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 <[email protected]>
  37  *
  38  *  Transport switch API copyright (C) 2005, Chuck Lever <[email protected]>
  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 #include "sysfs.h"
  59 #include "fail.h"
  60
  61 /*
  62  * Local variables
  63  */
  64
  65 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  66 # define RPCDBG_FACILITY        RPCDBG_XPRT
  67 #endif
  68
  69 /*
  70  * Local functions
  71  */
  72 static void      xprt_init(struct rpc_xprt *xprt, struct net *net);
  73 static __be32   xprt_alloc_xid(struct rpc_xprt *xprt);
  74 static void      xprt_destroy(struct rpc_xprt *xprt);
  75 static void      xprt_request_init(struct rpc_task *task);
  76
  77 static DEFINE_SPINLOCK(xprt_list_lock);
  78 static LIST_HEAD(xprt_list);
  79
  80 static unsigned long xprt_request_timeout(const struct rpc_rqst *req)
  81 {
  82         unsigned long timeout = jiffies + req->rq_timeout;
  83
  84         if (time_before(timeout, req->rq_majortimeo))
  85                 return timeout;
  86         return req->rq_majortimeo;
  87 }
  88
  89 /**
  90  * xprt_register_transport - register a transport implementation
  91  * @transport: transport to register
  92  *
  93  * If a transport implementation is loaded as a kernel module, it can
  94  * call this interface to make itself known to the RPC client.
  95  *
  96  * Returns:
  97  * 0:           transport successfully registered
  98  * -EEXIST:     transport already registered
  99  * -EINVAL:     transport module being unloaded
 100  */
 101 int xprt_register_transport(struct xprt_class *transport)
 102 {
 103         struct xprt_class *t;
 104         int result;
 105
 106         result = -EEXIST;
 107         spin_lock(&xprt_list_lock);
 108         list_for_each_entry(t, &xprt_list, list) {
 109                 /* don't register the same transport class twice */
 110                 if (t->ident == transport->ident)
 111                         goto out;
 112         }
 113
 114         list_add_tail(&transport->list, &xprt_list);
 115         printk(KERN_INFO "RPC: Registered %s transport module.\n",
 116                transport->name);
 117         result = 0;
 118
 119 out:
 120         spin_unlock(&xprt_list_lock);
 121         return result;
 122 }
 123 EXPORT_SYMBOL_GPL(xprt_register_transport);
 124
 125 /**
 126  * xprt_unregister_transport - unregister a transport implementation
 127  * @transport: transport to unregister
 128  *
 129  * Returns:
 130  * 0:           transport successfully unregistered
 131  * -ENOENT:     transport never registered
 132  */
 133 int xprt_unregister_transport(struct xprt_class *transport)
 134 {
 135         struct xprt_class *t;
 136         int result;
 137
 138         result = 0;
 139         spin_lock(&xprt_list_lock);
 140         list_for_each_entry(t, &xprt_list, list) {
 141                 if (t == transport) {
 142                         printk(KERN_INFO
 143                                 "RPC: Unregistered %s transport module.\n",
 144                                 transport->name);
 145                         list_del_init(&transport->list);
 146                         goto out;
 147                 }
 148         }
 149         result = -ENOENT;
 150
 151 out:
 152         spin_unlock(&xprt_list_lock);
 153         return result;
 154 }
 155 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 156
 157 static void
 158 xprt_class_release(const struct xprt_class *t)
 159 {
 160         module_put(t->owner);
 161 }
 162
 163 static const struct xprt_class *
 164 xprt_class_find_by_ident_locked(int ident)
 165 {
 166         const struct xprt_class *t;
 167
 168         list_for_each_entry(t, &xprt_list, list) {
 169                 if (t->ident != ident)
 170                         continue;
 171                 if (!try_module_get(t->owner))
 172                         continue;
 173                 return t;
 174         }
 175         return NULL;
 176 }
 177
 178 static const struct xprt_class *
 179 xprt_class_find_by_ident(int ident)
 180 {
 181         const struct xprt_class *t;
 182
 183         spin_lock(&xprt_list_lock);
 184         t = xprt_class_find_by_ident_locked(ident);
 185         spin_unlock(&xprt_list_lock);
 186         return t;
 187 }
 188
 189 static const struct xprt_class *
 190 xprt_class_find_by_netid_locked(const char *netid)
 191 {
 192         const struct xprt_class *t;
 193         unsigned int i;
 194
 195         list_for_each_entry(t, &xprt_list, list) {
 196                 for (i = 0; t->netid[i][0] != '\0'; i++) {
 197                         if (strcmp(t->netid[i], netid) != 0)
 198                                 continue;
 199                         if (!try_module_get(t->owner))
 200                                 continue;
 201                         return t;
 202                 }
 203         }
 204         return NULL;
 205 }
 206
 207 static const struct xprt_class *
 208 xprt_class_find_by_netid(const char *netid)
 209 {
 210         const struct xprt_class *t;
 211
 212         spin_lock(&xprt_list_lock);
 213         t = xprt_class_find_by_netid_locked(netid);
 214         if (!t) {
 215                 spin_unlock(&xprt_list_lock);
 216                 request_module("rpc%s", netid);
 217                 spin_lock(&xprt_list_lock);
 218                 t = xprt_class_find_by_netid_locked(netid);
 219         }
 220         spin_unlock(&xprt_list_lock);
 221         return t;
 222 }
 223
 224 /**
 225  * xprt_find_transport_ident - convert a netid into a transport identifier
 226  * @netid: transport to load
 227  *
 228  * Returns:
 229  * > 0:         transport identifier
 230  * -ENOENT:     transport module not available
 231  */
 232 int xprt_find_transport_ident(const char *netid)
 233 {
 234         const struct xprt_class *t;
 235         int ret;
 236
 237         t = xprt_class_find_by_netid(netid);
 238         if (!t)
 239                 return -ENOENT;
 240         ret = t->ident;
 241         xprt_class_release(t);
 242         return ret;
 243 }
 244 EXPORT_SYMBOL_GPL(xprt_find_transport_ident);
 245
 246 static void xprt_clear_locked(struct rpc_xprt *xprt)
 247 {
 248         xprt->snd_task = NULL;
 249         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 250                 smp_mb__before_atomic();
 251                 clear_bit(XPRT_LOCKED, &xprt->state);
 252                 smp_mb__after_atomic();
 253         } else
 254                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 255 }
 256
 257 /**
 258  * xprt_reserve_xprt - serialize write access to transports
 259  * @task: task that is requesting access to the transport
 260  * @xprt: pointer to the target transport
 261  *
 262  * This prevents mixing the payload of separate requests, and prevents
 263  * transport connects from colliding with writes.  No congestion control
 264  * is provided.
 265  */
 266 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 267 {
 268         struct rpc_rqst *req = task->tk_rqstp;
 269
 270         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 271                 if (task == xprt->snd_task)
 272                         goto out_locked;
 273                 goto out_sleep;
 274         }
 275         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 276                 goto out_unlock;
 277         xprt->snd_task = task;
 278
 279 out_locked:
 280         trace_xprt_reserve_xprt(xprt, task);
 281         return 1;
 282
 283 out_unlock:
 284         xprt_clear_locked(xprt);
 285 out_sleep:
 286         task->tk_status = -EAGAIN;
 287         if  (RPC_IS_SOFT(task))
 288                 rpc_sleep_on_timeout(&xprt->sending, task, NULL,
 289                                 xprt_request_timeout(req));
 290         else
 291                 rpc_sleep_on(&xprt->sending, task, NULL);
 292         return 0;
 293 }
 294 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 295
 296 static bool
 297 xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
 298 {
 299         return test_bit(XPRT_CWND_WAIT, &xprt->state);
 300 }
 301
 302 static void
 303 xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
 304 {
 305         if (!list_empty(&xprt->xmit_queue)) {
 306                 /* Peek at head of queue to see if it can make progress */
 307                 if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
 308                                         rq_xmit)->rq_cong)
 309                         return;
 310         }
 311         set_bit(XPRT_CWND_WAIT, &xprt->state);
 312 }
 313
 314 static void
 315 xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
 316 {
 317         if (!RPCXPRT_CONGESTED(xprt))
 318                 clear_bit(XPRT_CWND_WAIT, &xprt->state);
 319 }
 320
 321 /*
 322  * xprt_reserve_xprt_cong - serialize write access to transports
 323  * @task: task that is requesting access to the transport
 324  *
 325  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 326  * integrated into the decision of whether a request is allowed to be
 327  * woken up and given access to the transport.
