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) || xprt->shutdown) {
 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         if (unlikely(xprt->shutdown))
 508                 return;
 509
 510         spin_lock_bh(&xprt->transport_lock);
 511         if (xprt->snd_task) {
 512                 dprintk("RPC:       write space: waking waiting task on "
 513                                 "xprt %p\n", xprt);
 514                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
 515         }
 516         spin_unlock_bh(&xprt->transport_lock);
 517 }
 518 EXPORT_SYMBOL_GPL(xprt_write_space);
 519
 520 /**
 521  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 522  * @task: task whose timeout is to be set
 523  *
 524  * Set a request's retransmit timeout based on the transport's
 525  * default timeout parameters.  Used by transports that don't adjust
 526  * the retransmit timeout based on round-trip time estimation.
 527  */
 528 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 529 {
 530         task->tk_timeout = task->tk_rqstp->rq_timeout;
 531 }
 532 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
 533
 534 /*
 535  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 536  * @task: task whose timeout is to be set
 537  *
 538  * Set a request's retransmit timeout using the RTT estimator.
 539  */
 540 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 541 {
 542         int timer = task->tk_msg.rpc_proc->p_timer;
 543         struct rpc_clnt *clnt = task->tk_client;
 544         struct rpc_rtt *rtt = clnt->cl_rtt;
 545         struct rpc_rqst *req = task->tk_rqstp;
 546         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
 547
 548         task->tk_timeout = rpc_calc_rto(rtt, timer);
 549         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 550         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 551                 task->tk_timeout = max_timeout;
 552 }
 553 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 554
 555 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 556 {
 557         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 558
 559         req->rq_majortimeo = req->rq_timeout;
 560         if (to->to_exponential)
 561                 req->rq_majortimeo <<= to->to_retries;
 562         else
 563                 req->rq_majortimeo += to->to_increment * to->to_retries;
 564         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 565                 req->rq_majortimeo = to->to_maxval;
 566         req->rq_majortimeo += jiffies;
 567 }
 568
 569 /**
 570  * xprt_adjust_timeout - adjust timeout values for next retransmit
 571  * @req: RPC request containing parameters to use for the adjustment
 572  *
 573  */
 574 int xprt_adjust_timeout(struct rpc_rqst *req)
 575 {
 576         struct rpc_xprt *xprt = req->rq_xprt;
 577         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 578         int status = 0;
 579
 580         if (time_before(jiffies, req->rq_majortimeo)) {
 581                 if (to->to_exponential)
 582                         req->rq_timeout <<= 1;
 583                 else
 584                         req->rq_timeout += to->to_increment;
 585                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 586                         req->rq_timeout = to->to_maxval;
 587                 req->rq_retries++;
 588         } else {
 589                 req->rq_timeout = to->to_initval;
 590                 req->rq_retries = 0;
 591                 xprt_reset_majortimeo(req);
 592                 /* Reset the RTT counters == "slow start" */
 593                 spin_lock_bh(&xprt->transport_lock);
 594                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 595                 spin_unlock_bh(&xprt->transport_lock);
 596                 status = -ETIMEDOUT;
 597         }
 598
 599         if (req->rq_timeout == 0) {
 600                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 601                 req->rq_timeout = 5 * HZ;
 602         }
 603         return status;
 604 }
 605
 606 static void xprt_autoclose(struct work_struct *work)
 607 {
 608         struct rpc_xprt *xprt =
 609                 container_of(work, struct rpc_xprt, task_cleanup);
 610
 611         xprt->ops->close(xprt);
 612         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 613         xprt_release_write(xprt, NULL);
 614 }
 615
 616 /**
 617  * xprt_disconnect_done - mark a transport as disconnected
 618  * @xprt: transport to flag for disconnect
 619  *
 620  */
 621 void xprt_disconnect_done(struct rpc_xprt *xprt)
 622 {
 623         dprintk("RPC:       disconnected transport %p\n", xprt);
 624         spin_lock_bh(&xprt->transport_lock);
 625         xprt_clear_connected(xprt);
 626         xprt_wake_pending_tasks(xprt, -EAGAIN);
 627         spin_unlock_bh(&xprt->transport_lock);
 628 }
 629 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 630
 631 /**
 632  * xprt_force_disconnect - force a transport to disconnect
 633  * @xprt: transport to disconnect
 634  *
 635  */
 636 void xprt_force_disconnect(struct rpc_xprt *xprt)
 637 {
 638         /* Don't race with the test_bit() in xprt_clear_locked() */
 639         spin_lock_bh(&xprt->transport_lock);
 640         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 641         /* Try to schedule an autoclose RPC call */
 642         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 643                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 644         xprt_wake_pending_tasks(xprt, -EAGAIN);
 645         spin_unlock_bh(&xprt->transport_lock);
 646 }
 647
 648 /**
 649  * xprt_conditional_disconnect - force a transport to disconnect
 650  * @xprt: transport to disconnect
 651  * @cookie: 'connection cookie'
 652  *
 653  * This attempts to break the connection if and only if 'cookie' matches
 654  * the current transport 'connection cookie'. It ensures that we don't
 655  * try to break the connection more than once when we need to retransmit
 656  * a batch of RPC requests.
