net/sunrpc/xprt.c

   1 /*
   2  *  linux/net/sunrpc/xprt.c
   3  *
   4  *  This is a generic RPC call interface supporting congestion avoidance,
   5  *  and asynchronous calls.
   6  *
   7  *  The interface works like this:
   8  *
   9  *  -   When a process places a call, it allocates a request slot if
  10  *      one is available. Otherwise, it sleeps on the backlog queue
  11  *      (xprt_reserve).
  12  *  -   Next, the caller puts together the RPC message, stuffs it into
  13  *      the request struct, and calls xprt_transmit().
  14  *  -   xprt_transmit sends the message and installs the caller on the
  15  *      transport's wait list. At the same time, if a reply is expected,
  16  *      it installs a timer that is run after the packet's timeout has
  17  *      expired.
  18  *  -   When a packet arrives, the data_ready handler walks the list of
  19  *      pending requests for that transport. If a matching XID is found, the
  20  *      caller is woken up, and the timer removed.
  21  *  -   When no reply arrives within the timeout interval, the timer is
  22  *      fired by the kernel and runs xprt_timer(). It either adjusts the
  23  *      timeout values (minor timeout) or wakes up the caller with a status
  24  *      of -ETIMEDOUT.
  25  *  -   When the caller receives a notification from RPC that a reply arrived,
  26  *      it should release the RPC slot, and process the reply.
  27  *      If the call timed out, it may choose to retry the operation by
  28  *      adjusting the initial timeout value, and simply calling rpc_call
  29  *      again.
  30  *
  31  *  Support for async RPC is done through a set of RPC-specific scheduling
  32  *  primitives that `transparently' work for processes as well as async
  33  *  tasks that rely on callbacks.
  34  *
  35  *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
  36  *
  37  *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
  38  */
  39
  40 #include <linux/module.h>
  41
  42 #include <linux/types.h>
  43 #include <linux/interrupt.h>
  44 #include <linux/workqueue.h>
  45 #include <linux/net.h>
  46 #include <linux/ktime.h>
  47
  48 #include <linux/sunrpc/clnt.h>
  49 #include <linux/sunrpc/metrics.h>
  50 #include <linux/sunrpc/bc_xprt.h>
  51
  52 #include "sunrpc.h"
  53
  54 /*
  55  * Local variables
  56  */
  57
  58 #ifdef RPC_DEBUG
  59 # define RPCDBG_FACILITY        RPCDBG_XPRT
  60 #endif
  61
  62 /*
  63  * Local functions
  64  */
  65 static void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
  66 static void     xprt_connect_status(struct rpc_task *task);
  67 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
  68
  69 static DEFINE_SPINLOCK(xprt_list_lock);
  70 static LIST_HEAD(xprt_list);
  71
  72 /*
  73  * The transport code maintains an estimate on the maximum number of out-
  74  * standing RPC requests, using a smoothed version of the congestion
  75  * avoidance implemented in 44BSD. This is basically the Van Jacobson
  76  * congestion algorithm: If a retransmit occurs, the congestion window is
  77  * halved; otherwise, it is incremented by 1/cwnd when
  78  *
  79  *      -       a reply is received and
  80  *      -       a full number of requests are outstanding and
  81  *      -       the congestion window hasn't been updated recently.
  82  */
  83 #define RPC_CWNDSHIFT           (8U)
  84 #define RPC_CWNDSCALE           (1U << RPC_CWNDSHIFT)
  85 #define RPC_INITCWND            RPC_CWNDSCALE
  86 #define RPC_MAXCWND(xprt)       ((xprt)->max_reqs << RPC_CWNDSHIFT)
  87
  88 #define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
  89
  90 /**
  91  * xprt_register_transport - register a transport implementation
  92  * @transport: transport to register
  93  *
  94  * If a transport implementation is loaded as a kernel module, it can
  95  * call this interface to make itself known to the RPC client.
