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
  52 #include "sunrpc.h"
  53
  54 /*
  55  * Local variables
  56  */
  57
  58 #ifdef RPC_DEBUG
  59 # define RPCDBG_FACILITY        RPCDBG_XPRT
  60 #endif
  61
  62 /*
  63  * Local functions
  64  */
  65 static void      xprt_init(struct rpc_xprt *xprt, struct net *net);
  66 static void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
  67 static void     xprt_connect_status(struct rpc_task *task);
  68 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
  69 static void      xprt_destroy(struct rpc_xprt *xprt);
  70
  71 static DEFINE_SPINLOCK(xprt_list_lock);
  72 static LIST_HEAD(xprt_list);
  73
  74 /*
  75  * The transport code maintains an estimate on the maximum number of out-
  76  * standing RPC requests, using a smoothed version of the congestion
  77  * avoidance implemented in 44BSD. This is basically the Van Jacobson
  78  * congestion algorithm: If a retransmit occurs, the congestion window is
  79  * halved; otherwise, it is incremented by 1/cwnd when
  80  *
  81  *      -       a reply is received and
  82  *      -       a full number of requests are outstanding and
  83  *      -       the congestion window hasn't been updated recently.
  84  */
  85 #define RPC_CWNDSHIFT           (8U)
  86 #define RPC_CWNDSCALE           (1U << RPC_CWNDSHIFT)
  87 #define RPC_INITCWND            RPC_CWNDSCALE
  88 #define RPC_MAXCWND(xprt)       ((xprt)->max_reqs << RPC_CWNDSHIFT)
  89
  90 #define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
  91
  92 /**
  93  * xprt_register_transport - register a transport implementation
  94  * @transport: transport to register
  95  *
  96  * If a transport implementation is loaded as a kernel module, it can
  97  * call this interface to make itself known to the RPC client.
  98  *
  99  * Returns:
 100  * 0:           transport successfully registered
 101  * -EEXIST:     transport already registered
 102  * -EINVAL:     transport module being unloaded
 103  */
 104 int xprt_register_transport(struct xprt_class *transport)
 105 {
 106         struct xprt_class *t;
 107         int result;
 108
 109         result = -EEXIST;
 110         spin_lock(&xprt_list_lock);
 111         list_for_each_entry(t, &xprt_list, list) {
 112                 /* don't register the same transport class twice */
 113                 if (t->ident == transport->ident)
 114                         goto out;
 115         }
 116
 117         list_add_tail(&transport->list, &xprt_list);
 118         printk(KERN_INFO "RPC: Registered %s transport module.\n",
 119                transport->name);
 120         result = 0;
 121
 122 out:
 123         spin_unlock(&xprt_list_lock);
 124         return result;
 125 }
 126 EXPORT_SYMBOL_GPL(xprt_register_transport);
 127
 128 /**
 129  * xprt_unregister_transport - unregister a transport implementation
 130  * @transport: transport to unregister
 131  *
 132  * Returns:
 133  * 0:           transport successfully unregistered
 134  * -ENOENT:     transport never registered
 135  */
 136 int xprt_unregister_transport(struct xprt_class *transport)
 137 {
 138         struct xprt_class *t;
 139         int result;
 140
 141         result = 0;
 142         spin_lock(&xprt_list_lock);
 143         list_for_each_entry(t, &xprt_list, list) {
 144                 if (t == transport) {
 145                         printk(KERN_INFO
 146                                 "RPC: Unregistered %s transport module.\n",
 147                                 transport->name);
 148                         list_del_init(&transport->list);
 149                         goto out;
 150                 }
 151         }
 152         result = -ENOENT;
 153
 154 out:
 155         spin_unlock(&xprt_list_lock);
 156         return result;
 157 }
 158 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 159
 160 /**
 161  * xprt_load_transport - load a transport implementation
 162  * @transport_name: transport to load
 163  *
 164  * Returns:
 165  * 0:           transport successfully loaded
 166  * -ENOENT:     transport module not available
 167  */
 168 int xprt_load_transport(const char *transport_name)
 169 {
 170         struct xprt_class *t;
 171         int result;
 172
 173         result = 0;
 174         spin_lock(&xprt_list_lock);
 175         list_for_each_entry(t, &xprt_list, list) {
 176                 if (strcmp(t->name, transport_name) == 0) {
 177                         spin_unlock(&xprt_list_lock);
 178                         goto out;
 179                 }
 180         }
 181         spin_unlock(&xprt_list_lock);
 182         result = request_module("xprt%s", transport_name);
 183 out:
 184         return result;
 185 }
 186 EXPORT_SYMBOL_GPL(xprt_load_transport);
 187
 188 /**
 189  * xprt_reserve_xprt - serialize write access to transports
 190  * @task: task that is requesting access to the transport
 191  * @xprt: pointer to the target transport
 192  *
 193  * This prevents mixing the payload of separate requests, and prevents
 194  * transport connects from colliding with writes.  No congestion control
 195  * is provided.