 657  *
 658  */
 659 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 660 {
 661         /* Don't race with the test_bit() in xprt_clear_locked() */
 662         spin_lock_bh(&xprt->transport_lock);
 663         if (cookie != xprt->connect_cookie)
 664                 goto out;
 665         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
 666                 goto out;
 667         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 668         /* Try to schedule an autoclose RPC call */
 669         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 670                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 671         xprt_wake_pending_tasks(xprt, -EAGAIN);
 672 out:
 673         spin_unlock_bh(&xprt->transport_lock);
 674 }
 675
 676 static void
 677 xprt_init_autodisconnect(unsigned long data)
 678 {
 679         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 680
 681         spin_lock(&xprt->transport_lock);
 682         if (!list_empty(&xprt->recv) || xprt->shutdown)
 683                 goto out_abort;
 684         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 685                 goto out_abort;
 686         spin_unlock(&xprt->transport_lock);
 687         set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
 688         queue_work(rpciod_workqueue, &xprt->task_cleanup);
 689         return;
 690 out_abort:
 691         spin_unlock(&xprt->transport_lock);
 692 }
 693
 694 /**
 695  * xprt_connect - schedule a transport connect operation
 696  * @task: RPC task that is requesting the connect
 697  *
 698  */
 699 void xprt_connect(struct rpc_task *task)
 700 {
 701         struct rpc_xprt *xprt = task->tk_xprt;
 702
 703         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 704                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 705
 706         if (!xprt_bound(xprt)) {
 707                 task->tk_status = -EAGAIN;
 708                 return;
 709         }
 710         if (!xprt_lock_write(xprt, task))
 711                 return;
 712
 713         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
 714                 xprt->ops->close(xprt);
 715
 716         if (xprt_connected(xprt))
 717                 xprt_release_write(xprt, task);
 718         else {
 719                 task->tk_rqstp->rq_bytes_sent = 0;
 720                 task->tk_timeout = task->tk_rqstp->rq_timeout;
 721                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
 722
 723                 if (test_bit(XPRT_CLOSING, &xprt->state))
 724                         return;
 725                 if (xprt_test_and_set_connecting(xprt))
 726                         return;
 727                 xprt->stat.connect_start = jiffies;
 728                 xprt->ops->connect(task);
 729         }
 730 }
 731
 732 static void xprt_connect_status(struct rpc_task *task)
 733 {
 734         struct rpc_xprt *xprt = task->tk_xprt;
 735
 736         if (task->tk_status == 0) {
 737                 xprt->stat.connect_count++;
 738                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 739                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 740                                 task->tk_pid);
 741                 return;
 742         }
 743
 744         switch (task->tk_status) {
 745         case -EAGAIN:
 746                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
 747                 break;
 748         case -ETIMEDOUT:
 749                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 750                                 "out\n", task->tk_pid);
 751                 break;
 752         default:
 753                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 754                                 "server %s\n", task->tk_pid, -task->tk_status,
 755                                 xprt->servername);
 756                 xprt_release_write(xprt, task);
 757                 task->tk_status = -EIO;
 758         }
 759 }
 760
 761 /**
 762  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 763  * @xprt: transport on which the original request was transmitted
 764  * @xid: RPC XID of incoming reply
 765  *
 766  */
 767 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 768 {
 769         struct rpc_rqst *entry;
 770
 771         list_for_each_entry(entry, &xprt->recv, rq_list)
 772                 if (entry->rq_xid == xid)
 773                         return entry;
 774
 775         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 776                         ntohl(xid));
 777         xprt->stat.bad_xids++;
 778         return NULL;
 779 }
 780 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 781
 782 static void xprt_update_rtt(struct rpc_task *task)
 783 {
 784         struct rpc_rqst *req = task->tk_rqstp;
 785         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 786         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
 787         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
 788
 789         if (timer) {
 790                 if (req->rq_ntrans == 1)
 791                         rpc_update_rtt(rtt, timer, m);
 792                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 793         }
 794 }
 795
 796 /**
 797  * xprt_complete_rqst - called when reply processing is complete
 798  * @task: RPC request that recently completed
 799  * @copied: actual number of bytes received from the transport
 800  *
 801  * Caller holds transport lock.
