linux/net/sunrpc/xprt.c
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   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 */
  65static void      xprt_init(struct rpc_xprt *xprt, struct net *net);
  66static void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
  67static void     xprt_connect_status(struct rpc_task *task);
  68static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
  69static void      xprt_destroy(struct rpc_xprt *xprt);
  70
  71static DEFINE_SPINLOCK(xprt_list_lock);
  72static 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 */
 104int 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
 122out:
 123        spin_unlock(&xprt_list_lock);
 124        return result;
 125}
 126EXPORT_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 */
 136int 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
 154out:
 155        spin_unlock(&xprt_list_lock);
 156        return result;
 157}
 158EXPORT_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 */
 168int 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);
 183out:
 184        return result;
 185}
 186EXPORT_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 */
 197int 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
 215out_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}
 229EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 230
 231static 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 */
 250int 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);
 271out_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}
 284EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 285
 286static 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
 296static 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
 310static 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
 320static 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
 339static 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;
 347out_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 */
 358void 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}
 365EXPORT_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 */
 375void 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}
 382EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 383
 384static 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 */
 395static 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 */
 415static 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 */
 431void xprt_release_rqst_cong(struct rpc_task *task)
 432{
 433        __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
 434}
 435EXPORT_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 */
 444void 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}
 467EXPORT_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 */
 475void 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}
 482EXPORT_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 */
 489void 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}
 497EXPORT_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 */
 505void 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}
 518EXPORT_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 */
 528void xprt_set_retrans_timeout_def(struct rpc_task *task)
 529{
 530        task->tk_timeout = task->tk_rqstp->rq_timeout;
 531}
 532EXPORT_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 */
 540void 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}
 553EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 554
 555static 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 */
 574int 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
 606static 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 */
 621void 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}
 629EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 630
 631/**
 632 * xprt_force_disconnect - force a transport to disconnect
 633 * @xprt: transport to disconnect
 634 *
 635 */
 636void 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 */
 659void 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);
 672out:
 673        spin_unlock_bh(&xprt->transport_lock);
 674}
 675
 676static void
 677xprt_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;
 690out_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 */
 699void 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
 732static 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 */
 767struct 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}
 780EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 781
 782static 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 */
 803void 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}
 824EXPORT_SYMBOL_GPL(xprt_complete_rqst);
 825
 826static 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
 844static 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 */
 854int 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;
 869out_unlock:
 870        spin_unlock_bh(&xprt->transport_lock);
 871        return err;
 872}
 873
 874void 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 */
 885void 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
 948static 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);
 959out:
 960        return req;
 961}
 962
 963static 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
 972void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
 973{
 974        struct rpc_rqst *req;
 975
 976        spin_lock(&xprt->reserve_lock);
 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        spin_unlock(&xprt->reserve_lock);
 998        return;
 999out_init_req:
1000        task->tk_status = 0;
1001        task->tk_rqstp = req;
1002        xprt_request_init(task, xprt);
1003        spin_unlock(&xprt->reserve_lock);
1004}
1005EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1006
1007void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1008{
1009        /* Note: grabbing the xprt_lock_write() ensures that we throttle
1010         * new slot allocation if the transport is congested (i.e. when
1011         * reconnecting a stream transport or when out of socket write
1012         * buffer space).