 196  */
 197 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 198 {
 199         struct rpc_rqst *req = task->tk_rqstp;
 200         int priority;
 201
 202         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 203                 if (task == xprt->snd_task)
 204                         return 1;
 205                 goto out_sleep;
 206         }
 207         xprt->snd_task = task;
 208         if (req != NULL) {
 209                 req->rq_bytes_sent = 0;
 210                 req->rq_ntrans++;
 211         }
 212
 213         return 1;
 214
 215 out_sleep:
 216         dprintk("RPC: %5u failed to lock transport %p\n",
 217                         task->tk_pid, xprt);
 218         task->tk_timeout = 0;
 219         task->tk_status = -EAGAIN;
 220         if (req == NULL)
 221                 priority = RPC_PRIORITY_LOW;
 222         else if (!req->rq_ntrans)
 223                 priority = RPC_PRIORITY_NORMAL;
 224         else
 225                 priority = RPC_PRIORITY_HIGH;
 226         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
 227         return 0;
 228 }
 229 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 230
 231 static void xprt_clear_locked(struct rpc_xprt *xprt)
 232 {
 233         xprt->snd_task = NULL;
 234         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
 235                 smp_mb__before_clear_bit();
 236                 clear_bit(XPRT_LOCKED, &xprt->state);
 237                 smp_mb__after_clear_bit();
 238         } else
 239                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 240 }
 241
 242 /*
 243  * xprt_reserve_xprt_cong - serialize write access to transports
 244  * @task: task that is requesting access to the transport
 245  *
 246  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 247  * integrated into the decision of whether a request is allowed to be
 248  * woken up and given access to the transport.
 249  */
 250 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 251 {
 252         struct rpc_rqst *req = task->tk_rqstp;
 253         int priority;
 254
 255         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 256                 if (task == xprt->snd_task)
 257                         return 1;
 258                 goto out_sleep;
 259         }
 260         if (req == NULL) {
 261                 xprt->snd_task = task;
 262                 return 1;
 263         }
 264         if (__xprt_get_cong(xprt, task)) {
 265                 xprt->snd_task = task;
 266                 req->rq_bytes_sent = 0;
 267                 req->rq_ntrans++;
 268                 return 1;
 269         }
 270         xprt_clear_locked(xprt);
 271 out_sleep:
 272         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
 273         task->tk_timeout = 0;
 274         task->tk_status = -EAGAIN;
 275         if (req == NULL)
 276                 priority = RPC_PRIORITY_LOW;
 277         else if (!req->rq_ntrans)
 278                 priority = RPC_PRIORITY_NORMAL;
 279         else
 280                 priority = RPC_PRIORITY_HIGH;
 281         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
 282         return 0;
 283 }
 284 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 285
 286 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 287 {
 288         int retval;
 289
 290         spin_lock_bh(&xprt->transport_lock);
 291         retval = xprt->ops->reserve_xprt(xprt, task);
 292         spin_unlock_bh(&xprt->transport_lock);
 293         return retval;
 294 }
 295
 296 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
 297 {
 298         struct rpc_xprt *xprt = data;
 299         struct rpc_rqst *req;
 300
 301         req = task->tk_rqstp;
 302         xprt->snd_task = task;
 303         if (req) {
 304                 req->rq_bytes_sent = 0;
 305                 req->rq_ntrans++;
 306         }
 307         return true;
 308 }
 309
 310 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 311 {
 312         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 313                 return;
 314
 315         if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_func, xprt))
 316                 return;
 317         xprt_clear_locked(xprt);
 318 }
 319
 320 static bool __xprt_lock_write_cong_func(struct rpc_task *task, void *data)
 321 {
 322         struct rpc_xprt *xprt = data;
 323         struct rpc_rqst *req;
 324
 325         req = task->tk_rqstp;
 326         if (req == NULL) {
 327                 xprt->snd_task = task;
 328                 return true;
 329         }
 330         if (__xprt_get_cong(xprt, task)) {
 331                 xprt->snd_task = task;
 332                 req->rq_bytes_sent = 0;
 333                 req->rq_ntrans++;
 334                 return true;
 335         }
 336         return false;
 337 }
 338
 339 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 340 {
 341         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 342                 return;
 343         if (RPCXPRT_CONGESTED(xprt))
 344                 goto out_unlock;
 345         if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_cong_func, xprt))
 346                 return;
 347 out_unlock:
 348         xprt_clear_locked(xprt);
 349 }
 350
 351 /**
 352  * xprt_release_xprt - allow other requests to use a transport
 353  * @xprt: transport with other tasks potentially waiting
 354  * @task: task that is releasing access to the transport
 355  *
 356  * Note that "task" can be NULL.  No congestion control is provided.
 357  */
 358 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 359 {
 360         if (xprt->snd_task == task) {
 361                 xprt_clear_locked(xprt);
 362                 __xprt_lock_write_next(xprt);
 363         }
 364 }
 365 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 366
 367 /**
 368  * xprt_release_xprt_cong - allow other requests to use a transport
 369  * @xprt: transport with other tasks potentially waiting
 370  * @task: task that is releasing access to the transport
 371  *
 372  * Note that "task" can be NULL.  Another task is awoken to use the
 373  * transport if the transport's congestion window allows it.
