net/sunrpc/xprt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/net/sunrpc/xprt.c
   4  *
   5  *  This is a generic RPC call interface supporting congestion avoidance,
   6  *  and asynchronous calls.
   7  *
   8  *  The interface works like this:
   9  *
  10  *  -   When a process places a call, it allocates a request slot if
  11  *      one is available. Otherwise, it sleeps on the backlog queue
  12  *      (xprt_reserve).
  13  *  -   Next, the caller puts together the RPC message, stuffs it into
  14  *      the request struct, and calls xprt_transmit().
  15  *  -   xprt_transmit sends the message and installs the caller on the
  16  *      transport's wait list. At the same time, if a reply is expected,
  17  *      it installs a timer that is run after the packet's timeout has
  18  *      expired.
  19  *  -   When a packet arrives, the data_ready handler walks the list of
  20  *      pending requests for that transport. If a matching XID is found, the
  21  *      caller is woken up, and the timer removed.
  22  *  -   When no reply arrives within the timeout interval, the timer is
  23  *      fired by the kernel and runs xprt_timer(). It either adjusts the
  24  *      timeout values (minor timeout) or wakes up the caller with a status
  25  *      of -ETIMEDOUT.
  26  *  -   When the caller receives a notification from RPC that a reply arrived,
  27  *      it should release the RPC slot, and process the reply.
  28  *      If the call timed out, it may choose to retry the operation by
  29  *      adjusting the initial timeout value, and simply calling rpc_call
  30  *      again.
  31  *
  32  *  Support for async RPC is done through a set of RPC-specific scheduling
  33  *  primitives that `transparently' work for processes as well as async
  34  *  tasks that rely on callbacks.
  35  *
  36  *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
  37  *
  38  *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
  39  */
  40
  41 #include <linux/module.h>
  42
  43 #include <linux/types.h>
  44 #include <linux/interrupt.h>
  45 #include <linux/workqueue.h>
  46 #include <linux/net.h>
  47 #include <linux/ktime.h>
  48
  49 #include <linux/sunrpc/clnt.h>
  50 #include <linux/sunrpc/metrics.h>
  51 #include <linux/sunrpc/bc_xprt.h>
  52 #include <linux/rcupdate.h>
  53 #include <linux/sched/mm.h>
  54
  55 #include <trace/events/sunrpc.h>
  56
  57 #include "sunrpc.h"
  58
  59 /*
  60  * Local variables
  61  */
  62
  63 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  64 # define RPCDBG_FACILITY        RPCDBG_XPRT
  65 #endif
  66
  67 /*
  68  * Local functions
  69  */
  70 static void      xprt_init(struct rpc_xprt *xprt, struct net *net);
  71 static __be32   xprt_alloc_xid(struct rpc_xprt *xprt);
  72 static void      xprt_destroy(struct rpc_xprt *xprt);
  73
  74 static DEFINE_SPINLOCK(xprt_list_lock);
  75 static LIST_HEAD(xprt_list);
  76
  77 static unsigned long xprt_request_timeout(const struct rpc_rqst *req)
  78 {
  79         unsigned long timeout = jiffies + req->rq_timeout;
  80
  81         if (time_before(timeout, req->rq_majortimeo))
  82                 return timeout;
  83         return req->rq_majortimeo;
  84 }
  85
  86 /**
  87  * xprt_register_transport - register a transport implementation
  88  * @transport: transport to register
  89  *
  90  * If a transport implementation is loaded as a kernel module, it can
  91  * call this interface to make itself known to the RPC client.
  92  *
  93  * Returns:
  94  * 0:           transport successfully registered
  95  * -EEXIST:     transport already registered
  96  * -EINVAL:     transport module being unloaded
  97  */
  98 int xprt_register_transport(struct xprt_class *transport)
  99 {
 100         struct xprt_class *t;
 101         int result;
 102
 103         result = -EEXIST;
 104         spin_lock(&xprt_list_lock);
 105         list_for_each_entry(t, &xprt_list, list) {
 106                 /* don't register the same transport class twice */
 107                 if (t->ident == transport->ident)
 108                         goto out;
 109         }
 110
 111         list_add_tail(&transport->list, &xprt_list);
 112         printk(KERN_INFO "RPC: Registered %s transport module.\n",
 113                transport->name);
 114         result = 0;
 115
 116 out:
 117         spin_unlock(&xprt_list_lock);
 118         return result;
 119 }
 120 EXPORT_SYMBOL_GPL(xprt_register_transport);
 121
 122 /**
 123  * xprt_unregister_transport - unregister a transport implementation
 124  * @transport: transport to unregister
 125  *
 126  * Returns:
 127  * 0:           transport successfully unregistered
 128  * -ENOENT:     transport never registered
 129  */
 130 int xprt_unregister_transport(struct xprt_class *transport)
 131 {
 132         struct xprt_class *t;
 133         int result;
 134
 135         result = 0;
 136         spin_lock(&xprt_list_lock);
 137         list_for_each_entry(t, &xprt_list, list) {
 138                 if (t == transport) {
 139                         printk(KERN_INFO
 140                                 "RPC: Unregistered %s transport module.\n",
 141                                 transport->name);
 142                         list_del_init(&transport->list);
 143                         goto out;
 144                 }
 145         }
 146         result = -ENOENT;
 147
 148 out:
 149         spin_unlock(&xprt_list_lock);
 150         return result;
 151 }
 152 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 153
 154 static void
 155 xprt_class_release(const struct xprt_class *t)
 156 {
 157         module_put(t->owner);
 158 }
 159
 160 static const struct xprt_class *
 161 xprt_class_find_by_netid_locked(const char *netid)
 162 {
 163         const struct xprt_class *t;
 164         unsigned int i;
 165
 166         list_for_each_entry(t, &xprt_list, list) {
 167                 for (i = 0; t->netid[i][0] != '\0'; i++) {
 168                         if (strcmp(t->netid[i], netid) != 0)
 169                                 continue;
 170                         if (!try_module_get(t->owner))
 171                                 continue;
 172                         return t;
 173                 }
 174         }
 175         return NULL;
 176 }
 177
 178 static const struct xprt_class *
 179 xprt_class_find_by_netid(const char *netid)
 180 {
 181         const struct xprt_class *t;
 182
 183         spin_lock(&xprt_list_lock);
 184         t = xprt_class_find_by_netid_locked(netid);
 185         if (!t) {
 186                 spin_unlock(&xprt_list_lock);
 187                 request_module("rpc%s", netid);
 188                 spin_lock(&xprt_list_lock);
 189                 t = xprt_class_find_by_netid_locked(netid);
 190         }
 191         spin_unlock(&xprt_list_lock);
 192         return t;
 193 }
 194
 195 /**
 196  * xprt_load_transport - load a transport implementation
 197  * @netid: transport to load
 198  *
 199  * Returns:
 200  * 0:           transport successfully loaded
 201  * -ENOENT:     transport module not available
 202  */
 203 int xprt_load_transport(const char *netid)
 204 {
 205         const struct xprt_class *t;
 206
 207         t = xprt_class_find_by_netid(netid);
 208         if (!t)
 209                 return -ENOENT;
 210         xprt_class_release(t);
 211         return 0;
 212 }
 213 EXPORT_SYMBOL_GPL(xprt_load_transport);
 214
 215 static void xprt_clear_locked(struct rpc_xprt *xprt)
 216 {
 217         xprt->snd_task = NULL;
 218         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 219                 smp_mb__before_atomic();
 220                 clear_bit(XPRT_LOCKED, &xprt->state);
 221                 smp_mb__after_atomic();
 222         } else
 223                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 224 }
 225
 226 /**
 227  * xprt_reserve_xprt - serialize write access to transports
 228  * @task: task that is requesting access to the transport
 229  * @xprt: pointer to the target transport
 230  *
 231  * This prevents mixing the payload of separate requests, and prevents
 232  * transport connects from colliding with writes.  No congestion control
 233  * is provided.