  96  *
  97  * Returns:
  98  * 0:           transport successfully registered
  99  * -EEXIST:     transport already registered
 100  * -EINVAL:     transport module being unloaded
 101  */
 102 int xprt_register_transport(struct xprt_class *transport)
 103 {
 104         struct xprt_class *t;
 105         int result;
 106
 107         result = -EEXIST;
 108         spin_lock(&xprt_list_lock);
 109         list_for_each_entry(t, &xprt_list, list) {
 110                 /* don't register the same transport class twice */
 111                 if (t->ident == transport->ident)
 112                         goto out;
 113         }
 114
 115         list_add_tail(&transport->list, &xprt_list);
 116         printk(KERN_INFO "RPC: Registered %s transport module.\n",
 117                transport->name);
 118         result = 0;
 119
 120 out:
 121         spin_unlock(&xprt_list_lock);
 122         return result;
 123 }
 124 EXPORT_SYMBOL_GPL(xprt_register_transport);
 125
 126 /**
 127  * xprt_unregister_transport - unregister a transport implementation
 128  * @transport: transport to unregister
 129  *
 130  * Returns:
 131  * 0:           transport successfully unregistered
 132  * -ENOENT:     transport never registered
 133  */
 134 int xprt_unregister_transport(struct xprt_class *transport)
 135 {
 136         struct xprt_class *t;
 137         int result;
 138
 139         result = 0;
 140         spin_lock(&xprt_list_lock);
 141         list_for_each_entry(t, &xprt_list, list) {
 142                 if (t == transport) {
 143                         printk(KERN_INFO
 144                                 "RPC: Unregistered %s transport module.\n",
 145                                 transport->name);
 146                         list_del_init(&transport->list);
 147                         goto out;
 148                 }
 149         }
 150         result = -ENOENT;
 151
 152 out:
 153         spin_unlock(&xprt_list_lock);
 154         return result;
 155 }
 156 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 157
 158 /**
 159  * xprt_load_transport - load a transport implementation
 160  * @transport_name: transport to load
 161  *
 162  * Returns:
 163  * 0:           transport successfully loaded
 164  * -ENOENT:     transport module not available
 165  */
 166 int xprt_load_transport(const char *transport_name)
 167 {
 168         struct xprt_class *t;
 169         char module_name[sizeof t->name + 5];
 170         int result;
 171
 172         result = 0;
 173         spin_lock(&xprt_list_lock);
 174         list_for_each_entry(t, &xprt_list, list) {
 175                 if (strcmp(t->name, transport_name) == 0) {
 176                         spin_unlock(&xprt_list_lock);
 177                         goto out;
 178                 }
 179         }
 180         spin_unlock(&xprt_list_lock);
 181         strcpy(module_name, "xprt");
 182         strncat(module_name, transport_name, sizeof t->name);
 183         result = request_module(module_name);
 184 out:
 185         return result;
 186 }
 187 EXPORT_SYMBOL_GPL(xprt_load_transport);
 188
 189 /**
 190  * xprt_reserve_xprt - serialize write access to transports
 191  * @task: task that is requesting access to the transport
 192  *
 193  * This prevents mixing the payload of separate requests, and prevents
 194  * transport connects from colliding with writes.  No congestion control
 195  * is provided.
 196  */
 197 int xprt_reserve_xprt(struct rpc_task *task)
 198 {
 199         struct rpc_rqst *req = task->tk_rqstp;
 200         struct rpc_xprt *xprt = req->rq_xprt;
 201
 202         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 203                 if (task == xprt->snd_task)
 204                         return 1;
 205                 if (task == NULL)
 206                         return 0;
 207                 goto out_sleep;
 208         }
 209         xprt->snd_task = task;
 210         if (req) {
 211                 req->rq_bytes_sent = 0;
 212                 req->rq_ntrans++;
 213         }
 214         return 1;
 215
 216 out_sleep:
 217         dprintk("RPC: %5u failed to lock transport %p\n",
 218                         task->tk_pid, xprt);
 219         task->tk_timeout = 0;
 220         task->tk_status = -EAGAIN;
 221         if (req && req->rq_ntrans)
 222                 rpc_sleep_on(&xprt->resend, task, NULL);
 223         else
 224                 rpc_sleep_on(&xprt->sending, task, NULL);
 225         return 0;
 226 }
 227 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 228
 229 static void xprt_clear_locked(struct rpc_xprt *xprt)
 230 {
 231         xprt->snd_task = NULL;
 232         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
 233                 smp_mb__before_clear_bit();
 234                 clear_bit(XPRT_LOCKED, &xprt->state);
 235                 smp_mb__after_clear_bit();
 236         } else
 237                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 238 }
 239
 240 /*
 241  * xprt_reserve_xprt_cong - serialize write access to transports
 242  * @task: task that is requesting access to the transport
 243  *
 244  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 245  * integrated into the decision of whether a request is allowed to be
 246  * woken up and given access to the transport.
