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 static void      xprt_request_init(struct rpc_task *task);
  74
  75 static DEFINE_SPINLOCK(xprt_list_lock);
  76 static LIST_HEAD(xprt_list);
  77
  78 static unsigned long xprt_request_timeout(const struct rpc_rqst *req)
  79 {
  80         unsigned long timeout = jiffies + req->rq_timeout;
  81
  82         if (time_before(timeout, req->rq_majortimeo))
  83                 return timeout;
  84         return req->rq_majortimeo;
  85 }
  86
  87 /**
  88  * xprt_register_transport - register a transport implementation
  89  * @transport: transport to register
  90  *
  91  * If a transport implementation is loaded as a kernel module, it can
  92  * call this interface to make itself known to the RPC client.
  93  *
  94  * Returns:
  95  * 0:           transport successfully registered
  96  * -EEXIST:     transport already registered
  97  * -EINVAL:     transport module being unloaded
  98  */
  99 int xprt_register_transport(struct xprt_class *transport)
 100 {
 101         struct xprt_class *t;
 102         int result;
 103
 104         result = -EEXIST;
 105         spin_lock(&xprt_list_lock);
 106         list_for_each_entry(t, &xprt_list, list) {
 107                 /* don't register the same transport class twice */
 108                 if (t->ident == transport->ident)
 109                         goto out;
 110         }
 111
 112         list_add_tail(&transport->list, &xprt_list);
 113         printk(KERN_INFO "RPC: Registered %s transport module.\n",
 114                transport->name);
 115         result = 0;
 116
 117 out:
 118         spin_unlock(&xprt_list_lock);
 119         return result;
 120 }
 121 EXPORT_SYMBOL_GPL(xprt_register_transport);
 122
 123 /**
 124  * xprt_unregister_transport - unregister a transport implementation
 125  * @transport: transport to unregister
 126  *
 127  * Returns:
 128  * 0:           transport successfully unregistered
 129  * -ENOENT:     transport never registered
 130  */
 131 int xprt_unregister_transport(struct xprt_class *transport)
 132 {
 133         struct xprt_class *t;
 134         int result;
 135
 136         result = 0;
 137         spin_lock(&xprt_list_lock);
 138         list_for_each_entry(t, &xprt_list, list) {
 139                 if (t == transport) {
 140                         printk(KERN_INFO
 141                                 "RPC: Unregistered %s transport module.\n",
 142                                 transport->name);
 143                         list_del_init(&transport->list);
 144                         goto out;
 145                 }
 146         }
 147         result = -ENOENT;
 148
 149 out:
 150         spin_unlock(&xprt_list_lock);
 151         return result;
 152 }
 153 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 154
 155 static void
 156 xprt_class_release(const struct xprt_class *t)
 157 {
 158         module_put(t->owner);
 159 }
 160
 161 static const struct xprt_class *
 162 xprt_class_find_by_netid_locked(const char *netid)
 163 {
 164         const struct xprt_class *t;
 165         unsigned int i;
 166
 167         list_for_each_entry(t, &xprt_list, list) {
 168                 for (i = 0; t->netid[i][0] != '\0'; i++) {
 169                         if (strcmp(t->netid[i], netid) != 0)
 170                                 continue;
 171                         if (!try_module_get(t->owner))
 172                                 continue;
 173                         return t;
 174                 }
 175         }
 176         return NULL;
 177 }
 178
 179 static const struct xprt_class *
 180 xprt_class_find_by_netid(const char *netid)
 181 {
 182         const struct xprt_class *t;
 183
 184         spin_lock(&xprt_list_lock);
 185         t = xprt_class_find_by_netid_locked(netid);
 186         if (!t) {
 187                 spin_unlock(&xprt_list_lock);
 188                 request_module("rpc%s", netid);
 189                 spin_lock(&xprt_list_lock);
 190                 t = xprt_class_find_by_netid_locked(netid);
 191         }
 192         spin_unlock(&xprt_list_lock);
 193         return t;
 194 }
 195
 196 /**
 197  * xprt_load_transport - load a transport implementation
 198  * @netid: transport to load
 199  *
 200  * Returns:
 201  * 0:           transport successfully loaded
 202  * -ENOENT:     transport module not available
 203  */
 204 int xprt_load_transport(const char *netid)
 205 {
 206         const struct xprt_class *t;
 207
 208         t = xprt_class_find_by_netid(netid);
 209         if (!t)
 210                 return -ENOENT;
 211         xprt_class_release(t);
 212         return 0;
 213 }
 214 EXPORT_SYMBOL_GPL(xprt_load_transport);
 215
 216 static void xprt_clear_locked(struct rpc_xprt *xprt)
 217 {
 218         xprt->snd_task = NULL;
 219         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 220                 smp_mb__before_atomic();
 221                 clear_bit(XPRT_LOCKED, &xprt->state);
 222                 smp_mb__after_atomic();
 223         } else
 224                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 225 }
 226
 227 /**
 228  * xprt_reserve_xprt - serialize write access to transports
 229  * @task: task that is requesting access to the transport
 230  * @xprt: pointer to the target transport
 231  *
 232  * This prevents mixing the payload of separate requests, and prevents
 233  * transport connects from colliding with writes.  No congestion control
 234  * is provided.
 235  */
 236 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 237 {
 238         struct rpc_rqst *req = task->tk_rqstp;
 239
 240         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 241                 if (task == xprt->snd_task)
 242                         goto out_locked;
 243                 goto out_sleep;
 244         }
 245         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 246                 goto out_unlock;
 247         xprt->snd_task = task;
 248
 249 out_locked:
 250         trace_xprt_reserve_xprt(xprt, task);
 251         return 1;
 252
 253 out_unlock:
 254         xprt_clear_locked(xprt);
 255 out_sleep:
 256         task->tk_status = -EAGAIN;
 257         if  (RPC_IS_SOFT(task))
 258                 rpc_sleep_on_timeout(&xprt->sending, task, NULL,
 259                                 xprt_request_timeout(req));
 260         else
 261                 rpc_sleep_on(&xprt->sending, task, NULL);
 262         return 0;
 263 }
 264 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 265
 266 static bool
 267 xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
 268 {
 269         return test_bit(XPRT_CWND_WAIT, &xprt->state);
 270 }
 271
 272 static void
 273 xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
 274 {
 275         if (!list_empty(&xprt->xmit_queue)) {
 276                 /* Peek at head of queue to see if it can make progress */
 277                 if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
 278                                         rq_xmit)->rq_cong)
 279                         return;
 280         }
 281         set_bit(XPRT_CWND_WAIT, &xprt->state);
 282 }
 283
 284 static void
 285 xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
 286 {
 287         if (!RPCXPRT_CONGESTED(xprt))
 288                 clear_bit(XPRT_CWND_WAIT, &xprt->state);
 289 }
 290
 291 /*
 292  * xprt_reserve_xprt_cong - serialize write access to transports
 293  * @task: task that is requesting access to the transport
 294  *
 295  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 296  * integrated into the decision of whether a request is allowed to be
 297  * woken up and given access to the transport.
 298  * Note that the lock is only granted if we know there are free slots.