 234  */
 235 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 236 {
 237         struct rpc_rqst *req = task->tk_rqstp;
 238
 239         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 240                 if (task == xprt->snd_task)
 241                         return 1;
 242                 goto out_sleep;
 243         }
 244         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 245                 goto out_unlock;
 246         xprt->snd_task = task;
 247
 248         return 1;
 249
 250 out_unlock:
 251         xprt_clear_locked(xprt);
 252 out_sleep:
 253         dprintk("RPC: %5u failed to lock transport %p\n",
 254                         task->tk_pid, xprt);
 255         task->tk_status = -EAGAIN;
 256         if  (RPC_IS_SOFT(task))
 257                 rpc_sleep_on_timeout(&xprt->sending, task, NULL,
 258                                 xprt_request_timeout(req));
 259         else
 260                 rpc_sleep_on(&xprt->sending, task, NULL);
 261         return 0;
 262 }
 263 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 264
 265 static bool
 266 xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
 267 {
 268         return test_bit(XPRT_CWND_WAIT, &xprt->state);
 269 }
 270
 271 static void
 272 xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
 273 {
 274         if (!list_empty(&xprt->xmit_queue)) {
 275                 /* Peek at head of queue to see if it can make progress */
 276                 if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
 277                                         rq_xmit)->rq_cong)
 278                         return;
 279         }
 280         set_bit(XPRT_CWND_WAIT, &xprt->state);
 281 }
 282
 283 static void
 284 xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
 285 {
 286         if (!RPCXPRT_CONGESTED(xprt))
 287                 clear_bit(XPRT_CWND_WAIT, &xprt->state);
 288 }
 289
 290 /*
 291  * xprt_reserve_xprt_cong - serialize write access to transports
 292  * @task: task that is requesting access to the transport
 293  *
 294  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 295  * integrated into the decision of whether a request is allowed to be
 296  * woken up and given access to the transport.
 297  * Note that the lock is only granted if we know there are free slots.
 298  */
 299 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 300 {
 301         struct rpc_rqst *req = task->tk_rqstp;
 302
 303         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 304                 if (task == xprt->snd_task)
 305                         return 1;
 306                 goto out_sleep;
 307         }
 308         if (req == NULL) {
 309                 xprt->snd_task = task;
 310                 return 1;
 311         }
 312         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 313                 goto out_unlock;
 314         if (!xprt_need_congestion_window_wait(xprt)) {
 315                 xprt->snd_task = task;
 316                 return 1;
 317         }
 318 out_unlock:
 319         xprt_clear_locked(xprt);
 320 out_sleep:
 321         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
 322         task->tk_status = -EAGAIN;
 323         if (RPC_IS_SOFT(task))
 324                 rpc_sleep_on_timeout(&xprt->sending, task, NULL,
 325                                 xprt_request_timeout(req));
 326         else
 327                 rpc_sleep_on(&xprt->sending, task, NULL);
 328         return 0;
 329 }
 330 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 331
 332 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 333 {
 334         int retval;
 335
 336         if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
 337                 return 1;
 338         spin_lock(&xprt->transport_lock);
 339         retval = xprt->ops->reserve_xprt(xprt, task);
 340         spin_unlock(&xprt->transport_lock);
 341         return retval;
 342 }
 343
 344 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
 345 {
 346         struct rpc_xprt *xprt = data;
 347
 348         xprt->snd_task = task;
 349         return true;
 350 }
 351
 352 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 353 {
 354         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 355                 return;
 356         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 357                 goto out_unlock;
 358         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 359                                 __xprt_lock_write_func, xprt))
 360                 return;
 361 out_unlock:
 362         xprt_clear_locked(xprt);
 363 }
 364
 365 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 366 {
 367         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 368                 return;
 369         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 370                 goto out_unlock;
 371         if (xprt_need_congestion_window_wait(xprt))
 372                 goto out_unlock;
 373         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 374                                 __xprt_lock_write_func, xprt))
 375                 return;
 376 out_unlock:
 377         xprt_clear_locked(xprt);
 378 }
 379
 380 /**
 381  * xprt_release_xprt - allow other requests to use a transport
 382  * @xprt: transport with other tasks potentially waiting
 383  * @task: task that is releasing access to the transport
 384  *
 385  * Note that "task" can be NULL.  No congestion control is provided.
 386  */
 387 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 388 {
 389         if (xprt->snd_task == task) {
 390                 xprt_clear_locked(xprt);
 391                 __xprt_lock_write_next(xprt);
 392         }
 393 }
 394 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 395
 396 /**
 397  * xprt_release_xprt_cong - allow other requests to use a transport
 398  * @xprt: transport with other tasks potentially waiting
 399  * @task: task that is releasing access to the transport
 400  *
 401  * Note that "task" can be NULL.  Another task is awoken to use the
 402  * transport if the transport's congestion window allows it.
 403  */
 404 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 405 {
 406         if (xprt->snd_task == task) {
 407                 xprt_clear_locked(xprt);
 408                 __xprt_lock_write_next_cong(xprt);
 409         }
 410 }
 411 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 412
 413 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 414 {
 415         if (xprt->snd_task != task)
 416                 return;
 417         spin_lock(&xprt->transport_lock);
 418         xprt->ops->release_xprt(xprt, task);
 419         spin_unlock(&xprt->transport_lock);
 420 }
 421
 422 /*
 423  * Van Jacobson congestion avoidance. Check if the congestion window
 424  * overflowed. Put the task to sleep if this is the case.
 425  */
 426 static int
 427 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 428 {
 429         if (req->rq_cong)
 430                 return 1;
 431         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
 432                         req->rq_task->tk_pid, xprt->cong, xprt->cwnd);
 433         if (RPCXPRT_CONGESTED(xprt)) {
 434                 xprt_set_congestion_window_wait(xprt);
 435                 return 0;
 436         }
 437         req->rq_cong = 1;
 438         xprt->cong += RPC_CWNDSCALE;
 439         return 1;
 440 }
 441
 442 /*
 443  * Adjust the congestion window, and wake up the next task
 444  * that has been sleeping due to congestion
 445  */
 446 static void
 447 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 448 {
 449         if (!req->rq_cong)
 450                 return;
 451         req->rq_cong = 0;
 452         xprt->cong -= RPC_CWNDSCALE;
 453         xprt_test_and_clear_congestion_window_wait(xprt);
 454         __xprt_lock_write_next_cong(xprt);
 455 }
 456
 457 /**
 458  * xprt_request_get_cong - Request congestion control credits
 459  * @xprt: pointer to transport
 460  * @req: pointer to RPC request
 461  *
 462  * Useful for transports that require congestion control.
 463  */
 464 bool
 465 xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 466 {
 467         bool ret = false;
 468
 469         if (req->rq_cong)
 470                 return true;
 471         spin_lock(&xprt->transport_lock);
 472         ret = __xprt_get_cong(xprt, req) != 0;
 473         spin_unlock(&xprt->transport_lock);
 474         return ret;
 475 }
 476 EXPORT_SYMBOL_GPL(xprt_request_get_cong);
 477
 478 /**
 479  * xprt_release_rqst_cong - housekeeping when request is complete
 480  * @task: RPC request that recently completed
 481  *
 482  * Useful for transports that require congestion control.
 483  */
 484 void xprt_release_rqst_cong(struct rpc_task *task)
 485 {
 486         struct rpc_rqst *req = task->tk_rqstp;
 487
 488         __xprt_put_cong(req->rq_xprt, req);
 489 }
 490 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 491
 492 static void xprt_clear_congestion_window_wait_locked(struct rpc_xprt *xprt)
 493 {
 494         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state))
 495                 __xprt_lock_write_next_cong(xprt);
 496 }
 497
 498 /*
 499  * Clear the congestion window wait flag and wake up the next
 500  * entry on xprt->sending
 501  */
 502 static void
 503 xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
 504 {
 505         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
 506                 spin_lock(&xprt->transport_lock);
 507                 __xprt_lock_write_next_cong(xprt);
 508                 spin_unlock(&xprt->transport_lock);
 509         }
 510 }
 511
 512 /**
 513  * xprt_adjust_cwnd - adjust transport congestion window
 514  * @xprt: pointer to xprt
 515  * @task: recently completed RPC request used to adjust window
 516  * @result: result code of completed RPC request
 517  *
 518  * The transport code maintains an estimate on the maximum number of out-
 519  * standing RPC requests, using a smoothed version of the congestion
 520  * avoidance implemented in 44BSD. This is basically the Van Jacobson
 521  * congestion algorithm: If a retransmit occurs, the congestion window is
 522  * halved; otherwise, it is incremented by 1/cwnd when
 523  *
 524  *      -       a reply is received and
 525  *      -       a full number of requests are outstanding and
 526  *      -       the congestion window hasn't been updated recently.
