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 <[email protected]>
  36  *
  37  *  Transport switch API copyright (C) 2005, Chuck Lever <[email protected]>
  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                 xprt->stat.connect_start = jiffies;
 830                 xprt->ops->connect(xprt, task);
 831         }
 832         xprt_release_write(xprt, task);
 833 }
 834
 835 static void xprt_connect_status(struct rpc_task *task)
 836 {
 837         switch (task->tk_status) {
 838         case 0:
 839                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 840                                 task->tk_pid);
 841                 break;
 842         case -ECONNREFUSED:
 843         case -ECONNRESET:
 844         case -ECONNABORTED:
 845         case -ENETUNREACH:
 846         case -EHOSTUNREACH:
 847         case -EPIPE:
 848         case -EAGAIN:
 849                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
 850                 break;
 851         case -ETIMEDOUT:
 852                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 853                                 "out\n", task->tk_pid);
 854                 break;
 855         default:
 856                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 857                                 "server %s\n", task->tk_pid, -task->tk_status,
 858                                 task->tk_rqstp->rq_xprt->servername);
 859                 task->tk_status = -EIO;
 860         }
 861 }
 862
 863 enum xprt_xid_rb_cmp {
 864         XID_RB_EQUAL,
 865         XID_RB_LEFT,
 866         XID_RB_RIGHT,
 867 };
 868 static enum xprt_xid_rb_cmp
 869 xprt_xid_cmp(__be32 xid1, __be32 xid2)
 870 {
 871         if (xid1 == xid2)
 872                 return XID_RB_EQUAL;
 873         if ((__force u32)xid1 < (__force u32)xid2)
 874                 return XID_RB_LEFT;
 875         return XID_RB_RIGHT;
 876 }
 877
 878 static struct rpc_rqst *
 879 xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
 880 {
 881         struct rb_node *n = xprt->recv_queue.rb_node;
 882         struct rpc_rqst *req;
 883
 884         while (n != NULL) {
 885                 req = rb_entry(n, struct rpc_rqst, rq_recv);
 886                 switch (xprt_xid_cmp(xid, req->rq_xid)) {
 887                 case XID_RB_LEFT:
 888                         n = n->rb_left;
 889                         break;
 890                 case XID_RB_RIGHT:
 891                         n = n->rb_right;
 892                         break;
 893                 case XID_RB_EQUAL:
 894                         return req;
 895                 }
 896         }
 897         return NULL;
 898 }
 899
 900 static void
 901 xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
 902 {
 903         struct rb_node **p = &xprt->recv_queue.rb_node;
 904         struct rb_node *n = NULL;
 905         struct rpc_rqst *req;
 906
 907         while (*p != NULL) {
 908                 n = *p;
 909                 req = rb_entry(n, struct rpc_rqst, rq_recv);
 910                 switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
 911                 case XID_RB_LEFT:
 912                         p = &n->rb_left;
 913                         break;
 914                 case XID_RB_RIGHT:
 915                         p = &n->rb_right;
 916                         break;
 917                 case XID_RB_EQUAL:
 918                         WARN_ON_ONCE(new != req);
 919                         return;
 920                 }
 921         }
 922         rb_link_node(&new->rq_recv, n, p);
 923         rb_insert_color(&new->rq_recv, &xprt->recv_queue);
 924 }
 925
 926 static void
 927 xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
 928 {
 929         rb_erase(&req->rq_recv, &xprt->recv_queue);
 930 }
 931
 932 /**
 933  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 934  * @xprt: transport on which the original request was transmitted
 935  * @xid: RPC XID of incoming reply
 936  *
 937  * Caller holds xprt->queue_lock.
 938  */
 939 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 940 {
 941         struct rpc_rqst *entry;
 942
 943         entry = xprt_request_rb_find(xprt, xid);
 944         if (entry != NULL) {
 945                 trace_xprt_lookup_rqst(xprt, xid, 0);
 946                 entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
 947                 return entry;
 948         }
 949
 950         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 951                         ntohl(xid));
 952         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
 953         xprt->stat.bad_xids++;
 954         return NULL;
 955 }
 956 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 957
 958 static bool
 959 xprt_is_pinned_rqst(struct rpc_rqst *req)
 960 {
 961         return atomic_read(&req->rq_pin) != 0;
 962 }
 963
 964 /**
 965  * xprt_pin_rqst - Pin a request on the transport receive list
 966  * @req: Request to pin
 967  *
 968  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
 969  * so should be holding the xprt receive lock.