 374  */
 375 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 376 {
 377         if (xprt->snd_task == task) {
 378                 xprt_clear_locked(xprt);
 379                 __xprt_lock_write_next_cong(xprt);
 380         }
 381 }
 382 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 383
 384 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 385 {
 386         spin_lock_bh(&xprt->transport_lock);
 387         xprt->ops->release_xprt(xprt, task);
 388         spin_unlock_bh(&xprt->transport_lock);
 389 }
 390
 391 /*
 392  * Van Jacobson congestion avoidance. Check if the congestion window
 393  * overflowed. Put the task to sleep if this is the case.
 394  */
 395 static int
 396 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 397 {
 398         struct rpc_rqst *req = task->tk_rqstp;
 399
 400         if (req->rq_cong)
 401                 return 1;
 402         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
 403                         task->tk_pid, xprt->cong, xprt->cwnd);
 404         if (RPCXPRT_CONGESTED(xprt))
 405                 return 0;
 406         req->rq_cong = 1;
 407         xprt->cong += RPC_CWNDSCALE;
 408         return 1;
 409 }
 410
 411 /*
 412  * Adjust the congestion window, and wake up the next task
 413  * that has been sleeping due to congestion
 414  */
 415 static void
 416 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 417 {
 418         if (!req->rq_cong)
 419                 return;
 420         req->rq_cong = 0;
 421         xprt->cong -= RPC_CWNDSCALE;
 422         __xprt_lock_write_next_cong(xprt);
 423 }
 424
 425 /**
 426  * xprt_release_rqst_cong - housekeeping when request is complete
 427  * @task: RPC request that recently completed
 428  *
 429  * Useful for transports that require congestion control.
 430  */
 431 void xprt_release_rqst_cong(struct rpc_task *task)
 432 {
 433         __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
 434 }
 435 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 436
 437 /**
 438  * xprt_adjust_cwnd - adjust transport congestion window
 439  * @task: recently completed RPC request used to adjust window
 440  * @result: result code of completed RPC request
 441  *
 442  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
 443  */
 444 void xprt_adjust_cwnd(struct rpc_task *task, int result)
 445 {
 446         struct rpc_rqst *req = task->tk_rqstp;
 447         struct rpc_xprt *xprt = task->tk_xprt;
 448         unsigned long cwnd = xprt->cwnd;
 449
 450         if (result >= 0 && cwnd <= xprt->cong) {
 451                 /* The (cwnd >> 1) term makes sure
 452                  * the result gets rounded properly. */
 453                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 454                 if (cwnd > RPC_MAXCWND(xprt))
 455                         cwnd = RPC_MAXCWND(xprt);
 456                 __xprt_lock_write_next_cong(xprt);
 457         } else if (result == -ETIMEDOUT) {
 458                 cwnd >>= 1;
 459                 if (cwnd < RPC_CWNDSCALE)
 460                         cwnd = RPC_CWNDSCALE;
 461         }
 462         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 463                         xprt->cong, xprt->cwnd, cwnd);
 464         xprt->cwnd = cwnd;
 465         __xprt_put_cong(xprt, req);
 466 }
 467 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 468
 469 /**
 470  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 471  * @xprt: transport with waiting tasks
 472  * @status: result code to plant in each task before waking it
 473  *
 474  */
 475 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 476 {
 477         if (status < 0)
 478                 rpc_wake_up_status(&xprt->pending, status);
 479         else
 480                 rpc_wake_up(&xprt->pending);
 481 }
 482 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 483
 484 /**
 485  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 486  * @task: task to be put to sleep
 487  * @action: function pointer to be executed after wait
 488  */
 489 void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
 490 {
 491         struct rpc_rqst *req = task->tk_rqstp;
 492         struct rpc_xprt *xprt = req->rq_xprt;
 493
 494         task->tk_timeout = req->rq_timeout;
 495         rpc_sleep_on(&xprt->pending, task, action);
 496 }
 497 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 498
 499 /**
 500  * xprt_write_space - wake the task waiting for transport output buffer space
 501  * @xprt: transport with waiting tasks
 502  *
 503  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 504  */
 505 void xprt_write_space(struct rpc_xprt *xprt)
 506 {
 507         spin_lock_bh(&xprt->transport_lock);
 508         if (xprt->snd_task) {
 509                 dprintk("RPC:       write space: waking waiting task on "
 510                                 "xprt %p\n", xprt);
 511                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
 512         }
 513         spin_unlock_bh(&xprt->transport_lock);
 514 }
 515 EXPORT_SYMBOL_GPL(xprt_write_space);
 516
 517 /**
 518  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 519  * @task: task whose timeout is to be set
 520  *
 521  * Set a request's retransmit timeout based on the transport's
 522  * default timeout parameters.  Used by transports that don't adjust
 523  * the retransmit timeout based on round-trip time estimation.