 247  */
 248 int xprt_reserve_xprt_cong(struct rpc_task *task)
 249 {
 250         struct rpc_xprt *xprt = task->tk_xprt;
 251         struct rpc_rqst *req = task->tk_rqstp;
 252
 253         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 254                 if (task == xprt->snd_task)
 255                         return 1;
 256                 goto out_sleep;
 257         }
 258         if (__xprt_get_cong(xprt, task)) {
 259                 xprt->snd_task = task;
 260                 if (req) {
 261                         req->rq_bytes_sent = 0;
 262                         req->rq_ntrans++;
 263                 }
 264                 return 1;
 265         }
 266         xprt_clear_locked(xprt);
 267 out_sleep:
 268         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
 269         task->tk_timeout = 0;
 270         task->tk_status = -EAGAIN;
 271         if (req && req->rq_ntrans)
 272                 rpc_sleep_on(&xprt->resend, task, NULL);
 273         else
 274                 rpc_sleep_on(&xprt->sending, task, NULL);
 275         return 0;
 276 }
 277 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 278
 279 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 280 {
 281         int retval;
 282
 283         spin_lock_bh(&xprt->transport_lock);
 284         retval = xprt->ops->reserve_xprt(task);
 285         spin_unlock_bh(&xprt->transport_lock);
 286         return retval;
 287 }
 288
 289 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 290 {
 291         struct rpc_task *task;
 292         struct rpc_rqst *req;
 293
 294         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 295                 return;
 296
 297         task = rpc_wake_up_next(&xprt->resend);
 298         if (!task) {
 299                 task = rpc_wake_up_next(&xprt->sending);
 300                 if (!task)
 301                         goto out_unlock;
 302         }
 303
 304         req = task->tk_rqstp;
 305         xprt->snd_task = task;
 306         if (req) {
 307                 req->rq_bytes_sent = 0;
 308                 req->rq_ntrans++;
 309         }
 310         return;
 311
 312 out_unlock:
 313         xprt_clear_locked(xprt);
 314 }
 315
 316 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 317 {
 318         struct rpc_task *task;
 319
 320         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 321                 return;
 322         if (RPCXPRT_CONGESTED(xprt))
 323                 goto out_unlock;
 324         task = rpc_wake_up_next(&xprt->resend);
 325         if (!task) {
 326                 task = rpc_wake_up_next(&xprt->sending);
 327                 if (!task)
 328                         goto out_unlock;
 329         }
 330         if (__xprt_get_cong(xprt, task)) {
 331                 struct rpc_rqst *req = task->tk_rqstp;
 332                 xprt->snd_task = task;
 333                 if (req) {
 334                         req->rq_bytes_sent = 0;
 335                         req->rq_ntrans++;
 336                 }
 337                 return;
 338         }
 339 out_unlock:
 340         xprt_clear_locked(xprt);
 341 }
 342
 343 /**
 344  * xprt_release_xprt - allow other requests to use a transport
 345  * @xprt: transport with other tasks potentially waiting
 346  * @task: task that is releasing access to the transport
 347  *
 348  * Note that "task" can be NULL.  No congestion control is provided.
 349  */
 350 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 351 {
 352         if (xprt->snd_task == task) {
 353                 xprt_clear_locked(xprt);
 354                 __xprt_lock_write_next(xprt);
 355         }
 356 }
 357 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 358
 359 /**
 360  * xprt_release_xprt_cong - allow other requests to use a transport
 361  * @xprt: transport with other tasks potentially waiting
 362  * @task: task that is releasing access to the transport
 363  *
 364  * Note that "task" can be NULL.  Another task is awoken to use the
 365  * transport if the transport's congestion window allows it.
 366  */
 367 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 368 {
 369         if (xprt->snd_task == task) {
 370                 xprt_clear_locked(xprt);
 371                 __xprt_lock_write_next_cong(xprt);
 372         }
 373 }
 374 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 375
 376 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 377 {
 378         spin_lock_bh(&xprt->transport_lock);
 379         xprt->ops->release_xprt(xprt, task);
 380         spin_unlock_bh(&xprt->transport_lock);
 381 }
 382
 383 /*
 384  * Van Jacobson congestion avoidance. Check if the congestion window
 385  * overflowed. Put the task to sleep if this is the case.
 386  */
 387 static int
 388 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 389 {
 390         struct rpc_rqst *req = task->tk_rqstp;
 391
 392         if (req->rq_cong)
 393                 return 1;
 394         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
 395                         task->tk_pid, xprt->cong, xprt->cwnd);
 396         if (RPCXPRT_CONGESTED(xprt))
 397                 return 0;
 398         req->rq_cong = 1;
 399         xprt->cong += RPC_CWNDSCALE;
 400         return 1;
 401 }
 402
 403 /*
 404  * Adjust the congestion window, and wake up the next task
 405  * that has been sleeping due to congestion
 406  */
 407 static void
 408 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 409 {
 410         if (!req->rq_cong)
 411                 return;
 412         req->rq_cong = 0;
 413         xprt->cong -= RPC_CWNDSCALE;
 414         __xprt_lock_write_next_cong(xprt);
 415 }
 416
 417 /**
 418  * xprt_release_rqst_cong - housekeeping when request is complete
 419  * @task: RPC request that recently completed
 420  *
 421  * Useful for transports that require congestion control.
