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 void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
  70 static void     xprt_connect_status(struct rpc_task *task);
  71 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
  72 static void     __xprt_put_cong(struct rpc_xprt *, struct rpc_rqst *);
  73 static void      xprt_destroy(struct rpc_xprt *xprt);
  74
  75 static DEFINE_SPINLOCK(xprt_list_lock);
  76 static LIST_HEAD(xprt_list);
  77
  78 /**
  79  * xprt_register_transport - register a transport implementation
  80  * @transport: transport to register
  81  *
  82  * If a transport implementation is loaded as a kernel module, it can
  83  * call this interface to make itself known to the RPC client.
  84  *
  85  * Returns:
  86  * 0:           transport successfully registered
  87  * -EEXIST:     transport already registered
  88  * -EINVAL:     transport module being unloaded
  89  */
  90 int xprt_register_transport(struct xprt_class *transport)
  91 {
  92         struct xprt_class *t;
  93         int result;
  94
  95         result = -EEXIST;
  96         spin_lock(&xprt_list_lock);
  97         list_for_each_entry(t, &xprt_list, list) {
  98                 /* don't register the same transport class twice */
  99                 if (t->ident == transport->ident)
 100                         goto out;
 101         }
 102
 103         list_add_tail(&transport->list, &xprt_list);
 104         printk(KERN_INFO "RPC: Registered %s transport module.\n",
 105                transport->name);
 106         result = 0;
 107
 108 out:
 109         spin_unlock(&xprt_list_lock);
 110         return result;
 111 }
 112 EXPORT_SYMBOL_GPL(xprt_register_transport);
 113
 114 /**
 115  * xprt_unregister_transport - unregister a transport implementation
 116  * @transport: transport to unregister
 117  *
 118  * Returns:
 119  * 0:           transport successfully unregistered
 120  * -ENOENT:     transport never registered
 121  */
 122 int xprt_unregister_transport(struct xprt_class *transport)
 123 {
 124         struct xprt_class *t;
 125         int result;
 126
 127         result = 0;
 128         spin_lock(&xprt_list_lock);
 129         list_for_each_entry(t, &xprt_list, list) {
 130                 if (t == transport) {
 131                         printk(KERN_INFO
 132                                 "RPC: Unregistered %s transport module.\n",
 133                                 transport->name);
 134                         list_del_init(&transport->list);
 135                         goto out;
 136                 }
 137         }
 138         result = -ENOENT;
 139
 140 out:
 141         spin_unlock(&xprt_list_lock);
 142         return result;
 143 }
 144 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 145
 146 static void
 147 xprt_class_release(const struct xprt_class *t)
 148 {
 149         module_put(t->owner);
 150 }
 151
 152 static const struct xprt_class *
 153 xprt_class_find_by_netid_locked(const char *netid)
 154 {
 155         const struct xprt_class *t;
 156         unsigned int i;
 157
 158         list_for_each_entry(t, &xprt_list, list) {
 159                 for (i = 0; t->netid[i][0] != '\0'; i++) {
 160                         if (strcmp(t->netid[i], netid) != 0)
 161                                 continue;
 162                         if (!try_module_get(t->owner))
 163                                 continue;
 164                         return t;
 165                 }
 166         }
 167         return NULL;
 168 }
 169
 170 static const struct xprt_class *
 171 xprt_class_find_by_netid(const char *netid)
 172 {
 173         const struct xprt_class *t;
 174
 175         spin_lock(&xprt_list_lock);
 176         t = xprt_class_find_by_netid_locked(netid);
 177         if (!t) {
 178                 spin_unlock(&xprt_list_lock);
 179                 request_module("rpc%s", netid);
 180                 spin_lock(&xprt_list_lock);
 181                 t = xprt_class_find_by_netid_locked(netid);
 182         }
 183         spin_unlock(&xprt_list_lock);
 184         return t;
 185 }
 186
 187 /**
 188  * xprt_load_transport - load a transport implementation
 189  * @netid: transport to load
 190  *
 191  * Returns:
 192  * 0:           transport successfully loaded
 193  * -ENOENT:     transport module not available
 194  */
 195 int xprt_load_transport(const char *netid)
 196 {
 197         const struct xprt_class *t;
 198
 199         t = xprt_class_find_by_netid(netid);
 200         if (!t)
 201                 return -ENOENT;
 202         xprt_class_release(t);
 203         return 0;
 204 }
 205 EXPORT_SYMBOL_GPL(xprt_load_transport);
 206
 207 /**
 208  * xprt_reserve_xprt - serialize write access to transports
 209  * @task: task that is requesting access to the transport
 210  * @xprt: pointer to the target transport
 211  *
 212  * This prevents mixing the payload of separate requests, and prevents
 213  * transport connects from colliding with writes.  No congestion control
 214  * is provided.
 215  */
 216 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 217 {
 218         struct rpc_rqst *req = task->tk_rqstp;
 219         int priority;
 220
 221         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 222                 if (task == xprt->snd_task)
 223                         return 1;
 224                 goto out_sleep;
 225         }
 226         xprt->snd_task = task;
 227         if (req != NULL)
 228                 req->rq_ntrans++;
 229
 230         return 1;
 231
 232 out_sleep:
 233         dprintk("RPC: %5u failed to lock transport %p\n",
 234                         task->tk_pid, xprt);
 235         task->tk_timeout = 0;
 236         task->tk_status = -EAGAIN;
 237         if (req == NULL)
 238                 priority = RPC_PRIORITY_LOW;
 239         else if (!req->rq_ntrans)
 240                 priority = RPC_PRIORITY_NORMAL;
 241         else
 242                 priority = RPC_PRIORITY_HIGH;
 243         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
 244         return 0;
 245 }
 246 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 247
 248 static void xprt_clear_locked(struct rpc_xprt *xprt)
 249 {
 250         xprt->snd_task = NULL;
 251         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 252                 smp_mb__before_atomic();
 253                 clear_bit(XPRT_LOCKED, &xprt->state);
 254                 smp_mb__after_atomic();
 255         } else
 256                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 257 }
 258
 259 /*
 260  * xprt_reserve_xprt_cong - serialize write access to transports
 261  * @task: task that is requesting access to the transport
 262  *
 263  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 264  * integrated into the decision of whether a request is allowed to be
 265  * woken up and given access to the transport.
