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)) {
 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        spin_lock_bh(&xprt->transport_lock);
 508        if (xprt->snd_task) {
 509                dprintk("RPC:       write space: waking waiting task on "
 510                                "xprt %p\n", xprt);
 511                rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
 512        }
 513        spin_unlock_bh(&xprt->transport_lock);
 514}
 515EXPORT_SYMBOL_GPL(xprt_write_space);
 516
 517/**
 518 * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 519 * @task: task whose timeout is to be set
 520 *
 521 * Set a request's retransmit timeout based on the transport's
 522 * default timeout parameters.  Used by transports that don't adjust
 523 * the retransmit timeout based on round-trip time estimation.
 524 */
 525void xprt_set_retrans_timeout_def(struct rpc_task *task)
 526{
 527        task->tk_timeout = task->tk_rqstp->rq_timeout;
 528}
 529EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
 530
 531/**
 532 * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 533 * @task: task whose timeout is to be set
 534 *
 535 * Set a request's retransmit timeout using the RTT estimator.
 536 */
 537void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 538{
 539        int timer = task->tk_msg.rpc_proc->p_timer;
 540        struct rpc_clnt *clnt = task->tk_client;
 541        struct rpc_rtt *rtt = clnt->cl_rtt;
 542        struct rpc_rqst *req = task->tk_rqstp;
 543        unsigned long max_timeout = clnt->cl_timeout->to_maxval;
 544
 545        task->tk_timeout = rpc_calc_rto(rtt, timer);
 546        task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 547        if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 548                task->tk_timeout = max_timeout;
 549}
 550EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 551
 552static void xprt_reset_majortimeo(struct rpc_rqst *req)
 553{
 554        const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 555
 556        req->rq_majortimeo = req->rq_timeout;
 557        if (to->to_exponential)
 558                req->rq_majortimeo <<= to->to_retries;
 559        else
 560                req->rq_majortimeo += to->to_increment * to->to_retries;
 561        if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 562                req->rq_majortimeo = to->to_maxval;
 563        req->rq_majortimeo += jiffies;
 564}
 565
 566/**
 567 * xprt_adjust_timeout - adjust timeout values for next retransmit
 568 * @req: RPC request containing parameters to use for the adjustment
 569 *
 570 */
 571int xprt_adjust_timeout(struct rpc_rqst *req)
 572{
 573        struct rpc_xprt *xprt = req->rq_xprt;
 574        const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 575        int status = 0;
 576
 577        if (time_before(jiffies, req->rq_majortimeo)) {
 578                if (to->to_exponential)
 579                        req->rq_timeout <<= 1;
 580                else
 581                        req->rq_timeout += to->to_increment;
 582                if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 583                        req->rq_timeout = to->to_maxval;
 584                req->rq_retries++;
 585        } else {
 586                req->rq_timeout = to->to_initval;
 587                req->rq_retries = 0;
 588                xprt_reset_majortimeo(req);
 589                /* Reset the RTT counters == "slow start" */
 590                spin_lock_bh(&xprt->transport_lock);
 591                rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 592                spin_unlock_bh(&xprt->transport_lock);
 593                status = -ETIMEDOUT;
 594        }
 595
 596        if (req->rq_timeout == 0) {
 597                printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 598                req->rq_timeout = 5 * HZ;
 599        }
 600        return status;
 601}
 602
 603static void xprt_autoclose(struct work_struct *work)
 604{
 605        struct rpc_xprt *xprt =
 606                container_of(work, struct rpc_xprt, task_cleanup);
 607
 608        xprt->ops->close(xprt);
 609        clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 610        xprt_release_write(xprt, NULL);
 611}
 612
 613/**
 614 * xprt_disconnect_done - mark a transport as disconnected
 615 * @xprt: transport to flag for disconnect
 616 *
 617 */
 618void xprt_disconnect_done(struct rpc_xprt *xprt)
 619{
 620        dprintk("RPC:       disconnected transport %p\n", xprt);
 621        spin_lock_bh(&xprt->transport_lock);
 622        xprt_clear_connected(xprt);
 623        xprt_wake_pending_tasks(xprt, -EAGAIN);
 624        spin_unlock_bh(&xprt->transport_lock);
 625}
 626EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 627
 628/**
 629 * xprt_force_disconnect - force a transport to disconnect
 630 * @xprt: transport to disconnect
 631 *
 632 */
 633void xprt_force_disconnect(struct rpc_xprt *xprt)
 634{
 635        /* Don't race with the test_bit() in xprt_clear_locked() */
 636        spin_lock_bh(&xprt->transport_lock);
 637        set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 638        /* Try to schedule an autoclose RPC call */
 639        if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 640                queue_work(rpciod_workqueue, &xprt->task_cleanup);
 641        xprt_wake_pending_tasks(xprt, -EAGAIN);
 642        spin_unlock_bh(&xprt->transport_lock);
 643}
 644
 645/**
 646 * xprt_conditional_disconnect - force a transport to disconnect
 647 * @xprt: transport to disconnect
 648 * @cookie: 'connection cookie'
 649 *
 650 * This attempts to break the connection if and only if 'cookie' matches
 651 * the current transport 'connection cookie'. It ensures that we don't
 652 * try to break the connection more than once when we need to retransmit
 653 * a batch of RPC requests.