 328  * Note that the lock is only granted if we know there are free slots.
 329  */
 330 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 331 {
 332         struct rpc_rqst *req = task->tk_rqstp;
 333
 334         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 335                 if (task == xprt->snd_task)
 336                         goto out_locked;
 337                 goto out_sleep;
 338         }
 339         if (req == NULL) {
 340                 xprt->snd_task = task;
 341                 goto out_locked;
 342         }
 343         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 344                 goto out_unlock;
 345         if (!xprt_need_congestion_window_wait(xprt)) {
 346                 xprt->snd_task = task;
 347                 goto out_locked;
 348         }
 349 out_unlock:
 350         xprt_clear_locked(xprt);
 351 out_sleep:
 352         task->tk_status = -EAGAIN;
 353         if (RPC_IS_SOFT(task))
 354                 rpc_sleep_on_timeout(&xprt->sending, task, NULL,
 355                                 xprt_request_timeout(req));
 356         else
 357                 rpc_sleep_on(&xprt->sending, task, NULL);
 358         return 0;
 359 out_locked:
 360         trace_xprt_reserve_cong(xprt, task);
 361         return 1;
 362 }
 363 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 364
 365 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 366 {
 367         int retval;
 368
 369         if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
 370                 return 1;
 371         spin_lock(&xprt->transport_lock);
 372         retval = xprt->ops->reserve_xprt(xprt, task);
 373         spin_unlock(&xprt->transport_lock);
 374         return retval;
 375 }
 376
 377 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
 378 {
 379         struct rpc_xprt *xprt = data;
 380
 381         xprt->snd_task = task;
 382         return true;
 383 }
 384
 385 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 386 {
 387         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 388                 return;
 389         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 390                 goto out_unlock;
 391         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 392                                 __xprt_lock_write_func, xprt))
 393                 return;
 394 out_unlock:
 395         xprt_clear_locked(xprt);
 396 }
 397
 398 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 399 {
 400         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 401                 return;
 402         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 403                 goto out_unlock;
 404         if (xprt_need_congestion_window_wait(xprt))
 405                 goto out_unlock;
 406         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 407                                 __xprt_lock_write_func, xprt))
 408                 return;
 409 out_unlock:
 410         xprt_clear_locked(xprt);
 411 }
 412
 413 /**
 414  * xprt_release_xprt - allow other requests to use a transport
 415  * @xprt: transport with other tasks potentially waiting
 416  * @task: task that is releasing access to the transport
 417  *
 418  * Note that "task" can be NULL.  No congestion control is provided.
 419  */
 420 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 421 {
 422         if (xprt->snd_task == task) {
 423                 xprt_clear_locked(xprt);
 424                 __xprt_lock_write_next(xprt);
 425         }
 426         trace_xprt_release_xprt(xprt, task);
 427 }
 428 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 429
 430 /**
 431  * xprt_release_xprt_cong - allow other requests to use a transport
 432  * @xprt: transport with other tasks potentially waiting
 433  * @task: task that is releasing access to the transport
 434  *
 435  * Note that "task" can be NULL.  Another task is awoken to use the
 436  * transport if the transport's congestion window allows it.
 437  */
 438 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 439 {
 440         if (xprt->snd_task == task) {
 441                 xprt_clear_locked(xprt);
 442                 __xprt_lock_write_next_cong(xprt);
 443         }
 444         trace_xprt_release_cong(xprt, task);
 445 }
 446 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 447
 448 void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 449 {
 450         if (xprt->snd_task != task)
 451                 return;
 452         spin_lock(&xprt->transport_lock);
 453         xprt->ops->release_xprt(xprt, task);
 454         spin_unlock(&xprt->transport_lock);
 455 }
 456
 457 /*
 458  * Van Jacobson congestion avoidance. Check if the congestion window
 459  * overflowed. Put the task to sleep if this is the case.
 460  */
 461 static int
 462 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 463 {
 464         if (req->rq_cong)
 465                 return 1;
 466         trace_xprt_get_cong(xprt, req->rq_task);
 467         if (RPCXPRT_CONGESTED(xprt)) {
 468                 xprt_set_congestion_window_wait(xprt);
 469                 return 0;
 470         }
 471         req->rq_cong = 1;
 472         xprt->cong += RPC_CWNDSCALE;
 473         return 1;
 474 }
 475
 476 /*
 477  * Adjust the congestion window, and wake up the next task
 478  * that has been sleeping due to congestion
 479  */
 480 static void
 481 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 482 {
 483         if (!req->rq_cong)
 484                 return;
 485         req->rq_cong = 0;
 486         xprt->cong -= RPC_CWNDSCALE;
 487         xprt_test_and_clear_congestion_window_wait(xprt);
 488         trace_xprt_put_cong(xprt, req->rq_task);
 489         __xprt_lock_write_next_cong(xprt);
 490 }
 491
 492 /**
 493  * xprt_request_get_cong - Request congestion control credits
 494  * @xprt: pointer to transport
 495  * @req: pointer to RPC request
 496  *
 497  * Useful for transports that require congestion control.
 498  */
 499 bool
 500 xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 501 {
 502         bool ret = false;
 503
 504         if (req->rq_cong)
 505                 return true;
 506         spin_lock(&xprt->transport_lock);
 507         ret = __xprt_get_cong(xprt, req) != 0;
 508         spin_unlock(&xprt->transport_lock);
 509         return ret;
 510 }
 511 EXPORT_SYMBOL_GPL(xprt_request_get_cong);
 512
 513 /**
 514  * xprt_release_rqst_cong - housekeeping when request is complete
 515  * @task: RPC request that recently completed
 516  *
 517  * Useful for transports that require congestion control.
 518  */
 519 void xprt_release_rqst_cong(struct rpc_task *task)
 520 {
 521         struct rpc_rqst *req = task->tk_rqstp;
 522
 523         __xprt_put_cong(req->rq_xprt, req);
 524 }
 525 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 526
 527 static void xprt_clear_congestion_window_wait_locked(struct rpc_xprt *xprt)
 528 {
 529         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state))
 530                 __xprt_lock_write_next_cong(xprt);
 531 }
 532
 533 /*
 534  * Clear the congestion window wait flag and wake up the next
 535  * entry on xprt->sending
 536  */
 537 static void
 538 xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
 539 {
 540         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
 541                 spin_lock(&xprt->transport_lock);
 542                 __xprt_lock_write_next_cong(xprt);
 543                 spin_unlock(&xprt->transport_lock);
 544         }
 545 }
 546
 547 /**
 548  * xprt_adjust_cwnd - adjust transport congestion window
 549  * @xprt: pointer to xprt
 550  * @task: recently completed RPC request used to adjust window
 551  * @result: result code of completed RPC request
 552  *
 553  * The transport code maintains an estimate on the maximum number of out-
 554  * standing RPC requests, using a smoothed version of the congestion
 555  * avoidance implemented in 44BSD. This is basically the Van Jacobson
 556  * congestion algorithm: If a retransmit occurs, the congestion window is
 557  * halved; otherwise, it is incremented by 1/cwnd when
 558  *
 559  *      -       a reply is received and
 560  *      -       a full number of requests are outstanding and
 561  *      -       the congestion window hasn't been updated recently.
 562  */
 563 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
 564 {
 565         struct rpc_rqst *req = task->tk_rqstp;
 566         unsigned long cwnd = xprt->cwnd;
 567
 568         if (result >= 0 && cwnd <= xprt->cong) {
 569                 /* The (cwnd >> 1) term makes sure
 570                  * the result gets rounded properly. */
 571                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 572                 if (cwnd > RPC_MAXCWND(xprt))
 573                         cwnd = RPC_MAXCWND(xprt);
 574                 __xprt_lock_write_next_cong(xprt);
 575         } else if (result == -ETIMEDOUT) {
 576                 cwnd >>= 1;
 577                 if (cwnd < RPC_CWNDSCALE)
 578                         cwnd = RPC_CWNDSCALE;
 579         }
 580         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 581                         xprt->cong, xprt->cwnd, cwnd);
 582         xprt->cwnd = cwnd;
 583         __xprt_put_cong(xprt, req);
 584 }
 585 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 586
 587 /**
 588  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 589  * @xprt: transport with waiting tasks
 590  * @status: result code to plant in each task before waking it
 591  *
 592  */
 593 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 594 {
 595         if (status < 0)
 596                 rpc_wake_up_status(&xprt->pending, status);
 597         else
 598                 rpc_wake_up(&xprt->pending);
 599 }
 600 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 601
 602 /**
 603  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 604  * @xprt: transport
 605  *
 606  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
 607  * we don't in general want to force a socket disconnection due to
 608  * an incomplete RPC call transmission.