 422  */
 423 void xprt_release_rqst_cong(struct rpc_task *task)
 424 {
 425         __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
 426 }
 427 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 428
 429 /**
 430  * xprt_adjust_cwnd - adjust transport congestion window
 431  * @task: recently completed RPC request used to adjust window
 432  * @result: result code of completed RPC request
 433  *
 434  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
 435  */
 436 void xprt_adjust_cwnd(struct rpc_task *task, int result)
 437 {
 438         struct rpc_rqst *req = task->tk_rqstp;
 439         struct rpc_xprt *xprt = task->tk_xprt;
 440         unsigned long cwnd = xprt->cwnd;
 441
 442         if (result >= 0 && cwnd <= xprt->cong) {
 443                 /* The (cwnd >> 1) term makes sure
 444                  * the result gets rounded properly. */
 445                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 446                 if (cwnd > RPC_MAXCWND(xprt))
 447                         cwnd = RPC_MAXCWND(xprt);
 448                 __xprt_lock_write_next_cong(xprt);
 449         } else if (result == -ETIMEDOUT) {
 450                 cwnd >>= 1;
 451                 if (cwnd < RPC_CWNDSCALE)
 452                         cwnd = RPC_CWNDSCALE;
 453         }
 454         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 455                         xprt->cong, xprt->cwnd, cwnd);
 456         xprt->cwnd = cwnd;
 457         __xprt_put_cong(xprt, req);
 458 }
 459 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 460
 461 /**
 462  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 463  * @xprt: transport with waiting tasks
 464  * @status: result code to plant in each task before waking it
 465  *
 466  */
 467 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 468 {
 469         if (status < 0)
 470                 rpc_wake_up_status(&xprt->pending, status);
 471         else
 472                 rpc_wake_up(&xprt->pending);
 473 }
 474 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 475
 476 /**
 477  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 478  * @task: task to be put to sleep
 479  * @action: function pointer to be executed after wait
 480  */
 481 void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
 482 {
 483         struct rpc_rqst *req = task->tk_rqstp;
 484         struct rpc_xprt *xprt = req->rq_xprt;
 485
 486         task->tk_timeout = req->rq_timeout;
 487         rpc_sleep_on(&xprt->pending, task, action);
 488 }
 489 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 490
 491 /**
 492  * xprt_write_space - wake the task waiting for transport output buffer space
 493  * @xprt: transport with waiting tasks
 494  *
 495  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 496  */
 497 void xprt_write_space(struct rpc_xprt *xprt)
 498 {
 499         if (unlikely(xprt->shutdown))
 500                 return;
 501
 502         spin_lock_bh(&xprt->transport_lock);
 503         if (xprt->snd_task) {
 504                 dprintk("RPC:       write space: waking waiting task on "
 505                                 "xprt %p\n", xprt);
 506                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
 507         }
 508         spin_unlock_bh(&xprt->transport_lock);
 509 }
 510 EXPORT_SYMBOL_GPL(xprt_write_space);
 511
 512 /**
 513  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 514  * @task: task whose timeout is to be set
 515  *
 516  * Set a request's retransmit timeout based on the transport's
 517  * default timeout parameters.  Used by transports that don't adjust
 518  * the retransmit timeout based on round-trip time estimation.
 519  */
 520 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 521 {
 522         task->tk_timeout = task->tk_rqstp->rq_timeout;
 523 }
 524 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
 525
 526 /*
 527  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 528  * @task: task whose timeout is to be set
 529  *
 530  * Set a request's retransmit timeout using the RTT estimator.
 531  */
 532 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 533 {
 534         int timer = task->tk_msg.rpc_proc->p_timer;
 535         struct rpc_clnt *clnt = task->tk_client;
 536         struct rpc_rtt *rtt = clnt->cl_rtt;
 537         struct rpc_rqst *req = task->tk_rqstp;
 538         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
 539
 540         task->tk_timeout = rpc_calc_rto(rtt, timer);
 541         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 542         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 543                 task->tk_timeout = max_timeout;
 544 }
 545 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 546
 547 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 548 {
 549         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 550
 551         req->rq_majortimeo = req->rq_timeout;
 552         if (to->to_exponential)
 553                 req->rq_majortimeo <<= to->to_retries;
 554         else
 555                 req->rq_majortimeo += to->to_increment * to->to_retries;
 556         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 557                 req->rq_majortimeo = to->to_maxval;
 558         req->rq_majortimeo += jiffies;
 559 }
 560
 561 /**
 562  * xprt_adjust_timeout - adjust timeout values for next retransmit
 563  * @req: RPC request containing parameters to use for the adjustment
 564  *
 565  */
 566 int xprt_adjust_timeout(struct rpc_rqst *req)
 567 {
 568         struct rpc_xprt *xprt = req->rq_xprt;
 569         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 570         int status = 0;
 571
 572         if (time_before(jiffies, req->rq_majortimeo)) {