 527  */
 528 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
 529 {
 530         struct rpc_rqst *req = task->tk_rqstp;
 531         unsigned long cwnd = xprt->cwnd;
 532
 533         if (result >= 0 && cwnd <= xprt->cong) {
 534                 /* The (cwnd >> 1) term makes sure
 535                  * the result gets rounded properly. */
 536                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 537                 if (cwnd > RPC_MAXCWND(xprt))
 538                         cwnd = RPC_MAXCWND(xprt);
 539                 __xprt_lock_write_next_cong(xprt);
 540         } else if (result == -ETIMEDOUT) {
 541                 cwnd >>= 1;
 542                 if (cwnd < RPC_CWNDSCALE)
 543                         cwnd = RPC_CWNDSCALE;
 544         }
 545         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 546                         xprt->cong, xprt->cwnd, cwnd);
 547         xprt->cwnd = cwnd;
 548         __xprt_put_cong(xprt, req);
 549 }
 550 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 551
 552 /**
 553  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 554  * @xprt: transport with waiting tasks
 555  * @status: result code to plant in each task before waking it
 556  *
 557  */
 558 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 559 {
 560         if (status < 0)
 561                 rpc_wake_up_status(&xprt->pending, status);
 562         else
 563                 rpc_wake_up(&xprt->pending);
 564 }
 565 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 566
 567 /**
 568  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 569  * @xprt: transport
 570  *
 571  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
 572  * we don't in general want to force a socket disconnection due to
 573  * an incomplete RPC call transmission.
 574  */
 575 void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
 576 {
 577         set_bit(XPRT_WRITE_SPACE, &xprt->state);
 578 }
 579 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 580
 581 static bool
 582 xprt_clear_write_space_locked(struct rpc_xprt *xprt)
 583 {
 584         if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
 585                 __xprt_lock_write_next(xprt);
 586                 dprintk("RPC:       write space: waking waiting task on "
 587                                 "xprt %p\n", xprt);
 588                 return true;
 589         }
 590         return false;
 591 }
 592
 593 /**
 594  * xprt_write_space - wake the task waiting for transport output buffer space
 595  * @xprt: transport with waiting tasks
 596  *
 597  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 598  */
 599 bool xprt_write_space(struct rpc_xprt *xprt)
 600 {
 601         bool ret;
 602
 603         if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
 604                 return false;
 605         spin_lock(&xprt->transport_lock);
 606         ret = xprt_clear_write_space_locked(xprt);
 607         spin_unlock(&xprt->transport_lock);
 608         return ret;
 609 }
 610 EXPORT_SYMBOL_GPL(xprt_write_space);
 611
 612 static unsigned long xprt_abs_ktime_to_jiffies(ktime_t abstime)
 613 {
 614         s64 delta = ktime_to_ns(ktime_get() - abstime);
 615         return likely(delta >= 0) ?
 616                 jiffies - nsecs_to_jiffies(delta) :
 617                 jiffies + nsecs_to_jiffies(-delta);
 618 }
 619
 620 static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req)
 621 {
 622         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 623         unsigned long majortimeo = req->rq_timeout;
 624
 625         if (to->to_exponential)
 626                 majortimeo <<= to->to_retries;
 627         else
 628                 majortimeo += to->to_increment * to->to_retries;
 629         if (majortimeo > to->to_maxval || majortimeo == 0)
 630                 majortimeo = to->to_maxval;
 631         return majortimeo;
 632 }
 633
 634 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 635 {
 636         req->rq_majortimeo += xprt_calc_majortimeo(req);
 637 }
 638
 639 static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
 640 {
 641         unsigned long time_init;
 642         struct rpc_xprt *xprt = req->rq_xprt;
 643
 644         if (likely(xprt && xprt_connected(xprt)))
 645                 time_init = jiffies;
 646         else
 647                 time_init = xprt_abs_ktime_to_jiffies(task->tk_start);
 648         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
 649         req->rq_majortimeo = time_init + xprt_calc_majortimeo(req);
 650 }
 651
 652 /**
 653  * xprt_adjust_timeout - adjust timeout values for next retransmit
 654  * @req: RPC request containing parameters to use for the adjustment
 655  *
 656  */
 657 int xprt_adjust_timeout(struct rpc_rqst *req)
 658 {
 659         struct rpc_xprt *xprt = req->rq_xprt;
 660         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 661         int status = 0;
 662
 663         if (time_before(jiffies, req->rq_majortimeo)) {
 664                 if (to->to_exponential)
 665                         req->rq_timeout <<= 1;
 666                 else
 667                         req->rq_timeout += to->to_increment;
 668                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 669                         req->rq_timeout = to->to_maxval;
 670                 req->rq_retries++;
 671         } else {
 672                 req->rq_timeout = to->to_initval;
 673                 req->rq_retries = 0;
 674                 xprt_reset_majortimeo(req);
 675                 /* Reset the RTT counters == "slow start" */
 676                 spin_lock(&xprt->transport_lock);
 677                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 678                 spin_unlock(&xprt->transport_lock);
 679                 status = -ETIMEDOUT;
 680         }
 681
 682         if (req->rq_timeout == 0) {
 683                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 684                 req->rq_timeout = 5 * HZ;
 685         }
 686         return status;
 687 }
 688
 689 static void xprt_autoclose(struct work_struct *work)
 690 {
 691         struct rpc_xprt *xprt =
 692                 container_of(work, struct rpc_xprt, task_cleanup);
 693         unsigned int pflags = memalloc_nofs_save();
 694
 695         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 696         xprt->ops->close(xprt);
 697         xprt_release_write(xprt, NULL);
 698         wake_up_bit(&xprt->state, XPRT_LOCKED);
 699         memalloc_nofs_restore(pflags);
 700 }
 701
 702 /**
 703  * xprt_disconnect_done - mark a transport as disconnected
 704  * @xprt: transport to flag for disconnect
 705  *
 706  */
 707 void xprt_disconnect_done(struct rpc_xprt *xprt)
 708 {
 709         dprintk("RPC:       disconnected transport %p\n", xprt);
 710         spin_lock(&xprt->transport_lock);
 711         xprt_clear_connected(xprt);
 712         xprt_clear_write_space_locked(xprt);
 713         xprt_clear_congestion_window_wait_locked(xprt);
 714         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 715         spin_unlock(&xprt->transport_lock);
 716 }
 717 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 718
 719 /**
 720  * xprt_schedule_autoclose_locked - Try to schedule an autoclose RPC call
 721  * @xprt: transport to disconnect
 722  */
 723 static void xprt_schedule_autoclose_locked(struct rpc_xprt *xprt)
 724 {
 725         if (test_and_set_bit(XPRT_CLOSE_WAIT, &xprt->state))
 726                 return;
 727         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 728                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 729         else if (xprt->snd_task && !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
 730                 rpc_wake_up_queued_task_set_status(&xprt->pending,
 731                                                    xprt->snd_task, -ENOTCONN);
 732 }
 733
 734 /**
 735  * xprt_force_disconnect - force a transport to disconnect
 736  * @xprt: transport to disconnect
 737  *
 738  */
 739 void xprt_force_disconnect(struct rpc_xprt *xprt)
 740 {
 741         /* Don't race with the test_bit() in xprt_clear_locked() */
 742         spin_lock(&xprt->transport_lock);
 743         xprt_schedule_autoclose_locked(xprt);
 744         spin_unlock(&xprt->transport_lock);
 745 }
 746 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
 747
 748 static unsigned int
 749 xprt_connect_cookie(struct rpc_xprt *xprt)
 750 {
 751         return READ_ONCE(xprt->connect_cookie);
 752 }
 753
 754 static bool
 755 xprt_request_retransmit_after_disconnect(struct rpc_task *task)
 756 {
 757         struct rpc_rqst *req = task->tk_rqstp;
 758         struct rpc_xprt *xprt = req->rq_xprt;
 759
 760         return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
 761                 !xprt_connected(xprt);
 762 }
 763
 764 /**
 765  * xprt_conditional_disconnect - force a transport to disconnect
 766  * @xprt: transport to disconnect
 767  * @cookie: 'connection cookie'
 768  *
 769  * This attempts to break the connection if and only if 'cookie' matches
 770  * the current transport 'connection cookie'. It ensures that we don't
 771  * try to break the connection more than once when we need to retransmit
 772  * a batch of RPC requests.
