git.rot13.org Git - linux/blob - 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_connect_status(struct rpc_task *task);
  71 static void      xprt_destroy(struct rpc_xprt *xprt);
  72
  73 static DEFINE_SPINLOCK(xprt_list_lock);
  74 static LIST_HEAD(xprt_list);
  75
  76 /**
  77  * xprt_register_transport - register a transport implementation
  78  * @transport: transport to register
  79  *
  80  * If a transport implementation is loaded as a kernel module, it can
  81  * call this interface to make itself known to the RPC client.
  82  *
  83  * Returns:
  84  * 0:           transport successfully registered
  85  * -EEXIST:     transport already registered
  86  * -EINVAL:     transport module being unloaded
  87  */
  88 int xprt_register_transport(struct xprt_class *transport)
  89 {
  90         struct xprt_class *t;
  91         int result;
  92
  93         result = -EEXIST;
  94         spin_lock(&xprt_list_lock);
  95         list_for_each_entry(t, &xprt_list, list) {
  96                 /* don't register the same transport class twice */
  97                 if (t->ident == transport->ident)
  98                         goto out;
  99         }
 100
 101         list_add_tail(&transport->list, &xprt_list);
 102         printk(KERN_INFO "RPC: Registered %s transport module.\n",
 103                transport->name);
 104         result = 0;
 105
 106 out:
 107         spin_unlock(&xprt_list_lock);
 108         return result;
 109 }
 110 EXPORT_SYMBOL_GPL(xprt_register_transport);
 111
 112 /**
 113  * xprt_unregister_transport - unregister a transport implementation
 114  * @transport: transport to unregister
 115  *
 116  * Returns:
 117  * 0:           transport successfully unregistered
 118  * -ENOENT:     transport never registered
 119  */
 120 int xprt_unregister_transport(struct xprt_class *transport)
 121 {
 122         struct xprt_class *t;
 123         int result;
 124
 125         result = 0;
 126         spin_lock(&xprt_list_lock);
 127         list_for_each_entry(t, &xprt_list, list) {
 128                 if (t == transport) {
 129                         printk(KERN_INFO
 130                                 "RPC: Unregistered %s transport module.\n",
 131                                 transport->name);
 132                         list_del_init(&transport->list);
 133                         goto out;
 134                 }
 135         }
 136         result = -ENOENT;
 137
 138 out:
 139         spin_unlock(&xprt_list_lock);
 140         return result;
 141 }
 142 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 143
 144 /**
 145  * xprt_load_transport - load a transport implementation
 146  * @transport_name: transport to load
 147  *
 148  * Returns:
 149  * 0:           transport successfully loaded
 150  * -ENOENT:     transport module not available
 151  */
 152 int xprt_load_transport(const char *transport_name)
 153 {
 154         struct xprt_class *t;
 155         int result;
 156
 157         result = 0;
 158         spin_lock(&xprt_list_lock);
 159         list_for_each_entry(t, &xprt_list, list) {
 160                 if (strcmp(t->name, transport_name) == 0) {
 161                         spin_unlock(&xprt_list_lock);
 162                         goto out;
 163                 }
 164         }
 165         spin_unlock(&xprt_list_lock);
 166         result = request_module("xprt%s", transport_name);
 167 out:
 168         return result;
 169 }
 170 EXPORT_SYMBOL_GPL(xprt_load_transport);
 171
 172 static void xprt_clear_locked(struct rpc_xprt *xprt)
 173 {
 174         xprt->snd_task = NULL;
 175         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 176                 smp_mb__before_atomic();
 177                 clear_bit(XPRT_LOCKED, &xprt->state);
 178                 smp_mb__after_atomic();
 179         } else
 180                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 181 }
 182
 183 /**
 184  * xprt_reserve_xprt - serialize write access to transports
 185  * @task: task that is requesting access to the transport
 186  * @xprt: pointer to the target transport
 187  *
 188  * This prevents mixing the payload of separate requests, and prevents
 189  * transport connects from colliding with writes.  No congestion control
 190  * is provided.
 191  */
 192 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 193 {
 194         struct rpc_rqst *req = task->tk_rqstp;
 195
 196         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 197                 if (task == xprt->snd_task)
 198                         return 1;
 199                 goto out_sleep;
 200         }
 201         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 202                 goto out_unlock;
 203         xprt->snd_task = task;
 204
 205         return 1;
 206
 207 out_unlock:
 208         xprt_clear_locked(xprt);
 209 out_sleep:
 210         dprintk("RPC: %5u failed to lock transport %p\n",
 211                         task->tk_pid, xprt);
 212         task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
 213         task->tk_status = -EAGAIN;
 214         rpc_sleep_on(&xprt->sending, task, NULL);
 215         return 0;
 216 }
 217 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 218
 219 static bool
 220 xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
 221 {
 222         return test_bit(XPRT_CWND_WAIT, &xprt->state);
 223 }
 224
 225 static void
 226 xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
 227 {
 228         if (!list_empty(&xprt->xmit_queue)) {
 229                 /* Peek at head of queue to see if it can make progress */
 230                 if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
 231                                         rq_xmit)->rq_cong)
 232                         return;
 233         }
 234         set_bit(XPRT_CWND_WAIT, &xprt->state);
 235 }
 236
 237 static void
 238 xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
 239 {
 240         if (!RPCXPRT_CONGESTED(xprt))
 241                 clear_bit(XPRT_CWND_WAIT, &xprt->state);
 242 }
 243
 244 /*
 245  * xprt_reserve_xprt_cong - serialize write access to transports
 246  * @task: task that is requesting access to the transport
 247  *
 248  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 249  * integrated into the decision of whether a request is allowed to be
 250  * woken up and given access to the transport.
 251  * Note that the lock is only granted if we know there are free slots.
 252  */
 253 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 254 {
 255         struct rpc_rqst *req = task->tk_rqstp;
 256
 257         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 258                 if (task == xprt->snd_task)
 259                         return 1;
 260                 goto out_sleep;
 261         }
 262         if (req == NULL) {
 263                 xprt->snd_task = task;
 264                 return 1;
 265         }
 266         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 267                 goto out_unlock;
 268         if (!xprt_need_congestion_window_wait(xprt)) {
 269                 xprt->snd_task = task;
 270                 return 1;
 271         }
 272 out_unlock:
 273         xprt_clear_locked(xprt);
 274 out_sleep:
 275         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
 276         task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
 277         task->tk_status = -EAGAIN;
 278         rpc_sleep_on(&xprt->sending, task, NULL);
 279         return 0;
 280 }
 281 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 282
 283 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 284 {
 285         int retval;
 286
 287         if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
 288                 return 1;
 289         spin_lock_bh(&xprt->transport_lock);
 290         retval = xprt->ops->reserve_xprt(xprt, task);
 291         spin_unlock_bh(&xprt->transport_lock);
 292         return retval;
 293 }
 294
 295 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
 296 {
 297         struct rpc_xprt *xprt = data;
 298
 299         xprt->snd_task = task;
 300         return true;
 301 }
 302
 303 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 304 {
 305         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 306                 return;
 307         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 308                 goto out_unlock;
 309         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 310                                 __xprt_lock_write_func, xprt))
 311                 return;
 312 out_unlock:
 313         xprt_clear_locked(xprt);
 314 }
 315
 316 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 317 {
 318         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 319                 return;
 320         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
 321                 goto out_unlock;
 322         if (xprt_need_congestion_window_wait(xprt))
 323                 goto out_unlock;
 324         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 325                                 __xprt_lock_write_func, xprt))
 326                 return;
 327 out_unlock:
 328         xprt_clear_locked(xprt);
 329 }
 330
 331 /**
 332  * xprt_release_xprt - allow other requests to use a transport
 333  * @xprt: transport with other tasks potentially waiting
 334  * @task: task that is releasing access to the transport
 335  *
 336  * Note that "task" can be NULL.  No congestion control is provided.