1013         */
1014        if (xprt_lock_write(xprt, task)) {
1015                xprt_alloc_slot(xprt, task);
1016                xprt_release_write(xprt, task);
1017        }
1018}
1019EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1020
1021static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1022{
1023        spin_lock(&xprt->reserve_lock);
1024        if (!xprt_dynamic_free_slot(xprt, req)) {
1025                memset(req, 0, sizeof(*req));   /* mark unused */
1026                list_add(&req->rq_list, &xprt->free);
1027        }
1028        rpc_wake_up_next(&xprt->backlog);
1029        spin_unlock(&xprt->reserve_lock);
1030}
1031
1032static void xprt_free_all_slots(struct rpc_xprt *xprt)
1033{
1034        struct rpc_rqst *req;
1035        while (!list_empty(&xprt->free)) {
1036                req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1037                list_del(&req->rq_list);
1038                kfree(req);
1039        }
1040}
1041
1042struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1043                unsigned int num_prealloc,
1044                unsigned int max_alloc)
1045{
1046        struct rpc_xprt *xprt;
1047        struct rpc_rqst *req;
1048        int i;
1049
1050        xprt = kzalloc(size, GFP_KERNEL);
1051        if (xprt == NULL)
1052                goto out;
1053
1054        xprt_init(xprt, net);
1055
1056        for (i = 0; i < num_prealloc; i++) {
1057                req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1058                if (!req)
1059                        break;
1060                list_add(&req->rq_list, &xprt->free);
1061        }
1062        if (i < num_prealloc)
1063                goto out_free;
1064        if (max_alloc > num_prealloc)
1065                xprt->max_reqs = max_alloc;
1066        else
1067                xprt->max_reqs = num_prealloc;
1068        xprt->min_reqs = num_prealloc;
1069        atomic_set(&xprt->num_reqs, num_prealloc);
1070
1071        return xprt;
1072
1073out_free:
1074        xprt_free(xprt);
1075out:
1076        return NULL;
1077}
1078EXPORT_SYMBOL_GPL(xprt_alloc);
1079
1080void xprt_free(struct rpc_xprt *xprt)
1081{
1082        put_net(xprt->xprt_net);
1083        xprt_free_all_slots(xprt);
1084        kfree(xprt);
1085}
1086EXPORT_SYMBOL_GPL(xprt_free);
1087
1088/**
1089 * xprt_reserve - allocate an RPC request slot
1090 * @task: RPC task requesting a slot allocation
1091 *
1092 * If no more slots are available, place the task on the transport's
1093 * backlog queue.
1094 */
1095void xprt_reserve(struct rpc_task *task)
1096{
1097        struct rpc_xprt *xprt = task->tk_xprt;
1098
1099        task->tk_status = 0;
1100        if (task->tk_rqstp != NULL)
1101                return;
1102
1103        task->tk_timeout = 0;
1104        task->tk_status = -EAGAIN;
1105        xprt->ops->alloc_slot(xprt, task);
1106}
1107
1108static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1109{
1110        return (__force __be32)xprt->xid++;
1111}
1112
1113static inline void xprt_init_xid(struct rpc_xprt *xprt)
1114{
1115        xprt->xid = net_random();
1116}
1117
1118static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1119{
1120        struct rpc_rqst *req = task->tk_rqstp;
1121
1122        INIT_LIST_HEAD(&req->rq_list);
1123        req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1124        req->rq_task    = task;
1125        req->rq_xprt    = xprt;
1126        req->rq_buffer  = NULL;
1127        req->rq_xid     = xprt_alloc_xid(xprt);
1128        req->rq_release_snd_buf = NULL;
1129        xprt_reset_majortimeo(req);
1130        dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1131                        req, ntohl(req->rq_xid));
1132}
1133
1134/**
1135 * xprt_release - release an RPC request slot
1136 * @task: task which is finished with the slot
1137 *
1138 */
1139void xprt_release(struct rpc_task *task)
1140{
1141        struct rpc_xprt *xprt;
1142        struct rpc_rqst *req;
1143
1144        if (!(req = task->tk_rqstp))
1145                return;
1146
1147        xprt = req->rq_xprt;
1148        if (task->tk_ops->rpc_count_stats != NULL)
1149                task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1150        else if (task->tk_client)
1151                rpc_count_iostats(task, task->tk_client->cl_metrics);
1152        spin_lock_bh(&xprt->transport_lock);
1153        xprt->ops->release_xprt(xprt, task);
1154        if (xprt->ops->release_request)
1155                xprt->ops->release_request(task);
1156        if (!list_empty(&req->rq_list))
1157                list_del(&req->rq_list);
1158        xprt->last_used = jiffies;
1159        if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1160                mod_timer(&xprt->timer,