 609  */
 610 void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
 611 {
 612         set_bit(XPRT_WRITE_SPACE, &xprt->state);
 613 }
 614 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 615
 616 static bool
 617 xprt_clear_write_space_locked(struct rpc_xprt *xprt)
 618 {
 619         if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
 620                 __xprt_lock_write_next(xprt);
 621                 dprintk("RPC:       write space: waking waiting task on "
 622                                 "xprt %p\n", xprt);
 623                 return true;
 624         }
 625         return false;
 626 }
 627
 628 /**
 629  * xprt_write_space - wake the task waiting for transport output buffer space
 630  * @xprt: transport with waiting tasks
 631  *
 632  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 633  */
 634 bool xprt_write_space(struct rpc_xprt *xprt)
 635 {
 636         bool ret;
 637
 638         if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
 639                 return false;
 640         spin_lock(&xprt->transport_lock);
 641         ret = xprt_clear_write_space_locked(xprt);
 642         spin_unlock(&xprt->transport_lock);
 643         return ret;
 644 }
 645 EXPORT_SYMBOL_GPL(xprt_write_space);
 646
 647 static unsigned long xprt_abs_ktime_to_jiffies(ktime_t abstime)
 648 {
 649         s64 delta = ktime_to_ns(ktime_get() - abstime);
 650         return likely(delta >= 0) ?
 651                 jiffies - nsecs_to_jiffies(delta) :
 652                 jiffies + nsecs_to_jiffies(-delta);
 653 }
 654
 655 static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req)
 656 {
 657         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 658         unsigned long majortimeo = req->rq_timeout;
 659
 660         if (to->to_exponential)
 661                 majortimeo <<= to->to_retries;
 662         else
 663                 majortimeo += to->to_increment * to->to_retries;
 664         if (majortimeo > to->to_maxval || majortimeo == 0)
 665                 majortimeo = to->to_maxval;
 666         return majortimeo;
 667 }
 668
 669 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 670 {
 671         req->rq_majortimeo += xprt_calc_majortimeo(req);
 672 }
 673
 674 static void xprt_reset_minortimeo(struct rpc_rqst *req)
 675 {
 676         req->rq_minortimeo += req->rq_timeout;
 677 }
 678
 679 static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
 680 {
 681         unsigned long time_init;
 682         struct rpc_xprt *xprt = req->rq_xprt;
 683
 684         if (likely(xprt && xprt_connected(xprt)))
 685                 time_init = jiffies;
 686         else
 687                 time_init = xprt_abs_ktime_to_jiffies(task->tk_start);
 688         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
 689         req->rq_majortimeo = time_init + xprt_calc_majortimeo(req);
 690         req->rq_minortimeo = time_init + req->rq_timeout;
 691 }
 692
 693 /**
 694  * xprt_adjust_timeout - adjust timeout values for next retransmit
 695  * @req: RPC request containing parameters to use for the adjustment
 696  *
 697  */
 698 int xprt_adjust_timeout(struct rpc_rqst *req)
 699 {
 700         struct rpc_xprt *xprt = req->rq_xprt;
 701         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 702         int status = 0;
 703
 704         if (time_before(jiffies, req->rq_majortimeo)) {
 705                 if (time_before(jiffies, req->rq_minortimeo))
 706                         return status;
 707                 if (to->to_exponential)
 708                         req->rq_timeout <<= 1;
 709                 else
 710                         req->rq_timeout += to->to_increment;
 711                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 712                         req->rq_timeout = to->to_maxval;
 713                 req->rq_retries++;
 714         } else {
 715                 req->rq_timeout = to->to_initval;
 716                 req->rq_retries = 0;
 717                 xprt_reset_majortimeo(req);
 718                 /* Reset the RTT counters == "slow start" */
 719                 spin_lock(&xprt->transport_lock);
 720                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 721                 spin_unlock(&xprt->transport_lock);
 722                 status = -ETIMEDOUT;
 723         }
 724         xprt_reset_minortimeo(req);
 725
 726         if (req->rq_timeout == 0) {
 727                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 728                 req->rq_timeout = 5 * HZ;
 729         }
 730         return status;
 731 }
 732
 733 static void xprt_autoclose(struct work_struct *work)
 734 {
 735         struct rpc_xprt *xprt =
 736                 container_of(work, struct rpc_xprt, task_cleanup);
 737         unsigned int pflags = memalloc_nofs_save();
 738
 739         trace_xprt_disconnect_auto(xprt);
 740         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 741         xprt->ops->close(xprt);
 742         xprt_release_write(xprt, NULL);
 743         wake_up_bit(&xprt->state, XPRT_LOCKED);
 744         memalloc_nofs_restore(pflags);
 745 }
 746
 747 /**
 748  * xprt_disconnect_done - mark a transport as disconnected
 749  * @xprt: transport to flag for disconnect
 750  *
 751  */
 752 void xprt_disconnect_done(struct rpc_xprt *xprt)
 753 {
 754         trace_xprt_disconnect_done(xprt);
 755         spin_lock(&xprt->transport_lock);
 756         xprt_clear_connected(xprt);
 757         xprt_clear_write_space_locked(xprt);
 758         xprt_clear_congestion_window_wait_locked(xprt);
 759         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 760         spin_unlock(&xprt->transport_lock);
 761 }
 762 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 763
 764 /**
 765  * xprt_schedule_autoclose_locked - Try to schedule an autoclose RPC call
 766  * @xprt: transport to disconnect
 767  */
 768 static void xprt_schedule_autoclose_locked(struct rpc_xprt *xprt)
 769 {
 770         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 771         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 772                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 773         else if (xprt->snd_task && !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
 774                 rpc_wake_up_queued_task_set_status(&xprt->pending,
 775                                                    xprt->snd_task, -ENOTCONN);
 776 }
 777
 778 /**
 779  * xprt_force_disconnect - force a transport to disconnect
 780  * @xprt: transport to disconnect
 781  *
 782  */
 783 void xprt_force_disconnect(struct rpc_xprt *xprt)
 784 {
 785         trace_xprt_disconnect_force(xprt);
 786
 787         /* Don't race with the test_bit() in xprt_clear_locked() */
 788         spin_lock(&xprt->transport_lock);
 789         xprt_schedule_autoclose_locked(xprt);
 790         spin_unlock(&xprt->transport_lock);
 791 }
 792 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
 793
 794 static unsigned int
 795 xprt_connect_cookie(struct rpc_xprt *xprt)
 796 {
 797         return READ_ONCE(xprt->connect_cookie);
 798 }
 799
 800 static bool
 801 xprt_request_retransmit_after_disconnect(struct rpc_task *task)
 802 {
 803         struct rpc_rqst *req = task->tk_rqstp;
 804         struct rpc_xprt *xprt = req->rq_xprt;
 805
 806         return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
 807                 !xprt_connected(xprt);
 808 }
 809
 810 /**
 811  * xprt_conditional_disconnect - force a transport to disconnect
 812  * @xprt: transport to disconnect
 813  * @cookie: 'connection cookie'
 814  *
 815  * This attempts to break the connection if and only if 'cookie' matches
 816  * the current transport 'connection cookie'. It ensures that we don't
 817  * try to break the connection more than once when we need to retransmit
 818  * a batch of RPC requests.