 299  */
 300 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 301 {
 302         struct rpc_rqst *req = task->tk_rqstp;
 303
 304         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 305                 if (task == xprt->snd_task)
 306                         goto out_locked;
 307                 goto out_sleep;
 308         }
 309         if (req == NULL) {
 310                 xprt->snd_task = task;
 311                 goto out_locked;
 312         }
 313         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 314                 goto out_unlock;
 315         if (!xprt_need_congestion_window_wait(xprt)) {
 316                 xprt->snd_task = task;
 317                 goto out_locked;
 318         }
 319 out_unlock:
 320         xprt_clear_locked(xprt);
 321 out_sleep:
 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 out_locked:
 330         trace_xprt_reserve_cong(xprt, task);
 331         return 1;
 332 }
 333 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 334
 335 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 336 {
 337         int retval;
 338
 339         if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
 340                 return 1;
 341         spin_lock(&xprt->transport_lock);
 342         retval = xprt->ops->reserve_xprt(xprt, task);
 343         spin_unlock(&xprt->transport_lock);
 344         return retval;
 345 }
 346
 347 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
 348 {
 349         struct rpc_xprt *xprt = data;
 350
 351         xprt->snd_task = task;
 352         return true;
 353 }
 354
 355 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 356 {
 357         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 358                 return;
 359         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 360                 goto out_unlock;
 361         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 362                                 __xprt_lock_write_func, xprt))
 363                 return;
 364 out_unlock:
 365         xprt_clear_locked(xprt);
 366 }
 367
 368 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 369 {
 370         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 371                 return;
 372         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 373                 goto out_unlock;
 374         if (xprt_need_congestion_window_wait(xprt))
 375                 goto out_unlock;
 376         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 377                                 __xprt_lock_write_func, xprt))
 378                 return;
 379 out_unlock:
 380         xprt_clear_locked(xprt);
 381 }
 382
 383 /**
 384  * xprt_release_xprt - allow other requests to use a transport
 385  * @xprt: transport with other tasks potentially waiting
 386  * @task: task that is releasing access to the transport
 387  *
 388  * Note that "task" can be NULL.  No congestion control is provided.
 389  */
 390 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 391 {
 392         if (xprt->snd_task == task) {
 393                 xprt_clear_locked(xprt);
 394                 __xprt_lock_write_next(xprt);
 395         }
 396         trace_xprt_release_xprt(xprt, task);
 397 }
 398 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 399
 400 /**
 401  * xprt_release_xprt_cong - allow other requests to use a transport
 402  * @xprt: transport with other tasks potentially waiting
 403  * @task: task that is releasing access to the transport
 404  *
 405  * Note that "task" can be NULL.  Another task is awoken to use the
 406  * transport if the transport's congestion window allows it.
 407  */
 408 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 409 {
 410         if (xprt->snd_task == task) {
 411                 xprt_clear_locked(xprt);
 412                 __xprt_lock_write_next_cong(xprt);
 413         }
 414         trace_xprt_release_cong(xprt, task);
 415 }
 416 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 417
 418 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 419 {
 420         if (xprt->snd_task != task)
 421                 return;
 422         spin_lock(&xprt->transport_lock);
 423         xprt->ops->release_xprt(xprt, task);
 424         spin_unlock(&xprt->transport_lock);
 425 }
 426
 427 /*
 428  * Van Jacobson congestion avoidance. Check if the congestion window
 429  * overflowed. Put the task to sleep if this is the case.
 430  */
 431 static int
 432 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 433 {
 434         if (req->rq_cong)
 435                 return 1;
 436         trace_xprt_get_cong(xprt, req->rq_task);
 437         if (RPCXPRT_CONGESTED(xprt)) {
 438                 xprt_set_congestion_window_wait(xprt);
 439                 return 0;
 440         }
 441         req->rq_cong = 1;
 442         xprt->cong += RPC_CWNDSCALE;
 443         return 1;
 444 }
 445
 446 /*
 447  * Adjust the congestion window, and wake up the next task
 448  * that has been sleeping due to congestion
 449  */
 450 static void
 451 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 452 {
 453         if (!req->rq_cong)
 454                 return;
 455         req->rq_cong = 0;
 456         xprt->cong -= RPC_CWNDSCALE;
 457         xprt_test_and_clear_congestion_window_wait(xprt);
 458         trace_xprt_put_cong(xprt, req->rq_task);
 459         __xprt_lock_write_next_cong(xprt);
 460 }
 461
 462 /**
 463  * xprt_request_get_cong - Request congestion control credits
 464  * @xprt: pointer to transport
 465  * @req: pointer to RPC request
 466  *
 467  * Useful for transports that require congestion control.
 468  */
 469 bool
 470 xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 471 {
 472         bool ret = false;
 473
 474         if (req->rq_cong)
 475                 return true;
 476         spin_lock(&xprt->transport_lock);
 477         ret = __xprt_get_cong(xprt, req) != 0;
 478         spin_unlock(&xprt->transport_lock);
 479         return ret;
 480 }
 481 EXPORT_SYMBOL_GPL(xprt_request_get_cong);
 482
 483 /**
 484  * xprt_release_rqst_cong - housekeeping when request is complete
 485  * @task: RPC request that recently completed
 486  *
 487  * Useful for transports that require congestion control.
 488  */
 489 void xprt_release_rqst_cong(struct rpc_task *task)
 490 {
 491         struct rpc_rqst *req = task->tk_rqstp;
 492
 493         __xprt_put_cong(req->rq_xprt, req);
 494 }
 495 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 496
 497 static void xprt_clear_congestion_window_wait_locked(struct rpc_xprt *xprt)
 498 {
 499         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state))
 500                 __xprt_lock_write_next_cong(xprt);
 501 }
 502
 503 /*
 504  * Clear the congestion window wait flag and wake up the next
 505  * entry on xprt->sending
 506  */
 507 static void
 508 xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
 509 {
 510         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
 511                 spin_lock(&xprt->transport_lock);
 512                 __xprt_lock_write_next_cong(xprt);
 513                 spin_unlock(&xprt->transport_lock);
 514         }
 515 }
 516
 517 /**
 518  * xprt_adjust_cwnd - adjust transport congestion window
 519  * @xprt: pointer to xprt
 520  * @task: recently completed RPC request used to adjust window
 521  * @result: result code of completed RPC request
 522  *
 523  * The transport code maintains an estimate on the maximum number of out-
 524  * standing RPC requests, using a smoothed version of the congestion
 525  * avoidance implemented in 44BSD. This is basically the Van Jacobson
 526  * congestion algorithm: If a retransmit occurs, the congestion window is
 527  * halved; otherwise, it is incremented by 1/cwnd when
 528  *
 529  *      -       a reply is received and
 530  *      -       a full number of requests are outstanding and
 531  *      -       the congestion window hasn't been updated recently.
 532  */
 533 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
 534 {
 535         struct rpc_rqst *req = task->tk_rqstp;
 536         unsigned long cwnd = xprt->cwnd;
 537
 538         if (result >= 0 && cwnd <= xprt->cong) {
 539                 /* The (cwnd >> 1) term makes sure
 540                  * the result gets rounded properly. */
 541                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 542                 if (cwnd > RPC_MAXCWND(xprt))
 543                         cwnd = RPC_MAXCWND(xprt);
 544                 __xprt_lock_write_next_cong(xprt);
 545         } else if (result == -ETIMEDOUT) {
 546                 cwnd >>= 1;
 547                 if (cwnd < RPC_CWNDSCALE)
 548                         cwnd = RPC_CWNDSCALE;
 549         }
 550         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 551                         xprt->cong, xprt->cwnd, cwnd);
 552         xprt->cwnd = cwnd;
 553         __xprt_put_cong(xprt, req);
 554 }
 555 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 556
 557 /**
 558  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 559  * @xprt: transport with waiting tasks
 560  * @status: result code to plant in each task before waking it
 561  *
 562  */
 563 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 564 {
 565         if (status < 0)
 566                 rpc_wake_up_status(&xprt->pending, status);
 567         else
 568                 rpc_wake_up(&xprt->pending);
 569 }
 570 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 571
 572 /**
 573  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 574  * @xprt: transport
 575  *
 576  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
 577  * we don't in general want to force a socket disconnection due to
 578  * an incomplete RPC call transmission.