 524  */
 525 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 526 {
 527         task->tk_timeout = task->tk_rqstp->rq_timeout;
 528 }
 529 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
 530
 531 /**
 532  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 533  * @task: task whose timeout is to be set
 534  *
 535  * Set a request's retransmit timeout using the RTT estimator.
 536  */
 537 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 538 {
 539         int timer = task->tk_msg.rpc_proc->p_timer;
 540         struct rpc_clnt *clnt = task->tk_client;
 541         struct rpc_rtt *rtt = clnt->cl_rtt;
 542         struct rpc_rqst *req = task->tk_rqstp;
 543         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
 544
 545         task->tk_timeout = rpc_calc_rto(rtt, timer);
 546         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 547         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 548                 task->tk_timeout = max_timeout;
 549 }
 550 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 551
 552 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 553 {
 554         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 555
 556         req->rq_majortimeo = req->rq_timeout;
 557         if (to->to_exponential)
 558                 req->rq_majortimeo <<= to->to_retries;
 559         else
 560                 req->rq_majortimeo += to->to_increment * to->to_retries;
 561         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 562                 req->rq_majortimeo = to->to_maxval;
 563         req->rq_majortimeo += jiffies;
 564 }
 565
 566 /**
 567  * xprt_adjust_timeout - adjust timeout values for next retransmit
 568  * @req: RPC request containing parameters to use for the adjustment
 569  *
 570  */
 571 int xprt_adjust_timeout(struct rpc_rqst *req)
 572 {
 573         struct rpc_xprt *xprt = req->rq_xprt;
 574         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 575         int status = 0;
 576
 577         if (time_before(jiffies, req->rq_majortimeo)) {
 578                 if (to->to_exponential)
 579                         req->rq_timeout <<= 1;
 580                 else
 581                         req->rq_timeout += to->to_increment;
 582                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 583                         req->rq_timeout = to->to_maxval;
 584                 req->rq_retries++;
 585         } else {
 586                 req->rq_timeout = to->to_initval;
 587                 req->rq_retries = 0;
 588                 xprt_reset_majortimeo(req);
 589                 /* Reset the RTT counters == "slow start" */
 590                 spin_lock_bh(&xprt->transport_lock);
 591                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 592                 spin_unlock_bh(&xprt->transport_lock);
 593                 status = -ETIMEDOUT;
 594         }
 595
 596         if (req->rq_timeout == 0) {
 597                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 598                 req->rq_timeout = 5 * HZ;
 599         }
 600         return status;
 601 }
 602
 603 static void xprt_autoclose(struct work_struct *work)
 604 {
 605         struct rpc_xprt *xprt =
 606                 container_of(work, struct rpc_xprt, task_cleanup);
 607
 608         xprt->ops->close(xprt);
 609         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 610         xprt_release_write(xprt, NULL);
 611 }
 612
 613 /**
 614  * xprt_disconnect_done - mark a transport as disconnected
 615  * @xprt: transport to flag for disconnect
 616  *
 617  */
 618 void xprt_disconnect_done(struct rpc_xprt *xprt)
 619 {
 620         dprintk("RPC:       disconnected transport %p\n", xprt);
 621         spin_lock_bh(&xprt->transport_lock);
 622         xprt_clear_connected(xprt);
 623         xprt_wake_pending_tasks(xprt, -EAGAIN);
 624         spin_unlock_bh(&xprt->transport_lock);
 625 }
 626 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 627
 628 /**
 629  * xprt_force_disconnect - force a transport to disconnect
 630  * @xprt: transport to disconnect
 631  *
 632  */
 633 void xprt_force_disconnect(struct rpc_xprt *xprt)
 634 {
 635         /* Don't race with the test_bit() in xprt_clear_locked() */
 636         spin_lock_bh(&xprt->transport_lock);
 637         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 638         /* Try to schedule an autoclose RPC call */
 639         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 640                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 641         xprt_wake_pending_tasks(xprt, -EAGAIN);
 642         spin_unlock_bh(&xprt->transport_lock);
 643 }
 644
 645 /**
 646  * xprt_conditional_disconnect - force a transport to disconnect
 647  * @xprt: transport to disconnect
 648  * @cookie: 'connection cookie'
 649  *
 650  * This attempts to break the connection if and only if 'cookie' matches
 651  * the current transport 'connection cookie'. It ensures that we don't
 652  * try to break the connection more than once when we need to retransmit
 653  * a batch of RPC requests.