 654 *
 655 */
 656void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 657{
 658        /* Don't race with the test_bit() in xprt_clear_locked() */
 659        spin_lock_bh(&xprt->transport_lock);
 660        if (cookie != xprt->connect_cookie)
 661                goto out;
 662        if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
 663                goto out;
 664        set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 665        /* Try to schedule an autoclose RPC call */
 666        if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 667                queue_work(rpciod_workqueue, &xprt->task_cleanup);
 668        xprt_wake_pending_tasks(xprt, -EAGAIN);
 669out:
 670        spin_unlock_bh(&xprt->transport_lock);
 671}
 672
 673static void
 674xprt_init_autodisconnect(unsigned long data)
 675{
 676        struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 677
 678        spin_lock(&xprt->transport_lock);
 679        if (!list_empty(&xprt->recv))
 680                goto out_abort;
 681        if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 682                goto out_abort;
 683        spin_unlock(&xprt->transport_lock);
 684        set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
 685        queue_work(rpciod_workqueue, &xprt->task_cleanup);
 686        return;
 687out_abort:
 688        spin_unlock(&xprt->transport_lock);
 689}
 690
 691/**
 692 * xprt_connect - schedule a transport connect operation
 693 * @task: RPC task that is requesting the connect
 694 *
 695 */
 696void xprt_connect(struct rpc_task *task)
 697{
 698        struct rpc_xprt *xprt = task->tk_xprt;
 699
 700        dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 701                        xprt, (xprt_connected(xprt) ? "is" : "is not"));
 702
 703        if (!xprt_bound(xprt)) {
 704                task->tk_status = -EAGAIN;
 705                return;
 706        }
 707        if (!xprt_lock_write(xprt, task))
 708                return;
 709
 710        if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
 711                xprt->ops->close(xprt);
 712
 713        if (xprt_connected(xprt))
 714                xprt_release_write(xprt, task);
 715        else {
 716                task->tk_rqstp->rq_bytes_sent = 0;
 717                task->tk_timeout = task->tk_rqstp->rq_timeout;
 718                rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
 719
 720                if (test_bit(XPRT_CLOSING, &xprt->state))
 721                        return;
 722                if (xprt_test_and_set_connecting(xprt))
 723                        return;
 724                xprt->stat.connect_start = jiffies;
 725                xprt->ops->connect(task);
 726        }
 727}
 728
 729static void xprt_connect_status(struct rpc_task *task)
 730{
 731        struct rpc_xprt *xprt = task->tk_xprt;
 732
 733        if (task->tk_status == 0) {
 734                xprt->stat.connect_count++;
 735                xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 736                dprintk("RPC: %5u xprt_connect_status: connection established\n",
 737                                task->tk_pid);
 738                return;
 739        }
 740
 741        switch (task->tk_status) {
 742        case -EAGAIN:
 743                dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
 744                break;
 745        case -ETIMEDOUT:
 746                dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 747                                "out\n", task->tk_pid);
 748                break;
 749        default:
 750                dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 751                                "server %s\n", task->tk_pid, -task->tk_status,
 752                                xprt->servername);
 753                xprt_release_write(xprt, task);
 754                task->tk_status = -EIO;
 755        }
 756}
 757
 758/**
 759 * xprt_lookup_rqst - find an RPC request corresponding to an XID
 760 * @xprt: transport on which the original request was transmitted
 761 * @xid: RPC XID of incoming reply
 762 *
 763 */
 764struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 765{
 766        struct rpc_rqst *entry;
 767
 768        list_for_each_entry(entry, &xprt->recv, rq_list)
 769                if (entry->rq_xid == xid)
 770                        return entry;
 771
 772        dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 773                        ntohl(xid));
 774        xprt->stat.bad_xids++;
 775        return NULL;
 776}
 777EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 778
 779static void xprt_update_rtt(struct rpc_task *task)
 780{
 781        struct rpc_rqst *req = task->tk_rqstp;
 782        struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 783        unsigned int timer = task->tk_msg.rpc_proc->p_timer;
 784        long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
 785
 786        if (timer) {
 787                if (req->rq_ntrans == 1)
 788                        rpc_update_rtt(rtt, timer, m);
 789                rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 790        }
 791}
 792
 793/**
 794 * xprt_complete_rqst - called when reply processing is complete
 795 * @task: RPC request that recently completed
 796 * @copied: actual number of bytes received from the transport
 797 *
 798 * Caller holds transport lock.