 579  */
 580 void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
 581 {
 582         set_bit(XPRT_WRITE_SPACE, &xprt->state);
 583 }
 584 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 585
 586 static bool
 587 xprt_clear_write_space_locked(struct rpc_xprt *xprt)
 588 {
 589         if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
 590                 __xprt_lock_write_next(xprt);
 591                 dprintk("RPC:       write space: waking waiting task on "
 592                                 "xprt %p\n", xprt);
 593                 return true;
 594         }
 595         return false;
 596 }
 597
 598 /**
 599  * xprt_write_space - wake the task waiting for transport output buffer space
 600  * @xprt: transport with waiting tasks
 601  *
 602  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 603  */
 604 bool xprt_write_space(struct rpc_xprt *xprt)
 605 {
 606         bool ret;
 607
 608         if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
 609                 return false;
 610         spin_lock(&xprt->transport_lock);
 611         ret = xprt_clear_write_space_locked(xprt);
 612         spin_unlock(&xprt->transport_lock);
 613         return ret;
 614 }
 615 EXPORT_SYMBOL_GPL(xprt_write_space);
 616
 617 static unsigned long xprt_abs_ktime_to_jiffies(ktime_t abstime)
 618 {
 619         s64 delta = ktime_to_ns(ktime_get() - abstime);
 620         return likely(delta >= 0) ?
 621                 jiffies - nsecs_to_jiffies(delta) :
 622                 jiffies + nsecs_to_jiffies(-delta);
 623 }
 624
 625 static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req)
 626 {
 627         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 628         unsigned long majortimeo = req->rq_timeout;
 629
 630         if (to->to_exponential)
 631                 majortimeo <<= to->to_retries;
 632         else
 633                 majortimeo += to->to_increment * to->to_retries;
 634         if (majortimeo > to->to_maxval || majortimeo == 0)
 635                 majortimeo = to->to_maxval;
 636         return majortimeo;
 637 }
 638
 639 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 640 {
 641         req->rq_majortimeo += xprt_calc_majortimeo(req);
 642 }
 643
 644 static void xprt_reset_minortimeo(struct rpc_rqst *req)
 645 {
 646         req->rq_minortimeo += req->rq_timeout;
 647 }
 648
 649 static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
 650 {
 651         unsigned long time_init;
 652         struct rpc_xprt *xprt = req->rq_xprt;
 653
 654         if (likely(xprt && xprt_connected(xprt)))
 655                 time_init = jiffies;
 656         else
 657                 time_init = xprt_abs_ktime_to_jiffies(task->tk_start);
 658         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
 659         req->rq_majortimeo = time_init + xprt_calc_majortimeo(req);
 660         req->rq_minortimeo = time_init + req->rq_timeout;
 661 }
 662
 663 /**
 664  * xprt_adjust_timeout - adjust timeout values for next retransmit
 665  * @req: RPC request containing parameters to use for the adjustment
 666  *
 667  */
 668 int xprt_adjust_timeout(struct rpc_rqst *req)
 669 {
 670         struct rpc_xprt *xprt = req->rq_xprt;
 671         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 672         int status = 0;
 673
 674         if (time_before(jiffies, req->rq_majortimeo)) {
 675                 if (time_before(jiffies, req->rq_minortimeo))
 676                         return status;
 677                 if (to->to_exponential)
 678                         req->rq_timeout <<= 1;
 679                 else
 680                         req->rq_timeout += to->to_increment;
 681                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 682                         req->rq_timeout = to->to_maxval;
 683                 req->rq_retries++;
 684         } else {
 685                 req->rq_timeout = to->to_initval;
 686                 req->rq_retries = 0;
 687                 xprt_reset_majortimeo(req);
 688                 /* Reset the RTT counters == "slow start" */
 689                 spin_lock(&xprt->transport_lock);
 690                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 691                 spin_unlock(&xprt->transport_lock);
 692                 status = -ETIMEDOUT;
 693         }
 694         xprt_reset_minortimeo(req);
 695
 696         if (req->rq_timeout == 0) {
 697                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 698                 req->rq_timeout = 5 * HZ;
 699         }
 700         return status;
 701 }
 702
 703 static void xprt_autoclose(struct work_struct *work)
 704 {
 705         struct rpc_xprt *xprt =
 706                 container_of(work, struct rpc_xprt, task_cleanup);
 707         unsigned int pflags = memalloc_nofs_save();
 708
 709         trace_xprt_disconnect_auto(xprt);
 710         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 711         xprt->ops->close(xprt);
 712         xprt_release_write(xprt, NULL);
 713         wake_up_bit(&xprt->state, XPRT_LOCKED);
 714         memalloc_nofs_restore(pflags);
 715 }
 716
 717 /**
 718  * xprt_disconnect_done - mark a transport as disconnected
 719  * @xprt: transport to flag for disconnect
 720  *
 721  */
 722 void xprt_disconnect_done(struct rpc_xprt *xprt)
 723 {
 724         trace_xprt_disconnect_done(xprt);
 725         spin_lock(&xprt->transport_lock);
 726         xprt_clear_connected(xprt);
 727         xprt_clear_write_space_locked(xprt);
 728         xprt_clear_congestion_window_wait_locked(xprt);
 729         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 730         spin_unlock(&xprt->transport_lock);
 731 }
 732 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 733
 734 /**
 735  * xprt_schedule_autoclose_locked - Try to schedule an autoclose RPC call
 736  * @xprt: transport to disconnect
 737  */
 738 static void xprt_schedule_autoclose_locked(struct rpc_xprt *xprt)
 739 {
 740         if (test_and_set_bit(XPRT_CLOSE_WAIT, &xprt->state))
 741                 return;
 742         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 743                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 744         else if (xprt->snd_task && !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
 745                 rpc_wake_up_queued_task_set_status(&xprt->pending,
 746                                                    xprt->snd_task, -ENOTCONN);
 747 }
 748
 749 /**
 750  * xprt_force_disconnect - force a transport to disconnect
 751  * @xprt: transport to disconnect
 752  *
 753  */
 754 void xprt_force_disconnect(struct rpc_xprt *xprt)
 755 {
 756         trace_xprt_disconnect_force(xprt);
 757
 758         /* Don't race with the test_bit() in xprt_clear_locked() */
 759         spin_lock(&xprt->transport_lock);
 760         xprt_schedule_autoclose_locked(xprt);
 761         spin_unlock(&xprt->transport_lock);
 762 }
 763 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
 764
 765 static unsigned int
 766 xprt_connect_cookie(struct rpc_xprt *xprt)
 767 {
 768         return READ_ONCE(xprt->connect_cookie);
 769 }
 770
 771 static bool
 772 xprt_request_retransmit_after_disconnect(struct rpc_task *task)
 773 {
 774         struct rpc_rqst *req = task->tk_rqstp;
 775         struct rpc_xprt *xprt = req->rq_xprt;
 776
 777         return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
 778                 !xprt_connected(xprt);
 779 }
 780
 781 /**
 782  * xprt_conditional_disconnect - force a transport to disconnect
 783  * @xprt: transport to disconnect
 784  * @cookie: 'connection cookie'
 785  *
 786  * This attempts to break the connection if and only if 'cookie' matches
 787  * the current transport 'connection cookie'. It ensures that we don't
 788  * try to break the connection more than once when we need to retransmit
 789  * a batch of RPC requests.