 819  *
 820  */
 821 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 822 {
 823         /* Don't race with the test_bit() in xprt_clear_locked() */
 824         spin_lock(&xprt->transport_lock);
 825         if (cookie != xprt->connect_cookie)
 826                 goto out;
 827         if (test_bit(XPRT_CLOSING, &xprt->state))
 828                 goto out;
 829         xprt_schedule_autoclose_locked(xprt);
 830 out:
 831         spin_unlock(&xprt->transport_lock);
 832 }
 833
 834 static bool
 835 xprt_has_timer(const struct rpc_xprt *xprt)
 836 {
 837         return xprt->idle_timeout != 0;
 838 }
 839
 840 static void
 841 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
 842         __must_hold(&xprt->transport_lock)
 843 {
 844         xprt->last_used = jiffies;
 845         if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))
 846                 mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
 847 }
 848
 849 static void
 850 xprt_init_autodisconnect(struct timer_list *t)
 851 {
 852         struct rpc_xprt *xprt = from_timer(xprt, t, timer);
 853
 854         if (!RB_EMPTY_ROOT(&xprt->recv_queue))
 855                 return;
 856         /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
 857         xprt->last_used = jiffies;
 858         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 859                 return;
 860         queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 861 }
 862
 863 #if IS_ENABLED(CONFIG_FAIL_SUNRPC)
 864 static void xprt_inject_disconnect(struct rpc_xprt *xprt)
 865 {
 866         if (!fail_sunrpc.ignore_client_disconnect &&
 867             should_fail(&fail_sunrpc.attr, 1))
 868                 xprt->ops->inject_disconnect(xprt);
 869 }
 870 #else
 871 static inline void xprt_inject_disconnect(struct rpc_xprt *xprt)
 872 {
 873 }
 874 #endif
 875
 876 bool xprt_lock_connect(struct rpc_xprt *xprt,
 877                 struct rpc_task *task,
 878                 void *cookie)
 879 {
 880         bool ret = false;
 881
 882         spin_lock(&xprt->transport_lock);
 883         if (!test_bit(XPRT_LOCKED, &xprt->state))
 884                 goto out;
 885         if (xprt->snd_task != task)
 886                 goto out;
 887         set_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 888         xprt->snd_task = cookie;
 889         ret = true;
 890 out:
 891         spin_unlock(&xprt->transport_lock);
 892         return ret;
 893 }
 894 EXPORT_SYMBOL_GPL(xprt_lock_connect);
 895
 896 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
 897 {
 898         spin_lock(&xprt->transport_lock);
 899         if (xprt->snd_task != cookie)
 900                 goto out;
 901         if (!test_bit(XPRT_LOCKED, &xprt->state))
 902                 goto out;
 903         xprt->snd_task =NULL;
 904         clear_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 905         xprt->ops->release_xprt(xprt, NULL);
 906         xprt_schedule_autodisconnect(xprt);
 907 out:
 908         spin_unlock(&xprt->transport_lock);
 909         wake_up_bit(&xprt->state, XPRT_LOCKED);
 910 }
 911 EXPORT_SYMBOL_GPL(xprt_unlock_connect);
 912
 913 /**
 914  * xprt_connect - schedule a transport connect operation
 915  * @task: RPC task that is requesting the connect
 916  *
 917  */
 918 void xprt_connect(struct rpc_task *task)
 919 {
 920         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 921
 922         trace_xprt_connect(xprt);
 923
 924         if (!xprt_bound(xprt)) {
 925                 task->tk_status = -EAGAIN;
 926                 return;
 927         }
 928         if (!xprt_lock_write(xprt, task))
 929                 return;
 930
 931         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 932                 trace_xprt_disconnect_cleanup(xprt);
 933                 xprt->ops->close(xprt);
 934         }
 935
 936         if (!xprt_connected(xprt)) {
 937                 task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
 938                 rpc_sleep_on_timeout(&xprt->pending, task, NULL,
 939                                 xprt_request_timeout(task->tk_rqstp));
 940
 941                 if (test_bit(XPRT_CLOSING, &xprt->state))
 942                         return;
 943                 if (xprt_test_and_set_connecting(xprt))
 944                         return;
 945                 /* Race breaker */
 946                 if (!xprt_connected(xprt)) {
 947                         xprt->stat.connect_start = jiffies;
 948                         xprt->ops->connect(xprt, task);
 949                 } else {
 950                         xprt_clear_connecting(xprt);
 951                         task->tk_status = 0;
 952                         rpc_wake_up_queued_task(&xprt->pending, task);
 953                 }
 954         }
 955         xprt_release_write(xprt, task);
 956 }
 957
 958 /**
 959  * xprt_reconnect_delay - compute the wait before scheduling a connect
 960  * @xprt: transport instance
 961  *
 962  */
 963 unsigned long xprt_reconnect_delay(const struct rpc_xprt *xprt)
 964 {
 965         unsigned long start, now = jiffies;
 966
 967         start = xprt->stat.connect_start + xprt->reestablish_timeout;
 968         if (time_after(start, now))
 969                 return start - now;
 970         return 0;
 971 }
 972 EXPORT_SYMBOL_GPL(xprt_reconnect_delay);
 973
 974 /**
 975  * xprt_reconnect_backoff - compute the new re-establish timeout
 976  * @xprt: transport instance
 977  * @init_to: initial reestablish timeout
 978  *
 979  */
 980 void xprt_reconnect_backoff(struct rpc_xprt *xprt, unsigned long init_to)
 981 {
 982         xprt->reestablish_timeout <<= 1;
 983         if (xprt->reestablish_timeout > xprt->max_reconnect_timeout)
 984                 xprt->reestablish_timeout = xprt->max_reconnect_timeout;
 985         if (xprt->reestablish_timeout < init_to)
 986                 xprt->reestablish_timeout = init_to;
 987 }
 988 EXPORT_SYMBOL_GPL(xprt_reconnect_backoff);
 989
 990 enum xprt_xid_rb_cmp {
 991         XID_RB_EQUAL,
 992         XID_RB_LEFT,
 993         XID_RB_RIGHT,
 994 };
 995 static enum xprt_xid_rb_cmp
 996 xprt_xid_cmp(__be32 xid1, __be32 xid2)
 997 {
 998         if (xid1 == xid2)
 999                 return XID_RB_EQUAL;
1000         if ((__force u32)xid1 < (__force u32)xid2)
1001                 return XID_RB_LEFT;
1002         return XID_RB_RIGHT;
1003 }
1004
1005 static struct rpc_rqst *
1006 xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
1007 {
1008         struct rb_node *n = xprt->recv_queue.rb_node;
1009         struct rpc_rqst *req;
1010
1011         while (n != NULL) {
1012                 req = rb_entry(n, struct rpc_rqst, rq_recv);
1013                 switch (xprt_xid_cmp(xid, req->rq_xid)) {
1014                 case XID_RB_LEFT:
1015                         n = n->rb_left;
1016                         break;
1017                 case XID_RB_RIGHT:
1018                         n = n->rb_right;
1019                         break;
1020                 case XID_RB_EQUAL:
1021                         return req;
1022                 }
1023         }
1024         return NULL;
1025 }
1026
1027 static void
1028 xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
1029 {
1030         struct rb_node **p = &xprt->recv_queue.rb_node;
1031         struct rb_node *n = NULL;
1032         struct rpc_rqst *req;
1033
1034         while (*p != NULL) {
1035                 n = *p;
1036                 req = rb_entry(n, struct rpc_rqst, rq_recv);
1037                 switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
1038                 case XID_RB_LEFT:
1039                         p = &n->rb_left;
1040                         break;
1041                 case XID_RB_RIGHT:
1042                         p = &n->rb_right;
1043                         break;
1044                 case XID_RB_EQUAL:
1045                         WARN_ON_ONCE(new != req);
1046                         return;
1047                 }
1048         }
1049         rb_link_node(&new->rq_recv, n, p);
1050         rb_insert_color(&new->rq_recv, &xprt->recv_queue);
1051 }
1052
1053 static void
1054 xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
1055 {
1056         rb_erase(&req->rq_recv, &xprt->recv_queue);
1057 }
1058
1059 /**
1060  * xprt_lookup_rqst - find an RPC request corresponding to an XID
1061  * @xprt: transport on which the original request was transmitted
1062  * @xid: RPC XID of incoming reply
1063  *
1064  * Caller holds xprt->queue_lock.
1065  */
1066 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
1067 {
1068         struct rpc_rqst *entry;
1069
1070         entry = xprt_request_rb_find(xprt, xid);
1071         if (entry != NULL) {
1072                 trace_xprt_lookup_rqst(xprt, xid, 0);
1073                 entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
1074                 return entry;
1075         }
1076
1077         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
1078                         ntohl(xid));
1079         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
1080         xprt->stat.bad_xids++;
1081         return NULL;
1082 }
1083 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
1084
1085 static bool
1086 xprt_is_pinned_rqst(struct rpc_rqst *req)
1087 {
1088         return atomic_read(&req->rq_pin) != 0;
1089 }
1090
1091 /**
1092  * xprt_pin_rqst - Pin a request on the transport receive list
1093  * @req: Request to pin
1094  *
1095  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
1096  * so should be holding xprt->queue_lock.
1097  */
1098 void xprt_pin_rqst(struct rpc_rqst *req)
1099 {
1100         atomic_inc(&req->rq_pin);
1101 }
1102 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
1103
1104 /**
1105  * xprt_unpin_rqst - Unpin a request on the transport receive list
1106  * @req: Request to pin
1107  *
1108  * Caller should be holding xprt->queue_lock.