 773  *
 774  */
 775 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 776 {
 777         /* Don't race with the test_bit() in xprt_clear_locked() */
 778         spin_lock(&xprt->transport_lock);
 779         if (cookie != xprt->connect_cookie)
 780                 goto out;
 781         if (test_bit(XPRT_CLOSING, &xprt->state))
 782                 goto out;
 783         xprt_schedule_autoclose_locked(xprt);
 784 out:
 785         spin_unlock(&xprt->transport_lock);
 786 }
 787
 788 static bool
 789 xprt_has_timer(const struct rpc_xprt *xprt)
 790 {
 791         return xprt->idle_timeout != 0;
 792 }
 793
 794 static void
 795 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
 796         __must_hold(&xprt->transport_lock)
 797 {
 798         xprt->last_used = jiffies;
 799         if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))
 800                 mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
 801 }
 802
 803 static void
 804 xprt_init_autodisconnect(struct timer_list *t)
 805 {
 806         struct rpc_xprt *xprt = from_timer(xprt, t, timer);
 807
 808         if (!RB_EMPTY_ROOT(&xprt->recv_queue))
 809                 return;
 810         /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
 811         xprt->last_used = jiffies;
 812         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 813                 return;
 814         queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 815 }
 816
 817 bool xprt_lock_connect(struct rpc_xprt *xprt,
 818                 struct rpc_task *task,
 819                 void *cookie)
 820 {
 821         bool ret = false;
 822
 823         spin_lock(&xprt->transport_lock);
 824         if (!test_bit(XPRT_LOCKED, &xprt->state))
 825                 goto out;
 826         if (xprt->snd_task != task)
 827                 goto out;
 828         set_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 829         xprt->snd_task = cookie;
 830         ret = true;
 831 out:
 832         spin_unlock(&xprt->transport_lock);
 833         return ret;
 834 }
 835
 836 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
 837 {
 838         spin_lock(&xprt->transport_lock);
 839         if (xprt->snd_task != cookie)
 840                 goto out;
 841         if (!test_bit(XPRT_LOCKED, &xprt->state))
 842                 goto out;
 843         xprt->snd_task =NULL;
 844         clear_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 845         xprt->ops->release_xprt(xprt, NULL);
 846         xprt_schedule_autodisconnect(xprt);
 847 out:
 848         spin_unlock(&xprt->transport_lock);
 849         wake_up_bit(&xprt->state, XPRT_LOCKED);
 850 }
 851
 852 /**
 853  * xprt_connect - schedule a transport connect operation
 854  * @task: RPC task that is requesting the connect
 855  *
 856  */
 857 void xprt_connect(struct rpc_task *task)
 858 {
 859         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 860
 861         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 862                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 863
 864         if (!xprt_bound(xprt)) {
 865                 task->tk_status = -EAGAIN;
 866                 return;
 867         }
 868         if (!xprt_lock_write(xprt, task))
 869                 return;
 870
 871         if (!xprt_connected(xprt) && !test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 872                 task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
 873                 rpc_sleep_on_timeout(&xprt->pending, task, NULL,
 874                                 xprt_request_timeout(task->tk_rqstp));
 875
 876                 if (test_bit(XPRT_CLOSING, &xprt->state))
 877                         return;
 878                 if (xprt_test_and_set_connecting(xprt))
 879                         return;
 880                 /* Race breaker */
 881                 if (!xprt_connected(xprt)) {
 882                         xprt->stat.connect_start = jiffies;
 883                         xprt->ops->connect(xprt, task);
 884                 } else {
 885                         xprt_clear_connecting(xprt);
 886                         task->tk_status = 0;
 887                         rpc_wake_up_queued_task(&xprt->pending, task);
 888                 }
 889         }
 890         xprt_release_write(xprt, task);
 891 }
 892
 893 /**
 894  * xprt_reconnect_delay - compute the wait before scheduling a connect
 895  * @xprt: transport instance
 896  *
 897  */
 898 unsigned long xprt_reconnect_delay(const struct rpc_xprt *xprt)
 899 {
 900         unsigned long start, now = jiffies;
 901
 902         start = xprt->stat.connect_start + xprt->reestablish_timeout;
 903         if (time_after(start, now))
 904                 return start - now;
 905         return 0;
 906 }
 907 EXPORT_SYMBOL_GPL(xprt_reconnect_delay);
 908
 909 /**
 910  * xprt_reconnect_backoff - compute the new re-establish timeout
 911  * @xprt: transport instance
 912  * @init_to: initial reestablish timeout
 913  *
 914  */
 915 void xprt_reconnect_backoff(struct rpc_xprt *xprt, unsigned long init_to)
 916 {
 917         xprt->reestablish_timeout <<= 1;
 918         if (xprt->reestablish_timeout > xprt->max_reconnect_timeout)
 919                 xprt->reestablish_timeout = xprt->max_reconnect_timeout;
 920         if (xprt->reestablish_timeout < init_to)
 921                 xprt->reestablish_timeout = init_to;
 922 }
 923 EXPORT_SYMBOL_GPL(xprt_reconnect_backoff);
 924
 925 enum xprt_xid_rb_cmp {
 926         XID_RB_EQUAL,
 927         XID_RB_LEFT,
 928         XID_RB_RIGHT,
 929 };
 930 static enum xprt_xid_rb_cmp
 931 xprt_xid_cmp(__be32 xid1, __be32 xid2)
 932 {
 933         if (xid1 == xid2)
 934                 return XID_RB_EQUAL;
 935         if ((__force u32)xid1 < (__force u32)xid2)
 936                 return XID_RB_LEFT;
 937         return XID_RB_RIGHT;
 938 }
 939
 940 static struct rpc_rqst *
 941 xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
 942 {
 943         struct rb_node *n = xprt->recv_queue.rb_node;
 944         struct rpc_rqst *req;
 945
 946         while (n != NULL) {
 947                 req = rb_entry(n, struct rpc_rqst, rq_recv);
 948                 switch (xprt_xid_cmp(xid, req->rq_xid)) {
 949                 case XID_RB_LEFT:
 950                         n = n->rb_left;
 951                         break;
 952                 case XID_RB_RIGHT:
 953                         n = n->rb_right;
 954                         break;
 955                 case XID_RB_EQUAL:
 956                         return req;
 957                 }
 958         }
 959         return NULL;
 960 }
 961
 962 static void
 963 xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
 964 {
 965         struct rb_node **p = &xprt->recv_queue.rb_node;
 966         struct rb_node *n = NULL;
 967         struct rpc_rqst *req;
 968
 969         while (*p != NULL) {
 970                 n = *p;
 971                 req = rb_entry(n, struct rpc_rqst, rq_recv);
 972                 switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
 973                 case XID_RB_LEFT:
 974                         p = &n->rb_left;
 975                         break;
 976                 case XID_RB_RIGHT:
 977                         p = &n->rb_right;
 978                         break;
 979                 case XID_RB_EQUAL:
 980                         WARN_ON_ONCE(new != req);
 981                         return;
 982                 }
 983         }
 984         rb_link_node(&new->rq_recv, n, p);
 985         rb_insert_color(&new->rq_recv, &xprt->recv_queue);
 986 }
 987
 988 static void
 989 xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
 990 {
 991         rb_erase(&req->rq_recv, &xprt->recv_queue);
 992 }
 993
 994 /**
 995  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 996  * @xprt: transport on which the original request was transmitted
 997  * @xid: RPC XID of incoming reply
 998  *
 999  * Caller holds xprt->queue_lock.
1000  */
1001 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
1002 {
1003         struct rpc_rqst *entry;
1004
1005         entry = xprt_request_rb_find(xprt, xid);
1006         if (entry != NULL) {
1007                 trace_xprt_lookup_rqst(xprt, xid, 0);
1008                 entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
1009                 return entry;
1010         }
1011
1012         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
1013                         ntohl(xid));
1014         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
1015         xprt->stat.bad_xids++;
1016         return NULL;
1017 }
1018 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
1019
1020 static bool
1021 xprt_is_pinned_rqst(struct rpc_rqst *req)
1022 {
1023         return atomic_read(&req->rq_pin) != 0;
1024 }
1025
1026 /**
1027  * xprt_pin_rqst - Pin a request on the transport receive list
1028  * @req: Request to pin
1029  *
1030  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
1031  * so should be holding xprt->queue_lock.