 790  *
 791  */
 792 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 793 {
 794         /* Don't race with the test_bit() in xprt_clear_locked() */
 795         spin_lock(&xprt->transport_lock);
 796         if (cookie != xprt->connect_cookie)
 797                 goto out;
 798         if (test_bit(XPRT_CLOSING, &xprt->state))
 799                 goto out;
 800         xprt_schedule_autoclose_locked(xprt);
 801 out:
 802         spin_unlock(&xprt->transport_lock);
 803 }
 804
 805 static bool
 806 xprt_has_timer(const struct rpc_xprt *xprt)
 807 {
 808         return xprt->idle_timeout != 0;
 809 }
 810
 811 static void
 812 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
 813         __must_hold(&xprt->transport_lock)
 814 {
 815         xprt->last_used = jiffies;
 816         if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))
 817                 mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
 818 }
 819
 820 static void
 821 xprt_init_autodisconnect(struct timer_list *t)
 822 {
 823         struct rpc_xprt *xprt = from_timer(xprt, t, timer);
 824
 825         if (!RB_EMPTY_ROOT(&xprt->recv_queue))
 826                 return;
 827         /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
 828         xprt->last_used = jiffies;
 829         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 830                 return;
 831         queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 832 }
 833
 834 bool xprt_lock_connect(struct rpc_xprt *xprt,
 835                 struct rpc_task *task,
 836                 void *cookie)
 837 {
 838         bool ret = false;
 839
 840         spin_lock(&xprt->transport_lock);
 841         if (!test_bit(XPRT_LOCKED, &xprt->state))
 842                 goto out;
 843         if (xprt->snd_task != task)
 844                 goto out;
 845         set_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 846         xprt->snd_task = cookie;
 847         ret = true;
 848 out:
 849         spin_unlock(&xprt->transport_lock);
 850         return ret;
 851 }
 852 EXPORT_SYMBOL_GPL(xprt_lock_connect);
 853
 854 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
 855 {
 856         spin_lock(&xprt->transport_lock);
 857         if (xprt->snd_task != cookie)
 858                 goto out;
 859         if (!test_bit(XPRT_LOCKED, &xprt->state))
 860                 goto out;
 861         xprt->snd_task =NULL;
 862         clear_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 863         xprt->ops->release_xprt(xprt, NULL);
 864         xprt_schedule_autodisconnect(xprt);
 865 out:
 866         spin_unlock(&xprt->transport_lock);
 867         wake_up_bit(&xprt->state, XPRT_LOCKED);
 868 }
 869 EXPORT_SYMBOL_GPL(xprt_unlock_connect);
 870
 871 /**
 872  * xprt_connect - schedule a transport connect operation
 873  * @task: RPC task that is requesting the connect
 874  *
 875  */
 876 void xprt_connect(struct rpc_task *task)
 877 {
 878         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 879
 880         trace_xprt_connect(xprt);
 881
 882         if (!xprt_bound(xprt)) {
 883                 task->tk_status = -EAGAIN;
 884                 return;
 885         }
 886         if (!xprt_lock_write(xprt, task))
 887                 return;
 888
 889         if (!xprt_connected(xprt) && !test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 890                 task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
 891                 rpc_sleep_on_timeout(&xprt->pending, task, NULL,
 892                                 xprt_request_timeout(task->tk_rqstp));
 893
 894                 if (test_bit(XPRT_CLOSING, &xprt->state))
 895                         return;
 896                 if (xprt_test_and_set_connecting(xprt))
 897                         return;
 898                 /* Race breaker */
 899                 if (!xprt_connected(xprt)) {
 900                         xprt->stat.connect_start = jiffies;
 901                         xprt->ops->connect(xprt, task);
 902                 } else {
 903                         xprt_clear_connecting(xprt);
 904                         task->tk_status = 0;
 905                         rpc_wake_up_queued_task(&xprt->pending, task);
 906                 }
 907         }
 908         xprt_release_write(xprt, task);
 909 }
 910
 911 /**
 912  * xprt_reconnect_delay - compute the wait before scheduling a connect
 913  * @xprt: transport instance
 914  *
 915  */
 916 unsigned long xprt_reconnect_delay(const struct rpc_xprt *xprt)
 917 {
 918         unsigned long start, now = jiffies;
 919
 920         start = xprt->stat.connect_start + xprt->reestablish_timeout;
 921         if (time_after(start, now))
 922                 return start - now;
 923         return 0;
 924 }
 925 EXPORT_SYMBOL_GPL(xprt_reconnect_delay);
 926
 927 /**
 928  * xprt_reconnect_backoff - compute the new re-establish timeout
 929  * @xprt: transport instance
 930  * @init_to: initial reestablish timeout
 931  *
 932  */
 933 void xprt_reconnect_backoff(struct rpc_xprt *xprt, unsigned long init_to)
 934 {
 935         xprt->reestablish_timeout <<= 1;
 936         if (xprt->reestablish_timeout > xprt->max_reconnect_timeout)
 937                 xprt->reestablish_timeout = xprt->max_reconnect_timeout;
 938         if (xprt->reestablish_timeout < init_to)
 939                 xprt->reestablish_timeout = init_to;
 940 }
 941 EXPORT_SYMBOL_GPL(xprt_reconnect_backoff);
 942
 943 enum xprt_xid_rb_cmp {
 944         XID_RB_EQUAL,
 945         XID_RB_LEFT,
 946         XID_RB_RIGHT,
 947 };
 948 static enum xprt_xid_rb_cmp
 949 xprt_xid_cmp(__be32 xid1, __be32 xid2)
 950 {
 951         if (xid1 == xid2)
 952                 return XID_RB_EQUAL;
 953         if ((__force u32)xid1 < (__force u32)xid2)
 954                 return XID_RB_LEFT;
 955         return XID_RB_RIGHT;
 956 }
 957
 958 static struct rpc_rqst *
 959 xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
 960 {
 961         struct rb_node *n = xprt->recv_queue.rb_node;
 962         struct rpc_rqst *req;
 963
 964         while (n != NULL) {
 965                 req = rb_entry(n, struct rpc_rqst, rq_recv);
 966                 switch (xprt_xid_cmp(xid, req->rq_xid)) {
 967                 case XID_RB_LEFT:
 968                         n = n->rb_left;
 969                         break;
 970                 case XID_RB_RIGHT:
 971                         n = n->rb_right;
 972                         break;
 973                 case XID_RB_EQUAL:
 974                         return req;
 975                 }
 976         }
 977         return NULL;
 978 }
 979
 980 static void
 981 xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
 982 {
 983         struct rb_node **p = &xprt->recv_queue.rb_node;
 984         struct rb_node *n = NULL;
 985         struct rpc_rqst *req;
 986
 987         while (*p != NULL) {
 988                 n = *p;
 989                 req = rb_entry(n, struct rpc_rqst, rq_recv);
 990                 switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
 991                 case XID_RB_LEFT:
 992                         p = &n->rb_left;
 993                         break;
 994                 case XID_RB_RIGHT:
 995                         p = &n->rb_right;
 996                         break;
 997                 case XID_RB_EQUAL:
 998                         WARN_ON_ONCE(new != req);
 999                         return;
1000                 }
1001         }
1002         rb_link_node(&new->rq_recv, n, p);
1003         rb_insert_color(&new->rq_recv, &xprt->recv_queue);
1004 }
1005
1006 static void
1007 xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
1008 {
1009         rb_erase(&req->rq_recv, &xprt->recv_queue);
1010 }
1011
1012 /**
1013  * xprt_lookup_rqst - find an RPC request corresponding to an XID
1014  * @xprt: transport on which the original request was transmitted
1015  * @xid: RPC XID of incoming reply
1016  *
1017  * Caller holds xprt->queue_lock.
1018  */
1019 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
1020 {
1021         struct rpc_rqst *entry;
1022
1023         entry = xprt_request_rb_find(xprt, xid);
1024         if (entry != NULL) {
1025                 trace_xprt_lookup_rqst(xprt, xid, 0);
1026                 entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
1027                 return entry;
1028         }
1029
1030         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
1031                         ntohl(xid));
1032         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
1033         xprt->stat.bad_xids++;
1034         return NULL;
1035 }
1036 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
1037
1038 static bool
1039 xprt_is_pinned_rqst(struct rpc_rqst *req)
1040 {
1041         return atomic_read(&req->rq_pin) != 0;
1042 }
1043
1044 /**
1045  * xprt_pin_rqst - Pin a request on the transport receive list
1046  * @req: Request to pin
1047  *
1048  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
1049  * so should be holding xprt->queue_lock.
1050  */
1051 void xprt_pin_rqst(struct rpc_rqst *req)
1052 {
1053         atomic_inc(&req->rq_pin);
1054 }
1055 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
1056
1057 /**
1058  * xprt_unpin_rqst - Unpin a request on the transport receive list
1059  * @req: Request to pin
1060  *
1061  * Caller should be holding xprt->queue_lock.