 573                 if (to->to_exponential)
 574                         req->rq_timeout <<= 1;
 575                 else
 576                         req->rq_timeout += to->to_increment;
 577                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 578                         req->rq_timeout = to->to_maxval;
 579                 req->rq_retries++;
 580         } else {
 581                 req->rq_timeout = to->to_initval;
 582                 req->rq_retries = 0;
 583                 xprt_reset_majortimeo(req);
 584                 /* Reset the RTT counters == "slow start" */
 585                 spin_lock_bh(&xprt->transport_lock);
 586                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 587                 spin_unlock_bh(&xprt->transport_lock);
 588                 status = -ETIMEDOUT;
 589         }
 590
 591         if (req->rq_timeout == 0) {
 592                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 593                 req->rq_timeout = 5 * HZ;
 594         }
 595         return status;
 596 }
 597
 598 static void xprt_autoclose(struct work_struct *work)
 599 {
 600         struct rpc_xprt *xprt =
 601                 container_of(work, struct rpc_xprt, task_cleanup);
 602
 603         xprt->ops->close(xprt);
 604         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 605         xprt_release_write(xprt, NULL);
 606 }
 607
 608 /**
 609  * xprt_disconnect_done - mark a transport as disconnected
 610  * @xprt: transport to flag for disconnect
 611  *
 612  */
 613 void xprt_disconnect_done(struct rpc_xprt *xprt)
 614 {
 615         dprintk("RPC:       disconnected transport %p\n", xprt);
 616         spin_lock_bh(&xprt->transport_lock);
 617         xprt_clear_connected(xprt);
 618         xprt_wake_pending_tasks(xprt, -EAGAIN);
 619         spin_unlock_bh(&xprt->transport_lock);
 620 }
 621 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 622
 623 /**
 624  * xprt_force_disconnect - force a transport to disconnect
 625  * @xprt: transport to disconnect
 626  *
 627  */
 628 void xprt_force_disconnect(struct rpc_xprt *xprt)
 629 {
 630         /* Don't race with the test_bit() in xprt_clear_locked() */
 631         spin_lock_bh(&xprt->transport_lock);
 632         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 633         /* Try to schedule an autoclose RPC call */
 634         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 635                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 636         xprt_wake_pending_tasks(xprt, -EAGAIN);
 637         spin_unlock_bh(&xprt->transport_lock);
 638 }
 639
 640 /**
 641  * xprt_conditional_disconnect - force a transport to disconnect
 642  * @xprt: transport to disconnect
 643  * @cookie: 'connection cookie'
 644  *
 645  * This attempts to break the connection if and only if 'cookie' matches
 646  * the current transport 'connection cookie'. It ensures that we don't
 647  * try to break the connection more than once when we need to retransmit
 648  * a batch of RPC requests.
 649  *
 650  */
 651 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 652 {
 653         /* Don't race with the test_bit() in xprt_clear_locked() */
 654         spin_lock_bh(&xprt->transport_lock);
 655         if (cookie != xprt->connect_cookie)
 656                 goto out;
 657         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
 658                 goto out;
 659         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 660         /* Try to schedule an autoclose RPC call */
 661         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 662                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 663         xprt_wake_pending_tasks(xprt, -EAGAIN);
 664 out:
 665         spin_unlock_bh(&xprt->transport_lock);
 666 }
 667
 668 static void
 669 xprt_init_autodisconnect(unsigned long data)
 670 {
 671         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 672
 673         spin_lock(&xprt->transport_lock);
 674         if (!list_empty(&xprt->recv) || xprt->shutdown)
 675                 goto out_abort;
 676         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 677                 goto out_abort;
 678         spin_unlock(&xprt->transport_lock);
 679         set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
 680         queue_work(rpciod_workqueue, &xprt->task_cleanup);
 681         return;
 682 out_abort:
 683         spin_unlock(&xprt->transport_lock);
 684 }
 685
 686 /**
 687  * xprt_connect - schedule a transport connect operation
 688  * @task: RPC task that is requesting the connect
 689  *
 690  */
 691 void xprt_connect(struct rpc_task *task)
 692 {
 693         struct rpc_xprt *xprt = task->tk_xprt;
 694
 695         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 696                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 697
 698         if (!xprt_bound(xprt)) {
 699                 task->tk_status = -EAGAIN;
 700                 return;
 701         }
 702         if (!xprt_lock_write(xprt, task))
 703                 return;
 704
 705         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
 706                 xprt->ops->close(xprt);
 707
 708         if (xprt_connected(xprt))
 709                 xprt_release_write(xprt, task);
 710         else {
 711                 if (task->tk_rqstp)
 712                         task->tk_rqstp->rq_bytes_sent = 0;
 713
 714                 task->tk_timeout = task->tk_rqstp->rq_timeout;
 715                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
 716
 717                 if (test_bit(XPRT_CLOSING, &xprt->state))
 718                         return;
 719                 if (xprt_test_and_set_connecting(xprt))