 970  */
 971 void xprt_pin_rqst(struct rpc_rqst *req)
 972 {
 973         atomic_inc(&req->rq_pin);
 974 }
 975 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
 976
 977 /**
 978  * xprt_unpin_rqst - Unpin a request on the transport receive list
 979  * @req: Request to pin
 980  *
 981  * Caller should be holding the xprt receive lock.
 982  */
 983 void xprt_unpin_rqst(struct rpc_rqst *req)
 984 {
 985         if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
 986                 atomic_dec(&req->rq_pin);
 987                 return;
 988         }
 989         if (atomic_dec_and_test(&req->rq_pin))
 990                 wake_up_var(&req->rq_pin);
 991 }
 992 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
 993
 994 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
 995 {
 996         wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
 997 }
 998
 999 static bool
1000 xprt_request_data_received(struct rpc_task *task)
1001 {
1002         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1003                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
1004 }
1005
1006 static bool
1007 xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
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 /**
1014  * xprt_request_enqueue_receive - Add an request to the receive queue
1015  * @task: RPC task
1016  *
1017  */
1018 void
1019 xprt_request_enqueue_receive(struct rpc_task *task)
1020 {
1021         struct rpc_rqst *req = task->tk_rqstp;
1022         struct rpc_xprt *xprt = req->rq_xprt;
1023
1024         if (!xprt_request_need_enqueue_receive(task, req))
1025                 return;
1026         spin_lock(&xprt->queue_lock);
1027
1028         /* Update the softirq receive buffer */
1029         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1030                         sizeof(req->rq_private_buf));
1031
1032         /* Add request to the receive list */
1033         xprt_request_rb_insert(xprt, req);
1034         set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
1035         spin_unlock(&xprt->queue_lock);
1036
1037         xprt_reset_majortimeo(req);
1038         /* Turn off autodisconnect */
1039         del_singleshot_timer_sync(&xprt->timer);
1040 }
1041
1042 /**
1043  * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
1044  * @task: RPC task
1045  *
1046  * Caller must hold xprt->queue_lock.
1047  */
1048 static void
1049 xprt_request_dequeue_receive_locked(struct rpc_task *task)
1050 {
1051         struct rpc_rqst *req = task->tk_rqstp;
1052
1053         if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1054                 xprt_request_rb_remove(req->rq_xprt, req);
1055 }
1056
1057 /**
1058  * xprt_update_rtt - Update RPC RTT statistics
1059  * @task: RPC request that recently completed
1060  *
1061  * Caller holds xprt->queue_lock.
1062  */
1063 void xprt_update_rtt(struct rpc_task *task)
1064 {
1065         struct rpc_rqst *req = task->tk_rqstp;
1066         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
1067         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
1068         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
1069
1070         if (timer) {
1071                 if (req->rq_ntrans == 1)
1072                         rpc_update_rtt(rtt, timer, m);
1073                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
1074         }
1075 }
1076 EXPORT_SYMBOL_GPL(xprt_update_rtt);
1077
1078 /**
1079  * xprt_complete_rqst - called when reply processing is complete
1080  * @task: RPC request that recently completed
1081  * @copied: actual number of bytes received from the transport
1082  *
1083  * Caller holds xprt->queue_lock.
1084  */
1085 void xprt_complete_rqst(struct rpc_task *task, int copied)
1086 {
1087         struct rpc_rqst *req = task->tk_rqstp;
1088         struct rpc_xprt *xprt = req->rq_xprt;
1089
1090         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
1091                         task->tk_pid, ntohl(req->rq_xid), copied);
1092         trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
1093
1094         xprt->stat.recvs++;
1095
1096         req->rq_private_buf.len = copied;
1097         /* Ensure all writes are done before we update */
1098         /* req->rq_reply_bytes_recvd */
1099         smp_wmb();
1100         req->rq_reply_bytes_recvd = copied;
1101         xprt_request_dequeue_receive_locked(task);
1102         rpc_wake_up_queued_task(&xprt->pending, task);
1103 }
1104 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
1105
1106 static void xprt_timer(struct rpc_task *task)
1107 {
1108         struct rpc_rqst *req = task->tk_rqstp;
1109         struct rpc_xprt *xprt = req->rq_xprt;
1110
1111         if (task->tk_status != -ETIMEDOUT)
1112                 return;
1113
1114         trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
1115         if (!req->rq_reply_bytes_recvd) {
1116                 if (xprt->ops->timer)
1117                         xprt->ops->timer(xprt, task);
1118         } else
1119                 task->tk_status = 0;
1120 }
1121
1122 /**
1123  * xprt_request_wait_receive - wait for the reply to an RPC request
1124  * @task: RPC task about to send a request
1125  *
1126  */
1127 void xprt_request_wait_receive(struct rpc_task *task)
1128 {
1129         struct rpc_rqst *req = task->tk_rqstp;
1130         struct rpc_xprt *xprt = req->rq_xprt;
1131
1132         if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1133                 return;
1134         /*
1135          * Sleep on the pending queue if we're expecting a reply.