1062  */
1063 void xprt_unpin_rqst(struct rpc_rqst *req)
1064 {
1065         if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
1066                 atomic_dec(&req->rq_pin);
1067                 return;
1068         }
1069         if (atomic_dec_and_test(&req->rq_pin))
1070                 wake_up_var(&req->rq_pin);
1071 }
1072 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
1073
1074 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
1075 {
1076         wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
1077 }
1078
1079 static bool
1080 xprt_request_data_received(struct rpc_task *task)
1081 {
1082         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1083                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
1084 }
1085
1086 static bool
1087 xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
1088 {
1089         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1090                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
1091 }
1092
1093 /**
1094  * xprt_request_enqueue_receive - Add an request to the receive queue
1095  * @task: RPC task
1096  *
1097  */
1098 void
1099 xprt_request_enqueue_receive(struct rpc_task *task)
1100 {
1101         struct rpc_rqst *req = task->tk_rqstp;
1102         struct rpc_xprt *xprt = req->rq_xprt;
1103
1104         if (!xprt_request_need_enqueue_receive(task, req))
1105                 return;
1106
1107         xprt_request_prepare(task->tk_rqstp);
1108         spin_lock(&xprt->queue_lock);
1109
1110         /* Update the softirq receive buffer */
1111         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1112                         sizeof(req->rq_private_buf));
1113
1114         /* Add request to the receive list */
1115         xprt_request_rb_insert(xprt, req);
1116         set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
1117         spin_unlock(&xprt->queue_lock);
1118
1119         /* Turn off autodisconnect */
1120         del_singleshot_timer_sync(&xprt->timer);
1121 }
1122
1123 /**
1124  * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
1125  * @task: RPC task
1126  *
1127  * Caller must hold xprt->queue_lock.
1128  */
1129 static void
1130 xprt_request_dequeue_receive_locked(struct rpc_task *task)
1131 {
1132         struct rpc_rqst *req = task->tk_rqstp;
1133
1134         if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1135                 xprt_request_rb_remove(req->rq_xprt, req);
1136 }
1137
1138 /**
1139  * xprt_update_rtt - Update RPC RTT statistics
1140  * @task: RPC request that recently completed
1141  *
1142  * Caller holds xprt->queue_lock.
1143  */
1144 void xprt_update_rtt(struct rpc_task *task)
1145 {
1146         struct rpc_rqst *req = task->tk_rqstp;
1147         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
1148         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
1149         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
1150
1151         if (timer) {
1152                 if (req->rq_ntrans == 1)
1153                         rpc_update_rtt(rtt, timer, m);
1154                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
1155         }
1156 }
1157 EXPORT_SYMBOL_GPL(xprt_update_rtt);
1158
1159 /**
1160  * xprt_complete_rqst - called when reply processing is complete
1161  * @task: RPC request that recently completed
1162  * @copied: actual number of bytes received from the transport
1163  *
1164  * Caller holds xprt->queue_lock.
1165  */
1166 void xprt_complete_rqst(struct rpc_task *task, int copied)
1167 {
1168         struct rpc_rqst *req = task->tk_rqstp;
1169         struct rpc_xprt *xprt = req->rq_xprt;
1170
1171         xprt->stat.recvs++;
1172
1173         req->rq_private_buf.len = copied;
1174         /* Ensure all writes are done before we update */
1175         /* req->rq_reply_bytes_recvd */
1176         smp_wmb();
1177         req->rq_reply_bytes_recvd = copied;
1178         xprt_request_dequeue_receive_locked(task);
1179         rpc_wake_up_queued_task(&xprt->pending, task);
1180 }
1181 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
1182
1183 static void xprt_timer(struct rpc_task *task)
1184 {
1185         struct rpc_rqst *req = task->tk_rqstp;
1186         struct rpc_xprt *xprt = req->rq_xprt;
1187
1188         if (task->tk_status != -ETIMEDOUT)
1189                 return;
1190
1191         trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
1192         if (!req->rq_reply_bytes_recvd) {
1193                 if (xprt->ops->timer)
1194                         xprt->ops->timer(xprt, task);
1195         } else
1196                 task->tk_status = 0;
1197 }
1198
1199 /**
1200  * xprt_wait_for_reply_request_def - wait for reply
1201  * @task: pointer to rpc_task
1202  *
1203  * Set a request's retransmit timeout based on the transport's
1204  * default timeout parameters.  Used by transports that don't adjust
1205  * the retransmit timeout based on round-trip time estimation,
1206  * and put the task to sleep on the pending queue.
1207  */
1208 void xprt_wait_for_reply_request_def(struct rpc_task *task)
1209 {
1210         struct rpc_rqst *req = task->tk_rqstp;
1211
1212         rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1213                         xprt_request_timeout(req));
1214 }
1215 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_def);
1216
1217 /**
1218  * xprt_wait_for_reply_request_rtt - wait for reply using RTT estimator
1219  * @task: pointer to rpc_task
1220  *
1221  * Set a request's retransmit timeout using the RTT estimator,
1222  * and put the task to sleep on the pending queue.
1223  */
1224 void xprt_wait_for_reply_request_rtt(struct rpc_task *task)
1225 {
1226         int timer = task->tk_msg.rpc_proc->p_timer;
1227         struct rpc_clnt *clnt = task->tk_client;
1228         struct rpc_rtt *rtt = clnt->cl_rtt;
1229         struct rpc_rqst *req = task->tk_rqstp;
1230         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
1231         unsigned long timeout;
1232
1233         timeout = rpc_calc_rto(rtt, timer);
1234         timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
1235         if (timeout > max_timeout || timeout == 0)
1236                 timeout = max_timeout;
1237         rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1238                         jiffies + timeout);
1239 }
1240 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_rtt);
1241
1242 /**
1243  * xprt_request_wait_receive - wait for the reply to an RPC request
1244  * @task: RPC task about to send a request
1245  *
1246  */
1247 void xprt_request_wait_receive(struct rpc_task *task)
1248 {
1249         struct rpc_rqst *req = task->tk_rqstp;
1250         struct rpc_xprt *xprt = req->rq_xprt;
1251
1252         if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1253                 return;
1254         /*
1255          * Sleep on the pending queue if we're expecting a reply.
1256          * The spinlock ensures atomicity between the test of
1257          * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1258          */
1259         spin_lock(&xprt->queue_lock);
1260         if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
1261                 xprt->ops->wait_for_reply_request(task);
1262                 /*
1263                  * Send an extra queue wakeup call if the
1264                  * connection was dropped in case the call to
1265                  * rpc_sleep_on() raced.
1266                  */
1267                 if (xprt_request_retransmit_after_disconnect(task))
1268                         rpc_wake_up_queued_task_set_status(&xprt->pending,
1269                                         task, -ENOTCONN);
1270         }
1271         spin_unlock(&xprt->queue_lock);
1272 }
1273
1274 static bool
1275 xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
1276 {
1277         return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1278 }
1279
1280 /**
1281  * xprt_request_enqueue_transmit - queue a task for transmission
1282  * @task: pointer to rpc_task
1283  *
1284  * Add a task to the transmission queue.
1285  */
1286 void
1287 xprt_request_enqueue_transmit(struct rpc_task *task)
1288 {
1289         struct rpc_rqst *pos, *req = task->tk_rqstp;
1290         struct rpc_xprt *xprt = req->rq_xprt;
1291
1292         if (xprt_request_need_enqueue_transmit(task, req)) {
1293                 req->rq_bytes_sent = 0;
1294                 spin_lock(&xprt->queue_lock);
1295                 /*
1296                  * Requests that carry congestion control credits are added
1297                  * to the head of the list to avoid starvation issues.
