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 #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 static int      xprt_request_prepare(struct rpc_rqst *req, struct xdr_buf *buf);
  77
  78 static DEFINE_SPINLOCK(xprt_list_lock);
  79 static LIST_HEAD(xprt_list);
  80
  81 static unsigned long xprt_request_timeout(const struct rpc_rqst *req)
  82 {
  83         unsigned long timeout = jiffies + req->rq_timeout;
  84
  85         if (time_before(timeout, req->rq_majortimeo))
  86                 return timeout;
  87         return req->rq_majortimeo;
  88 }
  89
  90 /**
  91  * xprt_register_transport - register a transport implementation
  92  * @transport: transport to register
  93  *
  94  * If a transport implementation is loaded as a kernel module, it can
  95  * call this interface to make itself known to the RPC client.
  96  *
  97  * Returns:
  98  * 0:           transport successfully registered
  99  * -EEXIST:     transport already registered
 100  * -EINVAL:     transport module being unloaded
 101  */
 102 int xprt_register_transport(struct xprt_class *transport)
 103 {
 104         struct xprt_class *t;
 105         int result;
 106
 107         result = -EEXIST;
 108         spin_lock(&xprt_list_lock);
 109         list_for_each_entry(t, &xprt_list, list) {
 110                 /* don't register the same transport class twice */
 111                 if (t->ident == transport->ident)
 112                         goto out;
 113         }
 114
 115         list_add_tail(&transport->list, &xprt_list);
 116         printk(KERN_INFO "RPC: Registered %s transport module.\n",
 117                transport->name);
 118         result = 0;
 119
 120 out:
 121         spin_unlock(&xprt_list_lock);
 122         return result;
 123 }
 124 EXPORT_SYMBOL_GPL(xprt_register_transport);
 125
 126 /**
 127  * xprt_unregister_transport - unregister a transport implementation
 128  * @transport: transport to unregister
 129  *
 130  * Returns:
 131  * 0:           transport successfully unregistered
 132  * -ENOENT:     transport never registered
 133  */
 134 int xprt_unregister_transport(struct xprt_class *transport)
 135 {
 136         struct xprt_class *t;
 137         int result;
 138
 139         result = 0;
 140         spin_lock(&xprt_list_lock);
 141         list_for_each_entry(t, &xprt_list, list) {
 142                 if (t == transport) {
 143                         printk(KERN_INFO
 144                                 "RPC: Unregistered %s transport module.\n",
 145                                 transport->name);
 146                         list_del_init(&transport->list);
 147                         goto out;
 148                 }
 149         }
 150         result = -ENOENT;
 151
 152 out:
 153         spin_unlock(&xprt_list_lock);
 154         return result;
 155 }
 156 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 157
 158 static void
 159 xprt_class_release(const struct xprt_class *t)
 160 {
 161         module_put(t->owner);
 162 }
 163
 164 static const struct xprt_class *
 165 xprt_class_find_by_ident_locked(int ident)
 166 {
 167         const struct xprt_class *t;
 168
 169         list_for_each_entry(t, &xprt_list, list) {
 170                 if (t->ident != ident)
 171                         continue;
 172                 if (!try_module_get(t->owner))
 173                         continue;
 174                 return t;
 175         }
 176         return NULL;
 177 }
 178
 179 static const struct xprt_class *
 180 xprt_class_find_by_ident(int ident)
 181 {
 182         const struct xprt_class *t;
 183
 184         spin_lock(&xprt_list_lock);
 185         t = xprt_class_find_by_ident_locked(ident);
 186         spin_unlock(&xprt_list_lock);
 187         return t;
 188 }
 189
 190 static const struct xprt_class *
 191 xprt_class_find_by_netid_locked(const char *netid)
 192 {
 193         const struct xprt_class *t;
 194         unsigned int i;
 195
 196         list_for_each_entry(t, &xprt_list, list) {
 197                 for (i = 0; t->netid[i][0] != '\0'; i++) {
 198                         if (strcmp(t->netid[i], netid) != 0)
 199                                 continue;
 200                         if (!try_module_get(t->owner))
 201                                 continue;
 202                         return t;
 203                 }
 204         }
 205         return NULL;
 206 }
 207
 208 static const struct xprt_class *
 209 xprt_class_find_by_netid(const char *netid)
 210 {
 211         const struct xprt_class *t;
 212
 213         spin_lock(&xprt_list_lock);
 214         t = xprt_class_find_by_netid_locked(netid);
 215         if (!t) {
 216                 spin_unlock(&xprt_list_lock);
 217                 request_module("rpc%s", netid);
 218                 spin_lock(&xprt_list_lock);
 219                 t = xprt_class_find_by_netid_locked(netid);
 220         }
 221         spin_unlock(&xprt_list_lock);
 222         return t;
 223 }
 224
 225 /**
 226  * xprt_find_transport_ident - convert a netid into a transport identifier
 227  * @netid: transport to load
 228  *
 229  * Returns:
 230  * > 0:         transport identifier
 231  * -ENOENT:     transport module not available
 232  */
 233 int xprt_find_transport_ident(const char *netid)
 234 {
 235         const struct xprt_class *t;
 236         int ret;
 237
 238         t = xprt_class_find_by_netid(netid);
 239         if (!t)
 240                 return -ENOENT;
 241         ret = t->ident;
 242         xprt_class_release(t);
 243         return ret;
 244 }
 245 EXPORT_SYMBOL_GPL(xprt_find_transport_ident);
 246
 247 static void xprt_clear_locked(struct rpc_xprt *xprt)
 248 {
 249         xprt->snd_task = NULL;
 250         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state))
 251                 clear_bit_unlock(XPRT_LOCKED, &xprt->state);
 252         else
 253                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 254 }
 255
 256 /**
 257  * xprt_reserve_xprt - serialize write access to transports
 258  * @task: task that is requesting access to the transport
 259  * @xprt: pointer to the target transport
 260  *
 261  * This prevents mixing the payload of separate requests, and prevents
 262  * transport connects from colliding with writes.  No congestion control
 263  * is provided.
 264  */
 265 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 266 {
 267         struct rpc_rqst *req = task->tk_rqstp;
 268
 269         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 270                 if (task == xprt->snd_task)
 271                         goto out_locked;
 272                 goto out_sleep;
 273         }
 274         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 275                 goto out_unlock;
 276         xprt->snd_task = task;
 277
 278 out_locked:
 279         trace_xprt_reserve_xprt(xprt, task);
 280         return 1;
 281
 282 out_unlock:
 283         xprt_clear_locked(xprt);
 284 out_sleep:
 285         task->tk_status = -EAGAIN;
 286         if  (RPC_IS_SOFT(task))
 287                 rpc_sleep_on_timeout(&xprt->sending, task, NULL,
 288                                 xprt_request_timeout(req));
 289         else
 290                 rpc_sleep_on(&xprt->sending, task, NULL);
 291         return 0;
 292 }
 293 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 294
 295 static bool
 296 xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
 297 {
 298         return test_bit(XPRT_CWND_WAIT, &xprt->state);
 299 }
 300
 301 static void
 302 xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
 303 {
 304         if (!list_empty(&xprt->xmit_queue)) {
 305                 /* Peek at head of queue to see if it can make progress */
 306                 if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
 307                                         rq_xmit)->rq_cong)
 308                         return;
 309         }
 310         set_bit(XPRT_CWND_WAIT, &xprt->state);
 311 }
 312
 313 static void
 314 xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
 315 {
 316         if (!RPCXPRT_CONGESTED(xprt))
 317                 clear_bit(XPRT_CWND_WAIT, &xprt->state);
 318 }
 319
 320 /*
 321  * xprt_reserve_xprt_cong - serialize write access to transports
 322  * @task: task that is requesting access to the transport
 323  *
 324  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 325  * integrated into the decision of whether a request is allowed to be
 326  * woken up and given access to the transport.
 327  * Note that the lock is only granted if we know there are free slots.