 337  */
 338 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 339 {
 340         if (xprt->snd_task == task) {
 341                 xprt_clear_locked(xprt);
 342                 __xprt_lock_write_next(xprt);
 343         }
 344 }
 345 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 346
 347 /**
 348  * xprt_release_xprt_cong - allow other requests to use a transport
 349  * @xprt: transport with other tasks potentially waiting
 350  * @task: task that is releasing access to the transport
 351  *
 352  * Note that "task" can be NULL.  Another task is awoken to use the
 353  * transport if the transport's congestion window allows it.
 354  */
 355 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 356 {
 357         if (xprt->snd_task == task) {
 358                 xprt_clear_locked(xprt);
 359                 __xprt_lock_write_next_cong(xprt);
 360         }
 361 }
 362 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 363
 364 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 365 {
 366         if (xprt->snd_task != task)
 367                 return;
 368         spin_lock_bh(&xprt->transport_lock);
 369         xprt->ops->release_xprt(xprt, task);
 370         spin_unlock_bh(&xprt->transport_lock);
 371 }
 372
 373 /*
 374  * Van Jacobson congestion avoidance. Check if the congestion window
 375  * overflowed. Put the task to sleep if this is the case.
 376  */
 377 static int
 378 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 379 {
 380         if (req->rq_cong)
 381                 return 1;
 382         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
 383                         req->rq_task->tk_pid, xprt->cong, xprt->cwnd);
 384         if (RPCXPRT_CONGESTED(xprt)) {
 385                 xprt_set_congestion_window_wait(xprt);
 386                 return 0;
 387         }
 388         req->rq_cong = 1;
 389         xprt->cong += RPC_CWNDSCALE;
 390         return 1;
 391 }
 392
 393 /*
 394  * Adjust the congestion window, and wake up the next task
 395  * that has been sleeping due to congestion
 396  */
 397 static void
 398 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 399 {
 400         if (!req->rq_cong)
 401                 return;
 402         req->rq_cong = 0;
 403         xprt->cong -= RPC_CWNDSCALE;
 404         xprt_test_and_clear_congestion_window_wait(xprt);
 405         __xprt_lock_write_next_cong(xprt);
 406 }
 407
 408 /**
 409  * xprt_request_get_cong - Request congestion control credits
 410  * @xprt: pointer to transport
 411  * @req: pointer to RPC request
 412  *
 413  * Useful for transports that require congestion control.
 414  */
 415 bool
 416 xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 417 {
 418         bool ret = false;
 419
 420         if (req->rq_cong)
 421                 return true;
 422         spin_lock_bh(&xprt->transport_lock);
 423         ret = __xprt_get_cong(xprt, req) != 0;
 424         spin_unlock_bh(&xprt->transport_lock);
 425         return ret;
 426 }
 427 EXPORT_SYMBOL_GPL(xprt_request_get_cong);
 428
 429 /**
 430  * xprt_release_rqst_cong - housekeeping when request is complete
 431  * @task: RPC request that recently completed
 432  *
 433  * Useful for transports that require congestion control.
 434  */
 435 void xprt_release_rqst_cong(struct rpc_task *task)
 436 {
 437         struct rpc_rqst *req = task->tk_rqstp;
 438
 439         __xprt_put_cong(req->rq_xprt, req);
 440 }
 441 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 442
 443 /*
 444  * Clear the congestion window wait flag and wake up the next
 445  * entry on xprt->sending
 446  */
 447 static void
 448 xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
 449 {
 450         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
 451                 spin_lock_bh(&xprt->transport_lock);
 452                 __xprt_lock_write_next_cong(xprt);
 453                 spin_unlock_bh(&xprt->transport_lock);
 454         }
 455 }
 456
 457 /**
 458  * xprt_adjust_cwnd - adjust transport congestion window
 459  * @xprt: pointer to xprt
 460  * @task: recently completed RPC request used to adjust window
 461  * @result: result code of completed RPC request
 462  *
 463  * The transport code maintains an estimate on the maximum number of out-
 464  * standing RPC requests, using a smoothed version of the congestion
 465  * avoidance implemented in 44BSD. This is basically the Van Jacobson
 466  * congestion algorithm: If a retransmit occurs, the congestion window is
 467  * halved; otherwise, it is incremented by 1/cwnd when
 468  *
 469  *      -       a reply is received and
 470  *      -       a full number of requests are outstanding and
 471  *      -       the congestion window hasn't been updated recently.
 472  */
 473 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
 474 {
 475         struct rpc_rqst *req = task->tk_rqstp;
 476         unsigned long cwnd = xprt->cwnd;
 477
 478         if (result >= 0 && cwnd <= xprt->cong) {
 479                 /* The (cwnd >> 1) term makes sure
 480                  * the result gets rounded properly. */
 481                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 482                 if (cwnd > RPC_MAXCWND(xprt))
 483                         cwnd = RPC_MAXCWND(xprt);
 484                 __xprt_lock_write_next_cong(xprt);
 485         } else if (result == -ETIMEDOUT) {
 486                 cwnd >>= 1;
 487                 if (cwnd < RPC_CWNDSCALE)
 488                         cwnd = RPC_CWNDSCALE;
 489         }
 490         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 491                         xprt->cong, xprt->cwnd, cwnd);
 492         xprt->cwnd = cwnd;
 493         __xprt_put_cong(xprt, req);
 494 }
 495 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 496
 497 /**
 498  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 499  * @xprt: transport with waiting tasks
 500  * @status: result code to plant in each task before waking it
 501  *
 502  */
 503 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 504 {
 505         if (status < 0)
 506                 rpc_wake_up_status(&xprt->pending, status);
 507         else
 508                 rpc_wake_up(&xprt->pending);
 509 }
 510 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 511
 512 /**
 513  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 514  * @xprt: transport
 515  *
 516  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
 517  * we don't in general want to force a socket disconnection due to
 518  * an incomplete RPC call transmission.
 519  */
 520 void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
 521 {
 522         set_bit(XPRT_WRITE_SPACE, &xprt->state);
 523 }
 524 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 525
 526 static bool
 527 xprt_clear_write_space_locked(struct rpc_xprt *xprt)
 528 {
 529         if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
 530                 __xprt_lock_write_next(xprt);
 531                 dprintk("RPC:       write space: waking waiting task on "
 532                                 "xprt %p\n", xprt);
 533                 return true;
 534         }
 535         return false;
 536 }
 537
 538 /**
 539  * xprt_write_space - wake the task waiting for transport output buffer space
 540  * @xprt: transport with waiting tasks
 541  *
 542  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 543  */
 544 bool xprt_write_space(struct rpc_xprt *xprt)
 545 {
 546         bool ret;
 547
 548         if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
 549                 return false;
 550         spin_lock_bh(&xprt->transport_lock);
 551         ret = xprt_clear_write_space_locked(xprt);
 552         spin_unlock_bh(&xprt->transport_lock);
 553         return ret;
 554 }
 555 EXPORT_SYMBOL_GPL(xprt_write_space);
 556
 557 /**
 558  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 559  * @task: task whose timeout is to be set
 560  *
 561  * Set a request's retransmit timeout based on the transport's
 562  * default timeout parameters.  Used by transports that don't adjust
 563  * the retransmit timeout based on round-trip time estimation.