 802  */
 803 void xprt_complete_rqst(struct rpc_task *task, int copied)
 804 {
 805         struct rpc_rqst *req = task->tk_rqstp;
 806         struct rpc_xprt *xprt = req->rq_xprt;
 807
 808         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 809                         task->tk_pid, ntohl(req->rq_xid), copied);
 810
 811         xprt->stat.recvs++;
 812         req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
 813         if (xprt->ops->timer != NULL)
 814                 xprt_update_rtt(task);
 815
 816         list_del_init(&req->rq_list);
 817         req->rq_private_buf.len = copied;
 818         /* Ensure all writes are done before we update */
 819         /* req->rq_reply_bytes_recvd */
 820         smp_wmb();
 821         req->rq_reply_bytes_recvd = copied;
 822         rpc_wake_up_queued_task(&xprt->pending, task);
 823 }
 824 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
 825
 826 static void xprt_timer(struct rpc_task *task)
 827 {
 828         struct rpc_rqst *req = task->tk_rqstp;
 829         struct rpc_xprt *xprt = req->rq_xprt;
 830
 831         if (task->tk_status != -ETIMEDOUT)
 832                 return;
 833         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
 834
 835         spin_lock_bh(&xprt->transport_lock);
 836         if (!req->rq_reply_bytes_recvd) {
 837                 if (xprt->ops->timer)
 838                         xprt->ops->timer(task);
 839         } else
 840                 task->tk_status = 0;
 841         spin_unlock_bh(&xprt->transport_lock);
 842 }
 843
 844 static inline int xprt_has_timer(struct rpc_xprt *xprt)
 845 {
 846         return xprt->idle_timeout != 0;
 847 }
 848
 849 /**
 850  * xprt_prepare_transmit - reserve the transport before sending a request
 851  * @task: RPC task about to send a request
 852  *
 853  */
 854 int xprt_prepare_transmit(struct rpc_task *task)
 855 {
 856         struct rpc_rqst *req = task->tk_rqstp;
 857         struct rpc_xprt *xprt = req->rq_xprt;
 858         int err = 0;
 859
 860         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 861
 862         spin_lock_bh(&xprt->transport_lock);
 863         if (req->rq_reply_bytes_recvd && !req->rq_bytes_sent) {
 864                 err = req->rq_reply_bytes_recvd;
 865                 goto out_unlock;
 866         }
 867         if (!xprt->ops->reserve_xprt(xprt, task))
 868                 err = -EAGAIN;
 869 out_unlock:
 870         spin_unlock_bh(&xprt->transport_lock);
 871         return err;
 872 }
 873
 874 void xprt_end_transmit(struct rpc_task *task)
 875 {
 876         xprt_release_write(task->tk_rqstp->rq_xprt, task);
 877 }
 878
 879 /**
 880  * xprt_transmit - send an RPC request on a transport
 881  * @task: controlling RPC task
 882  *
 883  * We have to copy the iovec because sendmsg fiddles with its contents.