 328  */
 329 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 330 {
 331         struct rpc_rqst *req = task->tk_rqstp;
 332
 333         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 334                 if (task == xprt->snd_task)
 335                         goto out_locked;
 336                 goto out_sleep;
 337         }
 338         if (req == NULL) {
 339                 xprt->snd_task = task;
 340                 goto out_locked;
 341         }
 342         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 343                 goto out_unlock;
 344         if (!xprt_need_congestion_window_wait(xprt)) {
 345                 xprt->snd_task = task;
 346                 goto out_locked;
 347         }
 348 out_unlock:
 349         xprt_clear_locked(xprt);
 350 out_sleep:
 351         task->tk_status = -EAGAIN;
 352         if (RPC_IS_SOFT(task))
 353                 rpc_sleep_on_timeout(&xprt->sending, task, NULL,
 354                                 xprt_request_timeout(req));
 355         else
 356                 rpc_sleep_on(&xprt->sending, task, NULL);
 357         return 0;
 358 out_locked:
 359         trace_xprt_reserve_cong(xprt, task);
 360         return 1;
 361 }
 362 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 363
 364 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 365 {
 366         int retval;
 367
 368         if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
 369                 return 1;
 370         spin_lock(&xprt->transport_lock);
 371         retval = xprt->ops->reserve_xprt(xprt, task);
 372         spin_unlock(&xprt->transport_lock);
 373         return retval;
 374 }
 375
 376 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
 377 {
 378         struct rpc_xprt *xprt = data;
 379
 380         xprt->snd_task = task;
 381         return true;
 382 }
 383
 384 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 385 {
 386         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 387                 return;
 388         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 389                 goto out_unlock;
 390         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 391                                 __xprt_lock_write_func, xprt))
 392                 return;
 393 out_unlock:
 394         xprt_clear_locked(xprt);
 395 }
 396
 397 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 398 {
 399         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 400                 return;
 401         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 402                 goto out_unlock;
 403         if (xprt_need_congestion_window_wait(xprt))
 404                 goto out_unlock;
 405         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 406                                 __xprt_lock_write_func, xprt))
 407                 return;
 408 out_unlock:
 409         xprt_clear_locked(xprt);
 410 }
 411
 412 /**
 413  * xprt_release_xprt - allow other requests to use a transport
 414  * @xprt: transport with other tasks potentially waiting
 415  * @task: task that is releasing access to the transport
 416  *
 417  * Note that "task" can be NULL.  No congestion control is provided.
 418  */
 419 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 420 {
 421         if (xprt->snd_task == task) {
 422                 xprt_clear_locked(xprt);
 423                 __xprt_lock_write_next(xprt);
 424         }
 425         trace_xprt_release_xprt(xprt, task);
 426 }
 427 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 428
 429 /**
 430  * xprt_release_xprt_cong - allow other requests to use a transport
 431  * @xprt: transport with other tasks potentially waiting
 432  * @task: task that is releasing access to the transport
 433  *
 434  * Note that "task" can be NULL.  Another task is awoken to use the
 435  * transport if the transport's congestion window allows it.
 436  */
 437 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 438 {
 439         if (xprt->snd_task == task) {
 440                 xprt_clear_locked(xprt);
 441                 __xprt_lock_write_next_cong(xprt);
 442         }
 443         trace_xprt_release_cong(xprt, task);
 444 }
 445 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 446
 447 void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 448 {
 449         if (xprt->snd_task != task)
 450                 return;
 451         spin_lock(&xprt->transport_lock);
 452         xprt->ops->release_xprt(xprt, task);
 453         spin_unlock(&xprt->transport_lock);
 454 }
 455
 456 /*
 457  * Van Jacobson congestion avoidance. Check if the congestion window
 458  * overflowed. Put the task to sleep if this is the case.
 459  */
 460 static int
 461 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 462 {
 463         if (req->rq_cong)
 464                 return 1;
 465         trace_xprt_get_cong(xprt, req->rq_task);
 466         if (RPCXPRT_CONGESTED(xprt)) {
 467                 xprt_set_congestion_window_wait(xprt);
 468                 return 0;
 469         }
 470         req->rq_cong = 1;
 471         xprt->cong += RPC_CWNDSCALE;
 472         return 1;
 473 }
 474
 475 /*
 476  * Adjust the congestion window, and wake up the next task
 477  * that has been sleeping due to congestion
 478  */
 479 static void
 480 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 481 {
 482         if (!req->rq_cong)
 483                 return;
 484         req->rq_cong = 0;
 485         xprt->cong -= RPC_CWNDSCALE;
 486         xprt_test_and_clear_congestion_window_wait(xprt);
 487         trace_xprt_put_cong(xprt, req->rq_task);
 488         __xprt_lock_write_next_cong(xprt);
 489 }
 490
 491 /**
 492  * xprt_request_get_cong - Request congestion control credits
 493  * @xprt: pointer to transport
 494  * @req: pointer to RPC request
 495  *
 496  * Useful for transports that require congestion control.
 497  */
 498 bool
 499 xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 500 {
 501         bool ret = false;
 502
 503         if (req->rq_cong)
 504                 return true;
 505         spin_lock(&xprt->transport_lock);
 506         ret = __xprt_get_cong(xprt, req) != 0;
 507         spin_unlock(&xprt->transport_lock);
 508         return ret;
 509 }
 510 EXPORT_SYMBOL_GPL(xprt_request_get_cong);
 511
 512 /**
 513  * xprt_release_rqst_cong - housekeeping when request is complete
 514  * @task: RPC request that recently completed
 515  *
 516  * Useful for transports that require congestion control.
 517  */
 518 void xprt_release_rqst_cong(struct rpc_task *task)
 519 {
 520         struct rpc_rqst *req = task->tk_rqstp;
 521
 522         __xprt_put_cong(req->rq_xprt, req);
 523 }
 524 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 525
 526 static void xprt_clear_congestion_window_wait_locked(struct rpc_xprt *xprt)
 527 {
 528         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state))
 529                 __xprt_lock_write_next_cong(xprt);
 530 }
 531
 532 /*
 533  * Clear the congestion window wait flag and wake up the next
 534  * entry on xprt->sending
 535  */
 536 static void
 537 xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
 538 {
 539         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
 540                 spin_lock(&xprt->transport_lock);
 541                 __xprt_lock_write_next_cong(xprt);
 542                 spin_unlock(&xprt->transport_lock);
 543         }
 544 }
 545
 546 /**
 547  * xprt_adjust_cwnd - adjust transport congestion window
 548  * @xprt: pointer to xprt
 549  * @task: recently completed RPC request used to adjust window
 550  * @result: result code of completed RPC request
 551  *
 552  * The transport code maintains an estimate on the maximum number of out-
 553  * standing RPC requests, using a smoothed version of the congestion
 554  * avoidance implemented in 44BSD. This is basically the Van Jacobson
 555  * congestion algorithm: If a retransmit occurs, the congestion window is
 556  * halved; otherwise, it is incremented by 1/cwnd when
 557  *
 558  *      -       a reply is received and
 559  *      -       a full number of requests are outstanding and
 560  *      -       the congestion window hasn't been updated recently.
 561  */
 562 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
 563 {
 564         struct rpc_rqst *req = task->tk_rqstp;
 565         unsigned long cwnd = xprt->cwnd;
 566
 567         if (result >= 0 && cwnd <= xprt->cong) {
 568                 /* The (cwnd >> 1) term makes sure
 569                  * the result gets rounded properly. */
 570                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 571                 if (cwnd > RPC_MAXCWND(xprt))
 572                         cwnd = RPC_MAXCWND(xprt);
 573                 __xprt_lock_write_next_cong(xprt);
 574         } else if (result == -ETIMEDOUT) {
 575                 cwnd >>= 1;
 576                 if (cwnd < RPC_CWNDSCALE)
 577                         cwnd = RPC_CWNDSCALE;
 578         }
 579         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 580                         xprt->cong, xprt->cwnd, cwnd);
 581         xprt->cwnd = cwnd;
 582         __xprt_put_cong(xprt, req);
 583 }
 584 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 585
 586 /**
 587  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 588  * @xprt: transport with waiting tasks
 589  * @status: result code to plant in each task before waking it
 590  *
 591  */
 592 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 593 {
 594         if (status < 0)
 595                 rpc_wake_up_status(&xprt->pending, status);
 596         else
 597                 rpc_wake_up(&xprt->pending);
 598 }
 599 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 600
 601 /**
 602  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 603  * @xprt: transport
 604  *
 605  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
 606  * we don't in general want to force a socket disconnection due to
 607  * an incomplete RPC call transmission.
 608  */
 609 void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
 610 {
 611         set_bit(XPRT_WRITE_SPACE, &xprt->state);
 612 }
 613 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 614
 615 static bool
 616 xprt_clear_write_space_locked(struct rpc_xprt *xprt)
 617 {
 618         if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
 619                 __xprt_lock_write_next(xprt);
 620                 dprintk("RPC:       write space: waking waiting task on "
 621                                 "xprt %p\n", xprt);
 622                 return true;
 623         }
 624         return false;
 625 }
 626
 627 /**
 628  * xprt_write_space - wake the task waiting for transport output buffer space
 629  * @xprt: transport with waiting tasks
 630  *
 631  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 632  */
 633 bool xprt_write_space(struct rpc_xprt *xprt)
 634 {
 635         bool ret;
 636
 637         if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
 638                 return false;
 639         spin_lock(&xprt->transport_lock);
 640         ret = xprt_clear_write_space_locked(xprt);
 641         spin_unlock(&xprt->transport_lock);
 642         return ret;
 643 }
 644 EXPORT_SYMBOL_GPL(xprt_write_space);
 645
 646 static unsigned long xprt_abs_ktime_to_jiffies(ktime_t abstime)
 647 {
 648         s64 delta = ktime_to_ns(ktime_get() - abstime);
 649         return likely(delta >= 0) ?