1032  */
1033 void xprt_pin_rqst(struct rpc_rqst *req)
1034 {
1035         atomic_inc(&req->rq_pin);
1036 }
1037 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
1038
1039 /**
1040  * xprt_unpin_rqst - Unpin a request on the transport receive list
1041  * @req: Request to pin
1042  *
1043  * Caller should be holding xprt->queue_lock.
1044  */
1045 void xprt_unpin_rqst(struct rpc_rqst *req)
1046 {
1047         if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
1048                 atomic_dec(&req->rq_pin);
1049                 return;
1050         }
1051         if (atomic_dec_and_test(&req->rq_pin))
1052                 wake_up_var(&req->rq_pin);
1053 }
1054 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
1055
1056 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
1057 {
1058         wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
1059 }
1060
1061 static bool
1062 xprt_request_data_received(struct rpc_task *task)
1063 {
1064         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1065                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
1066 }
1067
1068 static bool
1069 xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
1070 {
1071         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1072                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
1073 }
1074
1075 /**
1076  * xprt_request_enqueue_receive - Add an request to the receive queue
1077  * @task: RPC task
1078  *
1079  */
1080 void
1081 xprt_request_enqueue_receive(struct rpc_task *task)
1082 {
1083         struct rpc_rqst *req = task->tk_rqstp;
1084         struct rpc_xprt *xprt = req->rq_xprt;
1085
1086         if (!xprt_request_need_enqueue_receive(task, req))
1087                 return;
1088
1089         xprt_request_prepare(task->tk_rqstp);
1090         spin_lock(&xprt->queue_lock);
1091
1092         /* Update the softirq receive buffer */
1093         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1094                         sizeof(req->rq_private_buf));
1095
1096         /* Add request to the receive list */
1097         xprt_request_rb_insert(xprt, req);
1098         set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
1099         spin_unlock(&xprt->queue_lock);
1100
1101         /* Turn off autodisconnect */
1102         del_singleshot_timer_sync(&xprt->timer);
1103 }
1104
1105 /**
1106  * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
1107  * @task: RPC task
1108  *
1109  * Caller must hold xprt->queue_lock.
1110  */
1111 static void
1112 xprt_request_dequeue_receive_locked(struct rpc_task *task)
1113 {
1114         struct rpc_rqst *req = task->tk_rqstp;
1115
1116         if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1117                 xprt_request_rb_remove(req->rq_xprt, req);
1118 }
1119
1120 /**
1121  * xprt_update_rtt - Update RPC RTT statistics
1122  * @task: RPC request that recently completed
1123  *
1124  * Caller holds xprt->queue_lock.
1125  */
1126 void xprt_update_rtt(struct rpc_task *task)
1127 {
1128         struct rpc_rqst *req = task->tk_rqstp;
1129         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
1130         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
1131         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
1132
1133         if (timer) {
1134                 if (req->rq_ntrans == 1)
1135                         rpc_update_rtt(rtt, timer, m);
1136                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
1137         }
1138 }
1139 EXPORT_SYMBOL_GPL(xprt_update_rtt);
1140
1141 /**
1142  * xprt_complete_rqst - called when reply processing is complete
1143  * @task: RPC request that recently completed
1144  * @copied: actual number of bytes received from the transport
1145  *
1146  * Caller holds xprt->queue_lock.
1147  */
1148 void xprt_complete_rqst(struct rpc_task *task, int copied)
1149 {
1150         struct rpc_rqst *req = task->tk_rqstp;
1151         struct rpc_xprt *xprt = req->rq_xprt;
1152
1153         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
1154                         task->tk_pid, ntohl(req->rq_xid), copied);
1155         trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
1156
1157         xprt->stat.recvs++;
1158
1159         req->rq_private_buf.len = copied;
1160         /* Ensure all writes are done before we update */
1161         /* req->rq_reply_bytes_recvd */
1162         smp_wmb();
1163         req->rq_reply_bytes_recvd = copied;
1164         xprt_request_dequeue_receive_locked(task);
1165         rpc_wake_up_queued_task(&xprt->pending, task);
1166 }
1167 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
1168
1169 static void xprt_timer(struct rpc_task *task)
1170 {
1171         struct rpc_rqst *req = task->tk_rqstp;
1172         struct rpc_xprt *xprt = req->rq_xprt;
1173
1174         if (task->tk_status != -ETIMEDOUT)
1175                 return;
1176
1177         trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
1178         if (!req->rq_reply_bytes_recvd) {
1179                 if (xprt->ops->timer)
1180                         xprt->ops->timer(xprt, task);
1181         } else
1182                 task->tk_status = 0;
1183 }
1184
1185 /**
1186  * xprt_wait_for_reply_request_def - wait for reply
1187  * @task: pointer to rpc_task
1188  *
1189  * Set a request's retransmit timeout based on the transport's
1190  * default timeout parameters.  Used by transports that don't adjust
1191  * the retransmit timeout based on round-trip time estimation,
1192  * and put the task to sleep on the pending queue.
1193  */
1194 void xprt_wait_for_reply_request_def(struct rpc_task *task)
1195 {
1196         struct rpc_rqst *req = task->tk_rqstp;
1197
1198         rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1199                         xprt_request_timeout(req));
1200 }
1201 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_def);
1202
1203 /**
1204  * xprt_wait_for_reply_request_rtt - wait for reply using RTT estimator
1205  * @task: pointer to rpc_task
1206  *
1207  * Set a request's retransmit timeout using the RTT estimator,
1208  * and put the task to sleep on the pending queue.
1209  */
1210 void xprt_wait_for_reply_request_rtt(struct rpc_task *task)
1211 {
1212         int timer = task->tk_msg.rpc_proc->p_timer;
1213         struct rpc_clnt *clnt = task->tk_client;
1214         struct rpc_rtt *rtt = clnt->cl_rtt;
1215         struct rpc_rqst *req = task->tk_rqstp;
1216         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
1217         unsigned long timeout;
1218
1219         timeout = rpc_calc_rto(rtt, timer);
1220         timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
1221         if (timeout > max_timeout || timeout == 0)
1222                 timeout = max_timeout;
1223         rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1224                         jiffies + timeout);
1225 }
1226 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_rtt);
1227
1228 /**
1229  * xprt_request_wait_receive - wait for the reply to an RPC request
1230  * @task: RPC task about to send a request
1231  *
1232  */
1233 void xprt_request_wait_receive(struct rpc_task *task)
1234 {
1235         struct rpc_rqst *req = task->tk_rqstp;
1236         struct rpc_xprt *xprt = req->rq_xprt;
1237
1238         if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1239                 return;
1240         /*
1241          * Sleep on the pending queue if we're expecting a reply.
1242          * The spinlock ensures atomicity between the test of
1243          * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1244          */
1245         spin_lock(&xprt->queue_lock);
1246         if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
1247                 xprt->ops->wait_for_reply_request(task);
1248                 /*
1249                  * Send an extra queue wakeup call if the
1250                  * connection was dropped in case the call to
1251                  * rpc_sleep_on() raced.
1252                  */
1253                 if (xprt_request_retransmit_after_disconnect(task))
1254                         rpc_wake_up_queued_task_set_status(&xprt->pending,
1255                                         task, -ENOTCONN);
1256         }
1257         spin_unlock(&xprt->queue_lock);
1258 }
1259
1260 static bool
1261 xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
1262 {
1263         return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1264 }
1265
1266 /**
1267  * xprt_request_enqueue_transmit - queue a task for transmission
1268  * @task: pointer to rpc_task
1269  *
1270  * Add a task to the transmission queue.
1271  */
1272 void
1273 xprt_request_enqueue_transmit(struct rpc_task *task)
1274 {
1275         struct rpc_rqst *pos, *req = task->tk_rqstp;
1276         struct rpc_xprt *xprt = req->rq_xprt;
1277
1278         if (xprt_request_need_enqueue_transmit(task, req)) {
1279                 req->rq_bytes_sent = 0;
1280                 spin_lock(&xprt->queue_lock);
1281                 /*
1282                  * Requests that carry congestion control credits are added
1283                  * to the head of the list to avoid starvation issues.