 884  */
 885 void xprt_transmit(struct rpc_task *task)
 886 {
 887         struct rpc_rqst *req = task->tk_rqstp;
 888         struct rpc_xprt *xprt = req->rq_xprt;
 889         int status, numreqs;
 890
 891         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 892
 893         if (!req->rq_reply_bytes_recvd) {
 894                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
 895                         /*
 896                          * Add to the list only if we're expecting a reply
 897                          */
 898                         spin_lock_bh(&xprt->transport_lock);
 899                         /* Update the softirq receive buffer */
 900                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 901                                         sizeof(req->rq_private_buf));
 902                         /* Add request to the receive list */
 903                         list_add_tail(&req->rq_list, &xprt->recv);
 904                         spin_unlock_bh(&xprt->transport_lock);
 905                         xprt_reset_majortimeo(req);
 906                         /* Turn off autodisconnect */
 907                         del_singleshot_timer_sync(&xprt->timer);
 908                 }
 909         } else if (!req->rq_bytes_sent)
 910                 return;
 911
 912         req->rq_connect_cookie = xprt->connect_cookie;
 913         req->rq_xtime = ktime_get();
 914         status = xprt->ops->send_request(task);
 915         if (status != 0) {
 916                 task->tk_status = status;
 917                 return;
 918         }
 919
 920         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
 921         task->tk_flags |= RPC_TASK_SENT;
 922         spin_lock_bh(&xprt->transport_lock);
 923
 924         xprt->ops->set_retrans_timeout(task);
 925
 926         numreqs = atomic_read(&xprt->num_reqs);
 927         if (numreqs > xprt->stat.max_slots)
 928                 xprt->stat.max_slots = numreqs;
 929         xprt->stat.sends++;
 930         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
 931         xprt->stat.bklog_u += xprt->backlog.qlen;
 932         xprt->stat.sending_u += xprt->sending.qlen;
 933         xprt->stat.pending_u += xprt->pending.qlen;
 934
 935         /* Don't race with disconnect */
 936         if (!xprt_connected(xprt))
 937                 task->tk_status = -ENOTCONN;
 938         else if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task)) {
 939                 /*
 940                  * Sleep on the pending queue since
 941                  * we're expecting a reply.
 942                  */
 943                 rpc_sleep_on(&xprt->pending, task, xprt_timer);
 944         }
 945         spin_unlock_bh(&xprt->transport_lock);
 946 }
 947
 948 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
 949 {
 950         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
 951
 952         if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
 953                 goto out;
 954         req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
 955         if (req != NULL)
 956                 goto out;
 957         atomic_dec(&xprt->num_reqs);
 958         req = ERR_PTR(-ENOMEM);
 959 out:
 960         return req;
 961 }
 962
 963 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
 964 {
 965         if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
 966                 kfree(req);
 967                 return true;
 968         }
 969         return false;
 970 }
 971
 972 static void xprt_alloc_slot(struct rpc_task *task)
 973 {
 974         struct rpc_xprt *xprt = task->tk_xprt;
 975         struct rpc_rqst *req;
 976
 977         if (!list_empty(&xprt->free)) {
 978                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 979                 list_del(&req->rq_list);
 980                 goto out_init_req;
 981         }
 982         req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
 983         if (!IS_ERR(req))
 984                 goto out_init_req;
 985         switch (PTR_ERR(req)) {
 986         case -ENOMEM:
 987                 dprintk("RPC:       dynamic allocation of request slot "
 988                                 "failed! Retrying\n");
 989                 task->tk_status = -ENOMEM;
 990                 break;
 991         case -EAGAIN:
 992                 rpc_sleep_on(&xprt->backlog, task, NULL);
 993                 dprintk("RPC:       waiting for request slot\n");
 994         default:
 995                 task->tk_status = -EAGAIN;
 996         }
 997         return;
 998 out_init_req:
 999         task->tk_status = 0;
1000         task->tk_rqstp = req;
1001         xprt_request_init(task, xprt);
1002 }
1003
1004 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1005 {
1006         spin_lock(&xprt->reserve_lock);
1007         if (!xprt_dynamic_free_slot(xprt, req)) {
