err.no Git - linux-2.6/blob - 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, it installs a timer that
  16  *      is run after the packet's timeout has expired.
  17  *  -   When a packet arrives, the data_ready handler walks the list of
  18  *      pending requests for that transport. If a matching XID is found, the
  19  *      caller is woken up, and the timer removed.
  20  *  -   When no reply arrives within the timeout interval, the timer is
  21  *      fired by the kernel and runs xprt_timer(). It either adjusts the
  22  *      timeout values (minor timeout) or wakes up the caller with a status
  23  *      of -ETIMEDOUT.
  24  *  -   When the caller receives a notification from RPC that a reply arrived,
  25  *      it should release the RPC slot, and process the reply.
  26  *      If the call timed out, it may choose to retry the operation by
  27  *      adjusting the initial timeout value, and simply calling rpc_call
  28  *      again.
  29  *
  30  *  Support for async RPC is done through a set of RPC-specific scheduling
  31  *  primitives that `transparently' work for processes as well as async
  32  *  tasks that rely on callbacks.
  33  *
  34  *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
  35  *
  36  *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
  37  */
  38
  39 #include <linux/module.h>
  40
  41 #include <linux/types.h>
  42 #include <linux/interrupt.h>
  43 #include <linux/workqueue.h>
  44 #include <linux/net.h>
  45
  46 #include <linux/sunrpc/clnt.h>
  47 #include <linux/sunrpc/metrics.h>
  48
  49 /*
  50  * Local variables
  51  */
  52
  53 #ifdef RPC_DEBUG
  54 # define RPCDBG_FACILITY        RPCDBG_XPRT
  55 #endif
  56
  57 /*
  58  * Local functions
  59  */
  60 static void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
  61 static inline void      do_xprt_reserve(struct rpc_task *);
  62 static void     xprt_connect_status(struct rpc_task *task);
  63 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
  64
  65 static DEFINE_SPINLOCK(xprt_list_lock);
  66 static LIST_HEAD(xprt_list);
  67
  68 /*
  69  * The transport code maintains an estimate on the maximum number of out-
  70  * standing RPC requests, using a smoothed version of the congestion
  71  * avoidance implemented in 44BSD. This is basically the Van Jacobson
  72  * congestion algorithm: If a retransmit occurs, the congestion window is
  73  * halved; otherwise, it is incremented by 1/cwnd when
  74  *
  75  *      -       a reply is received and
  76  *      -       a full number of requests are outstanding and
  77  *      -       the congestion window hasn't been updated recently.
  78  */
  79 #define RPC_CWNDSHIFT           (8U)
  80 #define RPC_CWNDSCALE           (1U << RPC_CWNDSHIFT)
  81 #define RPC_INITCWND            RPC_CWNDSCALE
  82 #define RPC_MAXCWND(xprt)       ((xprt)->max_reqs << RPC_CWNDSHIFT)
  83
  84 #define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
  85
  86 /**
  87  * xprt_register_transport - register a transport implementation
  88  * @transport: transport to register
  89  *
  90  * If a transport implementation is loaded as a kernel module, it can
  91  * call this interface to make itself known to the RPC client.
  92  *
  93  * Returns:
  94  * 0:           transport successfully registered
  95  * -EEXIST:     transport already registered
  96  * -EINVAL:     transport module being unloaded
  97  */
  98 int xprt_register_transport(struct xprt_class *transport)
  99 {
 100         struct xprt_class *t;
 101         int result;
 102
 103         result = -EEXIST;
 104         spin_lock(&xprt_list_lock);
 105         list_for_each_entry(t, &xprt_list, list) {
 106                 /* don't register the same transport class twice */
 107                 if (t->ident == transport->ident)
 108                         goto out;
 109         }
 110
 111         result = -EINVAL;
 112         if (try_module_get(THIS_MODULE)) {
 113                 list_add_tail(&transport->list, &xprt_list);
 114                 printk(KERN_INFO "RPC: Registered %s transport module.\n",
 115                         transport->name);
 116                 result = 0;
 117         }
 118
 119 out:
 120         spin_unlock(&xprt_list_lock);
 121         return result;
 122 }
 123 EXPORT_SYMBOL_GPL(xprt_register_transport);
 124
 125 /**
 126  * xprt_unregister_transport - unregister a transport implementation
 127  * @transport: transport to unregister
 128  *
 129  * Returns:
 130  * 0:           transport successfully unregistered
 131  * -ENOENT:     transport never registered
 132  */
 133 int xprt_unregister_transport(struct xprt_class *transport)
 134 {
 135         struct xprt_class *t;
 136         int result;
 137
 138         result = 0;
 139         spin_lock(&xprt_list_lock);
 140         list_for_each_entry(t, &xprt_list, list) {
 141                 if (t == transport) {
 142                         printk(KERN_INFO
 143                                 "RPC: Unregistered %s transport module.\n",
 144                                 transport->name);
 145                         list_del_init(&transport->list);
 146                         module_put(THIS_MODULE);
 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_reserve_xprt - serialize write access to transports
 160  * @task: task that is requesting access to the transport
 161  *
 162  * This prevents mixing the payload of separate requests, and prevents
 163  * transport connects from colliding with writes.  No congestion control
 164  * is provided.