 650                 jiffies - nsecs_to_jiffies(delta) :
 651                 jiffies + nsecs_to_jiffies(-delta);
 652 }
 653
 654 static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req)
 655 {
 656         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 657         unsigned long majortimeo = req->rq_timeout;
 658
 659         if (to->to_exponential)
 660                 majortimeo <<= to->to_retries;
 661         else
 662                 majortimeo += to->to_increment * to->to_retries;
 663         if (majortimeo > to->to_maxval || majortimeo == 0)
 664                 majortimeo = to->to_maxval;
 665         return majortimeo;
 666 }
 667
 668 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 669 {
 670         req->rq_majortimeo += xprt_calc_majortimeo(req);
 671 }
 672
 673 static void xprt_reset_minortimeo(struct rpc_rqst *req)
 674 {
 675         req->rq_minortimeo += req->rq_timeout;
 676 }
 677
 678 static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
 679 {
 680         unsigned long time_init;
 681         struct rpc_xprt *xprt = req->rq_xprt;
 682
 683         if (likely(xprt && xprt_connected(xprt)))
 684                 time_init = jiffies;
 685         else
 686                 time_init = xprt_abs_ktime_to_jiffies(task->tk_start);
 687         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
 688         req->rq_majortimeo = time_init + xprt_calc_majortimeo(req);
 689         req->rq_minortimeo = time_init + req->rq_timeout;
 690 }
 691
 692 /**
 693  * xprt_adjust_timeout - adjust timeout values for next retransmit
 694  * @req: RPC request containing parameters to use for the adjustment
 695  *
 696  */
 697 int xprt_adjust_timeout(struct rpc_rqst *req)
 698 {
 699         struct rpc_xprt *xprt = req->rq_xprt;
 700         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 701         int status = 0;
 702
 703         if (time_before(jiffies, req->rq_majortimeo)) {
 704                 if (time_before(jiffies, req->rq_minortimeo))
 705                         return status;
 706                 if (to->to_exponential)
 707                         req->rq_timeout <<= 1;
 708                 else
 709                         req->rq_timeout += to->to_increment;
 710                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 711                         req->rq_timeout = to->to_maxval;
 712                 req->rq_retries++;
 713         } else {
 714                 req->rq_timeout = to->to_initval;
 715                 req->rq_retries = 0;
 716                 xprt_reset_majortimeo(req);
 717                 /* Reset the RTT counters == "slow start" */
 718                 spin_lock(&xprt->transport_lock);
 719                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 720                 spin_unlock(&xprt->transport_lock);
 721                 status = -ETIMEDOUT;
 722         }
 723         xprt_reset_minortimeo(req);
 724
 725         if (req->rq_timeout == 0) {
 726                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 727                 req->rq_timeout = 5 * HZ;
 728         }
 729         return status;
 730 }
 731
 732 static void xprt_autoclose(struct work_struct *work)
 733 {
 734         struct rpc_xprt *xprt =
 735                 container_of(work, struct rpc_xprt, task_cleanup);
 736         unsigned int pflags = memalloc_nofs_save();
 737
 738         trace_xprt_disconnect_auto(xprt);
 739         xprt->connect_cookie++;
 740         smp_mb__before_atomic();
 741         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 742         xprt->ops->close(xprt);
 743         xprt_release_write(xprt, NULL);
 744         wake_up_bit(&xprt->state, XPRT_LOCKED);
 745         memalloc_nofs_restore(pflags);
 746 }
 747
 748 /**
 749  * xprt_disconnect_done - mark a transport as disconnected
 750  * @xprt: transport to flag for disconnect
 751  *
 752  */
 753 void xprt_disconnect_done(struct rpc_xprt *xprt)
 754 {
 755         trace_xprt_disconnect_done(xprt);
 756         spin_lock(&xprt->transport_lock);
 757         xprt_clear_connected(xprt);
 758         xprt_clear_write_space_locked(xprt);
 759         xprt_clear_congestion_window_wait_locked(xprt);
 760         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 761         spin_unlock(&xprt->transport_lock);
 762 }
 763 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 764
 765 /**
 766  * xprt_schedule_autoclose_locked - Try to schedule an autoclose RPC call
 767  * @xprt: transport to disconnect
 768  */
 769 static void xprt_schedule_autoclose_locked(struct rpc_xprt *xprt)
 770 {
 771         if (test_and_set_bit(XPRT_CLOSE_WAIT, &xprt->state))
 772                 return;
 773         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 774                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 775         else if (xprt->snd_task && !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
 776                 rpc_wake_up_queued_task_set_status(&xprt->pending,
 777                                                    xprt->snd_task, -ENOTCONN);
 778 }
 779
 780 /**
 781  * xprt_force_disconnect - force a transport to disconnect
 782  * @xprt: transport to disconnect
 783  *
 784  */
 785 void xprt_force_disconnect(struct rpc_xprt *xprt)
 786 {
 787         trace_xprt_disconnect_force(xprt);
 788
 789         /* Don't race with the test_bit() in xprt_clear_locked() */
 790         spin_lock(&xprt->transport_lock);
 791         xprt_schedule_autoclose_locked(xprt);
 792         spin_unlock(&xprt->transport_lock);
 793 }
 794 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
 795
 796 static unsigned int
 797 xprt_connect_cookie(struct rpc_xprt *xprt)
 798 {
 799         return READ_ONCE(xprt->connect_cookie);
 800 }
 801
 802 static bool
 803 xprt_request_retransmit_after_disconnect(struct rpc_task *task)
 804 {
 805         struct rpc_rqst *req = task->tk_rqstp;
 806         struct rpc_xprt *xprt = req->rq_xprt;
 807
 808         return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
 809                 !xprt_connected(xprt);
 810 }
 811
 812 /**
 813  * xprt_conditional_disconnect - force a transport to disconnect
 814  * @xprt: transport to disconnect
 815  * @cookie: 'connection cookie'
 816  *
 817  * This attempts to break the connection if and only if 'cookie' matches
 818  * the current transport 'connection cookie'. It ensures that we don't
 819  * try to break the connection more than once when we need to retransmit
 820  * a batch of RPC requests.