 799 */
 800void xprt_complete_rqst(struct rpc_task *task, int copied)
 801{
 802        struct rpc_rqst *req = task->tk_rqstp;
 803        struct rpc_xprt *xprt = req->rq_xprt;
 804
 805        dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 806                        task->tk_pid, ntohl(req->rq_xid), copied);
 807
 808        xprt->stat.recvs++;
 809        req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
 810        if (xprt->ops->timer != NULL)
 811                xprt_update_rtt(task);
 812
 813        list_del_init(&req->rq_list);
 814        req->rq_private_buf.len = copied;
 815        /* Ensure all writes are done before we update */
 816        /* req->rq_reply_bytes_recvd */
 817        smp_wmb();
 818        req->rq_reply_bytes_recvd = copied;
 819        rpc_wake_up_queued_task(&xprt->pending, task);
 820}
 821EXPORT_SYMBOL_GPL(xprt_complete_rqst);
 822
 823static void xprt_timer(struct rpc_task *task)
 824{
 825        struct rpc_rqst *req = task->tk_rqstp;
 826        struct rpc_xprt *xprt = req->rq_xprt;
 827
 828        if (task->tk_status != -ETIMEDOUT)
 829                return;
 830        dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
 831
 832        spin_lock_bh(&xprt->transport_lock);
 833        if (!req->rq_reply_bytes_recvd) {
 834                if (xprt->ops->timer)
 835                        xprt->ops->timer(task);
 836        } else
 837                task->tk_status = 0;
 838        spin_unlock_bh(&xprt->transport_lock);
 839}
 840
 841static inline int xprt_has_timer(struct rpc_xprt *xprt)
 842{
 843        return xprt->idle_timeout != 0;
 844}
 845
 846/**
 847 * xprt_prepare_transmit - reserve the transport before sending a request
 848 * @task: RPC task about to send a request
 849 *
 850 */
 851int xprt_prepare_transmit(struct rpc_task *task)
 852{
 853        struct rpc_rqst *req = task->tk_rqstp;
 854        struct rpc_xprt *xprt = req->rq_xprt;
 855        int err = 0;
 856
 857        dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 858
 859        spin_lock_bh(&xprt->transport_lock);
 860        if (req->rq_reply_bytes_recvd && !req->rq_bytes_sent) {
 861                err = req->rq_reply_bytes_recvd;
 862                goto out_unlock;
 863        }
 864        if (!xprt->ops->reserve_xprt(xprt, task))
 865                err = -EAGAIN;
 866out_unlock:
 867        spin_unlock_bh(&xprt->transport_lock);
 868        return err;
 869}
 870
 871void xprt_end_transmit(struct rpc_task *task)
 872{
 873        xprt_release_write(task->tk_rqstp->rq_xprt, task);
 874}
 875
 876/**
 877 * xprt_transmit - send an RPC request on a transport
 878 * @task: controlling RPC task
 879 *
 880 * We have to copy the iovec because sendmsg fiddles with its contents.