1109  */
1110 void xprt_unpin_rqst(struct rpc_rqst *req)
1111 {
1112         if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
1113                 atomic_dec(&req->rq_pin);
1114                 return;
1115         }
1116         if (atomic_dec_and_test(&req->rq_pin))
1117                 wake_up_var(&req->rq_pin);
1118 }
1119 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
1120
1121 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
1122 {
1123         wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
1124 }
1125
1126 static bool
1127 xprt_request_data_received(struct rpc_task *task)
1128 {
1129         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1130                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
1131 }
1132
1133 static bool
1134 xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
1135 {
1136         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1137                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
1138 }
1139
1140 /**
1141  * xprt_request_enqueue_receive - Add an request to the receive queue
1142  * @task: RPC task
1143  *
1144  */
1145 void
1146 xprt_request_enqueue_receive(struct rpc_task *task)
1147 {
1148         struct rpc_rqst *req = task->tk_rqstp;
1149         struct rpc_xprt *xprt = req->rq_xprt;
1150
1151         if (!xprt_request_need_enqueue_receive(task, req))
1152                 return;
1153
1154         xprt_request_prepare(task->tk_rqstp);
1155         spin_lock(&xprt->queue_lock);
1156
1157         /* Update the softirq receive buffer */
1158         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1159                         sizeof(req->rq_private_buf));
1160
1161         /* Add request to the receive list */
1162         xprt_request_rb_insert(xprt, req);
1163         set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
1164         spin_unlock(&xprt->queue_lock);
1165
1166         /* Turn off autodisconnect */
1167         del_singleshot_timer_sync(&xprt->timer);
1168 }
1169
1170 /**
1171  * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
1172  * @task: RPC task
1173  *
1174  * Caller must hold xprt->queue_lock.
1175  */
1176 static void
1177 xprt_request_dequeue_receive_locked(struct rpc_task *task)
1178 {
1179         struct rpc_rqst *req = task->tk_rqstp;
1180
1181         if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1182                 xprt_request_rb_remove(req->rq_xprt, req);
1183 }
1184
1185 /**
1186  * xprt_update_rtt - Update RPC RTT statistics
1187  * @task: RPC request that recently completed
1188  *
1189  * Caller holds xprt->queue_lock.
1190  */
1191 void xprt_update_rtt(struct rpc_task *task)
1192 {
1193         struct rpc_rqst *req = task->tk_rqstp;
1194         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
1195         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
1196         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
1197
1198         if (timer) {
1199                 if (req->rq_ntrans == 1)
1200                         rpc_update_rtt(rtt, timer, m);
1201                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
1202         }
1203 }
1204 EXPORT_SYMBOL_GPL(xprt_update_rtt);
1205
1206 /**
1207  * xprt_complete_rqst - called when reply processing is complete
1208  * @task: RPC request that recently completed
1209  * @copied: actual number of bytes received from the transport
1210  *
1211  * Caller holds xprt->queue_lock.
1212  */
1213 void xprt_complete_rqst(struct rpc_task *task, int copied)
1214 {
1215         struct rpc_rqst *req = task->tk_rqstp;
1216         struct rpc_xprt *xprt = req->rq_xprt;
1217
1218         xprt->stat.recvs++;
1219
1220         req->rq_private_buf.len = copied;
1221         /* Ensure all writes are done before we update */
1222         /* req->rq_reply_bytes_recvd */
1223         smp_wmb();
1224         req->rq_reply_bytes_recvd = copied;
1225         xprt_request_dequeue_receive_locked(task);
1226         rpc_wake_up_queued_task(&xprt->pending, task);
1227 }
1228 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
1229
1230 static void xprt_timer(struct rpc_task *task)
1231 {
1232         struct rpc_rqst *req = task->tk_rqstp;
1233         struct rpc_xprt *xprt = req->rq_xprt;
1234
1235         if (task->tk_status != -ETIMEDOUT)
1236                 return;
1237
1238         trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
1239         if (!req->rq_reply_bytes_recvd) {
1240                 if (xprt->ops->timer)
1241                         xprt->ops->timer(xprt, task);
1242         } else
1243                 task->tk_status = 0;
1244 }
1245
1246 /**
1247  * xprt_wait_for_reply_request_def - wait for reply
1248  * @task: pointer to rpc_task
1249  *
1250  * Set a request's retransmit timeout based on the transport's
1251  * default timeout parameters.  Used by transports that don't adjust
1252  * the retransmit timeout based on round-trip time estimation,
1253  * and put the task to sleep on the pending queue.
1254  */
1255 void xprt_wait_for_reply_request_def(struct rpc_task *task)
1256 {
1257         struct rpc_rqst *req = task->tk_rqstp;
1258
1259         rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1260                         xprt_request_timeout(req));
1261 }
1262 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_def);
1263
1264 /**
1265  * xprt_wait_for_reply_request_rtt - wait for reply using RTT estimator
1266  * @task: pointer to rpc_task
1267  *
1268  * Set a request's retransmit timeout using the RTT estimator,
1269  * and put the task to sleep on the pending queue.
1270  */
1271 void xprt_wait_for_reply_request_rtt(struct rpc_task *task)
1272 {
1273         int timer = task->tk_msg.rpc_proc->p_timer;
1274         struct rpc_clnt *clnt = task->tk_client;
1275         struct rpc_rtt *rtt = clnt->cl_rtt;
1276         struct rpc_rqst *req = task->tk_rqstp;
1277         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
1278         unsigned long timeout;
1279
1280         timeout = rpc_calc_rto(rtt, timer);
1281         timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
1282         if (timeout > max_timeout || timeout == 0)
1283                 timeout = max_timeout;
1284         rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1285                         jiffies + timeout);
1286 }
1287 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_rtt);
1288
1289 /**
1290  * xprt_request_wait_receive - wait for the reply to an RPC request
1291  * @task: RPC task about to send a request
1292  *
1293  */
1294 void xprt_request_wait_receive(struct rpc_task *task)
1295 {
1296         struct rpc_rqst *req = task->tk_rqstp;
1297         struct rpc_xprt *xprt = req->rq_xprt;
1298
1299         if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1300                 return;
1301         /*
1302          * Sleep on the pending queue if we're expecting a reply.
1303          * The spinlock ensures atomicity between the test of
1304          * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1305          */
1306         spin_lock(&xprt->queue_lock);
1307         if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
1308                 xprt->ops->wait_for_reply_request(task);
1309                 /*
1310                  * Send an extra queue wakeup call if the
1311                  * connection was dropped in case the call to
1312                  * rpc_sleep_on() raced.
1313                  */
1314                 if (xprt_request_retransmit_after_disconnect(task))
1315                         rpc_wake_up_queued_task_set_status(&xprt->pending,
1316                                         task, -ENOTCONN);
1317         }
1318         spin_unlock(&xprt->queue_lock);
1319 }
1320
1321 static bool
1322 xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
1323 {
1324         return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1325 }
1326
1327 /**
1328  * xprt_request_enqueue_transmit - queue a task for transmission
1329  * @task: pointer to rpc_task
1330  *
1331  * Add a task to the transmission queue.
1332  */
1333 void
1334 xprt_request_enqueue_transmit(struct rpc_task *task)
1335 {
1336         struct rpc_rqst *pos, *req = task->tk_rqstp;
1337         struct rpc_xprt *xprt = req->rq_xprt;
1338
1339         if (xprt_request_need_enqueue_transmit(task, req)) {
1340                 req->rq_bytes_sent = 0;
1341                 spin_lock(&xprt->queue_lock);
1342                 /*
1343                  * Requests that carry congestion control credits are added
1344                  * to the head of the list to avoid starvation issues.