 821  *
 822  */
 823 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 824 {
 825         /* Don't race with the test_bit() in xprt_clear_locked() */
 826         spin_lock(&xprt->transport_lock);
 827         if (cookie != xprt->connect_cookie)
 828                 goto out;
 829         if (test_bit(XPRT_CLOSING, &xprt->state))
 830                 goto out;
 831         xprt_schedule_autoclose_locked(xprt);
 832 out:
 833         spin_unlock(&xprt->transport_lock);
 834 }
 835
 836 static bool
 837 xprt_has_timer(const struct rpc_xprt *xprt)
 838 {
 839         return xprt->idle_timeout != 0;
 840 }
 841
 842 static void
 843 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
 844         __must_hold(&xprt->transport_lock)
 845 {
 846         xprt->last_used = jiffies;
 847         if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))
 848                 mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
 849 }
 850
 851 static void
 852 xprt_init_autodisconnect(struct timer_list *t)
 853 {
 854         struct rpc_xprt *xprt = from_timer(xprt, t, timer);
 855
 856         if (!RB_EMPTY_ROOT(&xprt->recv_queue))
 857                 return;
 858         /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
 859         xprt->last_used = jiffies;
 860         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 861                 return;
 862         queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 863 }
 864
 865 #if IS_ENABLED(CONFIG_FAIL_SUNRPC)
 866 static void xprt_inject_disconnect(struct rpc_xprt *xprt)
 867 {
 868         if (!fail_sunrpc.ignore_client_disconnect &&
 869             should_fail(&fail_sunrpc.attr, 1))
 870                 xprt->ops->inject_disconnect(xprt);
 871 }
 872 #else
 873 static inline void xprt_inject_disconnect(struct rpc_xprt *xprt)
 874 {
 875 }
 876 #endif
 877
 878 bool xprt_lock_connect(struct rpc_xprt *xprt,
 879                 struct rpc_task *task,
 880                 void *cookie)
 881 {
 882         bool ret = false;
 883
 884         spin_lock(&xprt->transport_lock);
 885         if (!test_bit(XPRT_LOCKED, &xprt->state))
 886                 goto out;
 887         if (xprt->snd_task != task)
 888                 goto out;
 889         set_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 890         xprt->snd_task = cookie;
 891         ret = true;
 892 out:
 893         spin_unlock(&xprt->transport_lock);
 894         return ret;
 895 }
 896 EXPORT_SYMBOL_GPL(xprt_lock_connect);
 897
 898 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
 899 {
 900         spin_lock(&xprt->transport_lock);
 901         if (xprt->snd_task != cookie)
 902                 goto out;
 903         if (!test_bit(XPRT_LOCKED, &xprt->state))
 904                 goto out;
 905         xprt->snd_task =NULL;
 906         clear_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 907         xprt->ops->release_xprt(xprt, NULL);
 908         xprt_schedule_autodisconnect(xprt);
 909 out:
 910         spin_unlock(&xprt->transport_lock);
 911         wake_up_bit(&xprt->state, XPRT_LOCKED);
 912 }
 913 EXPORT_SYMBOL_GPL(xprt_unlock_connect);
 914
 915 /**
 916  * xprt_connect - schedule a transport connect operation
 917  * @task: RPC task that is requesting the connect
 918  *
 919  */
 920 void xprt_connect(struct rpc_task *task)
 921 {
 922         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 923
 924         trace_xprt_connect(xprt);
 925
 926         if (!xprt_bound(xprt)) {
 927                 task->tk_status = -EAGAIN;
 928                 return;
 929         }
 930         if (!xprt_lock_write(xprt, task))
 931                 return;
 932
 933         if (!xprt_connected(xprt) && !test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 934                 task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
 935                 rpc_sleep_on_timeout(&xprt->pending, task, NULL,
 936                                 xprt_request_timeout(task->tk_rqstp));
 937
 938                 if (test_bit(XPRT_CLOSING, &xprt->state))
 939                         return;
 940                 if (xprt_test_and_set_connecting(xprt))
 941                         return;
 942                 /* Race breaker */
 943                 if (!xprt_connected(xprt)) {
 944                         xprt->stat.connect_start = jiffies;
 945                         xprt->ops->connect(xprt, task);
 946                 } else {
 947                         xprt_clear_connecting(xprt);
 948                         task->tk_status = 0;
 949                         rpc_wake_up_queued_task(&xprt->pending, task);
 950                 }
 951         }
 952         xprt_release_write(xprt, task);
 953 }
 954
 955 /**
 956  * xprt_reconnect_delay - compute the wait before scheduling a connect
 957  * @xprt: transport instance
 958  *
 959  */
 960 unsigned long xprt_reconnect_delay(const struct rpc_xprt *xprt)
 961 {
 962         unsigned long start, now = jiffies;
 963
 964         start = xprt->stat.connect_start + xprt->reestablish_timeout;
 965         if (time_after(start, now))
 966                 return start - now;
 967         return 0;
 968 }
 969 EXPORT_SYMBOL_GPL(xprt_reconnect_delay);
 970
 971 /**
 972  * xprt_reconnect_backoff - compute the new re-establish timeout
 973  * @xprt: transport instance
 974  * @init_to: initial reestablish timeout
 975  *
 976  */
 977 void xprt_reconnect_backoff(struct rpc_xprt *xprt, unsigned long init_to)
 978 {
 979         xprt->reestablish_timeout <<= 1;
 980         if (xprt->reestablish_timeout > xprt->max_reconnect_timeout)
 981                 xprt->reestablish_timeout = xprt->max_reconnect_timeout;
 982         if (xprt->reestablish_timeout < init_to)
 983                 xprt->reestablish_timeout = init_to;
 984 }
 985 EXPORT_SYMBOL_GPL(xprt_reconnect_backoff);
 986
 987 enum xprt_xid_rb_cmp {
 988         XID_RB_EQUAL,
 989         XID_RB_LEFT,
 990         XID_RB_RIGHT,
 991 };
 992 static enum xprt_xid_rb_cmp
 993 xprt_xid_cmp(__be32 xid1, __be32 xid2)
 994 {
 995         if (xid1 == xid2)
 996                 return XID_RB_EQUAL;
 997         if ((__force u32)xid1 < (__force u32)xid2)
 998                 return XID_RB_LEFT;
 999         return XID_RB_RIGHT;
1000 }
1001
1002 static struct rpc_rqst *
1003 xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
1004 {
1005         struct rb_node *n = xprt->recv_queue.rb_node;
1006         struct rpc_rqst *req;
1007
1008         while (n != NULL) {
1009                 req = rb_entry(n, struct rpc_rqst, rq_recv);
1010                 switch (xprt_xid_cmp(xid, req->rq_xid)) {
1011                 case XID_RB_LEFT:
1012                         n = n->rb_left;
1013                         break;
1014                 case XID_RB_RIGHT:
1015                         n = n->rb_right;
1016                         break;
1017                 case XID_RB_EQUAL:
1018                         return req;
1019                 }
1020         }
1021         return NULL;
1022 }
1023
1024 static void
1025 xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
1026 {
1027         struct rb_node **p = &xprt->recv_queue.rb_node;
1028         struct rb_node *n = NULL;
1029         struct rpc_rqst *req;
1030
1031         while (*p != NULL) {
1032                 n = *p;
1033                 req = rb_entry(n, struct rpc_rqst, rq_recv);
1034                 switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
1035                 case XID_RB_LEFT:
1036                         p = &n->rb_left;
1037                         break;
1038                 case XID_RB_RIGHT:
1039                         p = &n->rb_right;
1040                         break;
1041                 case XID_RB_EQUAL:
1042                         WARN_ON_ONCE(new != req);
1043                         return;
1044                 }
1045         }
1046         rb_link_node(&new->rq_recv, n, p);
1047         rb_insert_color(&new->rq_recv, &xprt->recv_queue);
1048 }
1049
1050 static void
1051 xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
1052 {
1053         rb_erase(&req->rq_recv, &xprt->recv_queue);
1054 }
1055
1056 /**
1057  * xprt_lookup_rqst - find an RPC request corresponding to an XID
1058  * @xprt: transport on which the original request was transmitted
1059  * @xid: RPC XID of incoming reply
1060  *
1061  * Caller holds xprt->queue_lock.
1062  */
1063 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
1064 {
1065         struct rpc_rqst *entry;
1066
1067         entry = xprt_request_rb_find(xprt, xid);
1068         if (entry != NULL) {
1069                 trace_xprt_lookup_rqst(xprt, xid, 0);
1070                 entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
1071                 return entry;
1072         }
1073
1074         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
1075                         ntohl(xid));
1076         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
1077         xprt->stat.bad_xids++;
1078         return NULL;
1079 }
1080 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
1081
1082 static bool
1083 xprt_is_pinned_rqst(struct rpc_rqst *req)
1084 {
1085         return atomic_read(&req->rq_pin) != 0;
1086 }
1087
1088 /**
1089  * xprt_pin_rqst - Pin a request on the transport receive list
1090  * @req: Request to pin
1091  *
1092  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
1093  * so should be holding xprt->queue_lock.
1094  */
1095 void xprt_pin_rqst(struct rpc_rqst *req)
1096 {
1097         atomic_inc(&req->rq_pin);
1098 }
1099 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
1100
1101 /**
1102  * xprt_unpin_rqst - Unpin a request on the transport receive list
1103  * @req: Request to pin
1104  *
1105  * Caller should be holding xprt->queue_lock.
1106  */
1107 void xprt_unpin_rqst(struct rpc_rqst *req)
1108 {
1109         if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
1110                 atomic_dec(&req->rq_pin);
1111                 return;
1112         }
1113         if (atomic_dec_and_test(&req->rq_pin))
1114                 wake_up_var(&req->rq_pin);
1115 }
1116 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
1117
1118 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
1119 {
1120         wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
1121 }
1122
1123 static bool
1124 xprt_request_data_received(struct rpc_task *task)
1125 {
1126         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1127                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
1128 }
1129
1130 static bool
1131 xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
1132 {
1133         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1134                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
1135 }
1136
1137 /**
1138  * xprt_request_enqueue_receive - Add an request to the receive queue
1139  * @task: RPC task
1140  *
1141  */
1142 int
1143 xprt_request_enqueue_receive(struct rpc_task *task)
1144 {
1145         struct rpc_rqst *req = task->tk_rqstp;
1146         struct rpc_xprt *xprt = req->rq_xprt;
1147         int ret;
1148
1149         if (!xprt_request_need_enqueue_receive(task, req))
1150                 return 0;
1151
1152         ret = xprt_request_prepare(task->tk_rqstp, &req->rq_rcv_buf);
1153         if (ret)
1154                 return ret;
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         return 0;
1169 }
1170
1171 /**
1172  * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
1173  * @task: RPC task
1174  *
1175  * Caller must hold xprt->queue_lock.