 564  */
 565 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 566 {
 567         task->tk_timeout = task->tk_rqstp->rq_timeout;
 568 }
 569 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
 570
 571 /**
 572  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 573  * @task: task whose timeout is to be set
 574  *
 575  * Set a request's retransmit timeout using the RTT estimator.
 576  */
 577 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 578 {
 579         int timer = task->tk_msg.rpc_proc->p_timer;
 580         struct rpc_clnt *clnt = task->tk_client;
 581         struct rpc_rtt *rtt = clnt->cl_rtt;
 582         struct rpc_rqst *req = task->tk_rqstp;
 583         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
 584
 585         task->tk_timeout = rpc_calc_rto(rtt, timer);
 586         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 587         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 588                 task->tk_timeout = max_timeout;
 589 }
 590 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 591
 592 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 593 {
 594         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 595
 596         req->rq_majortimeo = req->rq_timeout;
 597         if (to->to_exponential)
 598                 req->rq_majortimeo <<= to->to_retries;
 599         else
 600                 req->rq_majortimeo += to->to_increment * to->to_retries;
 601         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 602                 req->rq_majortimeo = to->to_maxval;
 603         req->rq_majortimeo += jiffies;
 604 }
 605
 606 /**
 607  * xprt_adjust_timeout - adjust timeout values for next retransmit
 608  * @req: RPC request containing parameters to use for the adjustment
 609  *
 610  */
 611 int xprt_adjust_timeout(struct rpc_rqst *req)
 612 {
 613         struct rpc_xprt *xprt = req->rq_xprt;
 614         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 615         int status = 0;
 616
 617         if (time_before(jiffies, req->rq_majortimeo)) {
 618                 if (to->to_exponential)
 619                         req->rq_timeout <<= 1;
 620                 else
 621                         req->rq_timeout += to->to_increment;
 622                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 623                         req->rq_timeout = to->to_maxval;
 624                 req->rq_retries++;
 625         } else {
 626                 req->rq_timeout = to->to_initval;
 627                 req->rq_retries = 0;
 628                 xprt_reset_majortimeo(req);
 629                 /* Reset the RTT counters == "slow start" */
 630                 spin_lock_bh(&xprt->transport_lock);
 631                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 632                 spin_unlock_bh(&xprt->transport_lock);
 633                 status = -ETIMEDOUT;
 634         }
 635
 636         if (req->rq_timeout == 0) {
 637                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 638                 req->rq_timeout = 5 * HZ;
 639         }
 640         return status;
 641 }
 642
 643 static void xprt_autoclose(struct work_struct *work)
 644 {
 645         struct rpc_xprt *xprt =
 646                 container_of(work, struct rpc_xprt, task_cleanup);
 647
 648         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 649         xprt->ops->close(xprt);
 650         xprt_release_write(xprt, NULL);
 651         wake_up_bit(&xprt->state, XPRT_LOCKED);
 652 }
 653
 654 /**
 655  * xprt_disconnect_done - mark a transport as disconnected
 656  * @xprt: transport to flag for disconnect
 657  *
 658  */
 659 void xprt_disconnect_done(struct rpc_xprt *xprt)
 660 {
 661         dprintk("RPC:       disconnected transport %p\n", xprt);
 662         spin_lock_bh(&xprt->transport_lock);
 663         xprt_clear_connected(xprt);
 664         xprt_clear_write_space_locked(xprt);
 665         xprt_wake_pending_tasks(xprt, -EAGAIN);
 666         spin_unlock_bh(&xprt->transport_lock);
 667 }
 668 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 669
 670 /**
 671  * xprt_force_disconnect - force a transport to disconnect
 672  * @xprt: transport to disconnect
 673  *
 674  */
 675 void xprt_force_disconnect(struct rpc_xprt *xprt)
 676 {
 677         /* Don't race with the test_bit() in xprt_clear_locked() */
 678         spin_lock_bh(&xprt->transport_lock);
 679         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 680         /* Try to schedule an autoclose RPC call */
 681         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 682                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 683         xprt_wake_pending_tasks(xprt, -EAGAIN);
 684         spin_unlock_bh(&xprt->transport_lock);
 685 }
 686 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
 687
 688 static unsigned int
 689 xprt_connect_cookie(struct rpc_xprt *xprt)
 690 {
 691         return READ_ONCE(xprt->connect_cookie);
 692 }
 693
 694 static bool
 695 xprt_request_retransmit_after_disconnect(struct rpc_task *task)
 696 {
 697         struct rpc_rqst *req = task->tk_rqstp;
 698         struct rpc_xprt *xprt = req->rq_xprt;
 699
 700         return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
 701                 !xprt_connected(xprt);
 702 }
 703
 704 /**
 705  * xprt_conditional_disconnect - force a transport to disconnect
 706  * @xprt: transport to disconnect
 707  * @cookie: 'connection cookie'
 708  *
 709  * This attempts to break the connection if and only if 'cookie' matches
 710  * the current transport 'connection cookie'. It ensures that we don't
 711  * try to break the connection more than once when we need to retransmit
 712  * a batch of RPC requests.