 881 */
 882void xprt_transmit(struct rpc_task *task)
 883{
 884        struct rpc_rqst *req = task->tk_rqstp;
 885        struct rpc_xprt *xprt = req->rq_xprt;
 886        int status, numreqs;
 887
 888        dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 889
 890        if (!req->rq_reply_bytes_recvd) {
 891                if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
 892                        /*
 893                         * Add to the list only if we're expecting a reply
 894                         */
 895                        spin_lock_bh(&xprt->transport_lock);
 896                        /* Update the softirq receive buffer */
 897                        memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 898                                        sizeof(req->rq_private_buf));
 899                        /* Add request to the receive list */
 900                        list_add_tail(&req->rq_list, &xprt->recv);
 901                        spin_unlock_bh(&xprt->transport_lock);
 902                        xprt_reset_majortimeo(req);
 903                        /* Turn off autodisconnect */
 904                        del_singleshot_timer_sync(&xprt->timer);
 905                }
 906        } else if (!req->rq_bytes_sent)
 907                return;
 908
 909        req->rq_connect_cookie = xprt->connect_cookie;
 910        req->rq_xtime = ktime_get();
 911        status = xprt->ops->send_request(task);
 912        if (status != 0) {
 913                task->tk_status = status;
 914                return;
 915        }
 916
 917        dprintk("RPC: %5u xmit complete\n", task->tk_pid);
 918        task->tk_flags |= RPC_TASK_SENT;
 919        spin_lock_bh(&xprt->transport_lock);
 920
 921        xprt->ops->set_retrans_timeout(task);
 922
 923        numreqs = atomic_read(&xprt->num_reqs);
 924        if (numreqs > xprt->stat.max_slots)
 925                xprt->stat.max_slots = numreqs;
 926        xprt->stat.sends++;
 927        xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
 928        xprt->stat.bklog_u += xprt->backlog.qlen;
 929        xprt->stat.sending_u += xprt->sending.qlen;
 930        xprt->stat.pending_u += xprt->pending.qlen;
 931
 932        /* Don't race with disconnect */
 933        if (!xprt_connected(xprt))
 934                task->tk_status = -ENOTCONN;
 935        else if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task)) {
 936                /*
 937                 * Sleep on the pending queue since
 938                 * we're expecting a reply.
 939                 */
 940                rpc_sleep_on(&xprt->pending, task, xprt_timer);
 941        }
 942        spin_unlock_bh(&xprt->transport_lock);
 943}
 944
 945static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
 946{
 947        struct rpc_rqst *req = ERR_PTR(-EAGAIN);
 948
 949        if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
 950                goto out;
 951        req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
 952        if (req != NULL)
 953                goto out;
 954        atomic_dec(&xprt->num_reqs);
 955        req = ERR_PTR(-ENOMEM);
 956out:
 957        return req;
 958}
 959
 960static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
 961{
 962        if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
 963                kfree(req);
 964                return true;
 965        }
 966        return false;
 967}
 968
 969void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
 970{
 971        struct rpc_rqst *req;
 972
 973        spin_lock(&xprt->reserve_lock);
 974        if (!list_empty(&xprt->free)) {
 975                req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 976                list_del(&req->rq_list);
 977                goto out_init_req;
 978        }
 979        req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
 980        if (!IS_ERR(req))
 981                goto out_init_req;
 982        switch (PTR_ERR(req)) {
 983        case -ENOMEM:
 984                dprintk("RPC:       dynamic allocation of request slot "
 985                                "failed! Retrying\n");
 986                task->tk_status = -ENOMEM;
 987                break;
 988        case -EAGAIN:
 989                rpc_sleep_on(&xprt->backlog, task, NULL);
 990                dprintk("RPC:       waiting for request slot\n");
 991        default:
 992                task->tk_status = -EAGAIN;
 993        }
 994        spin_unlock(&xprt->reserve_lock);
 995        return;
 996out_init_req:
 997        task->tk_status = 0;
 998        task->tk_rqstp = req;
 999        xprt_request_init(task, xprt);
1000        spin_unlock(&xprt->reserve_lock);
1001}
1002EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1003
1004void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1005{
1006        /* Note: grabbing the xprt_lock_write() ensures that we throttle
1007         * new slot allocation if the transport is congested (i.e. when
1008         * reconnecting a stream transport or when out of socket write
1009         * buffer space).