 266  */
 267 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 268 {
 269         struct rpc_rqst *req = task->tk_rqstp;
 270         int priority;
 271
 272         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 273                 if (task == xprt->snd_task)
 274                         return 1;
 275                 goto out_sleep;
 276         }
 277         if (req == NULL) {
 278                 xprt->snd_task = task;
 279                 return 1;
 280         }
 281         if (__xprt_get_cong(xprt, task)) {
 282                 xprt->snd_task = task;
 283                 req->rq_ntrans++;
 284                 return 1;
 285         }
 286         xprt_clear_locked(xprt);
 287 out_sleep:
 288         if (req)
 289                 __xprt_put_cong(xprt, req);
 290         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
 291         task->tk_timeout = 0;
 292         task->tk_status = -EAGAIN;
 293         if (req == NULL)
 294                 priority = RPC_PRIORITY_LOW;
 295         else if (!req->rq_ntrans)
 296                 priority = RPC_PRIORITY_NORMAL;
 297         else
 298                 priority = RPC_PRIORITY_HIGH;
 299         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
 300         return 0;
 301 }
 302 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 303
 304 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 305 {
 306         int retval;
 307
 308         spin_lock_bh(&xprt->transport_lock);
 309         retval = xprt->ops->reserve_xprt(xprt, task);
 310         spin_unlock_bh(&xprt->transport_lock);
 311         return retval;
 312 }
 313
 314 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
 315 {
 316         struct rpc_xprt *xprt = data;
 317         struct rpc_rqst *req;
 318
 319         req = task->tk_rqstp;
 320         xprt->snd_task = task;
 321         if (req)
 322                 req->rq_ntrans++;
 323         return true;
 324 }
 325
 326 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 327 {
 328         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 329                 return;
 330
 331         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 332                                 __xprt_lock_write_func, xprt))
 333                 return;
 334         xprt_clear_locked(xprt);
 335 }
 336
 337 static bool __xprt_lock_write_cong_func(struct rpc_task *task, void *data)
 338 {
 339         struct rpc_xprt *xprt = data;
 340         struct rpc_rqst *req;
 341
 342         req = task->tk_rqstp;
 343         if (req == NULL) {
 344                 xprt->snd_task = task;
 345                 return true;
 346         }
 347         if (__xprt_get_cong(xprt, task)) {
 348                 xprt->snd_task = task;
 349                 req->rq_ntrans++;
 350                 return true;
 351         }
 352         return false;
 353 }
 354
 355 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 356 {
 357         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 358                 return;
 359         if (RPCXPRT_CONGESTED(xprt))
 360                 goto out_unlock;
 361         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
 362                                 __xprt_lock_write_cong_func, xprt))
 363                 return;
 364 out_unlock:
 365         xprt_clear_locked(xprt);
 366 }
 367
 368 static void xprt_task_clear_bytes_sent(struct rpc_task *task)
 369 {
 370         if (task != NULL) {
 371                 struct rpc_rqst *req = task->tk_rqstp;
 372                 if (req != NULL)
 373                         req->rq_bytes_sent = 0;
 374         }
 375 }
 376
 377 /**
 378  * xprt_release_xprt - allow other requests to use a transport
 379  * @xprt: transport with other tasks potentially waiting
 380  * @task: task that is releasing access to the transport
 381  *
 382  * Note that "task" can be NULL.  No congestion control is provided.
 383  */
 384 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 385 {
 386         if (xprt->snd_task == task) {
 387                 xprt_task_clear_bytes_sent(task);
 388                 xprt_clear_locked(xprt);
 389                 __xprt_lock_write_next(xprt);
 390         }
 391 }
 392 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 393
 394 /**
 395  * xprt_release_xprt_cong - allow other requests to use a transport
 396  * @xprt: transport with other tasks potentially waiting
 397  * @task: task that is releasing access to the transport
 398  *
 399  * Note that "task" can be NULL.  Another task is awoken to use the
 400  * transport if the transport's congestion window allows it.
 401  */
 402 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 403 {
 404         if (xprt->snd_task == task) {
 405                 xprt_task_clear_bytes_sent(task);
 406                 xprt_clear_locked(xprt);
 407                 __xprt_lock_write_next_cong(xprt);
 408         }
 409 }
 410 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 411
 412 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 413 {
 414         spin_lock_bh(&xprt->transport_lock);
 415         xprt->ops->release_xprt(xprt, task);
 416         spin_unlock_bh(&xprt->transport_lock);
 417 }
 418
 419 /*
 420  * Van Jacobson congestion avoidance. Check if the congestion window
 421  * overflowed. Put the task to sleep if this is the case.