 165  */
 166 int xprt_reserve_xprt(struct rpc_task *task)
 167 {
 168         struct rpc_xprt *xprt = task->tk_xprt;
 169         struct rpc_rqst *req = task->tk_rqstp;
 170
 171         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 172                 if (task == xprt->snd_task)
 173                         return 1;
 174                 if (task == NULL)
 175                         return 0;
 176                 goto out_sleep;
 177         }
 178         xprt->snd_task = task;
 179         if (req) {
 180                 req->rq_bytes_sent = 0;
 181                 req->rq_ntrans++;
 182         }
 183         return 1;
 184
 185 out_sleep:
 186         dprintk("RPC: %5u failed to lock transport %p\n",
 187                         task->tk_pid, xprt);
 188         task->tk_timeout = 0;
 189         task->tk_status = -EAGAIN;
 190         if (req && req->rq_ntrans)
 191                 rpc_sleep_on(&xprt->resend, task, NULL);
 192         else
 193                 rpc_sleep_on(&xprt->sending, task, NULL);
 194         return 0;
 195 }
 196 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 197
 198 static void xprt_clear_locked(struct rpc_xprt *xprt)
 199 {
 200         xprt->snd_task = NULL;
 201         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
 202                 smp_mb__before_clear_bit();
 203                 clear_bit(XPRT_LOCKED, &xprt->state);
 204                 smp_mb__after_clear_bit();
 205         } else
 206                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 207 }
 208
 209 /*
 210  * xprt_reserve_xprt_cong - serialize write access to transports
 211  * @task: task that is requesting access to the transport
 212  *
 213  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 214  * integrated into the decision of whether a request is allowed to be
 215  * woken up and given access to the transport.
 216  */
 217 int xprt_reserve_xprt_cong(struct rpc_task *task)
 218 {
 219         struct rpc_xprt *xprt = task->tk_xprt;
 220         struct rpc_rqst *req = task->tk_rqstp;
 221
 222         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 223                 if (task == xprt->snd_task)
 224                         return 1;
 225                 goto out_sleep;
 226         }
 227         if (__xprt_get_cong(xprt, task)) {
 228                 xprt->snd_task = task;
 229                 if (req) {
 230                         req->rq_bytes_sent = 0;
 231                         req->rq_ntrans++;
 232                 }
 233                 return 1;
 234         }
 235         xprt_clear_locked(xprt);
 236 out_sleep:
 237         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
 238         task->tk_timeout = 0;
 239         task->tk_status = -EAGAIN;
 240         if (req && req->rq_ntrans)
 241                 rpc_sleep_on(&xprt->resend, task, NULL);
 242         else
 243                 rpc_sleep_on(&xprt->sending, task, NULL);
 244         return 0;
 245 }
 246 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 247
 248 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 249 {
 250         int retval;
 251
 252         spin_lock_bh(&xprt->transport_lock);
 253         retval = xprt->ops->reserve_xprt(task);
 254         spin_unlock_bh(&xprt->transport_lock);
 255         return retval;
 256 }
 257
 258 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 259 {
 260         struct rpc_task *task;
 261         struct rpc_rqst *req;
 262
 263         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 264                 return;
 265
 266         task = rpc_wake_up_next(&xprt->resend);
 267         if (!task) {
 268                 task = rpc_wake_up_next(&xprt->sending);
 269                 if (!task)
 270                         goto out_unlock;
 271         }
 272
 273         req = task->tk_rqstp;
 274         xprt->snd_task = task;
 275         if (req) {
 276                 req->rq_bytes_sent = 0;
 277                 req->rq_ntrans++;
 278         }
 279         return;
 280
 281 out_unlock:
 282         xprt_clear_locked(xprt);
 283 }
 284
 285 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 286 {
 287         struct rpc_task *task;
 288
 289         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 290                 return;
 291         if (RPCXPRT_CONGESTED(xprt))
 292                 goto out_unlock;
 293         task = rpc_wake_up_next(&xprt->resend);
 294         if (!task) {
 295                 task = rpc_wake_up_next(&xprt->sending);
 296                 if (!task)
 297                         goto out_unlock;
 298         }
 299         if (__xprt_get_cong(xprt, task)) {
 300                 struct rpc_rqst *req = task->tk_rqstp;
 301                 xprt->snd_task = task;
 302                 if (req) {
 303                         req->rq_bytes_sent = 0;
 304                         req->rq_ntrans++;
 305                 }
 306                 return;
 307         }
 308 out_unlock:
 309         xprt_clear_locked(xprt);
 310 }
 311
 312 /**
 313  * xprt_release_xprt - allow other requests to use a transport
 314  * @xprt: transport with other tasks potentially waiting
 315  * @task: task that is releasing access to the transport
 316  *
 317  * Note that "task" can be NULL.  No congestion control is provided.