1008                 memset(req, 0, sizeof(*req));   /* mark unused */
1009                 list_add(&req->rq_list, &xprt->free);
1010         }
1011         rpc_wake_up_next(&xprt->backlog);
1012         spin_unlock(&xprt->reserve_lock);
1013 }
1014
1015 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1016 {
1017         struct rpc_rqst *req;
1018         while (!list_empty(&xprt->free)) {
1019                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1020                 list_del(&req->rq_list);
1021                 kfree(req);
1022         }
1023 }
1024
1025 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1026                 unsigned int num_prealloc,
1027                 unsigned int max_alloc)
1028 {
1029         struct rpc_xprt *xprt;
1030         struct rpc_rqst *req;
1031         int i;
1032
1033         xprt = kzalloc(size, GFP_KERNEL);
1034         if (xprt == NULL)
1035                 goto out;
1036
1037         xprt_init(xprt, net);
1038
1039         for (i = 0; i < num_prealloc; i++) {
1040                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1041                 if (!req)
1042                         break;
1043                 list_add(&req->rq_list, &xprt->free);
1044         }
1045         if (i < num_prealloc)
1046                 goto out_free;
1047         if (max_alloc > num_prealloc)
1048                 xprt->max_reqs = max_alloc;
1049         else
1050                 xprt->max_reqs = num_prealloc;
1051         xprt->min_reqs = num_prealloc;
1052         atomic_set(&xprt->num_reqs, num_prealloc);
1053
1054         return xprt;
1055
1056 out_free:
1057         xprt_free(xprt);
1058 out:
1059         return NULL;
1060 }
1061 EXPORT_SYMBOL_GPL(xprt_alloc);
1062
1063 void xprt_free(struct rpc_xprt *xprt)
1064 {
1065         put_net(xprt->xprt_net);
1066         xprt_free_all_slots(xprt);
1067         kfree(xprt);
1068 }
1069 EXPORT_SYMBOL_GPL(xprt_free);
1070
1071 /**
1072  * xprt_reserve - allocate an RPC request slot
1073  * @task: RPC task requesting a slot allocation
1074  *
1075  * If no more slots are available, place the task on the transport's
1076  * backlog queue.
1077  */
1078 void xprt_reserve(struct rpc_task *task)
1079 {
1080         struct rpc_xprt *xprt = task->tk_xprt;
1081
1082         task->tk_status = 0;
1083         if (task->tk_rqstp != NULL)
1084                 return;
1085
1086         /* Note: grabbing the xprt_lock_write() here is not strictly needed,
1087          * but ensures that we throttle new slot allocation if the transport
1088          * is congested (e.g. if reconnecting or if we're out of socket
1089          * write buffer space).
1090          */
1091         task->tk_timeout = 0;
1092         task->tk_status = -EAGAIN;
1093         if (!xprt_lock_write(xprt, task))
1094                 return;
1095
1096         spin_lock(&xprt->reserve_lock);
1097         xprt_alloc_slot(task);
1098         spin_unlock(&xprt->reserve_lock);
1099         xprt_release_write(xprt, task);
1100 }
1101
1102 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1103 {
1104         return (__force __be32)xprt->xid++;
1105 }
1106
1107 static inline void xprt_init_xid(struct rpc_xprt *xprt)
1108 {
1109         xprt->xid = net_random();
1110 }
1111
1112 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1113 {
1114         struct rpc_rqst *req = task->tk_rqstp;
1115
1116         INIT_LIST_HEAD(&req->rq_list);
1117         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1118         req->rq_task    = task;
1119         req->rq_xprt    = xprt;
1120         req->rq_buffer  = NULL;
1121         req->rq_xid     = xprt_alloc_xid(xprt);
1122         req->rq_release_snd_buf = NULL;
1123         xprt_reset_majortimeo(req);
1124         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1125                         req, ntohl(req->rq_xid));
1126 }
1127
1128 /**
1129  * xprt_release - release an RPC request slot
1130  * @task: task which is finished with the slot
1131  *
1132  */
1133 void xprt_release(struct rpc_task *task)
1134 {
1135         struct rpc_xprt *xprt;
1136         struct rpc_rqst *req;
1137
1138         if (!(req = task->tk_rqstp))
1139                 return;
1140
1141         xprt = req->rq_xprt;
1142         if (task->tk_ops->rpc_count_stats != NULL)
1143                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1144         else if (task->tk_client)
1145                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1146         spin_lock_bh(&xprt->transport_lock);
1147         xprt->ops->release_xprt(xprt, task);
1148         if (xprt->ops->release_request)
1149                 xprt->ops->release_request(task);
1150         if (!list_empty(&req->rq_list))
1151                 list_del(&req->rq_list);
1152         xprt->last_used = jiffies;
1153         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1154                 mod_timer(&xprt->timer,