1010         */
1011        if (xprt_lock_write(xprt, task)) {
1012                xprt_alloc_slot(xprt, task);
1013                xprt_release_write(xprt, task);
1014        }
1015}
1016EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1017
1018static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1019{
1020        spin_lock(&xprt->reserve_lock);
1021        if (!xprt_dynamic_free_slot(xprt, req)) {
1022                memset(req, 0, sizeof(*req));   /* mark unused */
1023                list_add(&req->rq_list, &xprt->free);
1024        }
1025        rpc_wake_up_next(&xprt->backlog);
1026        spin_unlock(&xprt->reserve_lock);
1027}
1028
1029static void xprt_free_all_slots(struct rpc_xprt *xprt)
1030{
1031        struct rpc_rqst *req;
1032        while (!list_empty(&xprt->free)) {
1033                req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1034                list_del(&req->rq_list);
1035                kfree(req);
1036        }
1037}
1038
1039struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1040                unsigned int num_prealloc,
1041                unsigned int max_alloc)
1042{
1043        struct rpc_xprt *xprt;
1044        struct rpc_rqst *req;
1045        int i;
1046
1047        xprt = kzalloc(size, GFP_KERNEL);
1048        if (xprt == NULL)
1049                goto out;
1050
1051        xprt_init(xprt, net);
1052
1053        for (i = 0; i < num_prealloc; i++) {
1054                req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1055                if (!req)
1056                        break;
1057                list_add(&req->rq_list, &xprt->free);
1058        }
1059        if (i < num_prealloc)
1060                goto out_free;
1061        if (max_alloc > num_prealloc)
1062                xprt->max_reqs = max_alloc;
1063        else
1064                xprt->max_reqs = num_prealloc;
1065        xprt->min_reqs = num_prealloc;
1066        atomic_set(&xprt->num_reqs, num_prealloc);
1067
1068        return xprt;
1069
1070out_free:
1071        xprt_free(xprt);
1072out:
1073        return NULL;
1074}
1075EXPORT_SYMBOL_GPL(xprt_alloc);
1076
1077void xprt_free(struct rpc_xprt *xprt)
1078{
1079        put_net(xprt->xprt_net);
1080        xprt_free_all_slots(xprt);
1081        kfree(xprt);
1082}
1083EXPORT_SYMBOL_GPL(xprt_free);
1084
1085/**
1086 * xprt_reserve - allocate an RPC request slot
1087 * @task: RPC task requesting a slot allocation
1088 *
1089 * If no more slots are available, place the task on the transport's
1090 * backlog queue.
1091 */
1092void xprt_reserve(struct rpc_task *task)
1093{
1094        struct rpc_xprt *xprt = task->tk_xprt;
1095
1096        task->tk_status = 0;
1097        if (task->tk_rqstp != NULL)
1098                return;
1099
1100        task->tk_timeout = 0;
1101        task->tk_status = -EAGAIN;
1102        xprt->ops->alloc_slot(xprt, task);
1103}
1104
1105static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1106{
1107        return (__force __be32)xprt->xid++;
1108}
1109
1110static inline void xprt_init_xid(struct rpc_xprt *xprt)
1111{
1112        xprt->xid = net_random();
1113}
1114
1115static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1116{
1117        struct rpc_rqst *req = task->tk_rqstp;
1118
1119        INIT_LIST_HEAD(&req->rq_list);
1120        req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1121        req->rq_task    = task;
1122        req->rq_xprt    = xprt;
1123        req->rq_buffer  = NULL;
1124        req->rq_xid     = xprt_alloc_xid(xprt);
1125        req->rq_release_snd_buf = NULL;
1126        xprt_reset_majortimeo(req);
1127        dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1128                        req, ntohl(req->rq_xid));
1129}
1130
1131/**
1132 * xprt_release - release an RPC request slot
1133 * @task: task which is finished with the slot
1134 *
1135 */
1136void xprt_release(struct rpc_task *task)
1137{
1138        struct rpc_xprt *xprt;
1139        struct rpc_rqst *req;
1140
1141        if (!(req = task->tk_rqstp))
1142                return;
1143
1144        xprt = req->rq_xprt;
1145        if (task->tk_ops->rpc_count_stats != NULL)
1146                task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1147        else if (task->tk_client)
1148                rpc_count_iostats(task, task->tk_client->cl_metrics);
1149        spin_lock_bh(&xprt->transport_lock);
1150        xprt->ops->release_xprt(xprt, task);
1151        if (xprt->ops->release_request)
1152                xprt->ops->release_request(task);
1153        if (!list_empty(&req->rq_list))
1154                list_del(&req->rq_list);
1155        xprt->last_used = jiffies;
1156        if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1157                mod_timer(&xprt->timer,