 318  */
 319 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 320 {
 321         if (xprt->snd_task == task) {
 322                 xprt_clear_locked(xprt);
 323                 __xprt_lock_write_next(xprt);
 324         }
 325 }
 326 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 327
 328 /**
 329  * xprt_release_xprt_cong - allow other requests to use a transport
 330  * @xprt: transport with other tasks potentially waiting
 331  * @task: task that is releasing access to the transport
 332  *
 333  * Note that "task" can be NULL.  Another task is awoken to use the
 334  * transport if the transport's congestion window allows it.
 335  */
 336 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 337 {
 338         if (xprt->snd_task == task) {
 339                 xprt_clear_locked(xprt);
 340                 __xprt_lock_write_next_cong(xprt);
 341         }
 342 }
 343 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 344
 345 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 346 {
 347         spin_lock_bh(&xprt->transport_lock);
 348         xprt->ops->release_xprt(xprt, task);
 349         spin_unlock_bh(&xprt->transport_lock);
 350 }
 351
 352 /*
 353  * Van Jacobson congestion avoidance. Check if the congestion window
 354  * overflowed. Put the task to sleep if this is the case.
 355  */
 356 static int
 357 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 358 {
 359         struct rpc_rqst *req = task->tk_rqstp;
 360
 361         if (req->rq_cong)
 362                 return 1;
 363         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
 364                         task->tk_pid, xprt->cong, xprt->cwnd);
 365         if (RPCXPRT_CONGESTED(xprt))
 366                 return 0;
 367         req->rq_cong = 1;
 368         xprt->cong += RPC_CWNDSCALE;
 369         return 1;
 370 }
 371
 372 /*
 373  * Adjust the congestion window, and wake up the next task
 374  * that has been sleeping due to congestion
 375  */
 376 static void
 377 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 378 {
 379         if (!req->rq_cong)
 380                 return;
 381         req->rq_cong = 0;
 382         xprt->cong -= RPC_CWNDSCALE;
 383         __xprt_lock_write_next_cong(xprt);
 384 }
 385
 386 /**
 387  * xprt_release_rqst_cong - housekeeping when request is complete
 388  * @task: RPC request that recently completed
 389  *
 390  * Useful for transports that require congestion control.