 654  *
 655  */
 656 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 657 {
 658         /* Don't race with the test_bit() in xprt_clear_locked() */
 659         spin_lock_bh(&xprt->transport_lock);
 660         if (cookie != xprt->connect_cookie)
 661                 goto out;
 662         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
 663                 goto out;
 664         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 665         /* Try to schedule an autoclose RPC call */
 666         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 667                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 668         xprt_wake_pending_tasks(xprt, -EAGAIN);
 669 out:
 670         spin_unlock_bh(&xprt->transport_lock);
 671 }
 672
 673 static void
 674 xprt_init_autodisconnect(unsigned long data)
 675 {
 676         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 677
 678         spin_lock(&xprt->transport_lock);
 679         if (!list_empty(&xprt->recv))
 680                 goto out_abort;
 681         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 682                 goto out_abort;
 683         spin_unlock(&xprt->transport_lock);
 684         set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
 685         queue_work(rpciod_workqueue, &xprt->task_cleanup);
 686         return;
 687 out_abort:
 688         spin_unlock(&xprt->transport_lock);
 689 }
 690
 691 /**
 692  * xprt_connect - schedule a transport connect operation
 693  * @task: RPC task that is requesting the connect
 694  *
 695  */
 696 void xprt_connect(struct rpc_task *task)
 697 {
 698         struct rpc_xprt *xprt = task->tk_xprt;
 699
 700         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 701                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 702
 703         if (!xprt_bound(xprt)) {
 704                 task->tk_status = -EAGAIN;
 705                 return;
 706         }
 707         if (!xprt_lock_write(xprt, task))
 708                 return;
 709
 710         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
 711                 xprt->ops->close(xprt);
 712
 713         if (xprt_connected(xprt))
 714                 xprt_release_write(xprt, task);
 715         else {
 716                 task->tk_rqstp->rq_bytes_sent = 0;
 717                 task->tk_timeout = task->tk_rqstp->rq_timeout;
 718                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
 719
 720                 if (test_bit(XPRT_CLOSING, &xprt->state))
 721                         return;
 722                 if (xprt_test_and_set_connecting(xprt))
 723                         return;
 724                 xprt->stat.connect_start = jiffies;
 725                 xprt->ops->connect(task);
 726         }
 727 }
 728
 729 static void xprt_connect_status(struct rpc_task *task)
 730 {
 731         struct rpc_xprt *xprt = task->tk_xprt;
 732
 733         if (task->tk_status == 0) {
 734                 xprt->stat.connect_count++;
 735                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 736                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 737                                 task->tk_pid);
 738                 return;
 739         }
 740
 741         switch (task->tk_status) {
 742         case -EAGAIN:
 743                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
 744                 break;
 745         case -ETIMEDOUT:
 746                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 747                                 "out\n", task->tk_pid);
 748                 break;
 749         default:
 750                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 751                                 "server %s\n", task->tk_pid, -task->tk_status,
 752                                 xprt->servername);
 753                 xprt_release_write(xprt, task);
 754                 task->tk_status = -EIO;
 755         }
 756 }
 757
 758 /**
 759  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 760  * @xprt: transport on which the original request was transmitted
 761  * @xid: RPC XID of incoming reply
 762  *
 763  */
 764 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 765 {
 766         struct rpc_rqst *entry;
 767
 768         list_for_each_entry(entry, &xprt->recv, rq_list)
 769                 if (entry->rq_xid == xid)
 770                         return entry;
 771
 772         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 773                         ntohl(xid));
 774         xprt->stat.bad_xids++;
 775         return NULL;
 776 }
 777 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 778
 779 static void xprt_update_rtt(struct rpc_task *task)
 780 {
 781         struct rpc_rqst *req = task->tk_rqstp;
 782         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 783         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
 784         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
 785
 786         if (timer) {
 787                 if (req->rq_ntrans == 1)
 788                         rpc_update_rtt(rtt, timer, m);
 789                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 790         }
 791 }
 792
 793 /**
 794  * xprt_complete_rqst - called when reply processing is complete
 795  * @task: RPC request that recently completed
 796  * @copied: actual number of bytes received from the transport
 797  *
 798  * Caller holds transport lock.
 799  */
 800 void xprt_complete_rqst(struct rpc_task *task, int copied)
 801 {
 802         struct rpc_rqst *req = task->tk_rqstp;
 803         struct rpc_xprt *xprt = req->rq_xprt;
 804
 805         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 806                         task->tk_pid, ntohl(req->rq_xid), copied);
 807
 808         xprt->stat.recvs++;
 809         req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
 810         if (xprt->ops->timer != NULL)
 811                 xprt_update_rtt(task);
 812
 813         list_del_init(&req->rq_list);
 814         req->rq_private_buf.len = copied;
 815         /* Ensure all writes are done before we update */
 816         /* req->rq_reply_bytes_recvd */
 817         smp_wmb();
 818         req->rq_reply_bytes_recvd = copied;
 819         rpc_wake_up_queued_task(&xprt->pending, task);
 820 }
 821 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
 822
 823 static void xprt_timer(struct rpc_task *task)
 824 {
 825         struct rpc_rqst *req = task->tk_rqstp;
 826         struct rpc_xprt *xprt = req->rq_xprt;
 827
 828         if (task->tk_status != -ETIMEDOUT)
 829                 return;
 830         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
 831
 832         spin_lock_bh(&xprt->transport_lock);
 833         if (!req->rq_reply_bytes_recvd) {
 834                 if (xprt->ops->timer)
 835                         xprt->ops->timer(task);
 836         } else
 837                 task->tk_status = 0;
 838         spin_unlock_bh(&xprt->transport_lock);
 839 }
 840
 841 static inline int xprt_has_timer(struct rpc_xprt *xprt)
 842 {
 843         return xprt->idle_timeout != 0;
 844 }
 845
 846 /**
 847  * xprt_prepare_transmit - reserve the transport before sending a request
 848  * @task: RPC task about to send a request
 849  *
 850  */
 851 int xprt_prepare_transmit(struct rpc_task *task)
 852 {
 853         struct rpc_rqst *req = task->tk_rqstp;
 854         struct rpc_xprt *xprt = req->rq_xprt;
 855         int err = 0;
 856
 857         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 858
 859         spin_lock_bh(&xprt->transport_lock);
 860         if (req->rq_reply_bytes_recvd && !req->rq_bytes_sent) {
 861                 err = req->rq_reply_bytes_recvd;
 862                 goto out_unlock;
 863         }
 864         if (!xprt->ops->reserve_xprt(xprt, task))
 865                 err = -EAGAIN;
 866 out_unlock:
 867         spin_unlock_bh(&xprt->transport_lock);
 868         return err;
 869 }
 870
 871 void xprt_end_transmit(struct rpc_task *task)
 872 {
 873         xprt_release_write(task->tk_rqstp->rq_xprt, task);
 874 }
 875
 876 /**
 877  * xprt_transmit - send an RPC request on a transport
 878  * @task: controlling RPC task
 879  *
 880  * We have to copy the iovec because sendmsg fiddles with its contents.