1136          * The spinlock ensures atomicity between the test of
1137          * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1138          */
1139         spin_lock(&xprt->queue_lock);
1140         if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
1141                 xprt->ops->set_retrans_timeout(task);
1142                 rpc_sleep_on(&xprt->pending, task, xprt_timer);
1143                 /*
1144                  * Send an extra queue wakeup call if the
1145                  * connection was dropped in case the call to
1146                  * rpc_sleep_on() raced.
1147                  */
1148                 if (xprt_request_retransmit_after_disconnect(task))
1149                         rpc_wake_up_queued_task_set_status(&xprt->pending,
1150                                         task, -ENOTCONN);
1151         }
1152         spin_unlock(&xprt->queue_lock);
1153 }
1154
1155 static bool
1156 xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
1157 {
1158         return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1159 }
1160
1161 /**
1162  * xprt_request_enqueue_transmit - queue a task for transmission
1163  * @task: pointer to rpc_task
1164  *
1165  * Add a task to the transmission queue.
1166  */
1167 void
1168 xprt_request_enqueue_transmit(struct rpc_task *task)
1169 {
1170         struct rpc_rqst *pos, *req = task->tk_rqstp;
1171         struct rpc_xprt *xprt = req->rq_xprt;
1172
1173         if (xprt_request_need_enqueue_transmit(task, req)) {
1174                 spin_lock(&xprt->queue_lock);
1175                 /*
1176                  * Requests that carry congestion control credits are added
1177                  * to the head of the list to avoid starvation issues.
1178                  */
1179                 if (req->rq_cong) {
1180                         xprt_clear_congestion_window_wait(xprt);
1181                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1182                                 if (pos->rq_cong)
1183                                         continue;
1184                                 /* Note: req is added _before_ pos */
1185                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1186                                 INIT_LIST_HEAD(&req->rq_xmit2);
1187                                 goto out;
1188                         }
1189                 } else if (RPC_IS_SWAPPER(task)) {
1190                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1191                                 if (pos->rq_cong || pos->rq_bytes_sent)
1192                                         continue;
1193                                 if (RPC_IS_SWAPPER(pos->rq_task))
1194                                         continue;
1195                                 /* Note: req is added _before_ pos */
1196                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1197                                 INIT_LIST_HEAD(&req->rq_xmit2);
1198                                 goto out;
1199                         }
1200                 } else {
1201                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1202                                 if (pos->rq_task->tk_owner != task->tk_owner)
1203                                         continue;
1204                                 list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
1205                                 INIT_LIST_HEAD(&req->rq_xmit);
1206                                 goto out;
1207                         }
1208                 }
1209                 list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
1210                 INIT_LIST_HEAD(&req->rq_xmit2);
1211 out:
1212                 set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1213                 spin_unlock(&xprt->queue_lock);
1214         }
1215 }
1216
1217 /**
1218  * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
1219  * @task: pointer to rpc_task
1220  *
1221  * Remove a task from the transmission queue
1222  * Caller must hold xprt->queue_lock
1223  */
1224 static void
1225 xprt_request_dequeue_transmit_locked(struct rpc_task *task)
1226 {
1227         struct rpc_rqst *req = task->tk_rqstp;
1228
1229         if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1230                 return;
1231         if (!list_empty(&req->rq_xmit)) {
1232                 list_del(&req->rq_xmit);
1233                 if (!list_empty(&req->rq_xmit2)) {
1234                         struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
1235                                         struct rpc_rqst, rq_xmit2);
1236                         list_del(&req->rq_xmit2);
1237                         list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
1238                 }
1239         } else
1240                 list_del(&req->rq_xmit2);
1241 }
1242
1243 /**
1244  * xprt_request_dequeue_transmit - remove a task from the transmission queue
1245  * @task: pointer to rpc_task
1246  *
1247  * Remove a task from the transmission queue
1248  */
1249 static void
1250 xprt_request_dequeue_transmit(struct rpc_task *task)
1251 {
1252         struct rpc_rqst *req = task->tk_rqstp;
1253         struct rpc_xprt *xprt = req->rq_xprt;
1254
1255         spin_lock(&xprt->queue_lock);
1256         xprt_request_dequeue_transmit_locked(task);
1257         spin_unlock(&xprt->queue_lock);
1258 }
1259
1260 /**
1261  * xprt_request_prepare - prepare an encoded request for transport
1262  * @req: pointer to rpc_rqst
1263  *
1264  * Calls into the transport layer to do whatever is needed to prepare
1265  * the request for transmission or receive.