1298                  */
1299                 if (req->rq_cong) {
1300                         xprt_clear_congestion_window_wait(xprt);
1301                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1302                                 if (pos->rq_cong)
1303                                         continue;
1304                                 /* Note: req is added _before_ pos */
1305                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1306                                 INIT_LIST_HEAD(&req->rq_xmit2);
1307                                 goto out;
1308                         }
1309                 } else if (!req->rq_seqno) {
1310                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1311                                 if (pos->rq_task->tk_owner != task->tk_owner)
1312                                         continue;
1313                                 list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
1314                                 INIT_LIST_HEAD(&req->rq_xmit);
1315                                 goto out;
1316                         }
1317                 }
1318                 list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
1319                 INIT_LIST_HEAD(&req->rq_xmit2);
1320 out:
1321                 set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1322                 spin_unlock(&xprt->queue_lock);
1323         }
1324 }
1325
1326 /**
1327  * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
1328  * @task: pointer to rpc_task
1329  *
1330  * Remove a task from the transmission queue
1331  * Caller must hold xprt->queue_lock
1332  */
1333 static void
1334 xprt_request_dequeue_transmit_locked(struct rpc_task *task)
1335 {
1336         struct rpc_rqst *req = task->tk_rqstp;
1337
1338         if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1339                 return;
1340         if (!list_empty(&req->rq_xmit)) {
1341                 list_del(&req->rq_xmit);
1342                 if (!list_empty(&req->rq_xmit2)) {
1343                         struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
1344                                         struct rpc_rqst, rq_xmit2);
1345                         list_del(&req->rq_xmit2);
1346                         list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
1347                 }
1348         } else
1349                 list_del(&req->rq_xmit2);
1350 }
1351
1352 /**
1353  * xprt_request_dequeue_transmit - remove a task from the transmission queue
1354  * @task: pointer to rpc_task
1355  *
1356  * Remove a task from the transmission queue
1357  */
1358 static void
1359 xprt_request_dequeue_transmit(struct rpc_task *task)
1360 {
1361         struct rpc_rqst *req = task->tk_rqstp;
1362         struct rpc_xprt *xprt = req->rq_xprt;
1363
1364         spin_lock(&xprt->queue_lock);
1365         xprt_request_dequeue_transmit_locked(task);
1366         spin_unlock(&xprt->queue_lock);
1367 }
1368
1369 /**
1370  * xprt_request_dequeue_xprt - remove a task from the transmit+receive queue
1371  * @task: pointer to rpc_task
1372  *
1373  * Remove a task from the transmit and receive queues, and ensure that
1374  * it is not pinned by the receive work item.
1375  */
1376 void
1377 xprt_request_dequeue_xprt(struct rpc_task *task)
1378 {
1379         struct rpc_rqst *req = task->tk_rqstp;
1380         struct rpc_xprt *xprt = req->rq_xprt;
1381
1382         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
1383             test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
1384             xprt_is_pinned_rqst(req)) {
1385                 spin_lock(&xprt->queue_lock);
1386                 xprt_request_dequeue_transmit_locked(task);
1387                 xprt_request_dequeue_receive_locked(task);
1388                 while (xprt_is_pinned_rqst(req)) {
1389                         set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1390                         spin_unlock(&xprt->queue_lock);
1391                         xprt_wait_on_pinned_rqst(req);
1392                         spin_lock(&xprt->queue_lock);
1393                         clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1394                 }
1395                 spin_unlock(&xprt->queue_lock);
1396         }
1397 }
1398
1399 /**
1400  * xprt_request_prepare - prepare an encoded request for transport
1401  * @req: pointer to rpc_rqst
1402  *
1403  * Calls into the transport layer to do whatever is needed to prepare
1404  * the request for transmission or receive.
1405  */
1406 void
1407 xprt_request_prepare(struct rpc_rqst *req)
1408 {
1409         struct rpc_xprt *xprt = req->rq_xprt;
1410
1411         if (xprt->ops->prepare_request)
1412                 xprt->ops->prepare_request(req);
1413 }
1414
1415 /**
1416  * xprt_request_need_retransmit - Test if a task needs retransmission
1417  * @task: pointer to rpc_task
1418  *
1419  * Test for whether a connection breakage requires the task to retransmit
1420  */
1421 bool
1422 xprt_request_need_retransmit(struct rpc_task *task)
1423 {
1424         return xprt_request_retransmit_after_disconnect(task);
1425 }
1426
1427 /**
1428  * xprt_prepare_transmit - reserve the transport before sending a request
1429  * @task: RPC task about to send a request
1430  *
1431  */
1432 bool xprt_prepare_transmit(struct rpc_task *task)
1433 {
1434         struct rpc_rqst *req = task->tk_rqstp;
1435         struct rpc_xprt *xprt = req->rq_xprt;
1436
1437         if (!xprt_lock_write(xprt, task)) {
1438                 /* Race breaker: someone may have transmitted us */
1439                 if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1440                         rpc_wake_up_queued_task_set_status(&xprt->sending,
1441                                         task, 0);
1442                 return false;
1443
1444         }
1445         return true;
1446 }
1447
1448 void xprt_end_transmit(struct rpc_task *task)
1449 {
1450         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
1451
1452         xprt_inject_disconnect(xprt);
1453         xprt_release_write(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         trace_rpc_xdr_sendto(task, &req->rq_snd_buf);
1499         connect_cookie = xprt->connect_cookie;
1500         status = xprt->ops->send_request(req);
1501         if (status != 0) {
1502                 req->rq_ntrans--;
1503                 trace_xprt_transmit(req, status);
1504                 return status;
1505         }
1506
1507         if (is_retrans)
1508                 task->tk_client->cl_stats->rpcretrans++;
1509
1510         xprt_inject_disconnect(xprt);
1511
1512         task->tk_flags |= RPC_TASK_SENT;
1513         spin_lock(&xprt->transport_lock);
1514
1515         xprt->stat.sends++;
1516         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1517         xprt->stat.bklog_u += xprt->backlog.qlen;
1518         xprt->stat.sending_u += xprt->sending.qlen;
1519         xprt->stat.pending_u += xprt->pending.qlen;
1520         spin_unlock(&xprt->transport_lock);
1521
1522         req->rq_connect_cookie = connect_cookie;
1523 out_dequeue:
1524         trace_xprt_transmit(req, status);
1525         xprt_request_dequeue_transmit(task);
1526         rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
1527         return status;
1528 }
1529
1530 /**
1531  * xprt_transmit - send an RPC request on a transport
1532  * @task: controlling RPC task
1533  *
1534  * Attempts to drain the transmit queue. On exit, either the transport
1535  * signalled an error that needs to be handled before transmission can
1536  * resume, or @task finished transmitting, and detected that it already
1537  * received a reply.