 422  */
 423 static int
 424 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 425 {
 426         struct rpc_rqst *req = task->tk_rqstp;
 427
 428         if (req->rq_cong)
 429                 return 1;
 430         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
 431                         task->tk_pid, xprt->cong, xprt->cwnd);
 432         if (RPCXPRT_CONGESTED(xprt))
 433                 return 0;
 434         req->rq_cong = 1;
 435         xprt->cong += RPC_CWNDSCALE;
 436         return 1;
 437 }
 438
 439 /*
 440  * Adjust the congestion window, and wake up the next task
 441  * that has been sleeping due to congestion
 442  */
 443 static void
 444 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 445 {
 446         if (!req->rq_cong)
 447                 return;
 448         req->rq_cong = 0;
 449         xprt->cong -= RPC_CWNDSCALE;
 450         __xprt_lock_write_next_cong(xprt);
 451 }
 452
 453 /**
 454  * xprt_release_rqst_cong - housekeeping when request is complete
 455  * @task: RPC request that recently completed
 456  *
 457  * Useful for transports that require congestion control.
 458  */
 459 void xprt_release_rqst_cong(struct rpc_task *task)
 460 {
 461         struct rpc_rqst *req = task->tk_rqstp;
 462
 463         __xprt_put_cong(req->rq_xprt, req);
 464 }
 465 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 466
 467 /**
 468  * xprt_adjust_cwnd - adjust transport congestion window
 469  * @xprt: pointer to xprt
 470  * @task: recently completed RPC request used to adjust window
 471  * @result: result code of completed RPC request
 472  *
 473  * The transport code maintains an estimate on the maximum number of out-
 474  * standing RPC requests, using a smoothed version of the congestion
 475  * avoidance implemented in 44BSD. This is basically the Van Jacobson
 476  * congestion algorithm: If a retransmit occurs, the congestion window is
 477  * halved; otherwise, it is incremented by 1/cwnd when
 478  *
 479  *      -       a reply is received and
 480  *      -       a full number of requests are outstanding and
 481  *      -       the congestion window hasn't been updated recently.
 482  */
 483 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
 484 {
 485         struct rpc_rqst *req = task->tk_rqstp;
 486         unsigned long cwnd = xprt->cwnd;
 487
 488         if (result >= 0 && cwnd <= xprt->cong) {
 489                 /* The (cwnd >> 1) term makes sure
 490                  * the result gets rounded properly. */
 491                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 492                 if (cwnd > RPC_MAXCWND(xprt))
 493                         cwnd = RPC_MAXCWND(xprt);
 494                 __xprt_lock_write_next_cong(xprt);
 495         } else if (result == -ETIMEDOUT) {
 496                 cwnd >>= 1;
 497                 if (cwnd < RPC_CWNDSCALE)
 498                         cwnd = RPC_CWNDSCALE;
 499         }
 500         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 501                         xprt->cong, xprt->cwnd, cwnd);
 502         xprt->cwnd = cwnd;
 503         __xprt_put_cong(xprt, req);
 504 }
 505 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 506
 507 /**
 508  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 509  * @xprt: transport with waiting tasks
 510  * @status: result code to plant in each task before waking it
 511  *
 512  */
 513 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 514 {
 515         if (status < 0)
 516                 rpc_wake_up_status(&xprt->pending, status);
 517         else
 518                 rpc_wake_up(&xprt->pending);
 519 }
 520 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 521
 522 /**
 523  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 524  * @task: task to be put to sleep
 525  * @action: function pointer to be executed after wait
 526  *
 527  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
 528  * we don't in general want to force a socket disconnection due to
 529  * an incomplete RPC call transmission.
 530  */
 531 void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
 532 {
 533         struct rpc_rqst *req = task->tk_rqstp;
 534         struct rpc_xprt *xprt = req->rq_xprt;
 535
 536         task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
 537         rpc_sleep_on(&xprt->pending, task, action);
 538 }
 539 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 540
 541 /**
 542  * xprt_write_space - wake the task waiting for transport output buffer space
 543  * @xprt: transport with waiting tasks
 544  *
 545  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 546  */
 547 void xprt_write_space(struct rpc_xprt *xprt)
 548 {
 549         spin_lock_bh(&xprt->transport_lock);
 550         if (xprt->snd_task) {
 551                 dprintk("RPC:       write space: waking waiting task on "
 552                                 "xprt %p\n", xprt);
 553                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
 554         }
 555         spin_unlock_bh(&xprt->transport_lock);
 556 }
 557 EXPORT_SYMBOL_GPL(xprt_write_space);
 558
 559 /**
 560  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 561  * @task: task whose timeout is to be set
 562  *
 563  * Set a request's retransmit timeout based on the transport's
 564  * default timeout parameters.  Used by transports that don't adjust
 565  * the retransmit timeout based on round-trip time estimation.
 566  */
 567 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 568 {
 569         task->tk_timeout = task->tk_rqstp->rq_timeout;
 570 }
 571 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
 572
 573 /**
 574  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 575  * @task: task whose timeout is to be set
 576  *
 577  * Set a request's retransmit timeout using the RTT estimator.