 391  */
 392 void xprt_release_rqst_cong(struct rpc_task *task)
 393 {
 394         __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
 395 }
 396 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 397
 398 /**
 399  * xprt_adjust_cwnd - adjust transport congestion window
 400  * @task: recently completed RPC request used to adjust window
 401  * @result: result code of completed RPC request
 402  *
 403  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
 404  */
 405 void xprt_adjust_cwnd(struct rpc_task *task, int result)
 406 {
 407         struct rpc_rqst *req = task->tk_rqstp;
 408         struct rpc_xprt *xprt = task->tk_xprt;
 409         unsigned long cwnd = xprt->cwnd;
 410
 411         if (result >= 0 && cwnd <= xprt->cong) {
 412                 /* The (cwnd >> 1) term makes sure
 413                  * the result gets rounded properly. */
 414                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 415                 if (cwnd > RPC_MAXCWND(xprt))
 416                         cwnd = RPC_MAXCWND(xprt);
 417                 __xprt_lock_write_next_cong(xprt);
 418         } else if (result == -ETIMEDOUT) {
 419                 cwnd >>= 1;
 420                 if (cwnd < RPC_CWNDSCALE)
 421                         cwnd = RPC_CWNDSCALE;
 422         }
 423         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 424                         xprt->cong, xprt->cwnd, cwnd);
 425         xprt->cwnd = cwnd;
 426         __xprt_put_cong(xprt, req);
 427 }
 428 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 429
 430 /**
 431  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 432  * @xprt: transport with waiting tasks
 433  * @status: result code to plant in each task before waking it
 434  *
 435  */
 436 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 437 {
 438         if (status < 0)
 439                 rpc_wake_up_status(&xprt->pending, status);
 440         else
 441                 rpc_wake_up(&xprt->pending);
 442 }
 443 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 444
 445 /**
 446  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 447  * @task: task to be put to sleep
 448  * @action: function pointer to be executed after wait
 449  */
 450 void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
 451 {
 452         struct rpc_rqst *req = task->tk_rqstp;
 453         struct rpc_xprt *xprt = req->rq_xprt;
 454
 455         task->tk_timeout = req->rq_timeout;
 456         rpc_sleep_on(&xprt->pending, task, action);
 457 }
 458 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 459
 460 /**
 461  * xprt_write_space - wake the task waiting for transport output buffer space
 462  * @xprt: transport with waiting tasks
 463  *
 464  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 465  */
 466 void xprt_write_space(struct rpc_xprt *xprt)
 467 {
 468         if (unlikely(xprt->shutdown))
 469                 return;
 470
 471         spin_lock_bh(&xprt->transport_lock);
 472         if (xprt->snd_task) {
 473                 dprintk("RPC:       write space: waking waiting task on "
 474                                 "xprt %p\n", xprt);
 475                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
 476         }
 477         spin_unlock_bh(&xprt->transport_lock);
 478 }
 479 EXPORT_SYMBOL_GPL(xprt_write_space);
 480
 481 /**
 482  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 483  * @task: task whose timeout is to be set
 484  *
 485  * Set a request's retransmit timeout based on the transport's
 486  * default timeout parameters.  Used by transports that don't adjust
 487  * the retransmit timeout based on round-trip time estimation.
 488  */
 489 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 490 {
 491         task->tk_timeout = task->tk_rqstp->rq_timeout;
 492 }
 493 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
 494
 495 /*
 496  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 497  * @task: task whose timeout is to be set
 498  *
 499  * Set a request's retransmit timeout using the RTT estimator.
 500  */
 501 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 502 {
 503         int timer = task->tk_msg.rpc_proc->p_timer;
 504         struct rpc_clnt *clnt = task->tk_client;
 505         struct rpc_rtt *rtt = clnt->cl_rtt;
 506         struct rpc_rqst *req = task->tk_rqstp;
 507         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
 508
 509         task->tk_timeout = rpc_calc_rto(rtt, timer);
 510         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 511         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 512                 task->tk_timeout = max_timeout;
 513 }
 514 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 515
 516 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 517 {
 518         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 519
 520         req->rq_majortimeo = req->rq_timeout;
 521         if (to->to_exponential)
 522                 req->rq_majortimeo <<= to->to_retries;
 523         else
 524                 req->rq_majortimeo += to->to_increment * to->to_retries;
 525         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 526                 req->rq_majortimeo = to->to_maxval;
 527         req->rq_majortimeo += jiffies;
 528 }
 529
 530 /**
 531  * xprt_adjust_timeout - adjust timeout values for next retransmit
 532  * @req: RPC request containing parameters to use for the adjustment
 533  *
 534  */
 535 int xprt_adjust_timeout(struct rpc_rqst *req)
 536 {