1158                                xprt->last_used + xprt->idle_timeout);
1159        spin_unlock_bh(&xprt->transport_lock);
1160        if (req->rq_buffer)
1161                xprt->ops->buf_free(req->rq_buffer);
1162        if (req->rq_cred != NULL)
1163                put_rpccred(req->rq_cred);
1164        task->tk_rqstp = NULL;
1165        if (req->rq_release_snd_buf)
1166                req->rq_release_snd_buf(req);
1167
1168        dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1169        if (likely(!bc_prealloc(req)))
1170                xprt_free_slot(xprt, req);
1171        else
1172                xprt_free_bc_request(req);
1173}
1174
1175static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1176{
1177        atomic_set(&xprt->count, 1);
1178
1179        spin_lock_init(&xprt->transport_lock);
1180        spin_lock_init(&xprt->reserve_lock);
1181
1182        INIT_LIST_HEAD(&xprt->free);
1183        INIT_LIST_HEAD(&xprt->recv);
1184#if defined(CONFIG_SUNRPC_BACKCHANNEL)
1185        spin_lock_init(&xprt->bc_pa_lock);
1186        INIT_LIST_HEAD(&xprt->bc_pa_list);
1187#endif /* CONFIG_SUNRPC_BACKCHANNEL */
1188
1189        xprt->last_used = jiffies;
1190        xprt->cwnd = RPC_INITCWND;
1191        xprt->bind_index = 0;
1192
1193        rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1194        rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1195        rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1196        rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1197
1198        xprt_init_xid(xprt);
1199
1200        xprt->xprt_net = get_net(net);
1201}
1202
1203/**
1204 * xprt_create_transport - create an RPC transport
1205 * @args: rpc transport creation arguments
1206 *
1207 */
1208struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1209{
1210        struct rpc_xprt *xprt;
1211        struct xprt_class *t;
1212
1213        spin_lock(&xprt_list_lock);
1214        list_for_each_entry(t, &xprt_list, list) {
1215                if (t->ident == args->ident) {
1216                        spin_unlock(&xprt_list_lock);
1217                        goto found;
1218                }
1219        }
1220        spin_unlock(&xprt_list_lock);
1221        printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1222        return ERR_PTR(-EIO);
1223
1224found:
1225        xprt = t->setup(args);
1226        if (IS_ERR(xprt)) {
1227                dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1228                                -PTR_ERR(xprt));
1229                goto out;
1230        }
1231        INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1232        if (xprt_has_timer(xprt))
1233                setup_timer(&xprt->timer, xprt_init_autodisconnect,
1234                            (unsigned long)xprt);
1235        else
1236                init_timer(&xprt->timer);
1237
1238        if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1239                xprt_destroy(xprt);
1240                return ERR_PTR(-EINVAL);
1241        }
1242        xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1243        if (xprt->servername == NULL) {
1244                xprt_destroy(xprt);
1245                return ERR_PTR(-ENOMEM);
1246        }
1247
1248        dprintk("RPC:       created transport %p with %u slots\n", xprt,
1249                        xprt->max_reqs);
1250out:
1251        return xprt;
1252}
1253
1254/**
1255 * xprt_destroy - destroy an RPC transport, killing off all requests.
1256 * @xprt: transport to destroy
1257 *
1258 */
1259static void xprt_destroy(struct rpc_xprt *xprt)
1260{
1261        dprintk("RPC:       destroying transport %p\n", xprt);
1262        del_timer_sync(&xprt->timer);
1263
1264        rpc_destroy_wait_queue(&xprt->binding);
1265        rpc_destroy_wait_queue(&xprt->pending);
1266        rpc_destroy_wait_queue(&xprt->sending);
1267        rpc_destroy_wait_queue(&xprt->backlog);
1268        cancel_work_sync(&xprt->task_cleanup);
1269        kfree(xprt->servername);
1270        /*
1271         * Tear down transport state and free the rpc_xprt
1272         */
1273        xprt->ops->destroy(xprt);
1274}
1275
1276/**
1277 * xprt_put - release a reference to an RPC transport.
1278 * @xprt: pointer to the transport
1279 *
1280 */
1281void xprt_put(struct rpc_xprt *xprt)
1282{
1283        if (atomic_dec_and_test(&xprt->count))
1284                xprt_destroy(xprt);
1285}
1286
1287/**
1288 * xprt_get - return a reference to an RPC transport.
1289 * @xprt: pointer to the transport
1290 *
1291 */
1292struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1293{
1294        if (atomic_inc_not_zero(&xprt->count))
1295                return xprt;
1296        return NULL;
1297}
1298
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