1284                  */
1285                 if (req->rq_cong) {
1286                         xprt_clear_congestion_window_wait(xprt);
1287                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1288                                 if (pos->rq_cong)
1289                                         continue;
1290                                 /* Note: req is added _before_ pos */
1291                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1292                                 INIT_LIST_HEAD(&req->rq_xmit2);
1293                                 trace_xprt_enq_xmit(task, 1);
1294                                 goto out;
1295                         }
1296                 } else if (RPC_IS_SWAPPER(task)) {
1297                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1298                                 if (pos->rq_cong || pos->rq_bytes_sent)
1299                                         continue;
1300                                 if (RPC_IS_SWAPPER(pos->rq_task))
1301                                         continue;
1302                                 /* Note: req is added _before_ pos */
1303                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1304                                 INIT_LIST_HEAD(&req->rq_xmit2);
1305                                 trace_xprt_enq_xmit(task, 2);
1306                                 goto out;
1307                         }
1308                 } else if (!req->rq_seqno) {
1309                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1310                                 if (pos->rq_task->tk_owner != task->tk_owner)
1311                                         continue;
1312                                 list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
1313                                 INIT_LIST_HEAD(&req->rq_xmit);
1314                                 trace_xprt_enq_xmit(task, 3);
1315                                 goto out;
1316                         }
1317                 }
1318                 list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
1319                 INIT_LIST_HEAD(&req->rq_xmit2);
1320                 trace_xprt_enq_xmit(task, 4);
1321 out:
1322                 set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1323                 spin_unlock(&xprt->queue_lock);
1324         }
1325 }
1326
1327 /**
1328  * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
1329  * @task: pointer to rpc_task
1330  *
1331  * Remove a task from the transmission queue
1332  * Caller must hold xprt->queue_lock
1333  */
1334 static void
1335 xprt_request_dequeue_transmit_locked(struct rpc_task *task)
1336 {
1337         struct rpc_rqst *req = task->tk_rqstp;
1338
1339         if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1340                 return;
1341         if (!list_empty(&req->rq_xmit)) {
1342                 list_del(&req->rq_xmit);
1343                 if (!list_empty(&req->rq_xmit2)) {
1344                         struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
1345                                         struct rpc_rqst, rq_xmit2);
1346                         list_del(&req->rq_xmit2);
1347                         list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
1348                 }
1349         } else
1350                 list_del(&req->rq_xmit2);
1351 }
1352
1353 /**
1354  * xprt_request_dequeue_transmit - remove a task from the transmission queue
1355  * @task: pointer to rpc_task
1356  *
1357  * Remove a task from the transmission queue
1358  */
1359 static void
1360 xprt_request_dequeue_transmit(struct rpc_task *task)
1361 {
1362         struct rpc_rqst *req = task->tk_rqstp;
1363         struct rpc_xprt *xprt = req->rq_xprt;
1364
1365         spin_lock(&xprt->queue_lock);
1366         xprt_request_dequeue_transmit_locked(task);
1367         spin_unlock(&xprt->queue_lock);
1368 }
1369
1370 /**
1371  * xprt_request_dequeue_xprt - remove a task from the transmit+receive queue
1372  * @task: pointer to rpc_task
1373  *
1374  * Remove a task from the transmit and receive queues, and ensure that
1375  * it is not pinned by the receive work item.
1376  */
1377 void
1378 xprt_request_dequeue_xprt(struct rpc_task *task)
1379 {
1380         struct rpc_rqst *req = task->tk_rqstp;
1381         struct rpc_xprt *xprt = req->rq_xprt;
1382
1383         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
1384             test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
1385             xprt_is_pinned_rqst(req)) {
1386                 spin_lock(&xprt->queue_lock);
1387                 xprt_request_dequeue_transmit_locked(task);
1388                 xprt_request_dequeue_receive_locked(task);
1389                 while (xprt_is_pinned_rqst(req)) {
1390                         set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1391                         spin_unlock(&xprt->queue_lock);
1392                         xprt_wait_on_pinned_rqst(req);
1393                         spin_lock(&xprt->queue_lock);
1394                         clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1395                 }
1396                 spin_unlock(&xprt->queue_lock);
1397         }
1398 }
1399
1400 /**
1401  * xprt_request_prepare - prepare an encoded request for transport
1402  * @req: pointer to rpc_rqst
1403  *
1404  * Calls into the transport layer to do whatever is needed to prepare
1405  * the request for transmission or receive.
1406  */
1407 void
1408 xprt_request_prepare(struct rpc_rqst *req)
1409 {
1410         struct rpc_xprt *xprt = req->rq_xprt;
1411
1412         if (xprt->ops->prepare_request)
1413                 xprt->ops->prepare_request(req);
1414 }
1415
1416 /**
1417  * xprt_request_need_retransmit - Test if a task needs retransmission
1418  * @task: pointer to rpc_task
1419  *
1420  * Test for whether a connection breakage requires the task to retransmit
1421  */
1422 bool
1423 xprt_request_need_retransmit(struct rpc_task *task)
1424 {
1425         return xprt_request_retransmit_after_disconnect(task);
1426 }
1427
1428 /**
1429  * xprt_prepare_transmit - reserve the transport before sending a request
1430  * @task: RPC task about to send a request
1431  *
1432  */
1433 bool xprt_prepare_transmit(struct rpc_task *task)
1434 {
1435         struct rpc_rqst *req = task->tk_rqstp;
1436         struct rpc_xprt *xprt = req->rq_xprt;
1437
1438         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
1439
1440         if (!xprt_lock_write(xprt, task)) {
1441                 /* Race breaker: someone may have transmitted us */
1442                 if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1443                         rpc_wake_up_queued_task_set_status(&xprt->sending,
1444                                         task, 0);
1445                 return false;
1446
1447         }
1448         return true;
1449 }
1450
1451 void xprt_end_transmit(struct rpc_task *task)
1452 {
1453         xprt_release_write(task->tk_rqstp->rq_xprt, task);
1454 }
1455
1456 /**
1457  * xprt_request_transmit - send an RPC request on a transport
1458  * @req: pointer to request to transmit
1459  * @snd_task: RPC task that owns the transport lock
1460  *
1461  * This performs the transmission of a single request.
1462  * Note that if the request is not the same as snd_task, then it
1463  * does need to be pinned.
1464  * Returns '0' on success.
1465  */
1466 static int
1467 xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
1468 {
1469         struct rpc_xprt *xprt = req->rq_xprt;
1470         struct rpc_task *task = req->rq_task;
1471         unsigned int connect_cookie;
1472         int is_retrans = RPC_WAS_SENT(task);
1473         int status;
1474
1475         if (!req->rq_bytes_sent) {
1476                 if (xprt_request_data_received(task)) {
1477                         status = 0;
1478                         goto out_dequeue;
1479                 }
1480                 /* Verify that our message lies in the RPCSEC_GSS window */
1481                 if (rpcauth_xmit_need_reencode(task)) {
1482                         status = -EBADMSG;
1483                         goto out_dequeue;
1484                 }
1485                 if (RPC_SIGNALLED(task)) {
1486                         status = -ERESTARTSYS;
1487                         goto out_dequeue;
1488                 }
1489         }
1490
1491         /*
1492          * Update req->rq_ntrans before transmitting to avoid races with
1493          * xprt_update_rtt(), which needs to know that it is recording a
1494          * reply to the first transmission.
1495          */
1496         req->rq_ntrans++;
1497
1498         connect_cookie = xprt->connect_cookie;
1499         status = xprt->ops->send_request(req);
1500         if (status != 0) {
1501                 req->rq_ntrans--;
1502                 trace_xprt_transmit(req, status);
1503                 return status;
1504         }
1505
1506         if (is_retrans)
1507                 task->tk_client->cl_stats->rpcretrans++;
1508
1509         xprt_inject_disconnect(xprt);
1510
1511         task->tk_flags |= RPC_TASK_SENT;
1512         spin_lock(&xprt->transport_lock);
1513
1514         xprt->stat.sends++;
1515         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1516         xprt->stat.bklog_u += xprt->backlog.qlen;
1517         xprt->stat.sending_u += xprt->sending.qlen;
1518         xprt->stat.pending_u += xprt->pending.qlen;
1519         spin_unlock(&xprt->transport_lock);
1520
1521         req->rq_connect_cookie = connect_cookie;
1522 out_dequeue:
1523         trace_xprt_transmit(req, status);
1524         xprt_request_dequeue_transmit(task);
1525         rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
1526         return status;
1527 }
1528
1529 /**
1530  * xprt_transmit - send an RPC request on a transport
1531  * @task: controlling RPC task
1532  *
1533  * Attempts to drain the transmit queue. On exit, either the transport
1534  * signalled an error that needs to be handled before transmission can
1535  * resume, or @task finished transmitting, and detected that it already
1536  * received a reply.