1538  */
1539 void
1540 xprt_transmit(struct rpc_task *task)
1541 {
1542         struct rpc_rqst *next, *req = task->tk_rqstp;
1543         struct rpc_xprt *xprt = req->rq_xprt;
1544         int status;
1545
1546         spin_lock(&xprt->queue_lock);
1547         for (;;) {
1548                 next = list_first_entry_or_null(&xprt->xmit_queue,
1549                                                 struct rpc_rqst, rq_xmit);
1550                 if (!next)
1551                         break;
1552                 xprt_pin_rqst(next);
1553                 spin_unlock(&xprt->queue_lock);
1554                 status = xprt_request_transmit(next, task);
1555                 if (status == -EBADMSG && next != req)
1556                         status = 0;
1557                 spin_lock(&xprt->queue_lock);
1558                 xprt_unpin_rqst(next);
1559                 if (status < 0) {
1560                         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1561                                 task->tk_status = status;
1562                         break;
1563                 }
1564                 /* Was @task transmitted, and has it received a reply? */
1565                 if (xprt_request_data_received(task) &&
1566                     !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1567                         break;
1568                 cond_resched_lock(&xprt->queue_lock);
1569         }
1570         spin_unlock(&xprt->queue_lock);
1571 }
1572
1573 static void xprt_complete_request_init(struct rpc_task *task)
1574 {
1575         if (task->tk_rqstp)
1576                 xprt_request_init(task);
1577 }
1578
1579 void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1580 {
1581         set_bit(XPRT_CONGESTED, &xprt->state);
1582         rpc_sleep_on(&xprt->backlog, task, xprt_complete_request_init);
1583 }
1584 EXPORT_SYMBOL_GPL(xprt_add_backlog);
1585
1586 static bool __xprt_set_rq(struct rpc_task *task, void *data)
1587 {
1588         struct rpc_rqst *req = data;
1589
1590         if (task->tk_rqstp == NULL) {
1591                 memset(req, 0, sizeof(*req));   /* mark unused */
1592                 task->tk_rqstp = req;
1593                 return true;
1594         }
1595         return false;
1596 }
1597
1598 bool xprt_wake_up_backlog(struct rpc_xprt *xprt, struct rpc_rqst *req)
1599 {
1600         if (rpc_wake_up_first(&xprt->backlog, __xprt_set_rq, req) == NULL) {
1601                 clear_bit(XPRT_CONGESTED, &xprt->state);
1602                 return false;
1603         }
1604         return true;
1605 }
1606 EXPORT_SYMBOL_GPL(xprt_wake_up_backlog);
1607
1608 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1609 {
1610         bool ret = false;
1611
1612         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1613                 goto out;
1614         spin_lock(&xprt->reserve_lock);
1615         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1616                 xprt_add_backlog(xprt, task);
1617                 ret = true;
1618         }
1619         spin_unlock(&xprt->reserve_lock);
1620 out:
1621         return ret;
1622 }
1623
1624 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1625 {
1626         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1627         gfp_t gfp_mask = GFP_KERNEL;
1628
1629         if (xprt->num_reqs >= xprt->max_reqs)
1630                 goto out;
1631         ++xprt->num_reqs;
1632         spin_unlock(&xprt->reserve_lock);
1633         if (current->flags & PF_WQ_WORKER)
1634                 gfp_mask |= __GFP_NORETRY | __GFP_NOWARN;
1635         req = kzalloc(sizeof(*req), gfp_mask);
1636         spin_lock(&xprt->reserve_lock);
1637         if (req != NULL)
1638                 goto out;
1639         --xprt->num_reqs;
1640         req = ERR_PTR(-ENOMEM);
1641 out:
1642         return req;
1643 }
1644
1645 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1646 {
1647         if (xprt->num_reqs > xprt->min_reqs) {
1648                 --xprt->num_reqs;
1649                 kfree(req);
1650                 return true;
1651         }
1652         return false;
1653 }
1654
1655 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1656 {
1657         struct rpc_rqst *req;
1658
1659         spin_lock(&xprt->reserve_lock);
1660         if (!list_empty(&xprt->free)) {
1661                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1662                 list_del(&req->rq_list);
1663                 goto out_init_req;
1664         }
1665         req = xprt_dynamic_alloc_slot(xprt);
1666         if (!IS_ERR(req))
1667                 goto out_init_req;
1668         switch (PTR_ERR(req)) {
1669         case -ENOMEM:
1670                 dprintk("RPC:       dynamic allocation of request slot "
1671                                 "failed! Retrying\n");
1672                 task->tk_status = -ENOMEM;
1673                 break;
1674         case -EAGAIN:
1675                 xprt_add_backlog(xprt, task);
1676                 dprintk("RPC:       waiting for request slot\n");
1677                 fallthrough;
1678         default:
1679                 task->tk_status = -EAGAIN;
1680         }
1681         spin_unlock(&xprt->reserve_lock);
1682         return;
1683 out_init_req:
1684         xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
1685                                      xprt->num_reqs);
1686         spin_unlock(&xprt->reserve_lock);
1687
1688         task->tk_status = 0;
1689         task->tk_rqstp = req;
1690 }
1691 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1692
1693 void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1694 {
1695         spin_lock(&xprt->reserve_lock);
1696         if (!xprt_wake_up_backlog(xprt, req) &&
1697             !xprt_dynamic_free_slot(xprt, req)) {
1698                 memset(req, 0, sizeof(*req));   /* mark unused */
1699                 list_add(&req->rq_list, &xprt->free);
1700         }
1701         spin_unlock(&xprt->reserve_lock);
1702 }
1703 EXPORT_SYMBOL_GPL(xprt_free_slot);
1704
1705 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1706 {
1707         struct rpc_rqst *req;
1708         while (!list_empty(&xprt->free)) {
1709                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1710                 list_del(&req->rq_list);
1711                 kfree(req);
1712         }
1713 }
1714
1715 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1716                 unsigned int num_prealloc,
1717                 unsigned int max_alloc)
1718 {
1719         struct rpc_xprt *xprt;
1720         struct rpc_rqst *req;
1721         int i;
1722
1723         xprt = kzalloc(size, GFP_KERNEL);
1724         if (xprt == NULL)
1725                 goto out;
1726
1727         xprt_init(xprt, net);
1728
1729         for (i = 0; i < num_prealloc; i++) {
1730                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1731                 if (!req)
1732                         goto out_free;
1733                 list_add(&req->rq_list, &xprt->free);
1734         }
1735         if (max_alloc > num_prealloc)
1736                 xprt->max_reqs = max_alloc;
1737         else
1738                 xprt->max_reqs = num_prealloc;
1739         xprt->min_reqs = num_prealloc;
1740         xprt->num_reqs = num_prealloc;
1741
1742         return xprt;
1743
1744 out_free:
1745         xprt_free(xprt);
1746 out:
1747         return NULL;
1748 }
1749 EXPORT_SYMBOL_GPL(xprt_alloc);
1750
1751 void xprt_free(struct rpc_xprt *xprt)
1752 {
1753         put_net(xprt->xprt_net);
1754         xprt_free_all_slots(xprt);
1755         kfree_rcu(xprt, rcu);
1756 }
1757 EXPORT_SYMBOL_GPL(xprt_free);
1758
1759 static void
1760 xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
1761 {
1762         req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
1763 }
1764
1765 static __be32
1766 xprt_alloc_xid(struct rpc_xprt *xprt)
1767 {
1768         __be32 xid;
1769
1770         spin_lock(&xprt->reserve_lock);
1771         xid = (__force __be32)xprt->xid++;
1772         spin_unlock(&xprt->reserve_lock);
1773         return xid;
1774 }
1775
1776 static void
1777 xprt_init_xid(struct rpc_xprt *xprt)
1778 {
1779         xprt->xid = prandom_u32();
1780 }
1781
1782 static void
1783 xprt_request_init(struct rpc_task *task)
1784 {
1785         struct rpc_xprt *xprt = task->tk_xprt;
1786         struct rpc_rqst *req = task->tk_rqstp;
1787
1788         req->rq_task    = task;
1789         req->rq_xprt    = xprt;
1790         req->rq_buffer  = NULL;
1791         req->rq_xid     = xprt_alloc_xid(xprt);
1792         xprt_init_connect_cookie(req, xprt);
1793         req->rq_snd_buf.len = 0;
1794         req->rq_snd_buf.buflen = 0;
1795         req->rq_rcv_buf.len = 0;
1796         req->rq_rcv_buf.buflen = 0;
1797         req->rq_snd_buf.bvec = NULL;
1798         req->rq_rcv_buf.bvec = NULL;
1799         req->rq_release_snd_buf = NULL;
1800         xprt_init_majortimeo(task, req);
1801
1802         trace_xprt_reserve(req);
1803 }
1804
1805 static void
1806 xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
1807 {
1808         xprt->ops->alloc_slot(xprt, task);
1809         if (task->tk_rqstp != NULL)
1810                 xprt_request_init(task);
1811 }
1812
1813 /**
1814  * xprt_reserve - allocate an RPC request slot
1815  * @task: RPC task requesting a slot allocation
1816  *
1817  * If the transport is marked as being congested, or if no more
1818  * slots are available, place the task on the transport's
1819  * backlog queue.
1820  */
1821 void xprt_reserve(struct rpc_task *task)
1822 {
1823         struct rpc_xprt *xprt = task->tk_xprt;
1824
1825         task->tk_status = 0;
1826         if (task->tk_rqstp != NULL)
1827                 return;
1828
1829         task->tk_status = -EAGAIN;
1830         if (!xprt_throttle_congested(xprt, task))
1831                 xprt_do_reserve(xprt, task);
1832 }
1833
1834 /**
1835  * xprt_retry_reserve - allocate an RPC request slot
1836  * @task: RPC task requesting a slot allocation
1837  *
1838  * If no more slots are available, place the task on the transport's
1839  * backlog queue.