1266  */
1267 void
1268 xprt_request_prepare(struct rpc_rqst *req)
1269 {
1270         struct rpc_xprt *xprt = req->rq_xprt;
1271
1272         if (xprt->ops->prepare_request)
1273                 xprt->ops->prepare_request(req);
1274 }
1275
1276 /**
1277  * xprt_request_need_retransmit - Test if a task needs retransmission
1278  * @task: pointer to rpc_task
1279  *
1280  * Test for whether a connection breakage requires the task to retransmit
1281  */
1282 bool
1283 xprt_request_need_retransmit(struct rpc_task *task)
1284 {
1285         return xprt_request_retransmit_after_disconnect(task);
1286 }
1287
1288 /**
1289  * xprt_prepare_transmit - reserve the transport before sending a request
1290  * @task: RPC task about to send a request
1291  *
1292  */
1293 bool xprt_prepare_transmit(struct rpc_task *task)
1294 {
1295         struct rpc_rqst *req = task->tk_rqstp;
1296         struct rpc_xprt *xprt = req->rq_xprt;
1297
1298         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
1299
1300         if (!xprt_lock_write(xprt, task)) {
1301                 /* Race breaker: someone may have transmitted us */
1302                 if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1303                         rpc_wake_up_queued_task_set_status(&xprt->sending,
1304                                         task, 0);
1305                 return false;
1306
1307         }
1308         return true;
1309 }
1310
1311 void xprt_end_transmit(struct rpc_task *task)
1312 {
1313         xprt_release_write(task->tk_rqstp->rq_xprt, task);
1314 }
1315
1316 /**
1317  * xprt_request_transmit - send an RPC request on a transport
1318  * @req: pointer to request to transmit
1319  * @snd_task: RPC task that owns the transport lock
1320  *
1321  * This performs the transmission of a single request.
1322  * Note that if the request is not the same as snd_task, then it
1323  * does need to be pinned.
1324  * Returns '0' on success.
1325  */
1326 static int
1327 xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
1328 {
1329         struct rpc_xprt *xprt = req->rq_xprt;
1330         struct rpc_task *task = req->rq_task;
1331         unsigned int connect_cookie;
1332         int is_retrans = RPC_WAS_SENT(task);
1333         int status;
1334
1335         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
1336
1337         if (!req->rq_bytes_sent) {
1338                 if (xprt_request_data_received(task)) {
1339                         status = 0;
1340                         goto out_dequeue;
1341                 }
1342                 /* Verify that our message lies in the RPCSEC_GSS window */
1343                 if (rpcauth_xmit_need_reencode(task)) {
1344                         status = -EBADMSG;
1345                         goto out_dequeue;
1346                 }
1347         }
1348
1349         /*
1350          * Update req->rq_ntrans before transmitting to avoid races with
1351          * xprt_update_rtt(), which needs to know that it is recording a
1352          * reply to the first transmission.
1353          */
1354         req->rq_ntrans++;
1355
1356         connect_cookie = xprt->connect_cookie;
1357         status = xprt->ops->send_request(req);
1358         trace_xprt_transmit(xprt, req->rq_xid, status);
1359         if (status != 0) {
1360                 req->rq_ntrans--;
1361                 return status;
1362         }
1363
1364         if (is_retrans)
1365                 task->tk_client->cl_stats->rpcretrans++;
1366
1367         xprt_inject_disconnect(xprt);
1368
1369         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
1370         task->tk_flags |= RPC_TASK_SENT;
1371         spin_lock_bh(&xprt->transport_lock);
1372
1373         xprt->stat.sends++;
1374         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1375         xprt->stat.bklog_u += xprt->backlog.qlen;
1376         xprt->stat.sending_u += xprt->sending.qlen;
1377         xprt->stat.pending_u += xprt->pending.qlen;
1378         spin_unlock_bh(&xprt->transport_lock);
1379
1380         req->rq_connect_cookie = connect_cookie;
1381 out_dequeue:
1382         xprt_request_dequeue_transmit(task);
1383         rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
1384         return status;
1385 }
1386
1387 /**
1388  * xprt_transmit - send an RPC request on a transport
1389  * @task: controlling RPC task
1390  *
1391  * Attempts to drain the transmit queue. On exit, either the transport
1392  * signalled an error that needs to be handled before transmission can
1393  * resume, or @task finished transmitting, and detected that it already
1394  * received a reply.