 881  */
 882 void xprt_transmit(struct rpc_task *task)
 883 {
 884         struct rpc_rqst *req = task->tk_rqstp;
 885         struct rpc_xprt *xprt = req->rq_xprt;
 886         int status, numreqs;
 887
 888         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 889
 890         if (!req->rq_reply_bytes_recvd) {
 891                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
 892                         /*
 893                          * Add to the list only if we're expecting a reply
 894                          */
 895                         spin_lock_bh(&xprt->transport_lock);
 896                         /* Update the softirq receive buffer */
 897                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 898                                         sizeof(req->rq_private_buf));
 899                         /* Add request to the receive list */
 900                         list_add_tail(&req->rq_list, &xprt->recv);
 901                         spin_unlock_bh(&xprt->transport_lock);
 902                         xprt_reset_majortimeo(req);
 903                         /* Turn off autodisconnect */
 904                         del_singleshot_timer_sync(&xprt->timer);
 905                 }
 906         } else if (!req->rq_bytes_sent)
 907                 return;
 908
 909         req->rq_connect_cookie = xprt->connect_cookie;
 910         req->rq_xtime = ktime_get();
 911         status = xprt->ops->send_request(task);
 912         if (status != 0) {
 913                 task->tk_status = status;
 914                 return;
 915         }
 916
 917         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
 918         task->tk_flags |= RPC_TASK_SENT;
 919         spin_lock_bh(&xprt->transport_lock);
 920
 921         xprt->ops->set_retrans_timeout(task);
 922
 923         numreqs = atomic_read(&xprt->num_reqs);
 924         if (numreqs > xprt->stat.max_slots)
 925                 xprt->stat.max_slots = numreqs;
 926         xprt->stat.sends++;
 927         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
 928         xprt->stat.bklog_u += xprt->backlog.qlen;
 929         xprt->stat.sending_u += xprt->sending.qlen;
 930         xprt->stat.pending_u += xprt->pending.qlen;
 931
 932         /* Don't race with disconnect */
 933         if (!xprt_connected(xprt))
 934                 task->tk_status = -ENOTCONN;
 935         else if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task)) {
 936                 /*
 937                  * Sleep on the pending queue since
 938                  * we're expecting a reply.
 939                  */
 940                 rpc_sleep_on(&xprt->pending, task, xprt_timer);
 941         }
 942         spin_unlock_bh(&xprt->transport_lock);
 943 }
 944
 945 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
 946 {
 947         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
 948
 949         if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
 950                 goto out;
 951         req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
 952         if (req != NULL)
 953                 goto out;
 954         atomic_dec(&xprt->num_reqs);
 955         req = ERR_PTR(-ENOMEM);
 956 out:
 957         return req;
 958 }
 959
 960 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
 961 {
 962         if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
 963                 kfree(req);
 964                 return true;
 965         }
 966         return false;
 967 }
 968
 969 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
 970 {
 971         struct rpc_rqst *req;
 972
 973         spin_lock(&xprt->reserve_lock);
 974         if (!list_empty(&xprt->free)) {
 975                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 976                 list_del(&req->rq_list);
 977                 goto out_init_req;
 978         }
 979         req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
 980         if (!IS_ERR(req))
 981                 goto out_init_req;
 982         switch (PTR_ERR(req)) {
 983         case -ENOMEM:
 984                 dprintk("RPC:       dynamic allocation of request slot "
 985                                 "failed! Retrying\n");
 986                 task->tk_status = -ENOMEM;
 987                 break;
 988         case -EAGAIN:
 989                 rpc_sleep_on(&xprt->backlog, task, NULL);
 990                 dprintk("RPC:       waiting for request slot\n");
 991         default:
 992                 task->tk_status = -EAGAIN;
 993         }
 994         spin_unlock(&xprt->reserve_lock);
 995         return;
 996 out_init_req:
 997         task->tk_status = 0;
 998         task->tk_rqstp = req;
 999         xprt_request_init(task, xprt);
1000         spin_unlock(&xprt->reserve_lock);
1001 }
1002 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1003
1004 void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1005 {
1006         /* Note: grabbing the xprt_lock_write() ensures that we throttle
1007          * new slot allocation if the transport is congested (i.e. when
1008          * reconnecting a stream transport or when out of socket write
1009          * buffer space).
