net/sunrpc/xprt.c

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