1395  */
1396 void
1397 xprt_transmit(struct rpc_task *task)
1398 {
1399         struct rpc_rqst *next, *req = task->tk_rqstp;
1400         struct rpc_xprt *xprt = req->rq_xprt;
1401         int status;
1402
1403         spin_lock(&xprt->queue_lock);
1404         while (!list_empty(&xprt->xmit_queue)) {
1405                 next = list_first_entry(&xprt->xmit_queue,
1406                                 struct rpc_rqst, rq_xmit);
1407                 xprt_pin_rqst(next);
1408                 spin_unlock(&xprt->queue_lock);
1409                 status = xprt_request_transmit(next, task);
1410                 if (status == -EBADMSG && next != req)
1411                         status = 0;
1412                 cond_resched();
1413                 spin_lock(&xprt->queue_lock);
1414                 xprt_unpin_rqst(next);
1415                 if (status == 0) {
1416                         if (!xprt_request_data_received(task) ||
1417                             test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1418                                 continue;
1419                 } else if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1420                         task->tk_status = status;
1421                 break;
1422         }
1423         spin_unlock(&xprt->queue_lock);
1424 }
1425
1426 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1427 {
1428         set_bit(XPRT_CONGESTED, &xprt->state);
1429         rpc_sleep_on(&xprt->backlog, task, NULL);
1430 }
1431
1432 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
1433 {
1434         if (rpc_wake_up_next(&xprt->backlog) == NULL)
1435                 clear_bit(XPRT_CONGESTED, &xprt->state);
1436 }
1437
1438 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1439 {
1440         bool ret = false;
1441
1442         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1443                 goto out;
1444         spin_lock(&xprt->reserve_lock);
1445         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1446                 rpc_sleep_on(&xprt->backlog, task, NULL);
1447                 ret = true;
1448         }
1449         spin_unlock(&xprt->reserve_lock);
1450 out:
1451         return ret;
1452 }
1453
1454 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1455 {
1456         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1457
1458         if (xprt->num_reqs >= xprt->max_reqs)
1459                 goto out;
1460         ++xprt->num_reqs;
1461         spin_unlock(&xprt->reserve_lock);
1462         req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
1463         spin_lock(&xprt->reserve_lock);
1464         if (req != NULL)
1465                 goto out;
1466         --xprt->num_reqs;
1467         req = ERR_PTR(-ENOMEM);
1468 out:
1469         return req;
1470 }
1471
1472 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1473 {
1474         if (xprt->num_reqs > xprt->min_reqs) {
1475                 --xprt->num_reqs;
1476                 kfree(req);
1477                 return true;
1478         }
1479         return false;
1480 }
1481
1482 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1483 {
1484         struct rpc_rqst *req;
1485
1486         spin_lock(&xprt->reserve_lock);
1487         if (!list_empty(&xprt->free)) {
1488                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1489                 list_del(&req->rq_list);
1490                 goto out_init_req;
1491         }
1492         req = xprt_dynamic_alloc_slot(xprt);
1493         if (!IS_ERR(req))
1494                 goto out_init_req;
1495         switch (PTR_ERR(req)) {
1496         case -ENOMEM:
1497                 dprintk("RPC:       dynamic allocation of request slot "
1498                                 "failed! Retrying\n");
1499                 task->tk_status = -ENOMEM;
1500                 break;
1501         case -EAGAIN:
1502                 xprt_add_backlog(xprt, task);
1503                 dprintk("RPC:       waiting for request slot\n");
1504                 /* fall through */
1505         default:
1506                 task->tk_status = -EAGAIN;
1507         }
1508         spin_unlock(&xprt->reserve_lock);
1509         return;
1510 out_init_req:
1511         xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
1512                                      xprt->num_reqs);
1513         spin_unlock(&xprt->reserve_lock);
1514
1515         task->tk_status = 0;
1516         task->tk_rqstp = req;
1517 }
1518 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1519
1520 void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1521 {