 713  *
 714  */
 715 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 716 {
 717         /* Don't race with the test_bit() in xprt_clear_locked() */
 718         spin_lock_bh(&xprt->transport_lock);
 719         if (cookie != xprt->connect_cookie)
 720                 goto out;
 721         if (test_bit(XPRT_CLOSING, &xprt->state))
 722                 goto out;
 723         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 724         /* Try to schedule an autoclose RPC call */
 725         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 726                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 727         xprt_wake_pending_tasks(xprt, -EAGAIN);
 728 out:
 729         spin_unlock_bh(&xprt->transport_lock);
 730 }
 731
 732 static bool
 733 xprt_has_timer(const struct rpc_xprt *xprt)
 734 {
 735         return xprt->idle_timeout != 0;
 736 }
 737
 738 static void
 739 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
 740         __must_hold(&xprt->transport_lock)
 741 {
 742         if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))
 743                 mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
 744 }
 745
 746 static void
 747 xprt_init_autodisconnect(struct timer_list *t)
 748 {
 749         struct rpc_xprt *xprt = from_timer(xprt, t, timer);
 750
 751         spin_lock(&xprt->transport_lock);
 752         if (!RB_EMPTY_ROOT(&xprt->recv_queue))
 753                 goto out_abort;
 754         /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
 755         xprt->last_used = jiffies;
 756         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 757                 goto out_abort;
 758         spin_unlock(&xprt->transport_lock);
 759         queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 760         return;
 761 out_abort:
 762         spin_unlock(&xprt->transport_lock);
 763 }
 764
 765 bool xprt_lock_connect(struct rpc_xprt *xprt,
 766                 struct rpc_task *task,
 767                 void *cookie)
 768 {
 769         bool ret = false;
 770
 771         spin_lock_bh(&xprt->transport_lock);
 772         if (!test_bit(XPRT_LOCKED, &xprt->state))
 773                 goto out;
 774         if (xprt->snd_task != task)
 775                 goto out;
 776         xprt->snd_task = cookie;
 777         ret = true;
 778 out:
 779         spin_unlock_bh(&xprt->transport_lock);
 780         return ret;
 781 }
 782
 783 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
 784 {
 785         spin_lock_bh(&xprt->transport_lock);
 786         if (xprt->snd_task != cookie)
 787                 goto out;
 788         if (!test_bit(XPRT_LOCKED, &xprt->state))
 789                 goto out;
 790         xprt->snd_task =NULL;
 791         xprt->ops->release_xprt(xprt, NULL);
 792         xprt_schedule_autodisconnect(xprt);
 793 out:
 794         spin_unlock_bh(&xprt->transport_lock);
 795         wake_up_bit(&xprt->state, XPRT_LOCKED);
 796 }
 797
 798 /**
 799  * xprt_connect - schedule a transport connect operation
 800  * @task: RPC task that is requesting the connect
 801  *
 802  */
 803 void xprt_connect(struct rpc_task *task)
 804 {
 805         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 806
 807         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 808                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 809
 810         if (!xprt_bound(xprt)) {
 811                 task->tk_status = -EAGAIN;
 812                 return;
 813         }
 814         if (!xprt_lock_write(xprt, task))
 815                 return;
 816
 817         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
 818                 xprt->ops->close(xprt);
 819
 820         if (!xprt_connected(xprt)) {
 821                 task->tk_timeout = task->tk_rqstp->rq_timeout;
 822                 task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
 823                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
 824
 825                 if (test_bit(XPRT_CLOSING, &xprt->state))
 826                         return;
 827                 if (xprt_test_and_set_connecting(xprt))
 828                         return;
 829                 /* Race breaker */
 830                 if (!xprt_connected(xprt)) {
 831                         xprt->stat.connect_start = jiffies;
 832                         xprt->ops->connect(xprt, task);
 833                 } else {
 834                         xprt_clear_connecting(xprt);
 835                         task->tk_status = 0;
 836                         rpc_wake_up_queued_task(&xprt->pending, task);
 837                 }
 838         }
 839         xprt_release_write(xprt, task);
 840 }
 841
 842 static void xprt_connect_status(struct rpc_task *task)
 843 {
 844         switch (task->tk_status) {
 845         case 0:
 846                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 847                                 task->tk_pid);
 848                 break;
 849         case -ECONNREFUSED:
 850         case -ECONNRESET:
 851         case -ECONNABORTED:
 852         case -ENETUNREACH:
 853         case -EHOSTUNREACH:
 854         case -EPIPE:
 855         case -EAGAIN:
 856                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
 857                 break;
 858         case -ETIMEDOUT:
 859                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 860                                 "out\n", task->tk_pid);
 861                 break;
 862         default:
 863                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 864                                 "server %s\n", task->tk_pid, -task->tk_status,
 865                                 task->tk_rqstp->rq_xprt->servername);
 866                 task->tk_status = -EIO;
 867         }
 868 }
 869
 870 enum xprt_xid_rb_cmp {
 871         XID_RB_EQUAL,
 872         XID_RB_LEFT,
 873         XID_RB_RIGHT,
 874 };
 875 static enum xprt_xid_rb_cmp
 876 xprt_xid_cmp(__be32 xid1, __be32 xid2)
 877 {
 878         if (xid1 == xid2)
 879                 return XID_RB_EQUAL;
 880         if ((__force u32)xid1 < (__force u32)xid2)
 881                 return XID_RB_LEFT;
 882         return XID_RB_RIGHT;
 883 }
 884
 885 static struct rpc_rqst *
 886 xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
 887 {
 888         struct rb_node *n = xprt->recv_queue.rb_node;
 889         struct rpc_rqst *req;
 890
 891         while (n != NULL) {
 892                 req = rb_entry(n, struct rpc_rqst, rq_recv);
 893                 switch (xprt_xid_cmp(xid, req->rq_xid)) {
 894                 case XID_RB_LEFT:
 895                         n = n->rb_left;
 896                         break;
 897                 case XID_RB_RIGHT:
 898                         n = n->rb_right;
 899                         break;
 900                 case XID_RB_EQUAL:
 901                         return req;
 902                 }
 903         }
 904         return NULL;
 905 }
 906
 907 static void
 908 xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
 909 {
 910         struct rb_node **p = &xprt->recv_queue.rb_node;
 911         struct rb_node *n = NULL;
 912         struct rpc_rqst *req;
 913
 914         while (*p != NULL) {
 915                 n = *p;
 916                 req = rb_entry(n, struct rpc_rqst, rq_recv);
 917                 switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
 918                 case XID_RB_LEFT:
 919                         p = &n->rb_left;
 920                         break;
 921                 case XID_RB_RIGHT:
 922                         p = &n->rb_right;
 923                         break;
 924                 case XID_RB_EQUAL:
 925                         WARN_ON_ONCE(new != req);
 926                         return;
 927                 }
 928         }
 929         rb_link_node(&new->rq_recv, n, p);
 930         rb_insert_color(&new->rq_recv, &xprt->recv_queue);
 931 }
 932
 933 static void
 934 xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
 935 {
 936         rb_erase(&req->rq_recv, &xprt->recv_queue);
 937 }
 938
 939 /**
 940  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 941  * @xprt: transport on which the original request was transmitted
 942  * @xid: RPC XID of incoming reply
 943  *
 944  * Caller holds xprt->queue_lock.
 945  */
 946 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 947 {
 948         struct rpc_rqst *entry;
 949
 950         entry = xprt_request_rb_find(xprt, xid);
 951         if (entry != NULL) {
 952                 trace_xprt_lookup_rqst(xprt, xid, 0);
 953                 entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
 954                 return entry;
 955         }
 956
 957         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 958                         ntohl(xid));
 959         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
 960         xprt->stat.bad_xids++;
 961         return NULL;
 962 }
 963 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 964
 965 static bool
 966 xprt_is_pinned_rqst(struct rpc_rqst *req)
 967 {
 968         return atomic_read(&req->rq_pin) != 0;
 969 }
 970
 971 /**
 972  * xprt_pin_rqst - Pin a request on the transport receive list
 973  * @req: Request to pin
 974  *
 975  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
 976  * so should be holding the xprt receive lock.
 977  */
 978 void xprt_pin_rqst(struct rpc_rqst *req)
 979 {
 980         atomic_inc(&req->rq_pin);
 981 }
 982 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
 983
 984 /**
 985  * xprt_unpin_rqst - Unpin a request on the transport receive list
 986  * @req: Request to pin
 987  *
 988  * Caller should be holding the xprt receive lock.
 989  */
 990 void xprt_unpin_rqst(struct rpc_rqst *req)
 991 {
 992         if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
 993                 atomic_dec(&req->rq_pin);
 994                 return;
 995         }
 996         if (atomic_dec_and_test(&req->rq_pin))
 997                 wake_up_var(&req->rq_pin);
 998 }
 999 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
1000
1001 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
1002 {
1003         wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
1004 }
1005
1006 static bool
1007 xprt_request_data_received(struct rpc_task *task)
1008 {
1009         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1010                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
1011 }
1012
1013 static bool
1014 xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
1015 {
1016         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1017                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
1018 }
1019
1020 /**
1021  * xprt_request_enqueue_receive - Add an request to the receive queue
1022  * @task: RPC task
1023  *
1024  */
1025 void
1026 xprt_request_enqueue_receive(struct rpc_task *task)
1027 {
1028         struct rpc_rqst *req = task->tk_rqstp;
1029         struct rpc_xprt *xprt = req->rq_xprt;
1030
1031         if (!xprt_request_need_enqueue_receive(task, req))
1032                 return;
1033         spin_lock(&xprt->queue_lock);
1034
1035         /* Update the softirq receive buffer */
1036         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1037                         sizeof(req->rq_private_buf));
1038
1039         /* Add request to the receive list */
1040         xprt_request_rb_insert(xprt, req);
1041         set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
1042         spin_unlock(&xprt->queue_lock);
1043
1044         xprt_reset_majortimeo(req);
1045         /* Turn off autodisconnect */
1046         del_singleshot_timer_sync(&xprt->timer);
1047 }
1048
1049 /**
1050  * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
1051  * @task: RPC task
1052  *
1053  * Caller must hold xprt->queue_lock.