 578  */
 579 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 580 {
 581         int timer = task->tk_msg.rpc_proc->p_timer;
 582         struct rpc_clnt *clnt = task->tk_client;
 583         struct rpc_rtt *rtt = clnt->cl_rtt;
 584         struct rpc_rqst *req = task->tk_rqstp;
 585         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
 586
 587         task->tk_timeout = rpc_calc_rto(rtt, timer);
 588         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 589         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 590                 task->tk_timeout = max_timeout;
 591 }
 592 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 593
 594 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 595 {
 596         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 597
 598         req->rq_majortimeo = req->rq_timeout;
 599         if (to->to_exponential)
 600                 req->rq_majortimeo <<= to->to_retries;
 601         else
 602                 req->rq_majortimeo += to->to_increment * to->to_retries;
 603         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 604                 req->rq_majortimeo = to->to_maxval;
 605         req->rq_majortimeo += jiffies;
 606 }
 607
 608 /**
 609  * xprt_adjust_timeout - adjust timeout values for next retransmit
 610  * @req: RPC request containing parameters to use for the adjustment
 611  *
 612  */
 613 int xprt_adjust_timeout(struct rpc_rqst *req)
 614 {
 615         struct rpc_xprt *xprt = req->rq_xprt;
 616         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 617         int status = 0;
 618
 619         if (time_before(jiffies, req->rq_majortimeo)) {
 620                 if (to->to_exponential)
 621                         req->rq_timeout <<= 1;
 622                 else
 623                         req->rq_timeout += to->to_increment;
 624                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 625                         req->rq_timeout = to->to_maxval;
 626                 req->rq_retries++;
 627         } else {
 628                 req->rq_timeout = to->to_initval;
 629                 req->rq_retries = 0;
 630                 xprt_reset_majortimeo(req);
 631                 /* Reset the RTT counters == "slow start" */
 632                 spin_lock_bh(&xprt->transport_lock);
 633                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 634                 spin_unlock_bh(&xprt->transport_lock);
 635                 status = -ETIMEDOUT;
 636         }
 637
 638         if (req->rq_timeout == 0) {
 639                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 640                 req->rq_timeout = 5 * HZ;
 641         }
 642         return status;
 643 }
 644
 645 static void xprt_autoclose(struct work_struct *work)
 646 {
 647         struct rpc_xprt *xprt =
 648                 container_of(work, struct rpc_xprt, task_cleanup);
 649
 650         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 651         xprt->ops->close(xprt);
 652         xprt_release_write(xprt, NULL);
 653         wake_up_bit(&xprt->state, XPRT_LOCKED);
 654 }
 655
 656 /**
 657  * xprt_disconnect_done - mark a transport as disconnected
 658  * @xprt: transport to flag for disconnect
 659  *
 660  */
 661 void xprt_disconnect_done(struct rpc_xprt *xprt)
 662 {
 663         dprintk("RPC:       disconnected transport %p\n", xprt);
 664         spin_lock_bh(&xprt->transport_lock);
 665         xprt_clear_connected(xprt);
 666         xprt_wake_pending_tasks(xprt, -EAGAIN);
 667         spin_unlock_bh(&xprt->transport_lock);
 668 }
 669 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 670
 671 /**
 672  * xprt_force_disconnect - force a transport to disconnect
 673  * @xprt: transport to disconnect
 674  *
 675  */
 676 void xprt_force_disconnect(struct rpc_xprt *xprt)
 677 {
 678         /* Don't race with the test_bit() in xprt_clear_locked() */
 679         spin_lock_bh(&xprt->transport_lock);
 680         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 681         /* Try to schedule an autoclose RPC call */
 682         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 683                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 684         xprt_wake_pending_tasks(xprt, -EAGAIN);
 685         spin_unlock_bh(&xprt->transport_lock);
 686 }
 687
 688 /**
 689  * xprt_conditional_disconnect - force a transport to disconnect
 690  * @xprt: transport to disconnect
 691  * @cookie: 'connection cookie'
 692  *
 693  * This attempts to break the connection if and only if 'cookie' matches
 694  * the current transport 'connection cookie'. It ensures that we don't
 695  * try to break the connection more than once when we need to retransmit
 696  * a batch of RPC requests.
 697  *
 698  */
 699 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 700 {
 701         /* Don't race with the test_bit() in xprt_clear_locked() */
 702         spin_lock_bh(&xprt->transport_lock);
 703         if (cookie != xprt->connect_cookie)
 704                 goto out;
 705         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
 706                 goto out;
 707         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 708         /* Try to schedule an autoclose RPC call */
 709         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 710                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 711         xprt_wake_pending_tasks(xprt, -EAGAIN);
 712 out:
 713         spin_unlock_bh(&xprt->transport_lock);
 714 }
 715
 716 static bool
 717 xprt_has_timer(const struct rpc_xprt *xprt)
 718 {
 719         return xprt->idle_timeout != 0;
 720 }
 721
 722 static void
 723 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
 724         __must_hold(&xprt->transport_lock)
 725 {
 726         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
 727                 mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
 728 }
 729
 730 static void
 731 xprt_init_autodisconnect(unsigned long data)
 732 {
 733         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 734
 735         spin_lock(&xprt->transport_lock);
 736         if (!list_empty(&xprt->recv))
 737                 goto out_abort;
 738         /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
 739         xprt->last_used = jiffies;
 740         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 741                 goto out_abort;
 742         spin_unlock(&xprt->transport_lock);
 743         queue_work(xprtiod_workqueue, &xprt->task_cleanup);
 744         return;
 745 out_abort:
 746         spin_unlock(&xprt->transport_lock);
 747 }
 748
 749 bool xprt_lock_connect(struct rpc_xprt *xprt,
 750                 struct rpc_task *task,
 751                 void *cookie)
 752 {
 753         bool ret = false;
 754
 755         spin_lock_bh(&xprt->transport_lock);
 756         if (!test_bit(XPRT_LOCKED, &xprt->state))
 757                 goto out;
 758         if (xprt->snd_task != task)
 759                 goto out;
 760         xprt_task_clear_bytes_sent(task);
 761         xprt->snd_task = cookie;
 762         ret = true;
 763 out:
 764         spin_unlock_bh(&xprt->transport_lock);
 765         return ret;
 766 }
 767
 768 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
 769 {
 770         spin_lock_bh(&xprt->transport_lock);
 771         if (xprt->snd_task != cookie)
 772                 goto out;
 773         if (!test_bit(XPRT_LOCKED, &xprt->state))
 774                 goto out;
 775         xprt->snd_task =NULL;
 776         xprt->ops->release_xprt(xprt, NULL);
 777         xprt_schedule_autodisconnect(xprt);
 778 out:
 779         spin_unlock_bh(&xprt->transport_lock);
 780         wake_up_bit(&xprt->state, XPRT_LOCKED);
 781 }
 782
 783 /**
 784  * xprt_connect - schedule a transport connect operation
 785  * @task: RPC task that is requesting the connect
 786  *
 787  */