1155                                 xprt->last_used + xprt->idle_timeout);
1156         spin_unlock_bh(&xprt->transport_lock);
1157         if (req->rq_buffer)
1158                 xprt->ops->buf_free(req->rq_buffer);
1159         if (req->rq_cred != NULL)
1160                 put_rpccred(req->rq_cred);
1161         task->tk_rqstp = NULL;
1162         if (req->rq_release_snd_buf)
1163                 req->rq_release_snd_buf(req);
1164
1165         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1166         if (likely(!bc_prealloc(req)))
1167                 xprt_free_slot(xprt, req);
1168         else
1169                 xprt_free_bc_request(req);
1170 }
1171
1172 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1173 {
1174         atomic_set(&xprt->count, 1);
1175
1176         spin_lock_init(&xprt->transport_lock);
1177         spin_lock_init(&xprt->reserve_lock);
1178
1179         INIT_LIST_HEAD(&xprt->free);
1180         INIT_LIST_HEAD(&xprt->recv);
1181 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1182         spin_lock_init(&xprt->bc_pa_lock);
1183         INIT_LIST_HEAD(&xprt->bc_pa_list);
1184 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1185
1186         xprt->last_used = jiffies;
1187         xprt->cwnd = RPC_INITCWND;
1188         xprt->bind_index = 0;
1189
1190         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1191         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1192         rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1193         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1194
1195         xprt_init_xid(xprt);
1196
1197         xprt->xprt_net = get_net(net);
1198 }
1199
1200 /**
1201  * xprt_create_transport - create an RPC transport
1202  * @args: rpc transport creation arguments
1203  *
1204  */
1205 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1206 {
1207         struct rpc_xprt *xprt;
1208         struct xprt_class *t;
1209
1210         spin_lock(&xprt_list_lock);
1211         list_for_each_entry(t, &xprt_list, list) {
1212                 if (t->ident == args->ident) {
1213                         spin_unlock(&xprt_list_lock);
1214                         goto found;
1215                 }
1216         }
1217         spin_unlock(&xprt_list_lock);
1218         printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1219         return ERR_PTR(-EIO);
1220
1221 found:
1222         xprt = t->setup(args);
1223         if (IS_ERR(xprt)) {
1224                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1225                                 -PTR_ERR(xprt));
1226                 goto out;
1227         }
1228         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1229         if (xprt_has_timer(xprt))
1230                 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1231                             (unsigned long)xprt);
1232         else
1233                 init_timer(&xprt->timer);
1234
1235         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1236                 xprt_destroy(xprt);
1237                 return ERR_PTR(-EINVAL);
1238         }
1239         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1240         if (xprt->servername == NULL) {
1241                 xprt_destroy(xprt);
1242                 return ERR_PTR(-ENOMEM);
1243         }
1244
1245         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1246                         xprt->max_reqs);
1247 out:
1248         return xprt;
1249 }
1250
1251 /**
1252  * xprt_destroy - destroy an RPC transport, killing off all requests.
1253  * @xprt: transport to destroy
1254  *
1255  */
1256 static void xprt_destroy(struct rpc_xprt *xprt)
1257 {
1258         dprintk("RPC:       destroying transport %p\n", xprt);
1259         xprt->shutdown = 1;
1260         del_timer_sync(&xprt->timer);
1261
1262         rpc_destroy_wait_queue(&xprt->binding);
1263         rpc_destroy_wait_queue(&xprt->pending);
1264         rpc_destroy_wait_queue(&xprt->sending);
1265         rpc_destroy_wait_queue(&xprt->backlog);
1266         cancel_work_sync(&xprt->task_cleanup);
1267         kfree(xprt->servername);
1268         /*
1269          * Tear down transport state and free the rpc_xprt
1270          */
1271         xprt->ops->destroy(xprt);
1272 }
1273
1274 /**
1275  * xprt_put - release a reference to an RPC transport.
1276  * @xprt: pointer to the transport
1277  *
1278  */
1279 void xprt_put(struct rpc_xprt *xprt)
1280 {
1281         if (atomic_dec_and_test(&xprt->count))
1282                 xprt_destroy(xprt);
1283 }
1284
1285 /**
1286  * xprt_get - return a reference to an RPC transport.
1287  * @xprt: pointer to the transport
1288  *
1289  */
1290 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1291 {
1292         if (atomic_inc_not_zero(&xprt->count))
1293                 return xprt;
1294         return NULL;
1295 }