1537  */
1538 void
1539 xprt_transmit(struct rpc_task *task)
1540 {
1541         struct rpc_rqst *next, *req = task->tk_rqstp;
1542         struct rpc_xprt *xprt = req->rq_xprt;
1543         int status;
1544
1545         spin_lock(&xprt->queue_lock);
1546         for (;;) {
1547                 next = list_first_entry_or_null(&xprt->xmit_queue,
1548                                                 struct rpc_rqst, rq_xmit);
1549                 if (!next)
1550                         break;
1551                 xprt_pin_rqst(next);
1552                 spin_unlock(&xprt->queue_lock);
1553                 status = xprt_request_transmit(next, task);
1554                 if (status == -EBADMSG && next != req)
1555                         status = 0;
1556                 spin_lock(&xprt->queue_lock);
1557                 xprt_unpin_rqst(next);
1558                 if (status < 0) {
1559                         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1560                                 task->tk_status = status;
1561                         break;
1562                 }
1563                 /* Was @task transmitted, and has it received a reply? */
1564                 if (xprt_request_data_received(task) &&
1565                     !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1566                         break;
1567                 cond_resched_lock(&xprt->queue_lock);
1568         }
1569         spin_unlock(&xprt->queue_lock);
1570 }
1571
1572 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1573 {
1574         set_bit(XPRT_CONGESTED, &xprt->state);
1575         rpc_sleep_on(&xprt->backlog, task, NULL);
1576 }
1577
1578 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
1579 {
1580         if (rpc_wake_up_next(&xprt->backlog) == NULL)
1581                 clear_bit(XPRT_CONGESTED, &xprt->state);
1582 }
1583
1584 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1585 {
1586         bool ret = false;
1587
1588         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1589                 goto out;
1590         spin_lock(&xprt->reserve_lock);
1591         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1592                 rpc_sleep_on(&xprt->backlog, task, NULL);
1593                 ret = true;
1594         }
1595         spin_unlock(&xprt->reserve_lock);
1596 out:
1597         return ret;
1598 }
1599
1600 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1601 {
1602         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1603
1604         if (xprt->num_reqs >= xprt->max_reqs)
1605                 goto out;
1606         ++xprt->num_reqs;
1607         spin_unlock(&xprt->reserve_lock);
1608         req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
1609         spin_lock(&xprt->reserve_lock);
1610         if (req != NULL)
1611                 goto out;
1612         --xprt->num_reqs;
1613         req = ERR_PTR(-ENOMEM);
1614 out:
1615         return req;
1616 }
1617
1618 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1619 {
1620         if (xprt->num_reqs > xprt->min_reqs) {
1621                 --xprt->num_reqs;
1622                 kfree(req);
1623                 return true;
1624         }
1625         return false;
1626 }
1627
1628 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1629 {
1630         struct rpc_rqst *req;
1631
1632         spin_lock(&xprt->reserve_lock);
1633         if (!list_empty(&xprt->free)) {
1634                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1635                 list_del(&req->rq_list);
1636                 goto out_init_req;
1637         }
1638         req = xprt_dynamic_alloc_slot(xprt);
1639         if (!IS_ERR(req))
1640                 goto out_init_req;
1641         switch (PTR_ERR(req)) {
1642         case -ENOMEM:
1643                 dprintk("RPC:       dynamic allocation of request slot "
1644                                 "failed! Retrying\n");
1645                 task->tk_status = -ENOMEM;
1646                 break;
1647         case -EAGAIN:
1648                 xprt_add_backlog(xprt, task);
1649                 dprintk("RPC:       waiting for request slot\n");
1650                 /* fall through */
1651         default:
1652                 task->tk_status = -EAGAIN;
1653         }
1654         spin_unlock(&xprt->reserve_lock);
1655         return;
1656 out_init_req:
1657         xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
1658                                      xprt->num_reqs);
1659         spin_unlock(&xprt->reserve_lock);
1660
1661         task->tk_status = 0;
1662         task->tk_rqstp = req;
1663 }
1664 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1665
1666 void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1667 {
1668         spin_lock(&xprt->reserve_lock);
1669         if (!xprt_dynamic_free_slot(xprt, req)) {
1670                 memset(req, 0, sizeof(*req));   /* mark unused */
1671                 list_add(&req->rq_list, &xprt->free);
1672         }
1673         xprt_wake_up_backlog(xprt);
1674         spin_unlock(&xprt->reserve_lock);
1675 }
1676 EXPORT_SYMBOL_GPL(xprt_free_slot);
1677
1678 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1679 {
1680         struct rpc_rqst *req;
1681         while (!list_empty(&xprt->free)) {
1682                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1683                 list_del(&req->rq_list);
1684                 kfree(req);
1685         }
1686 }
1687
1688 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1689                 unsigned int num_prealloc,
1690                 unsigned int max_alloc)
1691 {
1692         struct rpc_xprt *xprt;
1693         struct rpc_rqst *req;
1694         int i;
1695
1696         xprt = kzalloc(size, GFP_KERNEL);
1697         if (xprt == NULL)
1698                 goto out;
1699
1700         xprt_init(xprt, net);
1701
1702         for (i = 0; i < num_prealloc; i++) {
1703                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1704                 if (!req)
1705                         goto out_free;
1706                 list_add(&req->rq_list, &xprt->free);
1707         }
1708         if (max_alloc > num_prealloc)
1709                 xprt->max_reqs = max_alloc;
1710         else
1711                 xprt->max_reqs = num_prealloc;
1712         xprt->min_reqs = num_prealloc;
1713         xprt->num_reqs = num_prealloc;
1714
1715         return xprt;
1716
1717 out_free:
1718         xprt_free(xprt);
1719 out:
1720         return NULL;
1721 }
1722 EXPORT_SYMBOL_GPL(xprt_alloc);
1723
1724 void xprt_free(struct rpc_xprt *xprt)
1725 {
1726         put_net(xprt->xprt_net);
1727         xprt_free_all_slots(xprt);
1728         kfree_rcu(xprt, rcu);
1729 }
1730 EXPORT_SYMBOL_GPL(xprt_free);
1731
1732 static void
1733 xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
1734 {
1735         req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
1736 }
1737
1738 static __be32
1739 xprt_alloc_xid(struct rpc_xprt *xprt)
1740 {
1741         __be32 xid;
1742
1743         spin_lock(&xprt->reserve_lock);
1744         xid = (__force __be32)xprt->xid++;
1745         spin_unlock(&xprt->reserve_lock);
1746         return xid;
1747 }
1748
1749 static void
1750 xprt_init_xid(struct rpc_xprt *xprt)
1751 {
1752         xprt->xid = prandom_u32();
1753 }
1754
1755 static void
1756 xprt_request_init(struct rpc_task *task)
1757 {
1758         struct rpc_xprt *xprt = task->tk_xprt;
1759         struct rpc_rqst *req = task->tk_rqstp;
1760
1761         req->rq_task    = task;
1762         req->rq_xprt    = xprt;
1763         req->rq_buffer  = NULL;
1764         req->rq_xid     = xprt_alloc_xid(xprt);
1765         xprt_init_connect_cookie(req, xprt);
1766         req->rq_snd_buf.len = 0;
1767         req->rq_snd_buf.buflen = 0;
1768         req->rq_rcv_buf.len = 0;
1769         req->rq_rcv_buf.buflen = 0;
1770         req->rq_snd_buf.bvec = NULL;
1771         req->rq_rcv_buf.bvec = NULL;
1772         req->rq_release_snd_buf = NULL;
1773         xprt_init_majortimeo(task, req);
1774         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1775                         req, ntohl(req->rq_xid));
1776 }
1777
1778 static void
1779 xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
1780 {
1781         xprt->ops->alloc_slot(xprt, task);
1782         if (task->tk_rqstp != NULL)
1783                 xprt_request_init(task);
1784 }
1785
1786 /**
1787  * xprt_reserve - allocate an RPC request slot
1788  * @task: RPC task requesting a slot allocation
1789  *
1790  * If the transport is marked as being congested, or if no more
1791  * slots are available, place the task on the transport's
1792  * backlog queue.