1840  * Note that the only difference with xprt_reserve is that we now
1841  * ignore the value of the XPRT_CONGESTED flag.
1842  */
1843 void xprt_retry_reserve(struct rpc_task *task)
1844 {
1845         struct rpc_xprt *xprt = task->tk_xprt;
1846
1847         task->tk_status = 0;
1848         if (task->tk_rqstp != NULL)
1849                 return;
1850
1851         task->tk_status = -EAGAIN;
1852         xprt_do_reserve(xprt, task);
1853 }
1854
1855 /**
1856  * xprt_release - release an RPC request slot
1857  * @task: task which is finished with the slot
1858  *
1859  */
1860 void xprt_release(struct rpc_task *task)
1861 {
1862         struct rpc_xprt *xprt;
1863         struct rpc_rqst *req = task->tk_rqstp;
1864
1865         if (req == NULL) {
1866                 if (task->tk_client) {
1867                         xprt = task->tk_xprt;
1868                         xprt_release_write(xprt, task);
1869                 }
1870                 return;
1871         }
1872
1873         xprt = req->rq_xprt;
1874         xprt_request_dequeue_xprt(task);
1875         spin_lock(&xprt->transport_lock);
1876         xprt->ops->release_xprt(xprt, task);
1877         if (xprt->ops->release_request)
1878                 xprt->ops->release_request(task);
1879         xprt_schedule_autodisconnect(xprt);
1880         spin_unlock(&xprt->transport_lock);
1881         if (req->rq_buffer)
1882                 xprt->ops->buf_free(task);
1883         xdr_free_bvec(&req->rq_rcv_buf);
1884         xdr_free_bvec(&req->rq_snd_buf);
1885         if (req->rq_cred != NULL)
1886                 put_rpccred(req->rq_cred);
1887         if (req->rq_release_snd_buf)
1888                 req->rq_release_snd_buf(req);
1889
1890         task->tk_rqstp = NULL;
1891         if (likely(!bc_prealloc(req)))
1892                 xprt->ops->free_slot(xprt, req);
1893         else
1894                 xprt_free_bc_request(req);
1895 }
1896
1897 #ifdef CONFIG_SUNRPC_BACKCHANNEL
1898 void
1899 xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
1900 {
1901         struct xdr_buf *xbufp = &req->rq_snd_buf;
1902
1903         task->tk_rqstp = req;
1904         req->rq_task = task;
1905         xprt_init_connect_cookie(req, req->rq_xprt);
1906         /*
1907          * Set up the xdr_buf length.
1908          * This also indicates that the buffer is XDR encoded already.
1909          */
1910         xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
1911                 xbufp->tail[0].iov_len;
1912 }
1913 #endif
1914
1915 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1916 {
1917         kref_init(&xprt->kref);
1918
1919         spin_lock_init(&xprt->transport_lock);
1920         spin_lock_init(&xprt->reserve_lock);
1921         spin_lock_init(&xprt->queue_lock);
1922
1923         INIT_LIST_HEAD(&xprt->free);
1924         xprt->recv_queue = RB_ROOT;
1925         INIT_LIST_HEAD(&xprt->xmit_queue);
1926 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1927         spin_lock_init(&xprt->bc_pa_lock);
1928         INIT_LIST_HEAD(&xprt->bc_pa_list);
1929 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1930         INIT_LIST_HEAD(&xprt->xprt_switch);
1931
1932         xprt->last_used = jiffies;
1933         xprt->cwnd = RPC_INITCWND;
1934         xprt->bind_index = 0;
1935
1936         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1937         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1938         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1939         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1940
1941         xprt_init_xid(xprt);
1942
1943         xprt->xprt_net = get_net(net);
1944 }
1945
1946 /**
1947  * xprt_create_transport - create an RPC transport
1948  * @args: rpc transport creation arguments
1949  *
1950  */
1951 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1952 {
1953         struct rpc_xprt *xprt;
1954         struct xprt_class *t;
1955
1956         spin_lock(&xprt_list_lock);
1957         list_for_each_entry(t, &xprt_list, list) {
1958                 if (t->ident == args->ident) {
1959                         spin_unlock(&xprt_list_lock);
1960                         goto found;
1961                 }
1962         }
1963         spin_unlock(&xprt_list_lock);
1964         dprintk("RPC: transport (%d) not supported\n", args->ident);
1965         return ERR_PTR(-EIO);
1966
1967 found:
1968         xprt = t->setup(args);
1969         if (IS_ERR(xprt))
1970                 goto out;
1971         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1972                 xprt->idle_timeout = 0;
1973         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1974         if (xprt_has_timer(xprt))
1975                 timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
1976         else
1977                 timer_setup(&xprt->timer, NULL, 0);
1978
1979         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1980                 xprt_destroy(xprt);
1981                 return ERR_PTR(-EINVAL);
1982         }
1983         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1984         if (xprt->servername == NULL) {
1985                 xprt_destroy(xprt);
1986                 return ERR_PTR(-ENOMEM);
1987         }
1988
1989         rpc_xprt_debugfs_register(xprt);
1990
1991         trace_xprt_create(xprt);
1992 out:
1993         return xprt;
1994 }
1995
1996 static void xprt_destroy_cb(struct work_struct *work)
1997 {
1998         struct rpc_xprt *xprt =
1999                 container_of(work, struct rpc_xprt, task_cleanup);
2000
2001         trace_xprt_destroy(xprt);
2002
2003         rpc_xprt_debugfs_unregister(xprt);
2004         rpc_destroy_wait_queue(&xprt->binding);
2005         rpc_destroy_wait_queue(&xprt->pending);
2006         rpc_destroy_wait_queue(&xprt->sending);
2007         rpc_destroy_wait_queue(&xprt->backlog);
2008         kfree(xprt->servername);
2009         /*
2010          * Destroy any existing back channel
2011          */
2012         xprt_destroy_backchannel(xprt, UINT_MAX);
2013
2014         /*
2015          * Tear down transport state and free the rpc_xprt
2016          */
2017         xprt->ops->destroy(xprt);
2018 }
2019
2020 /**
2021  * xprt_destroy - destroy an RPC transport, killing off all requests.
2022  * @xprt: transport to destroy
2023  *
2024  */
2025 static void xprt_destroy(struct rpc_xprt *xprt)
2026 {
2027         /*
2028          * Exclude transport connect/disconnect handlers and autoclose
2029          */
2030         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
2031
2032         /*
2033          * xprt_schedule_autodisconnect() can run after XPRT_LOCKED
2034          * is cleared.  We use ->transport_lock to ensure the mod_timer()
2035          * can only run *before* del_time_sync(), never after.
2036          */
2037         spin_lock(&xprt->transport_lock);
2038         del_timer_sync(&xprt->timer);
2039         spin_unlock(&xprt->transport_lock);
2040
2041         /*
2042          * Destroy sockets etc from the system workqueue so they can
2043          * safely flush receive work running on rpciod.
2044          */
2045         INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
2046         schedule_work(&xprt->task_cleanup);
2047 }
2048
2049 static void xprt_destroy_kref(struct kref *kref)
2050 {
2051         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
2052 }
2053
2054 /**
2055  * xprt_get - return a reference to an RPC transport.
2056  * @xprt: pointer to the transport
2057  *
2058  */
2059 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
2060 {
2061         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
2062                 return xprt;
2063         return NULL;
2064 }
2065 EXPORT_SYMBOL_GPL(xprt_get);
2066
2067 /**
2068  * xprt_put - release a reference to an RPC transport.
2069  * @xprt: pointer to the transport
2070  *
2071  */
2072 void xprt_put(struct rpc_xprt *xprt)
2073 {
2074         if (xprt != NULL)
2075                 kref_put(&xprt->kref, xprt_destroy_kref);
2076 }
2077 EXPORT_SYMBOL_GPL(xprt_put);