1054  */
1055 static void
1056 xprt_request_dequeue_receive_locked(struct rpc_task *task)
1057 {
1058         struct rpc_rqst *req = task->tk_rqstp;
1059
1060         if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1061                 xprt_request_rb_remove(req->rq_xprt, req);
1062 }
1063
1064 /**
1065  * xprt_update_rtt - Update RPC RTT statistics
1066  * @task: RPC request that recently completed
1067  *
1068  * Caller holds xprt->queue_lock.
1069  */
1070 void xprt_update_rtt(struct rpc_task *task)
1071 {
1072         struct rpc_rqst *req = task->tk_rqstp;
1073         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
1074         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
1075         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
1076
1077         if (timer) {
1078                 if (req->rq_ntrans == 1)
1079                         rpc_update_rtt(rtt, timer, m);
1080                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
1081         }
1082 }
1083 EXPORT_SYMBOL_GPL(xprt_update_rtt);
1084
1085 /**
1086  * xprt_complete_rqst - called when reply processing is complete
1087  * @task: RPC request that recently completed
1088  * @copied: actual number of bytes received from the transport
1089  *
1090  * Caller holds xprt->queue_lock.
1091  */
1092 void xprt_complete_rqst(struct rpc_task *task, int copied)
1093 {
1094         struct rpc_rqst *req = task->tk_rqstp;
1095         struct rpc_xprt *xprt = req->rq_xprt;
1096
1097         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
1098                         task->tk_pid, ntohl(req->rq_xid), copied);
1099         trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
1100
1101         xprt->stat.recvs++;
1102
1103         req->rq_private_buf.len = copied;
1104         /* Ensure all writes are done before we update */
1105         /* req->rq_reply_bytes_recvd */
1106         smp_wmb();
1107         req->rq_reply_bytes_recvd = copied;
1108         xprt_request_dequeue_receive_locked(task);
1109         rpc_wake_up_queued_task(&xprt->pending, task);
1110 }
1111 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
1112
1113 static void xprt_timer(struct rpc_task *task)
1114 {
1115         struct rpc_rqst *req = task->tk_rqstp;
1116         struct rpc_xprt *xprt = req->rq_xprt;
1117
1118         if (task->tk_status != -ETIMEDOUT)
1119                 return;
1120
1121         trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
1122         if (!req->rq_reply_bytes_recvd) {
1123                 if (xprt->ops->timer)
1124                         xprt->ops->timer(xprt, task);
1125         } else
1126                 task->tk_status = 0;
1127 }
1128
1129 /**
1130  * xprt_request_wait_receive - wait for the reply to an RPC request
1131  * @task: RPC task about to send a request
1132  *
1133  */
1134 void xprt_request_wait_receive(struct rpc_task *task)
1135 {
1136         struct rpc_rqst *req = task->tk_rqstp;
1137         struct rpc_xprt *xprt = req->rq_xprt;
1138
1139         if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1140                 return;
1141         /*
1142          * Sleep on the pending queue if we're expecting a reply.
1143          * The spinlock ensures atomicity between the test of
1144          * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1145          */
1146         spin_lock(&xprt->queue_lock);
1147         if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
1148                 xprt->ops->set_retrans_timeout(task);
1149                 rpc_sleep_on(&xprt->pending, task, xprt_timer);
1150                 /*
1151                  * Send an extra queue wakeup call if the
1152                  * connection was dropped in case the call to
1153                  * rpc_sleep_on() raced.
1154                  */
1155                 if (xprt_request_retransmit_after_disconnect(task))
1156                         rpc_wake_up_queued_task_set_status(&xprt->pending,
1157                                         task, -ENOTCONN);
1158         }
1159         spin_unlock(&xprt->queue_lock);
1160 }
1161
1162 static bool
1163 xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
1164 {
1165         return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1166 }
1167
1168 /**
1169  * xprt_request_enqueue_transmit - queue a task for transmission
1170  * @task: pointer to rpc_task
1171  *
1172  * Add a task to the transmission queue.
1173  */
1174 void
1175 xprt_request_enqueue_transmit(struct rpc_task *task)
1176 {
1177         struct rpc_rqst *pos, *req = task->tk_rqstp;
1178         struct rpc_xprt *xprt = req->rq_xprt;
1179
1180         if (xprt_request_need_enqueue_transmit(task, req)) {
1181                 spin_lock(&xprt->queue_lock);
1182                 /*
1183                  * Requests that carry congestion control credits are added
1184                  * to the head of the list to avoid starvation issues.
1185                  */
1186                 if (req->rq_cong) {
1187                         xprt_clear_congestion_window_wait(xprt);
1188                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1189                                 if (pos->rq_cong)
1190                                         continue;
1191                                 /* Note: req is added _before_ pos */
1192                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1193                                 INIT_LIST_HEAD(&req->rq_xmit2);
1194                                 goto out;
1195                         }
1196                 } else if (RPC_IS_SWAPPER(task)) {
1197                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1198                                 if (pos->rq_cong || pos->rq_bytes_sent)
1199                                         continue;
1200                                 if (RPC_IS_SWAPPER(pos->rq_task))
1201                                         continue;
1202                                 /* Note: req is added _before_ pos */
1203                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1204                                 INIT_LIST_HEAD(&req->rq_xmit2);
1205                                 goto out;
1206                         }
1207                 } else {
1208                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1209                                 if (pos->rq_task->tk_owner != task->tk_owner)
1210                                         continue;
1211                                 list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
1212                                 INIT_LIST_HEAD(&req->rq_xmit);
1213                                 goto out;
1214                         }
1215                 }
1216                 list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
1217                 INIT_LIST_HEAD(&req->rq_xmit2);
1218 out:
1219                 set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1220                 spin_unlock(&xprt->queue_lock);
1221         }
1222 }
1223
1224 /**
1225  * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
1226  * @task: pointer to rpc_task
1227  *
1228  * Remove a task from the transmission queue
1229  * Caller must hold xprt->queue_lock
1230  */
1231 static void
1232 xprt_request_dequeue_transmit_locked(struct rpc_task *task)
1233 {
1234         struct rpc_rqst *req = task->tk_rqstp;
1235
1236         if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1237                 return;
1238         if (!list_empty(&req->rq_xmit)) {
1239                 list_del(&req->rq_xmit);
1240                 if (!list_empty(&req->rq_xmit2)) {
1241                         struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
1242                                         struct rpc_rqst, rq_xmit2);
1243                         list_del(&req->rq_xmit2);
1244                         list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
1245                 }
1246         } else
1247                 list_del(&req->rq_xmit2);
1248 }
1249
1250 /**
1251  * xprt_request_dequeue_transmit - remove a task from the transmission queue
1252  * @task: pointer to rpc_task
1253  *
1254  * Remove a task from the transmission queue
1255  */
1256 static void
1257 xprt_request_dequeue_transmit(struct rpc_task *task)
1258 {
1259         struct rpc_rqst *req = task->tk_rqstp;
1260         struct rpc_xprt *xprt = req->rq_xprt;
1261
1262         spin_lock(&xprt->queue_lock);
1263         xprt_request_dequeue_transmit_locked(task);
1264         spin_unlock(&xprt->queue_lock);
1265 }
1266
1267 /**
1268  * xprt_request_prepare - prepare an encoded request for transport
1269  * @req: pointer to rpc_rqst
1270  *
1271  * Calls into the transport layer to do whatever is needed to prepare
1272  * the request for transmission or receive.