 788 void xprt_connect(struct rpc_task *task)
 789 {
 790         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 791
 792         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 793                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 794
 795         if (!xprt_bound(xprt)) {
 796                 task->tk_status = -EAGAIN;
 797                 return;
 798         }
 799         if (!xprt_lock_write(xprt, task))
 800                 return;
 801
 802         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
 803                 xprt->ops->close(xprt);
 804
 805         if (!xprt_connected(xprt)) {
 806                 task->tk_rqstp->rq_bytes_sent = 0;
 807                 task->tk_timeout = task->tk_rqstp->rq_timeout;
 808                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
 809
 810                 if (test_bit(XPRT_CLOSING, &xprt->state))
 811                         return;
 812                 if (xprt_test_and_set_connecting(xprt))
 813                         return;
 814                 /* Race breaker */
 815                 if (!xprt_connected(xprt)) {
 816                         xprt->stat.connect_start = jiffies;
 817                         xprt->ops->connect(xprt, task);
 818                 } else {
 819                         xprt_clear_connecting(xprt);
 820                         task->tk_status = 0;
 821                         rpc_wake_up_queued_task(&xprt->pending, task);
 822                 }
 823         }
 824         xprt_release_write(xprt, task);
 825 }
 826
 827 static void xprt_connect_status(struct rpc_task *task)
 828 {
 829         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
 830
 831         if (task->tk_status == 0) {
 832                 xprt->stat.connect_count++;
 833                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 834                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 835                                 task->tk_pid);
 836                 return;
 837         }
 838
 839         switch (task->tk_status) {
 840         case -ECONNREFUSED:
 841         case -ECONNRESET:
 842         case -ECONNABORTED:
 843         case -ENETUNREACH:
 844         case -EHOSTUNREACH:
 845         case -EPIPE:
 846         case -EAGAIN:
 847                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
 848                 break;
 849         case -ETIMEDOUT:
 850                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 851                                 "out\n", task->tk_pid);
 852                 break;
 853         default:
 854                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 855                                 "server %s\n", task->tk_pid, -task->tk_status,
 856                                 xprt->servername);
 857                 task->tk_status = -EIO;
 858         }
 859 }
 860
 861 /**
 862  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 863  * @xprt: transport on which the original request was transmitted
 864  * @xid: RPC XID of incoming reply
 865  *
 866  */
 867 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 868 {
 869         struct rpc_rqst *entry;
 870
 871         list_for_each_entry(entry, &xprt->recv, rq_list)
 872                 if (entry->rq_xid == xid) {
 873                         trace_xprt_lookup_rqst(xprt, xid, 0);
 874                         return entry;
 875                 }
 876
 877         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 878                         ntohl(xid));
 879         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
 880         xprt->stat.bad_xids++;
 881         return NULL;
 882 }
 883 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 884
 885 static void xprt_update_rtt(struct rpc_task *task)
 886 {
 887         struct rpc_rqst *req = task->tk_rqstp;
 888         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 889         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
 890         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
 891
 892         if (timer) {
 893                 if (req->rq_ntrans == 1)
 894                         rpc_update_rtt(rtt, timer, m);
 895                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 896         }
 897 }
 898
 899 /**
 900  * xprt_complete_rqst - called when reply processing is complete
 901  * @task: RPC request that recently completed
 902  * @copied: actual number of bytes received from the transport
 903  *
 904  * Caller holds transport lock.
 905  */
 906 void xprt_complete_rqst(struct rpc_task *task, int copied)
 907 {
 908         struct rpc_rqst *req = task->tk_rqstp;
 909         struct rpc_xprt *xprt = req->rq_xprt;
 910
 911         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 912                         task->tk_pid, ntohl(req->rq_xid), copied);
 913         trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
 914
 915         xprt->stat.recvs++;
 916         req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
 917         if (xprt->ops->timer != NULL)
 918                 xprt_update_rtt(task);
 919
 920         list_del_init(&req->rq_list);
 921         req->rq_private_buf.len = copied;
 922         /* Ensure all writes are done before we update */
 923         /* req->rq_reply_bytes_recvd */
 924         smp_wmb();
 925         req->rq_reply_bytes_recvd = copied;
 926         rpc_wake_up_queued_task(&xprt->pending, task);
 927 }
 928 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
 929
 930 static void xprt_timer(struct rpc_task *task)
 931 {
 932         struct rpc_rqst *req = task->tk_rqstp;
 933         struct rpc_xprt *xprt = req->rq_xprt;
 934
 935         if (task->tk_status != -ETIMEDOUT)
 936                 return;
 937         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
 938
 939         spin_lock_bh(&xprt->transport_lock);
 940         if (!req->rq_reply_bytes_recvd) {
 941                 if (xprt->ops->timer)
 942                         xprt->ops->timer(xprt, task);
 943         } else
 944                 task->tk_status = 0;
 945         spin_unlock_bh(&xprt->transport_lock);
 946 }
 947
 948 /**
 949  * xprt_prepare_transmit - reserve the transport before sending a request
 950  * @task: RPC task about to send a request
 951  *
 952  */
 953 bool xprt_prepare_transmit(struct rpc_task *task)
 954 {
 955         struct rpc_rqst *req = task->tk_rqstp;
 956         struct rpc_xprt *xprt = req->rq_xprt;
 957         bool ret = false;
 958
 959         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 960
 961         spin_lock_bh(&xprt->transport_lock);
 962         if (!req->rq_bytes_sent) {
 963                 if (req->rq_reply_bytes_recvd) {
 964                         task->tk_status = req->rq_reply_bytes_recvd;
 965                         goto out_unlock;
 966                 }
 967                 if ((task->tk_flags & RPC_TASK_NO_RETRANS_TIMEOUT)
 968                     && xprt_connected(xprt)
 969                     && req->rq_connect_cookie == xprt->connect_cookie) {
 970                         xprt->ops->set_retrans_timeout(task);
 971                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
 972                         goto out_unlock;
 973                 }
 974         }
 975         if (!xprt->ops->reserve_xprt(xprt, task)) {
 976                 task->tk_status = -EAGAIN;
 977                 goto out_unlock;
 978         }
 979         ret = true;
 980 out_unlock:
 981         spin_unlock_bh(&xprt->transport_lock);
 982         return ret;
 983 }
 984
 985 void xprt_end_transmit(struct rpc_task *task)
 986 {
 987         xprt_release_write(task->tk_rqstp->rq_xprt, task);
 988 }
 989
 990 /**
 991  * xprt_transmit - send an RPC request on a transport
 992  * @task: controlling RPC task
 993  *
 994  * We have to copy the iovec because sendmsg fiddles with its contents.
