          */
1364         xprt->ops->destroy(xprt);
1365 }
1366
1367 /**
1368  * xprt_put - release a reference to an RPC transport.
1369  * @xprt: pointer to the transport
1370  *
1371  */
1372 void xprt_put(struct rpc_xprt *xprt)
1373 {
1374         if (atomic_dec_and_test(&xprt->count))
1375                 xprt_destroy(xprt);
1376 }