1273  */
1274 void
1275 xprt_request_prepare(struct rpc_rqst *req)
1276 {
1277         struct rpc_xprt *xprt = req->rq_xprt;
1278
1279         if (xprt->ops->prepare_request)
1280                 xprt->ops->prepare_request(req);
1281 }
1282
1283 /**
1284  * xprt_request_need_retransmit - Test if a task needs retransmission
1285  * @task: pointer to rpc_task
1286  *
1287  * Test for whether a connection breakage requires the task to retransmit
1288  */
1289 bool
1290 xprt_request_need_retransmit(struct rpc_task *task)
1291 {
1292         return xprt_request_retransmit_after_disconnect(task);
1293 }
1294
1295 /**
1296  * xprt_prepare_transmit - reserve the transport before sending a request
1297  * @task: RPC task about to send a request
1298  *
1299  */
1300 bool xprt_prepare_transmit(struct rpc_task *task)
1301 {
1302         struct rpc_rqst *req = task->tk_rqstp;
1303         struct rpc_xprt *xprt = req->rq_xprt;
1304
1305         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
1306
1307         if (!xprt_lock_write(xprt, task)) {
1308                 /* Race breaker: someone may have transmitted us */
1309                 if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1310                         rpc_wake_up_queued_task_set_status(&xprt->sending,
1311                                         task, 0);
1312                 return false;
1313
1314         }
1315         return true;
1316 }
1317
1318 void xprt_end_transmit(struct rpc_task *task)
1319 {
1320         xprt_release_write(task->tk_rqstp->rq_xprt, task);
1321 }
1322
1323 /**
1324  * xprt_request_transmit - send an RPC request on a transport
1325  * @req: pointer to request to transmit
1326  * @snd_task: RPC task that owns the transport lock
1327  *
1328  * This performs the transmission of a single request.
1329  * Note that if the request is not the same as snd_task, then it
1330  * does need to be pinned.
1331  * Returns '0' on success.
1332  */
1333 static int
1334 xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
1335 {
1336         struct rpc_xprt *xprt = req->rq_xprt;
1337         struct rpc_task *task = req->rq_task;
1338         unsigned int connect_cookie;
1339         int is_retrans = RPC_WAS_SENT(task);
1340         int status;
1341
1342         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
1343
1344         if (!req->rq_bytes_sent) {
1345                 if (xprt_request_data_received(task)) {
1346                         status = 0;
1347                         goto out_dequeue;
1348                 }
1349                 /* Verify that our message lies in the RPCSEC_GSS window */
1350                 if (rpcauth_xmit_need_reencode(task)) {
1351                         status = -EBADMSG;
1352                         goto out_dequeue;
1353                 }
1354         }
1355
1356         /*
1357          * Update req->rq_ntrans before transmitting to avoid races with
1358          * xprt_update_rtt(), which needs to know that it is recording a
1359          * reply to the first transmission.
1360          */
1361         req->rq_ntrans++;
1362
1363         connect_cookie = xprt->connect_cookie;
1364         status = xprt->ops->send_request(req);
1365         trace_xprt_transmit(xprt, req->rq_xid, status);
1366         if (status != 0) {
1367                 req->rq_ntrans--;
1368                 return status;
1369         }
1370
1371         if (is_retrans)
1372                 task->tk_client->cl_stats->rpcretrans++;
1373
1374         xprt_inject_disconnect(xprt);
1375
1376         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
1377         task->tk_flags |= RPC_TASK_SENT;
1378         spin_lock_bh(&xprt->transport_lock);
1379
1380         xprt->stat.sends++;
1381         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1382         xprt->stat.bklog_u += xprt->backlog.qlen;
1383         xprt->stat.sending_u += xprt->sending.qlen;
1384         xprt->stat.pending_u += xprt->pending.qlen;
1385         spin_unlock_bh(&xprt->transport_lock);
1386
1387         req->rq_connect_cookie = connect_cookie;
1388 out_dequeue:
1389         xprt_request_dequeue_transmit(task);
1390         rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
1391         return status;
1392 }
1393
1394 /**
1395  * xprt_transmit - send an RPC request on a transport
1396  * @task: controlling RPC task
1397  *
1398  * Attempts to drain the transmit queue. On exit, either the transport
1399  * signalled an error that needs to be handled before transmission can
1400  * resume, or @task finished transmitting, and detected that it already
1401  * received a reply.
1402  */
1403 void
1404 xprt_transmit(struct rpc_task *task)
1405 {
1406         struct rpc_rqst *next, *req = task->tk_rqstp;
1407         struct rpc_xprt *xprt = req->rq_xprt;
1408         int status;
1409
1410         spin_lock(&xprt->queue_lock);
1411         while (!list_empty(&xprt->xmit_queue)) {
1412                 next = list_first_entry(&xprt->xmit_queue,
1413                                 struct rpc_rqst, rq_xmit);
1414                 xprt_pin_rqst(next);
1415                 spin_unlock(&xprt->queue_lock);
1416                 status = xprt_request_transmit(next, task);
1417                 if (status == -EBADMSG && next != req)
1418                         status = 0;
1419                 cond_resched();
1420                 spin_lock(&xprt->queue_lock);
1421                 xprt_unpin_rqst(next);
1422                 if (status == 0) {
1423                         if (!xprt_request_data_received(task) ||
1424                             test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1425                                 continue;
1426                 } else if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1427                         task->tk_status = status;
1428                 break;
1429         }
1430         spin_unlock(&xprt->queue_lock);
1431 }
1432
1433 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1434 {
1435         set_bit(XPRT_CONGESTED, &xprt->state);
1436         rpc_sleep_on(&xprt->backlog, task, NULL);
1437 }
1438
1439 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
1440 {
1441         if (rpc_wake_up_next(&xprt->backlog) == NULL)
1442                 clear_bit(XPRT_CONGESTED, &xprt->state);
1443 }
1444
1445 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1446 {
1447         bool ret = false;
1448
1449         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1450                 goto out;
1451         spin_lock(&xprt->reserve_lock);
1452         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1453                 rpc_sleep_on(&xprt->backlog, task, NULL);
1454                 ret = true;
1455         }
1456         spin_unlock(&xprt->reserve_lock);
1457 out:
1458         return ret;
1459 }
1460
1461 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1462 {
1463         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1464
1465         if (xprt->num_reqs >= xprt->max_reqs)