1176  */
1177 static void
1178 xprt_request_dequeue_receive_locked(struct rpc_task *task)
1179 {
1180         struct rpc_rqst *req = task->tk_rqstp;
1181
1182         if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1183                 xprt_request_rb_remove(req->rq_xprt, req);
1184 }
1185
1186 /**
1187  * xprt_update_rtt - Update RPC RTT statistics
1188  * @task: RPC request that recently completed
1189  *
1190  * Caller holds xprt->queue_lock.
1191  */
1192 void xprt_update_rtt(struct rpc_task *task)
1193 {
1194         struct rpc_rqst *req = task->tk_rqstp;
1195         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
1196         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
1197         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
1198
1199         if (timer) {
1200                 if (req->rq_ntrans == 1)
1201                         rpc_update_rtt(rtt, timer, m);
1202                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
1203         }
1204 }
1205 EXPORT_SYMBOL_GPL(xprt_update_rtt);
1206
1207 /**
1208  * xprt_complete_rqst - called when reply processing is complete
1209  * @task: RPC request that recently completed
1210  * @copied: actual number of bytes received from the transport
1211  *
1212  * Caller holds xprt->queue_lock.
1213  */
1214 void xprt_complete_rqst(struct rpc_task *task, int copied)
1215 {
1216         struct rpc_rqst *req = task->tk_rqstp;
1217         struct rpc_xprt *xprt = req->rq_xprt;
1218
1219         xprt->stat.recvs++;
1220
1221         xdr_free_bvec(&req->rq_rcv_buf);
1222         req->rq_private_buf.bvec = NULL;
1223         req->rq_private_buf.len = copied;
1224         /* Ensure all writes are done before we update */
1225         /* req->rq_reply_bytes_recvd */
1226         smp_wmb();
1227         req->rq_reply_bytes_recvd = copied;
1228         xprt_request_dequeue_receive_locked(task);
1229         rpc_wake_up_queued_task(&xprt->pending, task);
1230 }
1231 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
1232
1233 static void xprt_timer(struct rpc_task *task)
1234 {
1235         struct rpc_rqst *req = task->tk_rqstp;
1236         struct rpc_xprt *xprt = req->rq_xprt;
1237
1238         if (task->tk_status != -ETIMEDOUT)
1239                 return;
1240
1241         trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
1242         if (!req->rq_reply_bytes_recvd) {
1243                 if (xprt->ops->timer)
1244                         xprt->ops->timer(xprt, task);
1245         } else
1246                 task->tk_status = 0;
1247 }
1248
1249 /**
1250  * xprt_wait_for_reply_request_def - wait for reply
1251  * @task: pointer to rpc_task
1252  *
1253  * Set a request's retransmit timeout based on the transport's
1254  * default timeout parameters.  Used by transports that don't adjust
1255  * the retransmit timeout based on round-trip time estimation,
1256  * and put the task to sleep on the pending queue.
1257  */
1258 void xprt_wait_for_reply_request_def(struct rpc_task *task)
1259 {
1260         struct rpc_rqst *req = task->tk_rqstp;
1261
1262         rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1263                         xprt_request_timeout(req));
1264 }
1265 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_def);
1266
1267 /**
1268  * xprt_wait_for_reply_request_rtt - wait for reply using RTT estimator
1269  * @task: pointer to rpc_task
1270  *
1271  * Set a request's retransmit timeout using the RTT estimator,
1272  * and put the task to sleep on the pending queue.
1273  */
1274 void xprt_wait_for_reply_request_rtt(struct rpc_task *task)
1275 {
1276         int timer = task->tk_msg.rpc_proc->p_timer;
1277         struct rpc_clnt *clnt = task->tk_client;
1278         struct rpc_rtt *rtt = clnt->cl_rtt;
1279         struct rpc_rqst *req = task->tk_rqstp;
1280         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
1281         unsigned long timeout;
1282
1283         timeout = rpc_calc_rto(rtt, timer);
1284         timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
1285         if (timeout > max_timeout || timeout == 0)
1286                 timeout = max_timeout;
1287         rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1288                         jiffies + timeout);
1289 }
1290 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_rtt);
1291
1292 /**
1293  * xprt_request_wait_receive - wait for the reply to an RPC request
1294  * @task: RPC task about to send a request
1295  *
1296  */
1297 void xprt_request_wait_receive(struct rpc_task *task)
1298 {
1299         struct rpc_rqst *req = task->tk_rqstp;
1300         struct rpc_xprt *xprt = req->rq_xprt;
1301
1302         if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1303                 return;
1304         /*
1305          * Sleep on the pending queue if we're expecting a reply.
1306          * The spinlock ensures atomicity between the test of
1307          * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1308          */
1309         spin_lock(&xprt->queue_lock);
1310         if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
1311                 xprt->ops->wait_for_reply_request(task);
1312                 /*
1313                  * Send an extra queue wakeup call if the
1314                  * connection was dropped in case the call to
1315                  * rpc_sleep_on() raced.
1316                  */
1317                 if (xprt_request_retransmit_after_disconnect(task))
1318                         rpc_wake_up_queued_task_set_status(&xprt->pending,
1319                                         task, -ENOTCONN);
1320         }
1321         spin_unlock(&xprt->queue_lock);
1322 }
1323
1324 static bool
1325 xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
1326 {
1327         return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1328 }
1329
1330 /**
1331  * xprt_request_enqueue_transmit - queue a task for transmission
1332  * @task: pointer to rpc_task
1333  *
1334  * Add a task to the transmission queue.
1335  */
1336 void
1337 xprt_request_enqueue_transmit(struct rpc_task *task)
1338 {
1339         struct rpc_rqst *pos, *req = task->tk_rqstp;
1340         struct rpc_xprt *xprt = req->rq_xprt;
1341         int ret;
1342
1343         if (xprt_request_need_enqueue_transmit(task, req)) {
1344                 ret = xprt_request_prepare(task->tk_rqstp, &req->rq_snd_buf);
1345                 if (ret) {
1346                         task->tk_status = ret;
1347                         return;
1348                 }
1349                 req->rq_bytes_sent = 0;
1350                 spin_lock(&xprt->queue_lock);
1351                 /*
1352                  * Requests that carry congestion control credits are added
1353                  * to the head of the list to avoid starvation issues.
1354                  */
1355                 if (req->rq_cong) {
1356                         xprt_clear_congestion_window_wait(xprt);
1357                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1358                                 if (pos->rq_cong)
1359                                         continue;
1360                                 /* Note: req is added _before_ pos */
1361                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1362                                 INIT_LIST_HEAD(&req->rq_xmit2);
1363                                 goto out;
1364                         }
1365                 } else if (!req->rq_seqno) {
1366                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1367                                 if (pos->rq_task->tk_owner != task->tk_owner)
1368                                         continue;
1369                                 list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
1370                                 INIT_LIST_HEAD(&req->rq_xmit);
1371                                 goto out;
1372                         }
1373                 }
1374                 list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
1375                 INIT_LIST_HEAD(&req->rq_xmit2);
1376 out:
1377                 atomic_long_inc(&xprt->xmit_queuelen);
1378                 set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1379                 spin_unlock(&xprt->queue_lock);
1380         }
1381 }
1382
1383 /**
1384  * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
1385  * @task: pointer to rpc_task
1386  *
1387  * Remove a task from the transmission queue
1388  * Caller must hold xprt->queue_lock
1389  */
1390 static void
1391 xprt_request_dequeue_transmit_locked(struct rpc_task *task)
1392 {
1393         struct rpc_rqst *req = task->tk_rqstp;
1394
1395         if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1396                 return;
1397         if (!list_empty(&req->rq_xmit)) {
1398                 list_del(&req->rq_xmit);
1399                 if (!list_empty(&req->rq_xmit2)) {
1400                         struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
1401                                         struct rpc_rqst, rq_xmit2);
1402                         list_del(&req->rq_xmit2);
1403                         list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
1404                 }
1405         } else
1406                 list_del(&req->rq_xmit2);
1407         atomic_long_dec(&req->rq_xprt->xmit_queuelen);
1408         xdr_free_bvec(&req->rq_snd_buf);
1409 }
1410
1411 /**
1412  * xprt_request_dequeue_transmit - remove a task from the transmission queue
1413  * @task: pointer to rpc_task
1414  *
1415  * Remove a task from the transmission queue
1416  */
1417 static void
1418 xprt_request_dequeue_transmit(struct rpc_task *task)
1419 {
1420         struct rpc_rqst *req = task->tk_rqstp;
1421         struct rpc_xprt *xprt = req->rq_xprt;
1422
1423         spin_lock(&xprt->queue_lock);
1424         xprt_request_dequeue_transmit_locked(task);
1425         spin_unlock(&xprt->queue_lock);
1426 }
1427
1428 /**
1429  * xprt_request_dequeue_xprt - remove a task from the transmit+receive queue
1430  * @task: pointer to rpc_task
1431  *
1432  * Remove a task from the transmit and receive queues, and ensure that
1433  * it is not pinned by the receive work item.