 720                         return;
 721                 xprt->stat.connect_start = jiffies;
 722                 xprt->ops->connect(task);
 723         }
 724 }
 725
 726 static void xprt_connect_status(struct rpc_task *task)
 727 {
 728         struct rpc_xprt *xprt = task->tk_xprt;
 729
 730         if (task->tk_status == 0) {
 731                 xprt->stat.connect_count++;
 732                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 733                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 734                                 task->tk_pid);
 735                 return;
 736         }
 737
 738         switch (task->tk_status) {
 739         case -EAGAIN:
 740                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
 741                 break;
 742         case -ETIMEDOUT:
 743                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 744                                 "out\n", task->tk_pid);
 745                 break;
 746         default:
 747                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 748                                 "server %s\n", task->tk_pid, -task->tk_status,
 749                                 task->tk_client->cl_server);
 750                 xprt_release_write(xprt, task);
 751                 task->tk_status = -EIO;
 752         }
 753 }
 754
 755 /**
 756  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 757  * @xprt: transport on which the original request was transmitted
 758  * @xid: RPC XID of incoming reply
 759  *
 760  */
 761 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 762 {
 763         struct list_head *pos;
 764
 765         list_for_each(pos, &xprt->recv) {
 766                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
 767                 if (entry->rq_xid == xid)
 768                         return entry;
 769         }
 770
 771         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 772                         ntohl(xid));
 773         xprt->stat.bad_xids++;
 774         return NULL;
 775 }
 776 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 777
 778 static void xprt_update_rtt(struct rpc_task *task)
 779 {
 780         struct rpc_rqst *req = task->tk_rqstp;
 781         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 782         unsigned timer = task->tk_msg.rpc_proc->p_timer;
 783         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
 784
 785         if (timer) {
 786                 if (req->rq_ntrans == 1)
 787                         rpc_update_rtt(rtt, timer, m);
 788                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 789         }
 790 }
 791
 792 /**
 793  * xprt_complete_rqst - called when reply processing is complete
 794  * @task: RPC request that recently completed
 795  * @copied: actual number of bytes received from the transport
 796  *
 797  * Caller holds transport lock.
 798  */
 799 void xprt_complete_rqst(struct rpc_task *task, int copied)
 800 {
 801         struct rpc_rqst *req = task->tk_rqstp;
 802         struct rpc_xprt *xprt = req->rq_xprt;
 803
 804         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 805                         task->tk_pid, ntohl(req->rq_xid), copied);
 806
 807         xprt->stat.recvs++;
 808         req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
 809         if (xprt->ops->timer != NULL)
 810                 xprt_update_rtt(task);
 811
 812         list_del_init(&req->rq_list);
 813         req->rq_private_buf.len = copied;
 814         /* Ensure all writes are done before we update */
 815         /* req->rq_reply_bytes_recvd */
 816         smp_wmb();
 817         req->rq_reply_bytes_recvd = copied;
 818         rpc_wake_up_queued_task(&xprt->pending, task);
 819 }
 820 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
 821
 822 static void xprt_timer(struct rpc_task *task)
 823 {
 824         struct rpc_rqst *req = task->tk_rqstp;
 825         struct rpc_xprt *xprt = req->rq_xprt;
 826
 827         if (task->tk_status != -ETIMEDOUT)
 828                 return;
 829         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
 830
 831         spin_lock_bh(&xprt->transport_lock);
 832         if (!req->rq_reply_bytes_recvd) {
 833                 if (xprt->ops->timer)
 834                         xprt->ops->timer(task);
 835         } else
 836                 task->tk_status = 0;
 837         spin_unlock_bh(&xprt->transport_lock);
 838 }
 839
 840 static inline int xprt_has_timer(struct rpc_xprt *xprt)
 841 {
 842         return xprt->idle_timeout != 0;
 843 }
 844
 845 /**
 846  * xprt_prepare_transmit - reserve the transport before sending a request
 847  * @task: RPC task about to send a request
 848  *
 849  */
 850 int xprt_prepare_transmit(struct rpc_task *task)
 851 {
 852         struct rpc_rqst *req = task->tk_rqstp;
 853         struct rpc_xprt *xprt = req->rq_xprt;
 854         int err = 0;
 855
 856         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 857
 858         spin_lock_bh(&xprt->transport_lock);
 859         if (req->rq_reply_bytes_recvd && !req->rq_bytes_sent) {
 860                 err = req->rq_reply_bytes_recvd;
 861                 goto out_unlock;
 862         }
 863         if (!xprt->ops->reserve_xprt(task))
 864                 err = -EAGAIN;
 865 out_unlock:
 866         spin_unlock_bh(&xprt->transport_lock);
 867         return err;
 868 }
 869
 870 void xprt_end_transmit(struct rpc_task *task)
 871 {
 872         xprt_release_write(task->tk_rqstp->rq_xprt, task);
 873 }
 874
 875 /**
 876  * xprt_transmit - send an RPC request on a transport
 877  * @task: controlling RPC task
 878  *
 879  * We have to copy the iovec because sendmsg fiddles with its contents.