1466                 goto out;
1467         ++xprt->num_reqs;
1468         spin_unlock(&xprt->reserve_lock);
1469         req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
1470         spin_lock(&xprt->reserve_lock);
1471         if (req != NULL)
1472                 goto out;
1473         --xprt->num_reqs;
1474         req = ERR_PTR(-ENOMEM);
1475 out:
1476         return req;
1477 }
1478
1479 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1480 {
1481         if (xprt->num_reqs > xprt->min_reqs) {
1482                 --xprt->num_reqs;
1483                 kfree(req);
1484                 return true;
1485         }
1486         return false;
1487 }
1488
1489 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1490 {
1491         struct rpc_rqst *req;
1492
1493         spin_lock(&xprt->reserve_lock);
1494         if (!list_empty(&xprt->free)) {
1495                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1496                 list_del(&req->rq_list);
1497                 goto out_init_req;
1498         }
1499         req = xprt_dynamic_alloc_slot(xprt);
1500         if (!IS_ERR(req))
1501                 goto out_init_req;
1502         switch (PTR_ERR(req)) {
1503         case -ENOMEM:
1504                 dprintk("RPC:       dynamic allocation of request slot "
1505                                 "failed! Retrying\n");
1506                 task->tk_status = -ENOMEM;
1507                 break;
1508         case -EAGAIN:
1509                 xprt_add_backlog(xprt, task);
1510                 dprintk("RPC:       waiting for request slot\n");
1511                 /* fall through */
1512         default:
1513                 task->tk_status = -EAGAIN;
1514         }
1515         spin_unlock(&xprt->reserve_lock);
1516         return;
1517 out_init_req:
1518         xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
1519                                      xprt->num_reqs);
1520         spin_unlock(&xprt->reserve_lock);
1521
1522         task->tk_status = 0;
1523         task->tk_rqstp = req;
1524 }
1525 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1526
1527 void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1528 {
1529         spin_lock(&xprt->reserve_lock);
1530         if (!xprt_dynamic_free_slot(xprt, req)) {
1531                 memset(req, 0, sizeof(*req));   /* mark unused */
1532                 list_add(&req->rq_list, &xprt->free);
1533         }
1534         xprt_wake_up_backlog(xprt);
1535         spin_unlock(&xprt->reserve_lock);
1536 }
1537 EXPORT_SYMBOL_GPL(xprt_free_slot);
1538
1539 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1540 {
1541         struct rpc_rqst *req;
1542         while (!list_empty(&xprt->free)) {
1543                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1544                 list_del(&req->rq_list);
1545                 kfree(req);
1546         }
1547 }
1548
1549 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1550                 unsigned int num_prealloc,
1551                 unsigned int max_alloc)
1552 {
1553         struct rpc_xprt *xprt;
1554         struct rpc_rqst *req;
1555         int i;
1556
1557         xprt = kzalloc(size, GFP_KERNEL);
1558         if (xprt == NULL)
1559                 goto out;
1560
1561         xprt_init(xprt, net);
1562
1563         for (i = 0; i < num_prealloc; i++) {
1564                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1565                 if (!req)
1566                         goto out_free;
1567                 list_add(&req->rq_list, &xprt->free);
1568         }
1569         if (max_alloc > num_prealloc)
1570                 xprt->max_reqs = max_alloc;
1571         else
1572                 xprt->max_reqs = num_prealloc;
1573         xprt->min_reqs = num_prealloc;
1574         xprt->num_reqs = num_prealloc;
1575
1576         return xprt;
1577
1578 out_free:
1579         xprt_free(xprt);
1580 out:
1581         return NULL;
1582 }
1583 EXPORT_SYMBOL_GPL(xprt_alloc);
1584
1585 void xprt_free(struct rpc_xprt *xprt)
1586 {
1587         put_net(xprt->xprt_net);
1588         xprt_free_all_slots(xprt);
1589         kfree_rcu(xprt, rcu);
1590 }
1591 EXPORT_SYMBOL_GPL(xprt_free);
1592
1593 static void
1594 xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
1595 {
1596         req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
1597 }
1598
1599 static __be32
1600 xprt_alloc_xid(struct rpc_xprt *xprt)
1601 {
1602         __be32 xid;
1603
1604         spin_lock(&xprt->reserve_lock);
1605         xid = (__force __be32)xprt->xid++;
1606         spin_unlock(&xprt->reserve_lock);
1607         return xid;
1608 }
1609
1610 static void
1611 xprt_init_xid(struct rpc_xprt *xprt)
1612 {
1613         xprt->xid = prandom_u32();
1614 }
1615
1616 static void
1617 xprt_request_init(struct rpc_task *task)
1618 {
1619         struct rpc_xprt *xprt = task->tk_xprt;
1620         struct rpc_rqst *req = task->tk_rqstp;
1621
1622         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1623         req->rq_task    = task;
1624         req->rq_xprt    = xprt;
1625         req->rq_buffer  = NULL;
1626         req->rq_xid     = xprt_alloc_xid(xprt);
1627         xprt_init_connect_cookie(req, xprt);
1628         req->rq_bytes_sent = 0;
1629         req->rq_snd_buf.len = 0;
1630         req->rq_snd_buf.buflen = 0;
1631         req->rq_rcv_buf.len = 0;
1632         req->rq_rcv_buf.buflen = 0;
1633         req->rq_snd_buf.bvec = NULL;
1634         req->rq_rcv_buf.bvec = NULL;
1635         req->rq_release_snd_buf = NULL;
1636         xprt_reset_majortimeo(req);
1637         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1638                         req, ntohl(req->rq_xid));
1639 }
1640
1641 static void
1642 xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
1643 {
1644         xprt->ops->alloc_slot(xprt, task);
1645         if (task->tk_rqstp != NULL)
1646                 xprt_request_init(task);
1647 }
1648
1649 /**
1650  * xprt_reserve - allocate an RPC request slot
1651  * @task: RPC task requesting a slot allocation
1652  *
1653  * If the transport is marked as being congested, or if no more
1654  * slots are available, place the task on the transport's
1655  * backlog queue.
1656  */
1657 void xprt_reserve(struct rpc_task *task)
1658 {
1659         struct rpc_xprt *xprt = task->tk_xprt;
1660
1661         task->tk_status = 0;
1662         if (task->tk_rqstp != NULL)
1663                 return;
1664
1665         task->tk_timeout = 0;
1666         task->tk_status = -EAGAIN;
1667         if (!xprt_throttle_congested(xprt, task))
1668                 xprt_do_reserve(xprt, task);
1669 }
1670
1671 /**
1672  * xprt_retry_reserve - allocate an RPC request slot
1673  * @task: RPC task requesting a slot allocation
1674  *
1675  * If no more slots are available, place the task on the transport's
1676  * backlog queue.
1677  * Note that the only difference with xprt_reserve is that we now
1678  * ignore the value of the XPRT_CONGESTED flag.