1434  */
1435 void
1436 xprt_request_dequeue_xprt(struct rpc_task *task)
1437 {
1438         struct rpc_rqst *req = task->tk_rqstp;
1439         struct rpc_xprt *xprt = req->rq_xprt;
1440
1441         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
1442             test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
1443             xprt_is_pinned_rqst(req)) {
1444                 spin_lock(&xprt->queue_lock);
1445                 while (xprt_is_pinned_rqst(req)) {
1446                         set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1447                         spin_unlock(&xprt->queue_lock);
1448                         xprt_wait_on_pinned_rqst(req);
1449                         spin_lock(&xprt->queue_lock);
1450                         clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1451                 }
1452                 xprt_request_dequeue_transmit_locked(task);
1453                 xprt_request_dequeue_receive_locked(task);
1454                 spin_unlock(&xprt->queue_lock);
1455                 xdr_free_bvec(&req->rq_rcv_buf);
1456         }
1457 }
1458
1459 /**
1460  * xprt_request_prepare - prepare an encoded request for transport
1461  * @req: pointer to rpc_rqst
1462  * @buf: pointer to send/rcv xdr_buf
1463  *
1464  * Calls into the transport layer to do whatever is needed to prepare
1465  * the request for transmission or receive.
1466  * Returns error, or zero.
1467  */
1468 static int
1469 xprt_request_prepare(struct rpc_rqst *req, struct xdr_buf *buf)
1470 {
1471         struct rpc_xprt *xprt = req->rq_xprt;
1472
1473         if (xprt->ops->prepare_request)
1474                 return xprt->ops->prepare_request(req, buf);
1475         return 0;
1476 }
1477
1478 /**
1479  * xprt_request_need_retransmit - Test if a task needs retransmission
1480  * @task: pointer to rpc_task
1481  *
1482  * Test for whether a connection breakage requires the task to retransmit
1483  */
1484 bool
1485 xprt_request_need_retransmit(struct rpc_task *task)
1486 {
1487         return xprt_request_retransmit_after_disconnect(task);
1488 }
1489
1490 /**
1491  * xprt_prepare_transmit - reserve the transport before sending a request
1492  * @task: RPC task about to send a request
1493  *
1494  */
1495 bool xprt_prepare_transmit(struct rpc_task *task)
1496 {
1497         struct rpc_rqst *req = task->tk_rqstp;
1498         struct rpc_xprt *xprt = req->rq_xprt;
1499
1500         if (!xprt_lock_write(xprt, task)) {
1501                 /* Race breaker: someone may have transmitted us */
1502                 if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1503                         rpc_wake_up_queued_task_set_status(&xprt->sending,
1504                                         task, 0);
1505                 return false;
1506
1507         }
1508         if (atomic_read(&xprt->swapper))
1509                 /* This will be clear in __rpc_execute */
1510                 current->flags |= PF_MEMALLOC;
1511         return true;
1512 }
1513
1514 void xprt_end_transmit(struct rpc_task *task)
1515 {
1516         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
1517
1518         xprt_inject_disconnect(xprt);
1519         xprt_release_write(xprt, task);
1520 }
1521
1522 /**
1523  * xprt_request_transmit - send an RPC request on a transport
1524  * @req: pointer to request to transmit
1525  * @snd_task: RPC task that owns the transport lock
1526  *
1527  * This performs the transmission of a single request.
1528  * Note that if the request is not the same as snd_task, then it
1529  * does need to be pinned.
1530  * Returns '0' on success.
1531  */
1532 static int
1533 xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
1534 {
1535         struct rpc_xprt *xprt = req->rq_xprt;
1536         struct rpc_task *task = req->rq_task;
1537         unsigned int connect_cookie;
1538         int is_retrans = RPC_WAS_SENT(task);
1539         int status;
1540
1541         if (!req->rq_bytes_sent) {
1542                 if (xprt_request_data_received(task)) {
1543                         status = 0;
1544                         goto out_dequeue;
1545                 }
1546                 /* Verify that our message lies in the RPCSEC_GSS window */
1547                 if (rpcauth_xmit_need_reencode(task)) {
1548                         status = -EBADMSG;
1549                         goto out_dequeue;
1550                 }
1551                 if (RPC_SIGNALLED(task)) {
1552                         status = -ERESTARTSYS;
1553                         goto out_dequeue;
1554                 }
1555         }
1556
1557         /*
1558          * Update req->rq_ntrans before transmitting to avoid races with
1559          * xprt_update_rtt(), which needs to know that it is recording a
1560          * reply to the first transmission.
1561          */
1562         req->rq_ntrans++;
1563
1564         trace_rpc_xdr_sendto(task, &req->rq_snd_buf);
1565         connect_cookie = xprt->connect_cookie;
1566         status = xprt->ops->send_request(req);
1567         if (status != 0) {
1568                 req->rq_ntrans--;
1569                 trace_xprt_transmit(req, status);
1570                 return status;
1571         }
1572
1573         if (is_retrans) {
1574                 task->tk_client->cl_stats->rpcretrans++;
1575                 trace_xprt_retransmit(req);
1576         }
1577
1578         xprt_inject_disconnect(xprt);
1579
1580         task->tk_flags |= RPC_TASK_SENT;
1581         spin_lock(&xprt->transport_lock);
1582
1583         xprt->stat.sends++;
1584         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1585         xprt->stat.bklog_u += xprt->backlog.qlen;
1586         xprt->stat.sending_u += xprt->sending.qlen;
1587         xprt->stat.pending_u += xprt->pending.qlen;
1588         spin_unlock(&xprt->transport_lock);
1589
1590         req->rq_connect_cookie = connect_cookie;
1591 out_dequeue:
1592         trace_xprt_transmit(req, status);
1593         xprt_request_dequeue_transmit(task);
1594         rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
1595         return status;
1596 }
1597
1598 /**
1599  * xprt_transmit - send an RPC request on a transport
1600  * @task: controlling RPC task
1601  *
1602  * Attempts to drain the transmit queue. On exit, either the transport
1603  * signalled an error that needs to be handled before transmission can
1604  * resume, or @task finished transmitting, and detected that it already
1605  * received a reply.