 995  */
 996 void xprt_transmit(struct rpc_task *task)
 997 {
 998         struct rpc_rqst *req = task->tk_rqstp;
 999         struct rpc_xprt *xprt = req->rq_xprt;
1000         int status, numreqs;
1001
1002         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
1003
1004         if (!req->rq_reply_bytes_recvd) {
1005                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
1006                         /*
1007                          * Add to the list only if we're expecting a reply
1008                          */
1009                         spin_lock_bh(&xprt->transport_lock);
1010                         /* Update the softirq receive buffer */
1011                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1012                                         sizeof(req->rq_private_buf));
1013                         /* Add request to the receive list */
1014                         list_add_tail(&req->rq_list, &xprt->recv);
1015                         spin_unlock_bh(&xprt->transport_lock);
1016                         xprt_reset_majortimeo(req);
1017                         /* Turn off autodisconnect */
1018                         del_singleshot_timer_sync(&xprt->timer);
1019                 }
1020         } else if (!req->rq_bytes_sent)
1021                 return;
1022
1023         req->rq_xtime = ktime_get();
1024         status = xprt->ops->send_request(task);
1025         trace_xprt_transmit(xprt, req->rq_xid, status);
1026         if (status != 0) {
1027                 task->tk_status = status;
1028                 return;
1029         }
1030         xprt_inject_disconnect(xprt);
1031
1032         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
1033         task->tk_flags |= RPC_TASK_SENT;
1034         spin_lock_bh(&xprt->transport_lock);
1035
1036         xprt->ops->set_retrans_timeout(task);
1037
1038         numreqs = atomic_read(&xprt->num_reqs);
1039         if (numreqs > xprt->stat.max_slots)
1040                 xprt->stat.max_slots = numreqs;
1041         xprt->stat.sends++;
1042         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1043         xprt->stat.bklog_u += xprt->backlog.qlen;
1044         xprt->stat.sending_u += xprt->sending.qlen;
1045         xprt->stat.pending_u += xprt->pending.qlen;
1046
1047         /* Don't race with disconnect */
1048         if (!xprt_connected(xprt))
1049                 task->tk_status = -ENOTCONN;
1050         else {
1051                 /*
1052                  * Sleep on the pending queue since
1053                  * we're expecting a reply.
1054                  */
1055                 if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task))
1056                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
1057                 req->rq_connect_cookie = xprt->connect_cookie;
1058         }
1059         spin_unlock_bh(&xprt->transport_lock);
1060 }
1061
1062 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1063 {
1064         set_bit(XPRT_CONGESTED, &xprt->state);
1065         rpc_sleep_on(&xprt->backlog, task, NULL);
1066 }
1067
1068 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
1069 {
1070         if (rpc_wake_up_next(&xprt->backlog) == NULL)
1071                 clear_bit(XPRT_CONGESTED, &xprt->state);
1072 }
1073
1074 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1075 {
1076         bool ret = false;
1077
1078         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1079                 goto out;
1080         spin_lock(&xprt->reserve_lock);
1081         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1082                 rpc_sleep_on(&xprt->backlog, task, NULL);
1083                 ret = true;
1084         }
1085         spin_unlock(&xprt->reserve_lock);
1086 out:
1087         return ret;
1088 }
1089
1090 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
1091 {
1092         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1093
1094         if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
1095                 goto out;
1096         req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
1097         if (req != NULL)
1098                 goto out;
1099         atomic_dec(&xprt->num_reqs);
1100         req = ERR_PTR(-ENOMEM);
1101 out:
1102         return req;
1103 }
1104
1105 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1106 {
1107         if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
1108                 kfree(req);
1109                 return true;
1110         }
1111         return false;
1112 }
1113
1114 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1115 {
1116         struct rpc_rqst *req;
1117
1118         spin_lock(&xprt->reserve_lock);
1119         if (!list_empty(&xprt->free)) {
1120                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1121                 list_del(&req->rq_list);
1122                 goto out_init_req;
1123         }
1124         req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
1125         if (!IS_ERR(req))
1126                 goto out_init_req;
1127         switch (PTR_ERR(req)) {
1128         case -ENOMEM:
1129                 dprintk("RPC:       dynamic allocation of request slot "
1130                                 "failed! Retrying\n");
1131                 task->tk_status = -ENOMEM;
1132                 break;
1133         case -EAGAIN:
1134                 xprt_add_backlog(xprt, task);
1135                 dprintk("RPC:       waiting for request slot\n");
1136         default:
1137                 task->tk_status = -EAGAIN;
1138         }
1139         spin_unlock(&xprt->reserve_lock);
1140         return;
1141 out_init_req:
1142         task->tk_status = 0;
1143         task->tk_rqstp = req;
1144         xprt_request_init(task, xprt);
1145         spin_unlock(&xprt->reserve_lock);
1146 }
1147 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1148
1149 void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1150 {
1151         /* Note: grabbing the xprt_lock_write() ensures that we throttle
1152          * new slot allocation if the transport is congested (i.e. when
1153          * reconnecting a stream transport or when out of socket write
1154          * buffer space).