 537         struct rpc_xprt *xprt = req->rq_xprt;
 538         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 539         int status = 0;
 540
 541         if (time_before(jiffies, req->rq_majortimeo)) {
 542                 if (to->to_exponential)
 543                         req->rq_timeout <<= 1;
 544                 else
 545                         req->rq_timeout += to->to_increment;
 546                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 547                         req->rq_timeout = to->to_maxval;
 548                 req->rq_retries++;
 549         } else {
 550                 req->rq_timeout = to->to_initval;
 551                 req->rq_retries = 0;
 552                 xprt_reset_majortimeo(req);
 553                 /* Reset the RTT counters == "slow start" */
 554                 spin_lock_bh(&xprt->transport_lock);
 555                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 556                 spin_unlock_bh(&xprt->transport_lock);
 557                 status = -ETIMEDOUT;
 558         }
 559
 560         if (req->rq_timeout == 0) {
 561                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 562                 req->rq_timeout = 5 * HZ;
 563         }
 564         return status;
 565 }
 566
 567 static void xprt_autoclose(struct work_struct *work)
 568 {
 569         struct rpc_xprt *xprt =
 570                 container_of(work, struct rpc_xprt, task_cleanup);
 571
 572         xprt->ops->close(xprt);
 573         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 574         xprt_release_write(xprt, NULL);
 575 }
 576
 577 /**
 578  * xprt_disconnect_done - mark a transport as disconnected
 579  * @xprt: transport to flag for disconnect
 580  *
 581  */
 582 void xprt_disconnect_done(struct rpc_xprt *xprt)
 583 {
 584         dprintk("RPC:       disconnected transport %p\n", xprt);
 585         spin_lock_bh(&xprt->transport_lock);
 586         xprt_clear_connected(xprt);
 587         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 588         spin_unlock_bh(&xprt->transport_lock);
 589 }
 590 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 591
 592 /**
 593  * xprt_force_disconnect - force a transport to disconnect
 594  * @xprt: transport to disconnect
 595  *
 596  */
 597 void xprt_force_disconnect(struct rpc_xprt *xprt)
 598 {
 599         /* Don't race with the test_bit() in xprt_clear_locked() */
 600         spin_lock_bh(&xprt->transport_lock);
 601         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 602         /* Try to schedule an autoclose RPC call */
 603         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 604                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 605         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 606         spin_unlock_bh(&xprt->transport_lock);
 607 }
 608
 609 /**
 610  * xprt_conditional_disconnect - force a transport to disconnect
 611  * @xprt: transport to disconnect
 612  * @cookie: 'connection cookie'
 613  *
 614  * This attempts to break the connection if and only if 'cookie' matches
 615  * the current transport 'connection cookie'. It ensures that we don't
 616  * try to break the connection more than once when we need to retransmit
 617  * a batch of RPC requests.
 618  *
 619  */
 620 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 621 {
 622         /* Don't race with the test_bit() in xprt_clear_locked() */
 623         spin_lock_bh(&xprt->transport_lock);
 624         if (cookie != xprt->connect_cookie)
 625                 goto out;
 626         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
 627                 goto out;
 628         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 629         /* Try to schedule an autoclose RPC call */
 630         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 631                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 632         xprt_wake_pending_tasks(xprt, -ENOTCONN);
 633 out:
 634         spin_unlock_bh(&xprt->transport_lock);
 635 }
 636
 637 static void
 638 xprt_init_autodisconnect(unsigned long data)
 639 {
 640         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 641
 642         spin_lock(&xprt->transport_lock);
 643         if (!list_empty(&xprt->recv) || xprt->shutdown)
 644                 goto out_abort;
 645         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 646                 goto out_abort;
 647         spin_unlock(&xprt->transport_lock);
 648         if (xprt_connecting(xprt))
 649                 xprt_release_write(xprt, NULL);
 650         else
 651                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 652         return;
 653 out_abort:
 654         spin_unlock(&xprt->transport_lock);
 655 }
 656
 657 /**
 658  * xprt_connect - schedule a transport connect operation
 659  * @task: RPC task that is requesting the connect
 660  *
 661  */
 662 void xprt_connect(struct rpc_task *task)
 663 {
 664         struct rpc_xprt *xprt = task->tk_xprt;
 665
 666         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 667                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 668
 669         if (!xprt_bound(xprt)) {
 670                 task->tk_status = -EIO;
 671                 return;
 672         }
 673         if (!xprt_lock_write(xprt, task))
 674                 return;
 675         if (xprt_connected(xprt))
 676                 xprt_release_write(xprt, task);
 677         else {
 678                 if (task->tk_rqstp)