1606  */
1607 void
1608 xprt_transmit(struct rpc_task *task)
1609 {
1610         struct rpc_rqst *next, *req = task->tk_rqstp;
1611         struct rpc_xprt *xprt = req->rq_xprt;
1612         int status;
1613
1614         spin_lock(&xprt->queue_lock);
1615         for (;;) {
1616                 next = list_first_entry_or_null(&xprt->xmit_queue,
1617                                                 struct rpc_rqst, rq_xmit);
1618                 if (!next)
1619                         break;
1620                 xprt_pin_rqst(next);
1621                 spin_unlock(&xprt->queue_lock);
1622                 status = xprt_request_transmit(next, task);
1623                 if (status == -EBADMSG && next != req)
1624                         status = 0;
1625                 spin_lock(&xprt->queue_lock);
1626                 xprt_unpin_rqst(next);
1627                 if (status < 0) {
1628                         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1629                                 task->tk_status = status;
1630                         break;
1631                 }
1632                 /* Was @task transmitted, and has it received a reply? */
1633                 if (xprt_request_data_received(task) &&
1634                     !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1635                         break;
1636                 cond_resched_lock(&xprt->queue_lock);
1637         }
1638         spin_unlock(&xprt->queue_lock);
1639 }
1640
1641 static void xprt_complete_request_init(struct rpc_task *task)
1642 {
1643         if (task->tk_rqstp)
1644                 xprt_request_init(task);
1645 }
1646
1647 void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1648 {
1649         set_bit(XPRT_CONGESTED, &xprt->state);
1650         rpc_sleep_on(&xprt->backlog, task, xprt_complete_request_init);
1651 }
1652 EXPORT_SYMBOL_GPL(xprt_add_backlog);
1653
1654 static bool __xprt_set_rq(struct rpc_task *task, void *data)
1655 {
1656         struct rpc_rqst *req = data;
1657
1658         if (task->tk_rqstp == NULL) {
1659                 memset(req, 0, sizeof(*req));   /* mark unused */
1660                 task->tk_rqstp = req;
1661                 return true;
1662         }
1663         return false;
1664 }
1665
1666 bool xprt_wake_up_backlog(struct rpc_xprt *xprt, struct rpc_rqst *req)
1667 {
1668         if (rpc_wake_up_first(&xprt->backlog, __xprt_set_rq, req) == NULL) {
1669                 clear_bit(XPRT_CONGESTED, &xprt->state);
1670                 return false;
1671         }
1672         return true;
1673 }
1674 EXPORT_SYMBOL_GPL(xprt_wake_up_backlog);
1675
1676 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1677 {
1678         bool ret = false;
1679
1680         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1681                 goto out;
1682         spin_lock(&xprt->reserve_lock);
1683         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1684                 xprt_add_backlog(xprt, task);
1685                 ret = true;
1686         }
1687         spin_unlock(&xprt->reserve_lock);
1688 out:
1689         return ret;
1690 }
1691
1692 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1693 {
1694         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1695
1696         if (xprt->num_reqs >= xprt->max_reqs)
1697                 goto out;
1698         ++xprt->num_reqs;
1699         spin_unlock(&xprt->reserve_lock);
1700         req = kzalloc(sizeof(*req), rpc_task_gfp_mask());
1701         spin_lock(&xprt->reserve_lock);
1702         if (req != NULL)
1703                 goto out;
1704         --xprt->num_reqs;
1705         req = ERR_PTR(-ENOMEM);
1706 out:
1707         return req;
1708 }
1709
1710 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1711 {
1712         if (xprt->num_reqs > xprt->min_reqs) {
1713                 --xprt->num_reqs;
1714                 kfree(req);
1715                 return true;
1716         }
1717         return false;
1718 }
1719
1720 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1721 {
1722         struct rpc_rqst *req;
1723
1724         spin_lock(&xprt->reserve_lock);
1725         if (!list_empty(&xprt->free)) {
1726                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1727                 list_del(&req->rq_list);
1728                 goto out_init_req;
1729         }
1730         req = xprt_dynamic_alloc_slot(xprt);
1731         if (!IS_ERR(req))
1732                 goto out_init_req;
1733         switch (PTR_ERR(req)) {
1734         case -ENOMEM:
1735                 dprintk("RPC:       dynamic allocation of request slot "
1736                                 "failed! Retrying\n");
1737                 task->tk_status = -ENOMEM;
1738                 break;
1739         case -EAGAIN:
1740                 xprt_add_backlog(xprt, task);
1741                 dprintk("RPC:       waiting for request slot\n");
1742                 fallthrough;
1743         default:
1744                 task->tk_status = -EAGAIN;
1745         }
1746         spin_unlock(&xprt->reserve_lock);
1747         return;
1748 out_init_req:
1749         xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
1750                                      xprt->num_reqs);
1751         spin_unlock(&xprt->reserve_lock);
1752
1753         task->tk_status = 0;
1754         task->tk_rqstp = req;
1755 }
1756 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1757
1758 void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1759 {
1760         spin_lock(&xprt->reserve_lock);
1761         if (!xprt_wake_up_backlog(xprt, req) &&
1762             !xprt_dynamic_free_slot(xprt, req)) {
1763                 memset(req, 0, sizeof(*req));   /* mark unused */
1764                 list_add(&req->rq_list, &xprt->free);
1765         }
1766         spin_unlock(&xprt->reserve_lock);
1767 }
1768 EXPORT_SYMBOL_GPL(xprt_free_slot);
1769
1770 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1771 {
1772         struct rpc_rqst *req;
1773         while (!list_empty(&xprt->free)) {
1774                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1775                 list_del(&req->rq_list);
1776                 kfree(req);
1777         }
1778 }
1779
1780 static DEFINE_IDA(rpc_xprt_ids);
1781
1782 void xprt_cleanup_ids(void)
1783 {
1784         ida_destroy(&rpc_xprt_ids);
1785 }
1786
1787 static int xprt_alloc_id(struct rpc_xprt *xprt)
1788 {
1789         int id;
1790
1791         id = ida_alloc(&rpc_xprt_ids, GFP_KERNEL);
1792         if (id < 0)
1793                 return id;
1794
1795         xprt->id = id;
1796         return 0;
1797 }
1798
1799 static void xprt_free_id(struct rpc_xprt *xprt)
1800 {
1801         ida_free(&rpc_xprt_ids, xprt->id);
1802 }
1803
1804 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1805                 unsigned int num_prealloc,
1806                 unsigned int max_alloc)
1807 {
1808         struct rpc_xprt *xprt;
1809         struct rpc_rqst *req;
1810         int i;
1811
1812         xprt = kzalloc(size, GFP_KERNEL);
1813         if (xprt == NULL)
1814                 goto out;
1815
1816         xprt_alloc_id(xprt);
1817         xprt_init(xprt, net);
1818
1819         for (i = 0; i < num_prealloc; i++) {
1820                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1821                 if (!req)
1822                         goto out_free;
1823                 list_add(&req->rq_list, &xprt->free);
1824         }
1825         xprt->max_reqs = max_t(unsigned int, max_alloc, num_prealloc);
1826         xprt->min_reqs = num_prealloc;
1827         xprt->num_reqs = num_prealloc;
1828
1829         return xprt;
1830
1831 out_free:
1832         xprt_free(xprt);
1833 out:
1834         return NULL;
1835 }
1836 EXPORT_SYMBOL_GPL(xprt_alloc);
1837
1838 void xprt_free(struct rpc_xprt *xprt)
1839 {
1840         put_net_track(xprt->xprt_net, &xprt->ns_tracker);
1841         xprt_free_all_slots(xprt);
1842         xprt_free_id(xprt);
1843         rpc_sysfs_xprt_destroy(xprt);
1844         kfree_rcu(xprt, rcu);
1845 }
1846 EXPORT_SYMBOL_GPL(xprt_free);
1847
1848 static void
1849 xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
1850 {
1851         req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
1852 }
1853
1854 static __be32
1855 xprt_alloc_xid(struct rpc_xprt *xprt)
1856 {
1857         __be32 xid;
1858
1859         spin_lock(&xprt->reserve_lock);
1860         xid = (__force __be32)xprt->xid++;
1861         spin_unlock(&xprt->reserve_lock);
1862         return xid;
1863 }
1864
1865 static void
1866 xprt_init_xid(struct rpc_xprt *xprt)
1867 {
1868         xprt->xid = get_random_u32();
1869 }
1870
1871 static void
1872 xprt_request_init(struct rpc_task *task)
1873 {
1874         struct rpc_xprt *xprt = task->tk_xprt;
1875         struct rpc_rqst *req = task->tk_rqstp;
1876
1877         req->rq_task    = task;
1878         req->rq_xprt    = xprt;
1879         req->rq_buffer  = NULL;
1880         req->rq_xid     = xprt_alloc_xid(xprt);
1881         xprt_init_connect_cookie(req, xprt);
1882         req->rq_snd_buf.len = 0;
1883         req->rq_snd_buf.buflen = 0;
1884         req->rq_rcv_buf.len = 0;
1885         req->rq_rcv_buf.buflen = 0;
1886         req->rq_snd_buf.bvec = NULL;
1887         req->rq_rcv_buf.bvec = NULL;
1888         req->rq_release_snd_buf = NULL;
1889         xprt_init_majortimeo(task, req);
1890
1891         trace_xprt_reserve(req);
1892 }
1893
1894 static void
1895 xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
1896 {
1897         xprt->ops->alloc_slot(xprt, task);
1898         if (task->tk_rqstp != NULL)
1899                 xprt_request_init(task);
1900 }
1901
1902 /**
1903  * xprt_reserve - allocate an RPC request slot
1904  * @task: RPC task requesting a slot allocation
1905  *
1906  * If the transport is marked as being congested, or if no more
1907  * slots are available, place the task on the transport's
1908  * backlog queue.
1909  */
1910 void xprt_reserve(struct rpc_task *task)
1911 {
1912         struct rpc_xprt *xprt = task->tk_xprt;
1913
1914         task->tk_status = 0;
1915         if (task->tk_rqstp != NULL)
1916                 return;
1917
1918         task->tk_status = -EAGAIN;
1919         if (!xprt_throttle_congested(xprt, task))
1920                 xprt_do_reserve(xprt, task);
1921 }
1922
1923 /**
1924  * xprt_retry_reserve - allocate an RPC request slot
1925  * @task: RPC task requesting a slot allocation
1926  *
1927  * If no more slots are available, place the task on the transport's
1928  * backlog queue.
1929  * Note that the only difference with xprt_reserve is that we now
1930  * ignore the value of the XPRT_CONGESTED flag.