1522         spin_lock(&xprt->reserve_lock);
1523         if (!xprt_dynamic_free_slot(xprt, req)) {
1524                 memset(req, 0, sizeof(*req));   /* mark unused */
1525                 list_add(&req->rq_list, &xprt->free);
1526         }
1527         xprt_wake_up_backlog(xprt);
1528         spin_unlock(&xprt->reserve_lock);
1529 }
1530 EXPORT_SYMBOL_GPL(xprt_free_slot);
1531
1532 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1533 {
1534         struct rpc_rqst *req;
1535         while (!list_empty(&xprt->free)) {
1536                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1537                 list_del(&req->rq_list);
1538                 kfree(req);
1539         }
1540 }
1541
1542 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1543                 unsigned int num_prealloc,
1544                 unsigned int max_alloc)
1545 {
1546         struct rpc_xprt *xprt;
1547         struct rpc_rqst *req;
1548         int i;
1549
1550         xprt = kzalloc(size, GFP_KERNEL);
1551         if (xprt == NULL)
1552                 goto out;
1553
1554         xprt_init(xprt, net);
1555
1556         for (i = 0; i < num_prealloc; i++) {
1557                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1558                 if (!req)
1559                         goto out_free;
1560                 list_add(&req->rq_list, &xprt->free);
1561         }
1562         if (max_alloc > num_prealloc)
1563                 xprt->max_reqs = max_alloc;
1564         else
1565                 xprt->max_reqs = num_prealloc;
1566         xprt->min_reqs = num_prealloc;
1567         xprt->num_reqs = num_prealloc;
1568
1569         return xprt;
1570
1571 out_free:
1572         xprt_free(xprt);
1573 out:
1574         return NULL;
1575 }
1576 EXPORT_SYMBOL_GPL(xprt_alloc);
1577
1578 void xprt_free(struct rpc_xprt *xprt)
1579 {
1580         put_net(xprt->xprt_net);
1581         xprt_free_all_slots(xprt);
1582         kfree_rcu(xprt, rcu);
1583 }
1584 EXPORT_SYMBOL_GPL(xprt_free);
1585
1586 static void
1587 xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
1588 {
1589         req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
1590 }
1591
1592 static __be32
1593 xprt_alloc_xid(struct rpc_xprt *xprt)
1594 {
1595         __be32 xid;
1596
1597         spin_lock(&xprt->reserve_lock);
1598         xid = (__force __be32)xprt->xid++;
1599         spin_unlock(&xprt->reserve_lock);
1600         return xid;
1601 }
1602
1603 static void
1604 xprt_init_xid(struct rpc_xprt *xprt)
1605 {
1606         xprt->xid = prandom_u32();
1607 }
1608
1609 static void
1610 xprt_request_init(struct rpc_task *task)
1611 {
1612         struct rpc_xprt *xprt = task->tk_xprt;
1613         struct rpc_rqst *req = task->tk_rqstp;
1614
1615         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1616         req->rq_task    = task;
1617         req->rq_xprt    = xprt;
1618         req->rq_buffer  = NULL;
1619         req->rq_xid     = xprt_alloc_xid(xprt);
1620         xprt_init_connect_cookie(req, xprt);
1621         req->rq_bytes_sent = 0;
1622         req->rq_snd_buf.len = 0;
1623         req->rq_snd_buf.buflen = 0;
1624         req->rq_rcv_buf.len = 0;
1625         req->rq_rcv_buf.buflen = 0;
1626         req->rq_release_snd_buf = NULL;
1627         xprt_reset_majortimeo(req);
1628         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1629                         req, ntohl(req->rq_xid));
1630 }
1631
1632 static void
1633 xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
1634 {
1635         xprt->ops->alloc_slot(xprt, task);
1636         if (task->tk_rqstp != NULL)
1637                 xprt_request_init(task);
1638 }
1639
1640 /**
1641  * xprt_reserve - allocate an RPC request slot
1642  * @task: RPC task requesting a slot allocation
1643  *
1644  * If the transport is marked as being congested, or if no more
1645  * slots are available, place the task on the transport's
1646  * backlog queue.
1647  */
1648 void xprt_reserve(struct rpc_task *task)
1649 {
1650         struct rpc_xprt *xprt = task->tk_xprt;
1651
1652         task->tk_status = 0;
1653         if (task->tk_rqstp != NULL)
1654                 return;
1655
1656         task->tk_timeout = 0;
1657         task->tk_status = -EAGAIN;
1658         if (!xprt_throttle_congested(xprt, task))
1659                 xprt_do_reserve(xprt, task);
1660 }
1661
1662 /**
1663  * xprt_retry_reserve - allocate an RPC request slot
1664  * @task: RPC task requesting a slot allocation
1665  *
1666  * If no more slots are available, place the task on the transport's
1667  * backlog queue.