1679  */
1680 void xprt_retry_reserve(struct rpc_task *task)
1681 {
1682         struct rpc_xprt *xprt = task->tk_xprt;
1683
1684         task->tk_status = 0;
1685         if (task->tk_rqstp != NULL)
1686                 return;
1687
1688         task->tk_timeout = 0;
1689         task->tk_status = -EAGAIN;
1690         xprt_do_reserve(xprt, task);
1691 }
1692
1693 static void
1694 xprt_request_dequeue_all(struct rpc_task *task, struct rpc_rqst *req)
1695 {
1696         struct rpc_xprt *xprt = req->rq_xprt;
1697
1698         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
1699             test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
1700             xprt_is_pinned_rqst(req)) {
1701                 spin_lock(&xprt->queue_lock);
1702                 xprt_request_dequeue_transmit_locked(task);
1703                 xprt_request_dequeue_receive_locked(task);
1704                 while (xprt_is_pinned_rqst(req)) {
1705                         set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1706                         spin_unlock(&xprt->queue_lock);
1707                         xprt_wait_on_pinned_rqst(req);
1708                         spin_lock(&xprt->queue_lock);
1709                         clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1710                 }
1711                 spin_unlock(&xprt->queue_lock);
1712         }
1713 }
1714
1715 /**
1716  * xprt_release - release an RPC request slot
1717  * @task: task which is finished with the slot
1718  *
1719  */
1720 void xprt_release(struct rpc_task *task)
1721 {
1722         struct rpc_xprt *xprt;
1723         struct rpc_rqst *req = task->tk_rqstp;
1724
1725         if (req == NULL) {
1726                 if (task->tk_client) {
1727                         xprt = task->tk_xprt;
1728                         xprt_release_write(xprt, task);
1729                 }
1730                 return;
1731         }
1732
1733         xprt = req->rq_xprt;
1734         if (task->tk_ops->rpc_count_stats != NULL)
1735                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1736         else if (task->tk_client)
1737                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1738         xprt_request_dequeue_all(task, req);
1739         spin_lock_bh(&xprt->transport_lock);
1740         xprt->ops->release_xprt(xprt, task);
1741         if (xprt->ops->release_request)
1742                 xprt->ops->release_request(task);
1743         xprt->last_used = jiffies;
1744         xprt_schedule_autodisconnect(xprt);
1745         spin_unlock_bh(&xprt->transport_lock);
1746         if (req->rq_buffer)
1747                 xprt->ops->buf_free(task);
1748         xprt_inject_disconnect(xprt);
1749         xdr_free_bvec(&req->rq_rcv_buf);
1750         if (req->rq_cred != NULL)
1751                 put_rpccred(req->rq_cred);
1752         task->tk_rqstp = NULL;
1753         if (req->rq_release_snd_buf)
1754                 req->rq_release_snd_buf(req);
1755
1756         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1757         if (likely(!bc_prealloc(req)))
1758                 xprt->ops->free_slot(xprt, req);
1759         else
1760                 xprt_free_bc_request(req);
1761 }
1762
1763 #ifdef CONFIG_SUNRPC_BACKCHANNEL
1764 void
1765 xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
1766 {
1767         struct xdr_buf *xbufp = &req->rq_snd_buf;
1768
1769         task->tk_rqstp = req;
1770         req->rq_task = task;
1771         xprt_init_connect_cookie(req, req->rq_xprt);
1772         /*
1773          * Set up the xdr_buf length.
1774          * This also indicates that the buffer is XDR encoded already.
1775          */
1776         xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
1777                 xbufp->tail[0].iov_len;
1778         req->rq_bytes_sent = 0;
1779 }
1780 #endif
1781
1782 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1783 {
1784         kref_init(&xprt->kref);
1785
1786         spin_lock_init(&xprt->transport_lock);
1787         spin_lock_init(&xprt->reserve_lock);
1788         spin_lock_init(&xprt->queue_lock);
1789
1790         INIT_LIST_HEAD(&xprt->free);
1791         xprt->recv_queue = RB_ROOT;
1792         INIT_LIST_HEAD(&xprt->xmit_queue);
1793 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1794         spin_lock_init(&xprt->bc_pa_lock);
1795         INIT_LIST_HEAD(&xprt->bc_pa_list);
1796 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1797         INIT_LIST_HEAD(&xprt->xprt_switch);
1798
1799         xprt->last_used = jiffies;
1800         xprt->cwnd = RPC_INITCWND;
1801         xprt->bind_index = 0;
1802
1803         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1804         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1805         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1806         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1807
1808         xprt_init_xid(xprt);
1809
1810         xprt->xprt_net = get_net(net);
1811 }
1812
1813 /**
1814  * xprt_create_transport - create an RPC transport
1815  * @args: rpc transport creation arguments
1816  *
1817  */
1818 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1819 {
1820         struct rpc_xprt *xprt;
1821         struct xprt_class *t;
1822
1823         spin_lock(&xprt_list_lock);
1824         list_for_each_entry(t, &xprt_list, list) {
1825                 if (t->ident == args->ident) {
1826                         spin_unlock(&xprt_list_lock);
1827                         goto found;
1828                 }
1829         }
1830         spin_unlock(&xprt_list_lock);
1831         dprintk("RPC: transport (%d) not supported\n", args->ident);
1832         return ERR_PTR(-EIO);
1833
1834 found:
1835         xprt = t->setup(args);
1836         if (IS_ERR(xprt)) {
1837                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1838                                 -PTR_ERR(xprt));
1839                 goto out;
1840         }
1841         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1842                 xprt->idle_timeout = 0;
1843         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1844         if (xprt_has_timer(xprt))
1845                 timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
1846         else
1847                 timer_setup(&xprt->timer, NULL, 0);
1848
1849         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1850                 xprt_destroy(xprt);
1851                 return ERR_PTR(-EINVAL);
1852         }
1853         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1854         if (xprt->servername == NULL) {
1855                 xprt_destroy(xprt);
1856                 return ERR_PTR(-ENOMEM);
1857         }
1858
1859         rpc_xprt_debugfs_register(xprt);
1860
1861         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1862                         xprt->max_reqs);
1863 out:
1864         return xprt;
1865 }
1866
1867 static void xprt_destroy_cb(struct work_struct *work)
1868 {
1869         struct rpc_xprt *xprt =
1870                 container_of(work, struct rpc_xprt, task_cleanup);
1871
1872         rpc_xprt_debugfs_unregister(xprt);
1873         rpc_destroy_wait_queue(&xprt->binding);
1874         rpc_destroy_wait_queue(&xprt->pending);
1875         rpc_destroy_wait_queue(&xprt->sending);
1876         rpc_destroy_wait_queue(&xprt->backlog);
1877         kfree(xprt->servername);
1878         /*
1879          * Tear down transport state and free the rpc_xprt
1880          */
1881         xprt->ops->destroy(xprt);
1882 }
1883
1884 /**
1885  * xprt_destroy - destroy an RPC transport, killing off all requests.
1886  * @xprt: transport to destroy
1887  *
1888  */
1889 static void xprt_destroy(struct rpc_xprt *xprt)
1890 {
1891         dprintk("RPC:       destroying transport %p\n", xprt);
1892
1893         /*
1894          * Exclude transport connect/disconnect handlers and autoclose
1895          */
1896         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
1897
1898         del_timer_sync(&xprt->timer);
1899
1900         /*
1901          * Destroy sockets etc from the system workqueue so they can
1902          * safely flush receive work running on rpciod.
1903          */
1904         INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
1905         schedule_work(&xprt->task_cleanup);
1906 }
1907
1908 static void xprt_destroy_kref(struct kref *kref)
1909 {
1910         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
1911 }
1912
1913 /**
1914  * xprt_get - return a reference to an RPC transport.
1915  * @xprt: pointer to the transport
1916  *
1917  */
1918 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1919 {
1920         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
1921                 return xprt;
1922         return NULL;
1923 }
1924 EXPORT_SYMBOL_GPL(xprt_get);
1925
1926 /**
1927  * xprt_put - release a reference to an RPC transport.
1928  * @xprt: pointer to the transport
1929  *
1930  */
1931 void xprt_put(struct rpc_xprt *xprt)
1932 {
1933         if (xprt != NULL)
1934                 kref_put(&xprt->kref, xprt_destroy_kref);
1935 }
1936 EXPORT_SYMBOL_GPL(xprt_put);