1931  */
1932 void xprt_retry_reserve(struct rpc_task *task)
1933 {
1934         struct rpc_xprt *xprt = task->tk_xprt;
1935
1936         task->tk_status = 0;
1937         if (task->tk_rqstp != NULL)
1938                 return;
1939
1940         task->tk_status = -EAGAIN;
1941         xprt_do_reserve(xprt, task);
1942 }
1943
1944 /**
1945  * xprt_release - release an RPC request slot
1946  * @task: task which is finished with the slot
1947  *
1948  */
1949 void xprt_release(struct rpc_task *task)
1950 {
1951         struct rpc_xprt *xprt;
1952         struct rpc_rqst *req = task->tk_rqstp;
1953
1954         if (req == NULL) {
1955                 if (task->tk_client) {
1956                         xprt = task->tk_xprt;
1957                         xprt_release_write(xprt, task);
1958                 }
1959                 return;
1960         }
1961
1962         xprt = req->rq_xprt;
1963         xprt_request_dequeue_xprt(task);
1964         spin_lock(&xprt->transport_lock);
1965         xprt->ops->release_xprt(xprt, task);
1966         if (xprt->ops->release_request)
1967                 xprt->ops->release_request(task);
1968         xprt_schedule_autodisconnect(xprt);
1969         spin_unlock(&xprt->transport_lock);
1970         if (req->rq_buffer)
1971                 xprt->ops->buf_free(task);
1972         if (req->rq_cred != NULL)
1973                 put_rpccred(req->rq_cred);
1974         if (req->rq_release_snd_buf)
1975                 req->rq_release_snd_buf(req);
1976
1977         task->tk_rqstp = NULL;
1978         if (likely(!bc_prealloc(req)))
1979                 xprt->ops->free_slot(xprt, req);
1980         else
1981                 xprt_free_bc_request(req);
1982 }
1983
1984 #ifdef CONFIG_SUNRPC_BACKCHANNEL
1985 void
1986 xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
1987 {
1988         struct xdr_buf *xbufp = &req->rq_snd_buf;
1989
1990         task->tk_rqstp = req;
1991         req->rq_task = task;
1992         xprt_init_connect_cookie(req, req->rq_xprt);
1993         /*
1994          * Set up the xdr_buf length.
1995          * This also indicates that the buffer is XDR encoded already.
1996          */
1997         xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
1998                 xbufp->tail[0].iov_len;
1999 }
2000 #endif
2001
2002 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
2003 {
2004         kref_init(&xprt->kref);
2005
2006         spin_lock_init(&xprt->transport_lock);
2007         spin_lock_init(&xprt->reserve_lock);
2008         spin_lock_init(&xprt->queue_lock);
2009
2010         INIT_LIST_HEAD(&xprt->free);
2011         xprt->recv_queue = RB_ROOT;
2012         INIT_LIST_HEAD(&xprt->xmit_queue);
2013 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
2014         spin_lock_init(&xprt->bc_pa_lock);
2015         INIT_LIST_HEAD(&xprt->bc_pa_list);
2016 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
2017         INIT_LIST_HEAD(&xprt->xprt_switch);
2018
2019         xprt->last_used = jiffies;
2020         xprt->cwnd = RPC_INITCWND;
2021         xprt->bind_index = 0;
2022
2023         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
2024         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
2025         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
2026         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
2027
2028         xprt_init_xid(xprt);
2029
2030         xprt->xprt_net = get_net_track(net, &xprt->ns_tracker, GFP_KERNEL);
2031 }
2032
2033 /**
2034  * xprt_create_transport - create an RPC transport
2035  * @args: rpc transport creation arguments
2036  *
2037  */
2038 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
2039 {
2040         struct rpc_xprt *xprt;
2041         const struct xprt_class *t;
2042
2043         t = xprt_class_find_by_ident(args->ident);
2044         if (!t) {
2045                 dprintk("RPC: transport (%d) not supported\n", args->ident);
2046                 return ERR_PTR(-EIO);
2047         }
2048
2049         xprt = t->setup(args);
2050         xprt_class_release(t);
2051
2052         if (IS_ERR(xprt))
2053                 goto out;
2054         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
2055                 xprt->idle_timeout = 0;
2056         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
2057         if (xprt_has_timer(xprt))
2058                 timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
2059         else
2060                 timer_setup(&xprt->timer, NULL, 0);
2061
2062         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
2063                 xprt_destroy(xprt);
2064                 return ERR_PTR(-EINVAL);
2065         }
2066         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
2067         if (xprt->servername == NULL) {
2068                 xprt_destroy(xprt);
2069                 return ERR_PTR(-ENOMEM);
2070         }
2071
2072         rpc_xprt_debugfs_register(xprt);
2073
2074         trace_xprt_create(xprt);
2075 out:
2076         return xprt;
2077 }
2078
2079 static void xprt_destroy_cb(struct work_struct *work)
2080 {
2081         struct rpc_xprt *xprt =
2082                 container_of(work, struct rpc_xprt, task_cleanup);
2083
2084         trace_xprt_destroy(xprt);
2085
2086         rpc_xprt_debugfs_unregister(xprt);
2087         rpc_destroy_wait_queue(&xprt->binding);
2088         rpc_destroy_wait_queue(&xprt->pending);
2089         rpc_destroy_wait_queue(&xprt->sending);
2090         rpc_destroy_wait_queue(&xprt->backlog);
2091         kfree(xprt->servername);
2092         /*
2093          * Destroy any existing back channel
2094          */
2095         xprt_destroy_backchannel(xprt, UINT_MAX);
2096
2097         /*
2098          * Tear down transport state and free the rpc_xprt
2099          */
2100         xprt->ops->destroy(xprt);
2101 }
2102
2103 /**
2104  * xprt_destroy - destroy an RPC transport, killing off all requests.
2105  * @xprt: transport to destroy
2106  *
2107  */
2108 static void xprt_destroy(struct rpc_xprt *xprt)
2109 {
2110         /*
2111          * Exclude transport connect/disconnect handlers and autoclose
2112          */
2113         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
2114
2115         /*
2116          * xprt_schedule_autodisconnect() can run after XPRT_LOCKED
2117          * is cleared.  We use ->transport_lock to ensure the mod_timer()
2118          * can only run *before* del_time_sync(), never after.
2119          */
2120         spin_lock(&xprt->transport_lock);
2121         del_timer_sync(&xprt->timer);
2122         spin_unlock(&xprt->transport_lock);
2123
2124         /*
2125          * Destroy sockets etc from the system workqueue so they can
2126          * safely flush receive work running on rpciod.
2127          */
2128         INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
2129         schedule_work(&xprt->task_cleanup);
2130 }
2131
2132 static void xprt_destroy_kref(struct kref *kref)
2133 {
2134         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
2135 }
2136
2137 /**
2138  * xprt_get - return a reference to an RPC transport.
2139  * @xprt: pointer to the transport
2140  *
2141  */
2142 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
2143 {
2144         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
2145                 return xprt;
2146         return NULL;
2147 }
2148 EXPORT_SYMBOL_GPL(xprt_get);
2149
2150 /**
2151  * xprt_put - release a reference to an RPC transport.
2152  * @xprt: pointer to the transport
2153  *
2154  */
2155 void xprt_put(struct rpc_xprt *xprt)
2156 {
2157         if (xprt != NULL)
2158                 kref_put(&xprt->kref, xprt_destroy_kref);
2159 }
2160 EXPORT_SYMBOL_GPL(xprt_put);
2161
2162 void xprt_set_offline_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps)
2163 {
2164         if (!test_and_set_bit(XPRT_OFFLINE, &xprt->state)) {
2165                 spin_lock(&xps->xps_lock);
2166                 xps->xps_nactive--;
2167                 spin_unlock(&xps->xps_lock);
2168         }
2169 }
2170
2171 void xprt_set_online_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps)
2172 {
2173         if (test_and_clear_bit(XPRT_OFFLINE, &xprt->state)) {
2174                 spin_lock(&xps->xps_lock);
2175                 xps->xps_nactive++;
2176                 spin_unlock(&xps->xps_lock);
2177         }
2178 }
2179
2180 void xprt_delete_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps)
2181 {
2182         if (test_and_set_bit(XPRT_REMOVE, &xprt->state))
2183                 return;
2184
2185         xprt_force_disconnect(xprt);
2186         if (!test_bit(XPRT_CONNECTED, &xprt->state))
2187                 return;
2188
2189         if (!xprt->sending.qlen && !xprt->pending.qlen &&
2190             !xprt->backlog.qlen && !atomic_long_read(&xprt->queuelen))
2191                 rpc_xprt_switch_remove_xprt(xps, xprt, true);
2192 }