1668  * Note that the only difference with xprt_reserve is that we now
1669  * ignore the value of the XPRT_CONGESTED flag.
1670  */
1671 void xprt_retry_reserve(struct rpc_task *task)
1672 {
1673         struct rpc_xprt *xprt = task->tk_xprt;
1674
1675         task->tk_status = 0;
1676         if (task->tk_rqstp != NULL)
1677                 return;
1678
1679         task->tk_timeout = 0;
1680         task->tk_status = -EAGAIN;
1681         xprt_do_reserve(xprt, task);
1682 }
1683
1684 static void
1685 xprt_request_dequeue_all(struct rpc_task *task, struct rpc_rqst *req)
1686 {
1687         struct rpc_xprt *xprt = req->rq_xprt;
1688
1689         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
1690             test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
1691             xprt_is_pinned_rqst(req)) {
1692                 spin_lock(&xprt->queue_lock);
1693                 xprt_request_dequeue_transmit_locked(task);
1694                 xprt_request_dequeue_receive_locked(task);
1695                 while (xprt_is_pinned_rqst(req)) {
1696                         set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1697                         spin_unlock(&xprt->queue_lock);
1698                         xprt_wait_on_pinned_rqst(req);
1699                         spin_lock(&xprt->queue_lock);
1700                         clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1701                 }
1702                 spin_unlock(&xprt->queue_lock);
1703         }
1704 }
1705
1706 /**
1707  * xprt_release - release an RPC request slot
1708  * @task: task which is finished with the slot
1709  *
1710  */
1711 void xprt_release(struct rpc_task *task)
1712 {
1713         struct rpc_xprt *xprt;
1714         struct rpc_rqst *req = task->tk_rqstp;
1715
1716         if (req == NULL) {
1717                 if (task->tk_client) {
1718                         xprt = task->tk_xprt;
1719                         xprt_release_write(xprt, task);
1720                 }
1721                 return;
1722         }
1723
1724         xprt = req->rq_xprt;
1725         if (task->tk_ops->rpc_count_stats != NULL)
1726                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1727         else if (task->tk_client)
1728                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1729         xprt_request_dequeue_all(task, req);
1730         spin_lock_bh(&xprt->transport_lock);
1731         xprt->ops->release_xprt(xprt, task);
1732         if (xprt->ops->release_request)
1733                 xprt->ops->release_request(task);
1734         xprt->last_used = jiffies;
1735         xprt_schedule_autodisconnect(xprt);
1736         spin_unlock_bh(&xprt->transport_lock);
1737         if (req->rq_buffer)
1738                 xprt->ops->buf_free(task);
1739         xprt_inject_disconnect(xprt);
1740         xdr_free_bvec(&req->rq_rcv_buf);
1741         if (req->rq_cred != NULL)
1742                 put_rpccred(req->rq_cred);
1743         task->tk_rqstp = NULL;
1744         if (req->rq_release_snd_buf)
1745                 req->rq_release_snd_buf(req);
1746
1747         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1748         if (likely(!bc_prealloc(req)))
1749                 xprt->ops->free_slot(xprt, req);
1750         else
1751                 xprt_free_bc_request(req);
1752 }
1753
1754 #ifdef CONFIG_SUNRPC_BACKCHANNEL
1755 void
1756 xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
1757 {
1758         struct xdr_buf *xbufp = &req->rq_snd_buf;
1759
1760         task->tk_rqstp = req;
1761         req->rq_task = task;
1762         xprt_init_connect_cookie(req, req->rq_xprt);
1763         /*
1764          * Set up the xdr_buf length.
1765          * This also indicates that the buffer is XDR encoded already.