1345                  */
1346                 if (req->rq_cong) {
1347                         xprt_clear_congestion_window_wait(xprt);
1348                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1349                                 if (pos->rq_cong)
1350                                         continue;
1351                                 /* Note: req is added _before_ pos */
1352                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1353                                 INIT_LIST_HEAD(&req->rq_xmit2);
1354                                 goto out;
1355                         }
1356                 } else if (RPC_IS_SWAPPER(task)) {
1357                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1358                                 if (pos->rq_cong || pos->rq_bytes_sent)
1359                                         continue;
1360                                 if (RPC_IS_SWAPPER(pos->rq_task))
1361                                         continue;
1362                                 /* Note: req is added _before_ pos */
1363                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1364                                 INIT_LIST_HEAD(&req->rq_xmit2);
1365                                 goto out;
1366                         }
1367                 } else if (!req->rq_seqno) {
1368                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1369                                 if (pos->rq_task->tk_owner != task->tk_owner)
1370                                         continue;
1371                                 list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
1372                                 INIT_LIST_HEAD(&req->rq_xmit);
1373                                 goto out;
1374                         }
1375                 }
1376                 list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
1377                 INIT_LIST_HEAD(&req->rq_xmit2);
1378 out:
1379                 atomic_long_inc(&xprt->xmit_queuelen);
1380                 set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1381                 spin_unlock(&xprt->queue_lock);
1382         }
1383 }
1384
1385 /**
1386  * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
1387  * @task: pointer to rpc_task
1388  *
1389  * Remove a task from the transmission queue
1390  * Caller must hold xprt->queue_lock
1391  */
1392 static void
1393 xprt_request_dequeue_transmit_locked(struct rpc_task *task)
1394 {
1395         struct rpc_rqst *req = task->tk_rqstp;
1396
1397         if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1398                 return;
1399         if (!list_empty(&req->rq_xmit)) {
1400                 list_del(&req->rq_xmit);
1401                 if (!list_empty(&req->rq_xmit2)) {
1402                         struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
1403                                         struct rpc_rqst, rq_xmit2);
1404                         list_del(&req->rq_xmit2);
1405                         list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
1406                 }
1407         } else
1408                 list_del(&req->rq_xmit2);
1409         atomic_long_dec(&req->rq_xprt->xmit_queuelen);
1410 }
1411
1412 /**
1413  * xprt_request_dequeue_transmit - remove a task from the transmission queue
1414  * @task: pointer to rpc_task
1415  *
1416  * Remove a task from the transmission queue
1417  */
1418 static void
1419 xprt_request_dequeue_transmit(struct rpc_task *task)
1420 {
1421         struct rpc_rqst *req = task->tk_rqstp;
1422         struct rpc_xprt *xprt = req->rq_xprt;
1423
1424         spin_lock(&xprt->queue_lock);
1425         xprt_request_dequeue_transmit_locked(task);
1426         spin_unlock(&xprt->queue_lock);
1427 }
1428
1429 /**
1430  * xprt_request_dequeue_xprt - remove a task from the transmit+receive queue
1431  * @task: pointer to rpc_task
1432  *
1433  * Remove a task from the transmit and receive queues, and ensure that
1434  * it is not pinned by the receive work item.
1435  */
1436 void
1437 xprt_request_dequeue_xprt(struct rpc_task *task)
1438 {
1439         struct rpc_rqst *req = task->tk_rqstp;
1440         struct rpc_xprt *xprt = req->rq_xprt;
1441
1442         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
1443             test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
1444             xprt_is_pinned_rqst(req)) {
1445                 spin_lock(&xprt->queue_lock);
1446                 xprt_request_dequeue_transmit_locked(task);
1447                 xprt_request_dequeue_receive_locked(task);
1448                 while (xprt_is_pinned_rqst(req)) {
1449                         set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1450                         spin_unlock(&xprt->queue_lock);
1451                         xprt_wait_on_pinned_rqst(req);
1452                         spin_lock(&xprt->queue_lock);
1453                         clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1454                 }
1455                 spin_unlock(&xprt->queue_lock);
1456         }
1457 }
1458
1459 /**
1460  * xprt_request_prepare - prepare an encoded request for transport
1461  * @req: pointer to rpc_rqst
1462  *
1463  * Calls into the transport layer to do whatever is needed to prepare
1464  * the request for transmission or receive.
1465  */
1466 void
1467 xprt_request_prepare(struct rpc_rqst *req)
1468 {
1469         struct rpc_xprt *xprt = req->rq_xprt;
1470
1471         if (xprt->ops->prepare_request)
1472                 xprt->ops->prepare_request(req);
1473 }
1474
1475 /**
1476  * xprt_request_need_retransmit - Test if a task needs retransmission
1477  * @task: pointer to rpc_task
1478  *
1479  * Test for whether a connection breakage requires the task to retransmit
1480  */
1481 bool
1482 xprt_request_need_retransmit(struct rpc_task *task)
1483 {
1484         return xprt_request_retransmit_after_disconnect(task);
1485 }
1486
1487 /**
1488  * xprt_prepare_transmit - reserve the transport before sending a request
1489  * @task: RPC task about to send a request
1490  *
1491  */
1492 bool xprt_prepare_transmit(struct rpc_task *task)
1493 {
1494         struct rpc_rqst *req = task->tk_rqstp;
1495         struct rpc_xprt *xprt = req->rq_xprt;
1496
1497         if (!xprt_lock_write(xprt, task)) {
1498                 /* Race breaker: someone may have transmitted us */
1499                 if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1500                         rpc_wake_up_queued_task_set_status(&xprt->sending,
1501                                         task, 0);
1502                 return false;
1503
1504         }
1505         return true;
1506 }
1507
1508 void xprt_end_transmit(struct rpc_task *task)
1509 {
1510         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
1511
1512         xprt_inject_disconnect(xprt);
1513         xprt_release_write(xprt, task);
1514 }
1515
1516 /**
1517  * xprt_request_transmit - send an RPC request on a transport
1518  * @req: pointer to request to transmit
1519  * @snd_task: RPC task that owns the transport lock
1520  *
1521  * This performs the transmission of a single request.
1522  * Note that if the request is not the same as snd_task, then it
1523  * does need to be pinned.
1524  * Returns '0' on success.
1525  */
1526 static int
1527 xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
1528 {
1529         struct rpc_xprt *xprt = req->rq_xprt;
1530         struct rpc_task *task = req->rq_task;
1531         unsigned int connect_cookie;
1532         int is_retrans = RPC_WAS_SENT(task);
1533         int status;
1534
1535         if (!req->rq_bytes_sent) {
1536                 if (xprt_request_data_received(task)) {
1537                         status = 0;
1538                         goto out_dequeue;
1539                 }
1540                 /* Verify that our message lies in the RPCSEC_GSS window */
1541                 if (rpcauth_xmit_need_reencode(task)) {
1542                         status = -EBADMSG;
1543                         goto out_dequeue;
1544                 }
1545                 if (RPC_SIGNALLED(task)) {
1546                         status = -ERESTARTSYS;
1547                         goto out_dequeue;
1548                 }
1549         }
1550
1551         /*
1552          * Update req->rq_ntrans before transmitting to avoid races with
1553          * xprt_update_rtt(), which needs to know that it is recording a
1554          * reply to the first transmission.
1555          */
1556         req->rq_ntrans++;
1557
1558         trace_rpc_xdr_sendto(task, &req->rq_snd_buf);
1559         connect_cookie = xprt->connect_cookie;
1560         status = xprt->ops->send_request(req);
1561         if (status != 0) {
1562                 req->rq_ntrans--;
1563                 trace_xprt_transmit(req, status);
1564                 return status;
1565         }
1566
1567         if (is_retrans) {
1568                 task->tk_client->cl_stats->rpcretrans++;
1569                 trace_xprt_retransmit(req);
1570         }
1571
1572         xprt_inject_disconnect(xprt);
1573
1574         task->tk_flags |= RPC_TASK_SENT;
1575         spin_lock(&xprt->transport_lock);
1576
1577         xprt->stat.sends++;
1578         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1579         xprt->stat.bklog_u += xprt->backlog.qlen;
1580         xprt->stat.sending_u += xprt->sending.qlen;
1581         xprt->stat.pending_u += xprt->pending.qlen;
1582         spin_unlock(&xprt->transport_lock);
1583
1584         req->rq_connect_cookie = connect_cookie;
1585 out_dequeue:
1586         trace_xprt_transmit(req, status);
1587         xprt_request_dequeue_transmit(task);
1588         rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
1589         return status;
1590 }
1591
1592 /**
1593  * xprt_transmit - send an RPC request on a transport
1594  * @task: controlling RPC task
1595  *
1596  * Attempts to drain the transmit queue. On exit, either the transport
1597  * signalled an error that needs to be handled before transmission can
1598  * resume, or @task finished transmitting, and detected that it already
1599  * received a reply.