 880  */
 881 void xprt_transmit(struct rpc_task *task)
 882 {
 883         struct rpc_rqst *req = task->tk_rqstp;
 884         struct rpc_xprt *xprt = req->rq_xprt;
 885         int status;
 886
 887         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 888
 889         if (!req->rq_reply_bytes_recvd) {
 890                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
 891                         /*
 892                          * Add to the list only if we're expecting a reply
 893                          */
 894                         spin_lock_bh(&xprt->transport_lock);
 895                         /* Update the softirq receive buffer */
 896                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 897                                         sizeof(req->rq_private_buf));
 898                         /* Add request to the receive list */
 899                         list_add_tail(&req->rq_list, &xprt->recv);
 900                         spin_unlock_bh(&xprt->transport_lock);
 901                         xprt_reset_majortimeo(req);
 902                         /* Turn off autodisconnect */
 903                         del_singleshot_timer_sync(&xprt->timer);
 904                 }
 905         } else if (!req->rq_bytes_sent)
 906                 return;
 907
 908         req->rq_connect_cookie = xprt->connect_cookie;
 909         req->rq_xtime = ktime_get();
 910         status = xprt->ops->send_request(task);
 911         if (status != 0) {
 912                 task->tk_status = status;
 913                 return;
 914         }
 915
 916         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
 917         spin_lock_bh(&xprt->transport_lock);
 918
 919         xprt->ops->set_retrans_timeout(task);
 920
 921         xprt->stat.sends++;
 922         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
 923         xprt->stat.bklog_u += xprt->backlog.qlen;
 924
 925         /* Don't race with disconnect */
 926         if (!xprt_connected(xprt))
 927                 task->tk_status = -ENOTCONN;
 928         else if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task)) {
 929                 /*
 930                  * Sleep on the pending queue since
 931                  * we're expecting a reply.
 932                  */
 933                 rpc_sleep_on(&xprt->pending, task, xprt_timer);
 934         }
 935         spin_unlock_bh(&xprt->transport_lock);
 936 }
 937
 938 static void xprt_alloc_slot(struct rpc_task *task)
 939 {
 940         struct rpc_xprt *xprt = task->tk_xprt;
 941
 942         task->tk_status = 0;
 943         if (task->tk_rqstp)
 944                 return;
 945         if (!list_empty(&xprt->free)) {
 946                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 947                 list_del_init(&req->rq_list);
 948                 task->tk_rqstp = req;
 949                 xprt_request_init(task, xprt);
 950                 return;
 951         }
 952         dprintk("RPC:       waiting for request slot\n");
 953         task->tk_status = -EAGAIN;
 954         task->tk_timeout = 0;
 955         rpc_sleep_on(&xprt->backlog, task, NULL);
 956 }
 957
 958 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
 959 {
 960         memset(req, 0, sizeof(*req));   /* mark unused */
 961
 962         spin_lock(&xprt->reserve_lock);
 963         list_add(&req->rq_list, &xprt->free);
 964         rpc_wake_up_next(&xprt->backlog);
 965         spin_unlock(&xprt->reserve_lock);
 966 }
 967
 968 /**
 969  * xprt_reserve - allocate an RPC request slot
 970  * @task: RPC task requesting a slot allocation
 971  *
 972  * If no more slots are available, place the task on the transport's
 973  * backlog queue.