1766          */
1767         xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
1768                 xbufp->tail[0].iov_len;
1769         req->rq_bytes_sent = 0;
1770 }
1771 #endif
1772
1773 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1774 {
1775         kref_init(&xprt->kref);
1776
1777         spin_lock_init(&xprt->transport_lock);
1778         spin_lock_init(&xprt->reserve_lock);
1779         spin_lock_init(&xprt->queue_lock);
1780
1781         INIT_LIST_HEAD(&xprt->free);
1782         xprt->recv_queue = RB_ROOT;
1783         INIT_LIST_HEAD(&xprt->xmit_queue);
1784 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1785         spin_lock_init(&xprt->bc_pa_lock);
1786         INIT_LIST_HEAD(&xprt->bc_pa_list);
1787 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1788         INIT_LIST_HEAD(&xprt->xprt_switch);
1789
1790         xprt->last_used = jiffies;
1791         xprt->cwnd = RPC_INITCWND;
1792         xprt->bind_index = 0;
1793
1794         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1795         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1796         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1797         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1798
1799         xprt_init_xid(xprt);
1800
1801         xprt->xprt_net = get_net(net);
1802 }
1803
1804 /**
1805  * xprt_create_transport - create an RPC transport
1806  * @args: rpc transport creation arguments
1807  *
1808  */
1809 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1810 {
1811         struct rpc_xprt *xprt;
1812         struct xprt_class *t;
1813
1814         spin_lock(&xprt_list_lock);
1815         list_for_each_entry(t, &xprt_list, list) {
1816                 if (t->ident == args->ident) {
1817                         spin_unlock(&xprt_list_lock);
1818                         goto found;
1819                 }
1820         }
1821         spin_unlock(&xprt_list_lock);
1822         dprintk("RPC: transport (%d) not supported\n", args->ident);
1823         return ERR_PTR(-EIO);
1824
1825 found:
1826         xprt = t->setup(args);
1827         if (IS_ERR(xprt)) {
1828                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1829                                 -PTR_ERR(xprt));
1830                 goto out;
1831         }
1832         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1833                 xprt->idle_timeout = 0;
1834         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1835         if (xprt_has_timer(xprt))
1836                 timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
1837         else
1838                 timer_setup(&xprt->timer, NULL, 0);
1839
1840         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1841                 xprt_destroy(xprt);
1842                 return ERR_PTR(-EINVAL);
1843         }
1844         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1845         if (xprt->servername == NULL) {
1846                 xprt_destroy(xprt);
1847                 return ERR_PTR(-ENOMEM);
1848         }
1849
1850         rpc_xprt_debugfs_register(xprt);
1851
1852         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1853                         xprt->max_reqs);
1854 out:
1855         return xprt;
1856 }
1857
1858 static void xprt_destroy_cb(struct work_struct *work)
1859 {
1860         struct rpc_xprt *xprt =
1861                 container_of(work, struct rpc_xprt, task_cleanup);
1862
1863         rpc_xprt_debugfs_unregister(xprt);
1864         rpc_destroy_wait_queue(&xprt->binding);
1865         rpc_destroy_wait_queue(&xprt->pending);
1866         rpc_destroy_wait_queue(&xprt->sending);
1867         rpc_destroy_wait_queue(&xprt->backlog);
1868         kfree(xprt->servername);
1869         /*
1870          * Tear down transport state and free the rpc_xprt
1871          */
1872         xprt->ops->destroy(xprt);
1873 }
1874
1875 /**
1876  * xprt_destroy - destroy an RPC transport, killing off all requests.
1877  * @xprt: transport to destroy
1878  *
1879  */
1880 static void xprt_destroy(struct rpc_xprt *xprt)
1881 {
1882         dprintk("RPC:       destroying transport %p\n", xprt);
1883
1884         /*
1885          * Exclude transport connect/disconnect handlers and autoclose
1886          */
1887         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
1888
1889         del_timer_sync(&xprt->timer);
1890
1891         /*
1892          * Destroy sockets etc from the system workqueue so they can
1893          * safely flush receive work running on rpciod.
1894          */
1895         INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
1896         schedule_work(&xprt->task_cleanup);
1897 }
1898
1899 static void xprt_destroy_kref(struct kref *kref)
1900 {
1901         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
1902 }
1903
1904 /**
1905  * xprt_get - return a reference to an RPC transport.
1906  * @xprt: pointer to the transport
1907  *
1908  */
1909 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1910 {
1911         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
1912                 return xprt;
1913         return NULL;
1914 }
1915 EXPORT_SYMBOL_GPL(xprt_get);
1916
1917 /**
1918  * xprt_put - release a reference to an RPC transport.
1919  * @xprt: pointer to the transport
1920  *
1921  */
1922 void xprt_put(struct rpc_xprt *xprt)
1923 {
1924         if (xprt != NULL)
1925                 kref_put(&xprt->kref, xprt_destroy_kref);
1926 }
1927 EXPORT_SYMBOL_GPL(xprt_put);