1600  */
1601 void
1602 xprt_transmit(struct rpc_task *task)
1603 {
1604         struct rpc_rqst *next, *req = task->tk_rqstp;
1605         struct rpc_xprt *xprt = req->rq_xprt;
1606         int counter, status;
1607
1608         spin_lock(&xprt->queue_lock);
1609         counter = 0;
1610         while (!list_empty(&xprt->xmit_queue)) {
1611                 if (++counter == 20)
1612                         break;
1613                 next = list_first_entry(&xprt->xmit_queue,
1614                                 struct rpc_rqst, rq_xmit);
1615                 xprt_pin_rqst(next);
1616                 spin_unlock(&xprt->queue_lock);
1617                 status = xprt_request_transmit(next, task);
1618                 if (status == -EBADMSG && next != req)
1619                         status = 0;
1620                 spin_lock(&xprt->queue_lock);
1621                 xprt_unpin_rqst(next);
1622                 if (status == 0) {
1623                         if (!xprt_request_data_received(task) ||
1624                             test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1625                                 continue;
1626                 } else if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1627                         task->tk_status = status;
1628                 break;
1629         }
1630         spin_unlock(&xprt->queue_lock);
1631 }
1632
1633 static void xprt_complete_request_init(struct rpc_task *task)
1634 {
1635         if (task->tk_rqstp)
1636                 xprt_request_init(task);
1637 }
1638
1639 void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1640 {
1641         set_bit(XPRT_CONGESTED, &xprt->state);
1642         rpc_sleep_on(&xprt->backlog, task, xprt_complete_request_init);
1643 }
1644 EXPORT_SYMBOL_GPL(xprt_add_backlog);
1645
1646 static bool __xprt_set_rq(struct rpc_task *task, void *data)
1647 {
1648         struct rpc_rqst *req = data;
1649
1650         if (task->tk_rqstp == NULL) {
1651                 memset(req, 0, sizeof(*req));   /* mark unused */
1652                 task->tk_rqstp = req;
1653                 return true;
1654         }
1655         return false;
1656 }
1657
1658 bool xprt_wake_up_backlog(struct rpc_xprt *xprt, struct rpc_rqst *req)
1659 {
1660         if (rpc_wake_up_first(&xprt->backlog, __xprt_set_rq, req) == NULL) {
1661                 clear_bit(XPRT_CONGESTED, &xprt->state);
1662                 return false;
1663         }
1664         return true;
1665 }
1666 EXPORT_SYMBOL_GPL(xprt_wake_up_backlog);
1667
1668 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1669 {
1670         bool ret = false;
1671
1672         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1673                 goto out;
1674         spin_lock(&xprt->reserve_lock);
1675         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1676                 xprt_add_backlog(xprt, task);
1677                 ret = true;
1678         }
1679         spin_unlock(&xprt->reserve_lock);
1680 out:
1681         return ret;
1682 }
1683
1684 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1685 {
1686         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1687
1688         if (xprt->num_reqs >= xprt->max_reqs)
1689                 goto out;
1690         ++xprt->num_reqs;
1691         spin_unlock(&xprt->reserve_lock);
1692         req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
1693         spin_lock(&xprt->reserve_lock);
1694         if (req != NULL)
1695                 goto out;
1696         --xprt->num_reqs;
1697         req = ERR_PTR(-ENOMEM);
1698 out:
1699         return req;
1700 }
1701
1702 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1703 {
1704         if (xprt->num_reqs > xprt->min_reqs) {
1705                 --xprt->num_reqs;
1706                 kfree(req);
1707                 return true;
1708         }
1709         return false;
1710 }
1711
1712 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1713 {
1714         struct rpc_rqst *req;
1715
1716         spin_lock(&xprt->reserve_lock);
1717         if (!list_empty(&xprt->free)) {
1718                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1719                 list_del(&req->rq_list);
1720                 goto out_init_req;
1721         }
1722         req = xprt_dynamic_alloc_slot(xprt);
1723         if (!IS_ERR(req))
1724                 goto out_init_req;
1725         switch (PTR_ERR(req)) {
1726         case -ENOMEM:
1727                 dprintk("RPC:       dynamic allocation of request slot "
1728                                 "failed! Retrying\n");
1729                 task->tk_status = -ENOMEM;
1730                 break;
1731         case -EAGAIN:
1732                 xprt_add_backlog(xprt, task);
1733                 dprintk("RPC:       waiting for request slot\n");
1734                 fallthrough;
1735         default:
1736                 task->tk_status = -EAGAIN;
1737         }
1738         spin_unlock(&xprt->reserve_lock);
1739         return;
1740 out_init_req:
1741         xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
1742                                      xprt->num_reqs);
1743         spin_unlock(&xprt->reserve_lock);
1744
1745         task->tk_status = 0;
1746         task->tk_rqstp = req;
1747 }
1748 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1749
1750 void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1751 {
1752         spin_lock(&xprt->reserve_lock);
1753         if (!xprt_wake_up_backlog(xprt, req) &&
1754             !xprt_dynamic_free_slot(xprt, req)) {
1755                 memset(req, 0, sizeof(*req));   /* mark unused */
1756                 list_add(&req->rq_list, &xprt->free);
1757         }
1758         spin_unlock(&xprt->reserve_lock);
1759 }
1760 EXPORT_SYMBOL_GPL(xprt_free_slot);
1761
1762 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1763 {
1764         struct rpc_rqst *req;
1765         while (!list_empty(&xprt->free)) {
1766                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1767                 list_del(&req->rq_list);
1768                 kfree(req);
1769         }
1770 }
1771
1772 static DEFINE_IDA(rpc_xprt_ids);
1773
1774 void xprt_cleanup_ids(void)
1775 {
1776         ida_destroy(&rpc_xprt_ids);
1777 }
1778
1779 static int xprt_alloc_id(struct rpc_xprt *xprt)
1780 {
1781         int id;
1782
1783         id = ida_simple_get(&rpc_xprt_ids, 0, 0, GFP_KERNEL);
1784         if (id < 0)
1785                 return id;
1786
1787         xprt->id = id;
1788         return 0;
1789 }
1790
1791 static void xprt_free_id(struct rpc_xprt *xprt)
1792 {
1793         ida_simple_remove(&rpc_xprt_ids, xprt->id);
1794 }
1795
1796 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1797                 unsigned int num_prealloc,
1798                 unsigned int max_alloc)
1799 {
1800         struct rpc_xprt *xprt;
1801         struct rpc_rqst *req;
1802         int i;
1803
1804         xprt = kzalloc(size, GFP_KERNEL);
1805         if (xprt == NULL)
1806                 goto out;
1807
1808         xprt_alloc_id(xprt);
1809         xprt_init(xprt, net);
1810
1811         for (i = 0; i < num_prealloc; i++) {
1812                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1813                 if (!req)
1814                         goto out_free;
1815                 list_add(&req->rq_list, &xprt->free);
1816         }
1817         if (max_alloc > num_prealloc)
1818                 xprt->max_reqs = max_alloc;
1819         else
1820                 xprt->max_reqs = num_prealloc;
1821         xprt->min_reqs = num_prealloc;
1822         xprt->num_reqs = num_prealloc;
1823
1824         return xprt;
1825
1826 out_free:
1827         xprt_free(xprt);
1828 out:
1829         return NULL;
1830 }
1831 EXPORT_SYMBOL_GPL(xprt_alloc);
1832
1833 void xprt_free(struct rpc_xprt *xprt)
1834 {
1835         put_net(xprt->xprt_net);
1836         xprt_free_all_slots(xprt);
1837         xprt_free_id(xprt);
1838         rpc_sysfs_xprt_destroy(xprt);
1839         kfree_rcu(xprt, rcu);
1840 }
1841 EXPORT_SYMBOL_GPL(xprt_free);
1842
1843 static void
1844 xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
1845 {
1846         req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
1847 }
1848
1849 static __be32
1850 xprt_alloc_xid(struct rpc_xprt *xprt)
1851 {
1852         __be32 xid;
1853
1854         spin_lock(&xprt->reserve_lock);
1855         xid = (__force __be32)xprt->xid++;
1856         spin_unlock(&xprt->reserve_lock);
1857         return xid;
1858 }
1859
1860 static void
1861 xprt_init_xid(struct rpc_xprt *xprt)
1862 {
1863         xprt->xid = prandom_u32();
1864 }
1865
1866 static void
1867 xprt_request_init(struct rpc_task *task)
1868 {
1869         struct rpc_xprt *xprt = task->tk_xprt;
1870         struct rpc_rqst *req = task->tk_rqstp;
1871
1872         req->rq_task    = task;
1873         req->rq_xprt    = xprt;
1874         req->rq_buffer  = NULL;
1875         req->rq_xid     = xprt_alloc_xid(xprt);
1876         xprt_init_connect_cookie(req, xprt);
1877         req->rq_snd_buf.len = 0;
1878         req->rq_snd_buf.buflen = 0;
1879         req->rq_rcv_buf.len = 0;
1880         req->rq_rcv_buf.buflen = 0;
1881         req->rq_snd_buf.bvec = NULL;
1882         req->rq_rcv_buf.bvec = NULL;
1883         req->rq_release_snd_buf = NULL;
1884         xprt_init_majortimeo(task, req);
1885
1886         trace_xprt_reserve(req);
1887 }
1888
1889 static void
1890 xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
1891 {
1892         xprt->ops->alloc_slot(xprt, task);
1893         if (task->tk_rqstp != NULL)
1894                 xprt_request_init(task);
1895 }
1896
1897 /**
1898  * xprt_reserve - allocate an RPC request slot
1899  * @task: RPC task requesting a slot allocation
1900  *
1901  * If the transport is marked as being congested, or if no more
1902  * slots are available, place the task on the transport's
1903  * backlog queue.