1793  */
1794 void xprt_reserve(struct rpc_task *task)
1795 {
1796         struct rpc_xprt *xprt = task->tk_xprt;
1797
1798         task->tk_status = 0;
1799         if (task->tk_rqstp != NULL)
1800                 return;
1801
1802         task->tk_status = -EAGAIN;
1803         if (!xprt_throttle_congested(xprt, task))
1804                 xprt_do_reserve(xprt, task);
1805 }
1806
1807 /**
1808  * xprt_retry_reserve - allocate an RPC request slot
1809  * @task: RPC task requesting a slot allocation
1810  *
1811  * If no more slots are available, place the task on the transport's
1812  * backlog queue.
1813  * Note that the only difference with xprt_reserve is that we now
1814  * ignore the value of the XPRT_CONGESTED flag.
1815  */
1816 void xprt_retry_reserve(struct rpc_task *task)
1817 {
1818         struct rpc_xprt *xprt = task->tk_xprt;
1819
1820         task->tk_status = 0;
1821         if (task->tk_rqstp != NULL)
1822                 return;
1823
1824         task->tk_status = -EAGAIN;
1825         xprt_do_reserve(xprt, task);
1826 }
1827
1828 /**
1829  * xprt_release - release an RPC request slot
1830  * @task: task which is finished with the slot
1831  *
1832  */
1833 void xprt_release(struct rpc_task *task)
1834 {
1835         struct rpc_xprt *xprt;
1836         struct rpc_rqst *req = task->tk_rqstp;
1837
1838         if (req == NULL) {
1839                 if (task->tk_client) {
1840                         xprt = task->tk_xprt;
1841                         xprt_release_write(xprt, task);
1842                 }
1843                 return;
1844         }
1845
1846         xprt = req->rq_xprt;
1847         xprt_request_dequeue_xprt(task);
1848         spin_lock(&xprt->transport_lock);
1849         xprt->ops->release_xprt(xprt, task);
1850         if (xprt->ops->release_request)
1851                 xprt->ops->release_request(task);
1852         xprt_schedule_autodisconnect(xprt);
1853         spin_unlock(&xprt->transport_lock);
1854         if (req->rq_buffer)
1855                 xprt->ops->buf_free(task);
1856         xprt_inject_disconnect(xprt);
1857         xdr_free_bvec(&req->rq_rcv_buf);
1858         xdr_free_bvec(&req->rq_snd_buf);
1859         if (req->rq_cred != NULL)
1860                 put_rpccred(req->rq_cred);
1861         task->tk_rqstp = NULL;
1862         if (req->rq_release_snd_buf)
1863                 req->rq_release_snd_buf(req);
1864
1865         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1866         if (likely(!bc_prealloc(req)))
1867                 xprt->ops->free_slot(xprt, req);
1868         else
1869                 xprt_free_bc_request(req);
1870 }
1871
1872 #ifdef CONFIG_SUNRPC_BACKCHANNEL
1873 void
1874 xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
1875 {
1876         struct xdr_buf *xbufp = &req->rq_snd_buf;
1877
1878         task->tk_rqstp = req;
1879         req->rq_task = task;
1880         xprt_init_connect_cookie(req, req->rq_xprt);
1881         /*
1882          * Set up the xdr_buf length.
1883          * This also indicates that the buffer is XDR encoded already.
1884          */
1885         xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
1886                 xbufp->tail[0].iov_len;
1887 }
1888 #endif
1889
1890 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1891 {
1892         kref_init(&xprt->kref);
1893
1894         spin_lock_init(&xprt->transport_lock);
1895         spin_lock_init(&xprt->reserve_lock);
1896         spin_lock_init(&xprt->queue_lock);
1897
1898         INIT_LIST_HEAD(&xprt->free);
1899         xprt->recv_queue = RB_ROOT;
1900         INIT_LIST_HEAD(&xprt->xmit_queue);
1901 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1902         spin_lock_init(&xprt->bc_pa_lock);
1903         INIT_LIST_HEAD(&xprt->bc_pa_list);
1904 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1905         INIT_LIST_HEAD(&xprt->xprt_switch);
1906
1907         xprt->last_used = jiffies;
1908         xprt->cwnd = RPC_INITCWND;
1909         xprt->bind_index = 0;
1910
1911         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1912         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1913         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1914         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1915
1916         xprt_init_xid(xprt);
1917
1918         xprt->xprt_net = get_net(net);
1919 }
1920
1921 /**
1922  * xprt_create_transport - create an RPC transport
1923  * @args: rpc transport creation arguments
1924  *
1925  */
1926 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1927 {
1928         struct rpc_xprt *xprt;
1929         struct xprt_class *t;
1930
1931         spin_lock(&xprt_list_lock);
1932         list_for_each_entry(t, &xprt_list, list) {
1933                 if (t->ident == args->ident) {
1934                         spin_unlock(&xprt_list_lock);
1935                         goto found;
1936                 }
1937         }
1938         spin_unlock(&xprt_list_lock);
1939         dprintk("RPC: transport (%d) not supported\n", args->ident);
1940         return ERR_PTR(-EIO);
1941
1942 found:
1943         xprt = t->setup(args);
1944         if (IS_ERR(xprt)) {
1945                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1946                                 -PTR_ERR(xprt));
1947                 goto out;
1948         }
1949         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1950                 xprt->idle_timeout = 0;
1951         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1952         if (xprt_has_timer(xprt))
1953                 timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
1954         else
1955                 timer_setup(&xprt->timer, NULL, 0);
1956
1957         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1958                 xprt_destroy(xprt);
1959                 return ERR_PTR(-EINVAL);
1960         }
1961         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1962         if (xprt->servername == NULL) {
1963                 xprt_destroy(xprt);
1964                 return ERR_PTR(-ENOMEM);
1965         }
1966
1967         rpc_xprt_debugfs_register(xprt);
1968
1969         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1970                         xprt->max_reqs);
1971 out:
1972         return xprt;
1973 }
1974
1975 static void xprt_destroy_cb(struct work_struct *work)
1976 {
1977         struct rpc_xprt *xprt =
1978                 container_of(work, struct rpc_xprt, task_cleanup);
1979
1980         rpc_xprt_debugfs_unregister(xprt);
1981         rpc_destroy_wait_queue(&xprt->binding);
1982         rpc_destroy_wait_queue(&xprt->pending);
1983         rpc_destroy_wait_queue(&xprt->sending);
1984         rpc_destroy_wait_queue(&xprt->backlog);
1985         kfree(xprt->servername);
1986         /*
1987          * Destroy any existing back channel
1988          */
1989         xprt_destroy_backchannel(xprt, UINT_MAX);
1990
1991         /*
1992          * Tear down transport state and free the rpc_xprt
1993          */
1994         xprt->ops->destroy(xprt);
1995 }
1996
1997 /**
1998  * xprt_destroy - destroy an RPC transport, killing off all requests.
1999  * @xprt: transport to destroy
2000  *
2001  */
2002 static void xprt_destroy(struct rpc_xprt *xprt)
2003 {
2004         dprintk("RPC:       destroying transport %p\n", xprt);
2005
2006         /*
2007          * Exclude transport connect/disconnect handlers and autoclose
2008          */
2009         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
2010
2011         /*
2012          * xprt_schedule_autodisconnect() can run after XPRT_LOCKED
2013          * is cleared.  We use ->transport_lock to ensure the mod_timer()
2014          * can only run *before* del_time_sync(), never after.
2015          */
2016         spin_lock(&xprt->transport_lock);
2017         del_timer_sync(&xprt->timer);
2018         spin_unlock(&xprt->transport_lock);
2019
2020         /*
2021          * Destroy sockets etc from the system workqueue so they can
2022          * safely flush receive work running on rpciod.
2023          */
2024         INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
2025         schedule_work(&xprt->task_cleanup);
2026 }
2027
2028 static void xprt_destroy_kref(struct kref *kref)
2029 {
2030         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
2031 }
2032
2033 /**
2034  * xprt_get - return a reference to an RPC transport.
2035  * @xprt: pointer to the transport
2036  *
2037  */
2038 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
2039 {
2040         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
2041                 return xprt;
2042         return NULL;
2043 }
2044 EXPORT_SYMBOL_GPL(xprt_get);
2045
2046 /**
2047  * xprt_put - release a reference to an RPC transport.
2048  * @xprt: pointer to the transport
2049  *
2050  */
2051 void xprt_put(struct rpc_xprt *xprt)
2052 {
2053         if (xprt != NULL)
2054                 kref_put(&xprt->kref, xprt_destroy_kref);
2055 }
2056 EXPORT_SYMBOL_GPL(xprt_put);