1161                                xprt->last_used + xprt->idle_timeout);
1162        spin_unlock_bh(&xprt->transport_lock);
1163        if (req->rq_buffer)
1164                xprt->ops->buf_free(req->rq_buffer);
1165        if (req->rq_cred != NULL)
1166                put_rpccred(req->rq_cred);
1167        task->tk_rqstp = NULL;
1168        if (req->rq_release_snd_buf)
1169                req->rq_release_snd_buf(req);
1170
1171        dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1172        if (likely(!bc_prealloc(req)))
1173                xprt_free_slot(xprt, req);
1174        else
1175                xprt_free_bc_request(req);
1176}
1177
1178static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1179{
1180        atomic_set(&xprt->count, 1);
1181
1182        spin_lock_init(&xprt->transport_lock);
1183        spin_lock_init(&xprt->reserve_lock);
1184
1185        INIT_LIST_HEAD(&xprt->free);
1186        INIT_LIST_HEAD(&xprt->recv);
1187#if defined(CONFIG_SUNRPC_BACKCHANNEL)
1188        spin_lock_init(&xprt->bc_pa_lock);
1189        INIT_LIST_HEAD(&xprt->bc_pa_list);
1190#endif /* CONFIG_SUNRPC_BACKCHANNEL */
1191
1192        xprt->last_used = jiffies;
1193        xprt->cwnd = RPC_INITCWND;
1194        xprt->bind_index = 0;
1195
1196        rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1197        rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1198        rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1199        rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1200
1201        xprt_init_xid(xprt);
1202
1203        xprt->xprt_net = get_net(net);
1204}
1205
1206/**
1207 * xprt_create_transport - create an RPC transport
1208 * @args: rpc transport creation arguments
1209 *
1210 */
1211struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1212{
1213        struct rpc_xprt *xprt;
1214        struct xprt_class *t;
1215
1216        spin_lock(&xprt_list_lock);
1217        list_for_each_entry(t, &xprt_list, list) {
1218                if (t->ident == args->ident) {
1219                        spin_unlock(&xprt_list_lock);
1220                        goto found;
1221                }
1222        }
1223        spin_unlock(&xprt_list_lock);
1224        printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1225        return ERR_PTR(-EIO);
1226
1227found:
1228        xprt = t->setup(args);
1229        if (IS_ERR(xprt)) {
1230                dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1231                                -PTR_ERR(xprt));
1232                goto out;
1233        }
1234        INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1235        if (xprt_has_timer(xprt))
1236                setup_timer(&xprt->timer, xprt_init_autodisconnect,
1237                            (unsigned long)xprt);
1238        else
1239                init_timer(&xprt->timer);
1240
1241        if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1242                xprt_destroy(xprt);
1243                return ERR_PTR(-EINVAL);
1244        }
1245        xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1246        if (xprt->servername == NULL) {
1247                xprt_destroy(xprt);
1248                return ERR_PTR(-ENOMEM);
1249        }
1250
1251        dprintk("RPC:       created transport %p with %u slots\n", xprt,
1252                        xprt->max_reqs);
1253out:
1254        return xprt;
1255}
1256
1257/**
1258 * xprt_destroy - destroy an RPC transport, killing off all requests.
1259 * @xprt: transport to destroy
1260 *
1261 */
1262static void xprt_destroy(struct rpc_xprt *xprt)
1263{
1264        dprintk("RPC:       destroying transport %p\n", xprt);
1265        xprt->shutdown = 1;
1266        del_timer_sync(&xprt->timer);
1267
1268        rpc_destroy_wait_queue(&xprt->binding);
1269        rpc_destroy_wait_queue(&xprt->pending);
1270        rpc_destroy_wait_queue(&xprt->sending);
1271        rpc_destroy_wait_queue(&xprt->backlog);
1272        cancel_work_sync(&xprt->task_cleanup);
1273        kfree(xprt->servername);
1274        /*
1275         * Tear down transport state and free the rpc_xprt
1276         */
1277        xprt->ops->destroy(xprt);
1278}
1279
1280/**
1281 * xprt_put - release a reference to an RPC transport.
1282 * @xprt: pointer to the transport
1283 *
1284 */
1285void xprt_put(struct rpc_xprt *xprt)
1286{
1287        if (atomic_dec_and_test(&xprt->count))
1288                xprt_destroy(xprt);
1289}
1290
1291/**
1292 * xprt_get - return a reference to an RPC transport.
1293 * @xprt: pointer to the transport
1294 *
1295 */
1296struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1297{
1298        if (atomic_inc_not_zero(&xprt->count))
1299                return xprt;
1300        return NULL;
1301}
1302
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