1155          */
1156         if (xprt_lock_write(xprt, task)) {
1157                 xprt_alloc_slot(xprt, task);
1158                 xprt_release_write(xprt, task);
1159         }
1160 }
1161 EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1162
1163 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1164 {
1165         spin_lock(&xprt->reserve_lock);
1166         if (!xprt_dynamic_free_slot(xprt, req)) {
1167                 memset(req, 0, sizeof(*req));   /* mark unused */
1168                 list_add(&req->rq_list, &xprt->free);
1169         }
1170         xprt_wake_up_backlog(xprt);
1171         spin_unlock(&xprt->reserve_lock);
1172 }
1173
1174 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1175 {
1176         struct rpc_rqst *req;
1177         while (!list_empty(&xprt->free)) {
1178                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1179                 list_del(&req->rq_list);
1180                 kfree(req);
1181         }
1182 }
1183
1184 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1185                 unsigned int num_prealloc,
1186                 unsigned int max_alloc)
1187 {
1188         struct rpc_xprt *xprt;
1189         struct rpc_rqst *req;
1190         int i;
1191
1192         xprt = kzalloc(size, GFP_KERNEL);
1193         if (xprt == NULL)
1194                 goto out;
1195
1196         xprt_init(xprt, net);
1197
1198         for (i = 0; i < num_prealloc; i++) {
1199                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1200                 if (!req)
1201                         goto out_free;
1202                 list_add(&req->rq_list, &xprt->free);
1203         }
1204         if (max_alloc > num_prealloc)
1205                 xprt->max_reqs = max_alloc;
1206         else
1207                 xprt->max_reqs = num_prealloc;
1208         xprt->min_reqs = num_prealloc;
1209         atomic_set(&xprt->num_reqs, num_prealloc);
1210
1211         return xprt;
1212
1213 out_free:
1214         xprt_free(xprt);
1215 out:
1216         return NULL;
1217 }
1218 EXPORT_SYMBOL_GPL(xprt_alloc);
1219
1220 void xprt_free(struct rpc_xprt *xprt)
1221 {
1222         put_net(xprt->xprt_net);
1223         xprt_free_all_slots(xprt);
1224         kfree_rcu(xprt, rcu);
1225 }
1226 EXPORT_SYMBOL_GPL(xprt_free);
1227
1228 /**
1229  * xprt_reserve - allocate an RPC request slot
1230  * @task: RPC task requesting a slot allocation
1231  *
1232  * If the transport is marked as being congested, or if no more
1233  * slots are available, place the task on the transport's
1234  * backlog queue.
1235  */
1236 void xprt_reserve(struct rpc_task *task)
1237 {
1238         struct rpc_xprt *xprt = task->tk_xprt;
1239
1240         task->tk_status = 0;
1241         if (task->tk_rqstp != NULL)
1242                 return;
1243
1244         task->tk_timeout = 0;
1245         task->tk_status = -EAGAIN;
1246         if (!xprt_throttle_congested(xprt, task))
1247                 xprt->ops->alloc_slot(xprt, task);
1248 }
1249
1250 /**
1251  * xprt_retry_reserve - allocate an RPC request slot
1252  * @task: RPC task requesting a slot allocation
1253  *
1254  * If no more slots are available, place the task on the transport's
1255  * backlog queue.
1256  * Note that the only difference with xprt_reserve is that we now
1257  * ignore the value of the XPRT_CONGESTED flag.
1258  */
1259 void xprt_retry_reserve(struct rpc_task *task)
1260 {
1261         struct rpc_xprt *xprt = task->tk_xprt;
1262
1263         task->tk_status = 0;
1264         if (task->tk_rqstp != NULL)
1265                 return;
1266
1267         task->tk_timeout = 0;
1268         task->tk_status = -EAGAIN;
1269         xprt->ops->alloc_slot(xprt, task);
1270 }
1271
1272 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1273 {
1274         return (__force __be32)xprt->xid++;
1275 }
1276
1277 static inline void xprt_init_xid(struct rpc_xprt *xprt)
1278 {
1279         xprt->xid = prandom_u32();
1280 }
1281
1282 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1283 {
1284         struct rpc_rqst *req = task->tk_rqstp;
1285
1286         INIT_LIST_HEAD(&req->rq_list);
1287         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1288         req->rq_task    = task;
1289         req->rq_xprt    = xprt;
1290         req->rq_buffer  = NULL;
1291         req->rq_xid     = xprt_alloc_xid(xprt);
1292         req->rq_connect_cookie = xprt->connect_cookie - 1;
1293         req->rq_bytes_sent = 0;
1294         req->rq_snd_buf.len = 0;
1295         req->rq_snd_buf.buflen = 0;
1296         req->rq_rcv_buf.len = 0;
1297         req->rq_rcv_buf.buflen = 0;
1298         req->rq_release_snd_buf = NULL;
1299         xprt_reset_majortimeo(req);
1300         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1301                         req, ntohl(req->rq_xid));
1302 }
1303
1304 /**
1305  * xprt_release - release an RPC request slot
1306  * @task: task which is finished with the slot
1307  *
1308  */
1309 void xprt_release(struct rpc_task *task)
1310 {
1311         struct rpc_xprt *xprt;
1312         struct rpc_rqst *req = task->tk_rqstp;
1313
1314         if (req == NULL) {
1315                 if (task->tk_client) {
1316                         xprt = task->tk_xprt;
1317                         if (xprt->snd_task == task)
1318                                 xprt_release_write(xprt, task);
1319                 }
1320                 return;
1321         }
1322
1323         xprt = req->rq_xprt;
1324         if (task->tk_ops->rpc_count_stats != NULL)
1325                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1326         else if (task->tk_client)
1327                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1328         spin_lock_bh(&xprt->transport_lock);