 974  */
 975 void xprt_reserve(struct rpc_task *task)
 976 {
 977         struct rpc_xprt *xprt = task->tk_xprt;
 978
 979         task->tk_status = -EIO;
 980         spin_lock(&xprt->reserve_lock);
 981         xprt_alloc_slot(task);
 982         spin_unlock(&xprt->reserve_lock);
 983 }
 984
 985 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
 986 {
 987         return (__force __be32)xprt->xid++;
 988 }
 989
 990 static inline void xprt_init_xid(struct rpc_xprt *xprt)
 991 {
 992         xprt->xid = net_random();
 993 }
 994
 995 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
 996 {
 997         struct rpc_rqst *req = task->tk_rqstp;
 998
 999         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1000         req->rq_task    = task;
1001         req->rq_xprt    = xprt;
1002         req->rq_buffer  = NULL;
1003         req->rq_xid     = xprt_alloc_xid(xprt);
1004         req->rq_release_snd_buf = NULL;
1005         xprt_reset_majortimeo(req);
1006         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1007                         req, ntohl(req->rq_xid));
1008 }
1009
1010 /**
1011  * xprt_release - release an RPC request slot
1012  * @task: task which is finished with the slot
1013  *
1014  */
1015 void xprt_release(struct rpc_task *task)
1016 {
1017         struct rpc_xprt *xprt;
1018         struct rpc_rqst *req;
1019
1020         if (!(req = task->tk_rqstp))
1021                 return;
1022
1023         xprt = req->rq_xprt;
1024         rpc_count_iostats(task);
1025         spin_lock_bh(&xprt->transport_lock);
1026         xprt->ops->release_xprt(xprt, task);
1027         if (xprt->ops->release_request)
1028                 xprt->ops->release_request(task);
1029         if (!list_empty(&req->rq_list))
1030                 list_del(&req->rq_list);
1031         xprt->last_used = jiffies;
1032         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1033                 mod_timer(&xprt->timer,
1034                                 xprt->last_used + xprt->idle_timeout);
1035         spin_unlock_bh(&xprt->transport_lock);
1036         if (req->rq_buffer)
1037                 xprt->ops->buf_free(req->rq_buffer);
1038         task->tk_rqstp = NULL;
1039         if (req->rq_release_snd_buf)
1040                 req->rq_release_snd_buf(req);
1041
1042         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1043         if (likely(!bc_prealloc(req)))
1044                 xprt_free_slot(xprt, req);
1045         else
1046                 xprt_free_bc_request(req);
1047 }
1048
1049 /**
1050  * xprt_create_transport - create an RPC transport
1051  * @args: rpc transport creation arguments
1052  *
1053  */
1054 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1055 {
1056         struct rpc_xprt *xprt;
1057         struct rpc_rqst *req;
1058         struct xprt_class *t;
1059
1060         spin_lock(&xprt_list_lock);
1061         list_for_each_entry(t, &xprt_list, list) {
1062                 if (t->ident == args->ident) {
1063                         spin_unlock(&xprt_list_lock);
1064                         goto found;
1065                 }
1066         }
1067         spin_unlock(&xprt_list_lock);
1068         printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1069         return ERR_PTR(-EIO);
1070
1071 found:
1072         xprt = t->setup(args);
1073         if (IS_ERR(xprt)) {
1074                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1075                                 -PTR_ERR(xprt));
1076                 return xprt;
1077         }
1078
1079         kref_init(&xprt->kref);
1080         spin_lock_init(&xprt->transport_lock);
1081         spin_lock_init(&xprt->reserve_lock);
1082
1083         INIT_LIST_HEAD(&xprt->free);
1084         INIT_LIST_HEAD(&xprt->recv);
1085 #if defined(CONFIG_NFS_V4_1)
1086         spin_lock_init(&xprt->bc_pa_lock);
1087         INIT_LIST_HEAD(&xprt->bc_pa_list);
1088 #endif /* CONFIG_NFS_V4_1 */
1089
1090         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1091         if (xprt_has_timer(xprt))
1092                 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1093                             (unsigned long)xprt);
1094         else
1095                 init_timer(&xprt->timer);
1096         xprt->last_used = jiffies;
1097         xprt->cwnd = RPC_INITCWND;
1098         xprt->bind_index = 0;
1099
1100         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1101         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1102         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1103         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
1104         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1105
1106         /* initialize free list */
1107         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
1108                 list_add(&req->rq_list, &xprt->free);
1109
1110         xprt_init_xid(xprt);
1111
1112         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1113                         xprt->max_reqs);
1114         return xprt;
1115 }
1116
1117 /**
1118  * xprt_destroy - destroy an RPC transport, killing off all requests.
1119  * @kref: kref for the transport to destroy
1120  *
1121  */
1122 static void xprt_destroy(struct kref *kref)
1123 {
1124         struct rpc_xprt *xprt = container_of(kref, struct rpc_xprt, kref);
1125
1126         dprintk("RPC:       destroying transport %p\n", xprt);
1127         xprt->shutdown = 1;
1128         del_timer_sync(&xprt->timer);
1129
1130         rpc_destroy_wait_queue(&xprt->binding);
1131         rpc_destroy_wait_queue(&xprt->pending);
1132         rpc_destroy_wait_queue(&xprt->sending);
1133         rpc_destroy_wait_queue(&xprt->resend);
1134         rpc_destroy_wait_queue(&xprt->backlog);
1135         /*
1136          * Tear down transport state and free the rpc_xprt
1137          */
1138         xprt->ops->destroy(xprt);
1139 }
1140
1141 /**
1142  * xprt_put - release a reference to an RPC transport.
1143  * @xprt: pointer to the transport
1144  *
1145  */
1146 void xprt_put(struct rpc_xprt *xprt)
1147 {
1148         kref_put(&xprt->kref, xprt_destroy);
1149 }
1150
1151 /**
1152  * xprt_get - return a reference to an RPC transport.
1153  * @xprt: pointer to the transport
1154  *
1155  */
1156 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1157 {
1158         kref_get(&xprt->kref);
1159         return xprt;
1160 }