1904  */
1905 void xprt_reserve(struct rpc_task *task)
1906 {
1907         struct rpc_xprt *xprt = task->tk_xprt;
1908
1909         task->tk_status = 0;
1910         if (task->tk_rqstp != NULL)
1911                 return;
1912
1913         task->tk_status = -EAGAIN;
1914         if (!xprt_throttle_congested(xprt, task))
1915                 xprt_do_reserve(xprt, task);
1916 }
1917
1918 /**
1919  * xprt_retry_reserve - allocate an RPC request slot
1920  * @task: RPC task requesting a slot allocation
1921  *
1922  * If no more slots are available, place the task on the transport's
1923  * backlog queue.
1924  * Note that the only difference with xprt_reserve is that we now
1925  * ignore the value of the XPRT_CONGESTED flag.
1926  */
1927 void xprt_retry_reserve(struct rpc_task *task)
1928 {
1929         struct rpc_xprt *xprt = task->tk_xprt;
1930
1931         task->tk_status = 0;
1932         if (task->tk_rqstp != NULL)
1933                 return;
1934
1935         task->tk_status = -EAGAIN;
1936         xprt_do_reserve(xprt, task);
1937 }
1938
1939 /**
1940  * xprt_release - release an RPC request slot
1941  * @task: task which is finished with the slot
1942  *
1943  */
1944 void xprt_release(struct rpc_task *task)
1945 {
1946         struct rpc_xprt *xprt;
1947         struct rpc_rqst *req = task->tk_rqstp;
1948
1949         if (req == NULL) {
1950                 if (task->tk_client) {
1951                         xprt = task->tk_xprt;
1952                         xprt_release_write(xprt, task);
1953                 }
1954                 return;
1955         }
1956
1957         xprt = req->rq_xprt;
1958         xprt_request_dequeue_xprt(task);
1959         spin_lock(&xprt->transport_lock);
1960         xprt->ops->release_xprt(xprt, task);
1961         if (xprt->ops->release_request)
1962                 xprt->ops->release_request(task);
1963         xprt_schedule_autodisconnect(xprt);
1964         spin_unlock(&xprt->transport_lock);
1965         if (req->rq_buffer)
1966                 xprt->ops->buf_free(task);
1967         xdr_free_bvec(&req->rq_rcv_buf);
1968         xdr_free_bvec(&req->rq_snd_buf);
1969         if (req->rq_cred != NULL)
1970                 put_rpccred(req->rq_cred);
1971         if (req->rq_release_snd_buf)
1972                 req->rq_release_snd_buf(req);
1973
1974         task->tk_rqstp = NULL;
1975         if (likely(!bc_prealloc(req)))
1976                 xprt->ops->free_slot(xprt, req);
1977         else
1978                 xprt_free_bc_request(req);
1979 }
1980
1981 #ifdef CONFIG_SUNRPC_BACKCHANNEL
1982 void
1983 xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
1984 {
1985         struct xdr_buf *xbufp = &req->rq_snd_buf;
1986
1987         task->tk_rqstp = req;
1988         req->rq_task = task;
1989         xprt_init_connect_cookie(req, req->rq_xprt);
1990         /*
1991          * Set up the xdr_buf length.
1992          * This also indicates that the buffer is XDR encoded already.
1993          */
1994         xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
1995                 xbufp->tail[0].iov_len;
1996 }
1997 #endif
1998
1999 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
2000 {
2001         kref_init(&xprt->kref);
2002
2003         spin_lock_init(&xprt->transport_lock);
2004         spin_lock_init(&xprt->reserve_lock);
2005         spin_lock_init(&xprt->queue_lock);
2006
2007         INIT_LIST_HEAD(&xprt->free);
2008         xprt->recv_queue = RB_ROOT;
2009         INIT_LIST_HEAD(&xprt->xmit_queue);
2010 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
2011         spin_lock_init(&xprt->bc_pa_lock);
2012         INIT_LIST_HEAD(&xprt->bc_pa_list);
2013 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
2014         INIT_LIST_HEAD(&xprt->xprt_switch);
2015
2016         xprt->last_used = jiffies;
2017         xprt->cwnd = RPC_INITCWND;
2018         xprt->bind_index = 0;
2019
2020         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
2021         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
2022         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
2023         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
2024
2025         xprt_init_xid(xprt);
2026
2027         xprt->xprt_net = get_net(net);
2028 }
2029
2030 /**
2031  * xprt_create_transport - create an RPC transport
2032  * @args: rpc transport creation arguments
2033  *
2034  */
2035 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
2036 {
2037         struct rpc_xprt *xprt;
2038         const struct xprt_class *t;
2039
2040         t = xprt_class_find_by_ident(args->ident);
2041         if (!t) {
2042                 dprintk("RPC: transport (%d) not supported\n", args->ident);
2043                 return ERR_PTR(-EIO);
2044         }
2045
2046         xprt = t->setup(args);
2047         xprt_class_release(t);
2048
2049         if (IS_ERR(xprt))
2050                 goto out;
2051         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
2052                 xprt->idle_timeout = 0;
2053         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
2054         if (xprt_has_timer(xprt))
2055                 timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
2056         else
2057                 timer_setup(&xprt->timer, NULL, 0);
2058
2059         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
2060                 xprt_destroy(xprt);
2061                 return ERR_PTR(-EINVAL);
2062         }
2063         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
2064         if (xprt->servername == NULL) {
2065                 xprt_destroy(xprt);
2066                 return ERR_PTR(-ENOMEM);
2067         }
2068
2069         rpc_xprt_debugfs_register(xprt);
2070
2071         trace_xprt_create(xprt);
2072 out:
2073         return xprt;
2074 }
2075
2076 static void xprt_destroy_cb(struct work_struct *work)
2077 {
2078         struct rpc_xprt *xprt =
2079                 container_of(work, struct rpc_xprt, task_cleanup);
2080
2081         trace_xprt_destroy(xprt);
2082
2083         rpc_xprt_debugfs_unregister(xprt);
2084         rpc_destroy_wait_queue(&xprt->binding);
2085         rpc_destroy_wait_queue(&xprt->pending);
2086         rpc_destroy_wait_queue(&xprt->sending);
2087         rpc_destroy_wait_queue(&xprt->backlog);
2088         kfree(xprt->servername);
2089         /*
2090          * Destroy any existing back channel
2091          */
2092         xprt_destroy_backchannel(xprt, UINT_MAX);
2093
2094         /*
2095          * Tear down transport state and free the rpc_xprt
2096          */
2097         xprt->ops->destroy(xprt);
2098 }
2099
2100 /**
2101  * xprt_destroy - destroy an RPC transport, killing off all requests.
2102  * @xprt: transport to destroy
2103  *
2104  */
2105 static void xprt_destroy(struct rpc_xprt *xprt)
2106 {
2107         /*
2108          * Exclude transport connect/disconnect handlers and autoclose
2109          */
2110         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
2111
2112         del_timer_sync(&xprt->timer);
2113
2114         /*
2115          * Destroy sockets etc from the system workqueue so they can
2116          * safely flush receive work running on rpciod.
2117          */
2118         INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
2119         schedule_work(&xprt->task_cleanup);
2120 }
2121
2122 static void xprt_destroy_kref(struct kref *kref)
2123 {
2124         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
2125 }
2126
2127 /**
2128  * xprt_get - return a reference to an RPC transport.
2129  * @xprt: pointer to the transport
2130  *
2131  */
2132 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
2133 {
2134         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
2135                 return xprt;
2136         return NULL;
2137 }
2138 EXPORT_SYMBOL_GPL(xprt_get);
2139
2140 /**
2141  * xprt_put - release a reference to an RPC transport.
2142  * @xprt: pointer to the transport
2143  *
2144  */
2145 void xprt_put(struct rpc_xprt *xprt)
2146 {
2147         if (xprt != NULL)
2148                 kref_put(&xprt->kref, xprt_destroy_kref);
2149 }
2150 EXPORT_SYMBOL_GPL(xprt_put);