1329         xprt->ops->release_xprt(xprt, task);
1330         if (xprt->ops->release_request)
1331                 xprt->ops->release_request(task);
1332         if (!list_empty(&req->rq_list))
1333                 list_del(&req->rq_list);
1334         xprt->last_used = jiffies;
1335         xprt_schedule_autodisconnect(xprt);
1336         spin_unlock_bh(&xprt->transport_lock);
1337         if (req->rq_buffer)
1338                 xprt->ops->buf_free(task);
1339         xprt_inject_disconnect(xprt);
1340         if (req->rq_cred != NULL)
1341                 put_rpccred(req->rq_cred);
1342         task->tk_rqstp = NULL;
1343         if (req->rq_release_snd_buf)
1344                 req->rq_release_snd_buf(req);
1345
1346         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1347         if (likely(!bc_prealloc(req)))
1348                 xprt_free_slot(xprt, req);
1349         else
1350                 xprt_free_bc_request(req);
1351 }
1352
1353 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1354 {
1355         kref_init(&xprt->kref);
1356
1357         spin_lock_init(&xprt->transport_lock);
1358         spin_lock_init(&xprt->reserve_lock);
1359
1360         INIT_LIST_HEAD(&xprt->free);
1361         INIT_LIST_HEAD(&xprt->recv);
1362 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1363         spin_lock_init(&xprt->bc_pa_lock);
1364         INIT_LIST_HEAD(&xprt->bc_pa_list);
1365 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1366         INIT_LIST_HEAD(&xprt->xprt_switch);
1367
1368         xprt->last_used = jiffies;
1369         xprt->cwnd = RPC_INITCWND;
1370         xprt->bind_index = 0;
1371
1372         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1373         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1374         rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1375         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1376
1377         xprt_init_xid(xprt);
1378
1379         xprt->xprt_net = get_net(net);
1380 }
1381
1382 /**
1383  * xprt_create_transport - create an RPC transport
1384  * @args: rpc transport creation arguments
1385  *
1386  */
1387 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1388 {
1389         struct rpc_xprt *xprt;
1390         struct xprt_class *t;
1391
1392         spin_lock(&xprt_list_lock);
1393         list_for_each_entry(t, &xprt_list, list) {
1394                 if (t->ident == args->ident) {
1395                         spin_unlock(&xprt_list_lock);
1396                         goto found;
1397                 }
1398         }
1399         spin_unlock(&xprt_list_lock);
1400         dprintk("RPC: transport (%d) not supported\n", args->ident);
1401         return ERR_PTR(-EIO);
1402
1403 found:
1404         xprt = t->setup(args);
1405         if (IS_ERR(xprt)) {
1406                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1407                                 -PTR_ERR(xprt));
1408                 goto out;
1409         }
1410         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1411                 xprt->idle_timeout = 0;
1412         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1413         if (xprt_has_timer(xprt))
1414                 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1415                             (unsigned long)xprt);
1416         else
1417                 init_timer(&xprt->timer);
1418
1419         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1420                 xprt_destroy(xprt);
1421                 return ERR_PTR(-EINVAL);
1422         }
1423         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1424         if (xprt->servername == NULL) {
1425                 xprt_destroy(xprt);
1426                 return ERR_PTR(-ENOMEM);
1427         }
1428
1429         rpc_xprt_debugfs_register(xprt);
1430
1431         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1432                         xprt->max_reqs);
1433 out:
1434         return xprt;
1435 }
1436
1437 /**
1438  * xprt_destroy - destroy an RPC transport, killing off all requests.
1439  * @xprt: transport to destroy
1440  *
1441  */
1442 static void xprt_destroy(struct rpc_xprt *xprt)
1443 {
1444         dprintk("RPC:       destroying transport %p\n", xprt);
1445
1446         /* Exclude transport connect/disconnect handlers */
1447         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
1448
1449         del_timer_sync(&xprt->timer);
1450
1451         rpc_xprt_debugfs_unregister(xprt);
1452         rpc_destroy_wait_queue(&xprt->binding);
1453         rpc_destroy_wait_queue(&xprt->pending);
1454         rpc_destroy_wait_queue(&xprt->sending);
1455         rpc_destroy_wait_queue(&xprt->backlog);
1456         cancel_work_sync(&xprt->task_cleanup);
1457         kfree(xprt->servername);
1458         /*
1459          * Tear down transport state and free the rpc_xprt
1460          */
1461         xprt->ops->destroy(xprt);
1462 }
1463
1464 static void xprt_destroy_kref(struct kref *kref)
1465 {
1466         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
1467 }
1468
1469 /**
1470  * xprt_get - return a reference to an RPC transport.
1471  * @xprt: pointer to the transport
1472  *
1473  */
1474 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1475 {
1476         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
1477                 return xprt;
1478         return NULL;
1479 }
1480 EXPORT_SYMBOL_GPL(xprt_get);
1481
1482 /**
1483  * xprt_put - release a reference to an RPC transport.
1484  * @xprt: pointer to the transport
1485  *
1486  */
1487 void xprt_put(struct rpc_xprt *xprt)
1488 {
1489         if (xprt != NULL)
1490                 kref_put(&xprt->kref, xprt_destroy_kref);
1491 }
1492 EXPORT_SYMBOL_GPL(xprt_put);