1010          */
1011         if (xprt_lock_write(xprt, task)) {
1012                 xprt_alloc_slot(xprt, task);
1013                 xprt_release_write(xprt, task);
1014         }
1015 }
1016 EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1017
1018 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1019 {
1020         spin_lock(&xprt->reserve_lock);
1021         if (!xprt_dynamic_free_slot(xprt, req)) {
1022                 memset(req, 0, sizeof(*req));   /* mark unused */
1023                 list_add(&req->rq_list, &xprt->free);
1024         }
1025         rpc_wake_up_next(&xprt->backlog);
1026         spin_unlock(&xprt->reserve_lock);
1027 }
1028
1029 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1030 {
1031         struct rpc_rqst *req;
1032         while (!list_empty(&xprt->free)) {
1033                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1034                 list_del(&req->rq_list);
1035                 kfree(req);
1036         }
1037 }
1038
1039 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1040                 unsigned int num_prealloc,
1041                 unsigned int max_alloc)
1042 {
1043         struct rpc_xprt *xprt;
1044         struct rpc_rqst *req;
1045         int i;
1046
1047         xprt = kzalloc(size, GFP_KERNEL);
1048         if (xprt == NULL)
1049                 goto out;
1050
1051         xprt_init(xprt, net);
1052
1053         for (i = 0; i < num_prealloc; i++) {
1054                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1055                 if (!req)
1056                         break;
1057                 list_add(&req->rq_list, &xprt->free);
1058         }
1059         if (i < num_prealloc)
1060                 goto out_free;
1061         if (max_alloc > num_prealloc)
1062                 xprt->max_reqs = max_alloc;
1063         else
1064                 xprt->max_reqs = num_prealloc;
1065         xprt->min_reqs = num_prealloc;
1066         atomic_set(&xprt->num_reqs, num_prealloc);
1067
1068         return xprt;
1069
1070 out_free:
1071         xprt_free(xprt);
1072 out:
1073         return NULL;
1074 }
1075 EXPORT_SYMBOL_GPL(xprt_alloc);
1076
1077 void xprt_free(struct rpc_xprt *xprt)
1078 {
1079         put_net(xprt->xprt_net);
1080         xprt_free_all_slots(xprt);
1081         kfree(xprt);
1082 }
1083 EXPORT_SYMBOL_GPL(xprt_free);
1084
1085 /**
1086  * xprt_reserve - allocate an RPC request slot
1087  * @task: RPC task requesting a slot allocation
1088  *
1089  * If no more slots are available, place the task on the transport's
1090  * backlog queue.
1091  */
1092 void xprt_reserve(struct rpc_task *task)
1093 {
1094         struct rpc_xprt *xprt = task->tk_xprt;
1095
1096         task->tk_status = 0;
1097         if (task->tk_rqstp != NULL)
1098                 return;
1099
1100         task->tk_timeout = 0;
1101         task->tk_status = -EAGAIN;
1102         xprt->ops->alloc_slot(xprt, task);
1103 }
1104
1105 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1106 {
1107         return (__force __be32)xprt->xid++;
1108 }
1109
1110 static inline void xprt_init_xid(struct rpc_xprt *xprt)
1111 {
1112         xprt->xid = net_random();
1113 }
1114
1115 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1116 {
1117         struct rpc_rqst *req = task->tk_rqstp;
1118
1119         INIT_LIST_HEAD(&req->rq_list);
1120         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1121         req->rq_task    = task;
1122         req->rq_xprt    = xprt;
1123         req->rq_buffer  = NULL;
1124         req->rq_xid     = xprt_alloc_xid(xprt);
1125         req->rq_release_snd_buf = NULL;
1126         xprt_reset_majortimeo(req);
1127         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1128                         req, ntohl(req->rq_xid));
1129 }
1130
1131 /**
1132  * xprt_release - release an RPC request slot
1133  * @task: task which is finished with the slot
1134  *
1135  */
1136 void xprt_release(struct rpc_task *task)
1137 {
1138         struct rpc_xprt *xprt;
1139         struct rpc_rqst *req = task->tk_rqstp;
1140
1141         if (req == NULL) {
1142                 if (task->tk_client) {
1143                         rcu_read_lock();
1144                         xprt = rcu_dereference(task->tk_client->cl_xprt);
1145                         if (xprt->snd_task == task)
1146                                 xprt_release_write(xprt, task);
1147                         rcu_read_unlock();
1148                 }
1149                 return;
1150         }
1151
1152         xprt = req->rq_xprt;
1153         if (task->tk_ops->rpc_count_stats != NULL)
1154                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1155         else if (task->tk_client)
1156                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1157         spin_lock_bh(&xprt->transport_lock);
1158         xprt->ops->release_xprt(xprt, task);
1159         if (xprt->ops->release_request)
1160                 xprt->ops->release_request(task);
1161         if (!list_empty(&req->rq_list))
1162                 list_del(&req->rq_list);
1163         xprt->last_used = jiffies;
1164         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1165                 mod_timer(&xprt->timer,
1166                                 xprt->last_used + xprt->idle_timeout);
1167         spin_unlock_bh(&xprt->transport_lock);
1168         if (req->rq_buffer)
1169                 xprt->ops->buf_free(req->rq_buffer);
1170         if (req->rq_cred != NULL)
1171                 put_rpccred(req->rq_cred);
1172         task->tk_rqstp = NULL;
1173         if (req->rq_release_snd_buf)
1174                 req->rq_release_snd_buf(req);
1175
1176         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1177         if (likely(!bc_prealloc(req)))
1178                 xprt_free_slot(xprt, req);
1179         else
1180                 xprt_free_bc_request(req);
1181 }
1182
1183 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1184 {
1185         atomic_set(&xprt->count, 1);
1186
1187         spin_lock_init(&xprt->transport_lock);
1188         spin_lock_init(&xprt->reserve_lock);
1189
1190         INIT_LIST_HEAD(&xprt->free);
1191         INIT_LIST_HEAD(&xprt->recv);
1192 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1193         spin_lock_init(&xprt->bc_pa_lock);
1194         INIT_LIST_HEAD(&xprt->bc_pa_list);
1195 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1196
1197         xprt->last_used = jiffies;
1198         xprt->cwnd = RPC_INITCWND;
1199         xprt->bind_index = 0;
1200
1201         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1202         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1203         rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1204         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1205
1206         xprt_init_xid(xprt);
1207
1208         xprt->xprt_net = get_net(net);
1209 }
1210
1211 /**
1212  * xprt_create_transport - create an RPC transport
1213  * @args: rpc transport creation arguments
1214  *
1215  */
1216 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1217 {
1218         struct rpc_xprt *xprt;
1219         struct xprt_class *t;
1220
1221         spin_lock(&xprt_list_lock);
1222         list_for_each_entry(t, &xprt_list, list) {
1223                 if (t->ident == args->ident) {
1224                         spin_unlock(&xprt_list_lock);
1225                         goto found;
1226                 }
1227         }
1228         spin_unlock(&xprt_list_lock);
1229         printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1230         return ERR_PTR(-EIO);
1231
1232 found:
1233         xprt = t->setup(args);
1234         if (IS_ERR(xprt)) {
1235                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1236                                 -PTR_ERR(xprt));
1237                 goto out;
1238         }
1239         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1240         if (xprt_has_timer(xprt))
1241                 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1242                             (unsigned long)xprt);
1243         else
1244                 init_timer(&xprt->timer);
1245
1246         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1247                 xprt_destroy(xprt);
1248                 return ERR_PTR(-EINVAL);
1249         }
1250         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1251         if (xprt->servername == NULL) {
1252                 xprt_destroy(xprt);
1253                 return ERR_PTR(-ENOMEM);
1254         }
1255
1256         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1257                         xprt->max_reqs);
1258 out:
1259         return xprt;
1260 }
1261
1262 /**
1263  * xprt_destroy - destroy an RPC transport, killing off all requests.
1264  * @xprt: transport to destroy
1265  *
1266  */
1267 static void xprt_destroy(struct rpc_xprt *xprt)
1268 {
1269         dprintk("RPC:       destroying transport %p\n", xprt);
1270         del_timer_sync(&xprt->timer);
1271
1272         rpc_destroy_wait_queue(&xprt->binding);
1273         rpc_destroy_wait_queue(&xprt->pending);
1274         rpc_destroy_wait_queue(&xprt->sending);
1275         rpc_destroy_wait_queue(&xprt->backlog);
1276         cancel_work_sync(&xprt->task_cleanup);
1277         kfree(xprt->servername);
1278         /*
1279          * Tear down transport state and free the rpc_xprt
1280          */
1281         xprt->ops->destroy(xprt);
1282 }
1283
1284 /**
1285  * xprt_put - release a reference to an RPC transport.
1286  * @xprt: pointer to the transport
1287  *
1288  */
1289 void xprt_put(struct rpc_xprt *xprt)
1290 {
1291         if (atomic_dec_and_test(&xprt->count))
1292                 xprt_destroy(xprt);
1293 }
1294
1295 /**
1296  * xprt_get - return a reference to an RPC transport.
1297  * @xprt: pointer to the transport
1298  *
1299  */
1300 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1301 {
1302         if (atomic_inc_not_zero(&xprt->count))
1303                 return xprt;
1304         return NULL;
1305 }