 679                         task->tk_rqstp->rq_bytes_sent = 0;
 680
 681                 task->tk_timeout = xprt->connect_timeout;
 682                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
 683                 xprt->stat.connect_start = jiffies;
 684                 xprt->ops->connect(task);
 685         }
 686         return;
 687 }
 688
 689 static void xprt_connect_status(struct rpc_task *task)
 690 {
 691         struct rpc_xprt *xprt = task->tk_xprt;
 692
 693         if (task->tk_status == 0) {
 694                 xprt->stat.connect_count++;
 695                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 696                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 697                                 task->tk_pid);
 698                 return;
 699         }
 700
 701         switch (task->tk_status) {
 702         case -ENOTCONN:
 703                 dprintk("RPC: %5u xprt_connect_status: connection broken\n",
 704                                 task->tk_pid);
 705                 break;
 706         case -ETIMEDOUT:
 707                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 708                                 "out\n", task->tk_pid);
 709                 break;
 710         default:
 711                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 712                                 "server %s\n", task->tk_pid, -task->tk_status,
 713                                 task->tk_client->cl_server);
 714                 xprt_release_write(xprt, task);
 715                 task->tk_status = -EIO;
 716         }
 717 }
 718
 719 /**
 720  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 721  * @xprt: transport on which the original request was transmitted
 722  * @xid: RPC XID of incoming reply
 723  *
 724  */
 725 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 726 {
 727         struct list_head *pos;
 728
 729         list_for_each(pos, &xprt->recv) {
 730                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
 731                 if (entry->rq_xid == xid)
 732                         return entry;
 733         }
 734
 735         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 736                         ntohl(xid));
 737         xprt->stat.bad_xids++;
 738         return NULL;
 739 }
 740 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 741
 742 /**
 743  * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
 744  * @task: RPC request that recently completed
 745  *
 746  */
 747 void xprt_update_rtt(struct rpc_task *task)
 748 {
 749         struct rpc_rqst *req = task->tk_rqstp;
 750         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 751         unsigned timer = task->tk_msg.rpc_proc->p_timer;
 752
 753         if (timer) {
 754                 if (req->rq_ntrans == 1)
 755                         rpc_update_rtt(rtt, timer,
 756                                         (long)jiffies - req->rq_xtime);
 757                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 758         }
 759 }
 760 EXPORT_SYMBOL_GPL(xprt_update_rtt);
 761
 762 /**
 763  * xprt_complete_rqst - called when reply processing is complete
 764  * @task: RPC request that recently completed
 765  * @copied: actual number of bytes received from the transport
 766  *
 767  * Caller holds transport lock.
 768  */
 769 void xprt_complete_rqst(struct rpc_task *task, int copied)
 770 {
 771         struct rpc_rqst *req = task->tk_rqstp;
 772         struct rpc_xprt *xprt = req->rq_xprt;
 773
 774         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 775                         task->tk_pid, ntohl(req->rq_xid), copied);
 776
 777         xprt->stat.recvs++;
 778         task->tk_rtt = (long)jiffies - req->rq_xtime;
 779
 780         list_del_init(&req->rq_list);
 781         req->rq_private_buf.len = copied;
 782         /* Ensure all writes are done before we update req->rq_received */
 783         smp_wmb();
 784         req->rq_received = copied;
 785         rpc_wake_up_queued_task(&xprt->pending, task);
 786 }
 787 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
 788
 789 static void xprt_timer(struct rpc_task *task)
 790 {
 791         struct rpc_rqst *req = task->tk_rqstp;
 792         struct rpc_xprt *xprt = req->rq_xprt;
 793
 794         if (task->tk_status != -ETIMEDOUT)
 795                 return;
 796         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
 797
 798         spin_lock_bh(&xprt->transport_lock);
 799         if (!req->rq_received) {
 800                 if (xprt->ops->timer)
 801                         xprt->ops->timer(task);
 802         } else
 803                 task->tk_status = 0;
 804         spin_unlock_bh(&xprt->transport_lock);
 805 }
 806
 807 /**
 808  * xprt_prepare_transmit - reserve the transport before sending a request
 809  * @task: RPC task about to send a request
 810  *
 811  */
 812 int xprt_prepare_transmit(struct rpc_task *task)
 813 {
 814         struct rpc_rqst *req = task->tk_rqstp;
 815         struct rpc_xprt *xprt = req->rq_xprt;
 816         int err = 0;
 817
 818         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 819
 820         spin_lock_bh(&xprt->transport_lock);
 821         if (req->rq_received && !req->rq_bytes_sent) {
 822                 err = req->rq_received;
 823                 goto out_unlock;
 824         }
 825         if (!xprt->ops->reserve_xprt(task)) {
 826                 err = -EAGAIN;
 827                 goto out_unlock;
 828         }
 829
 830         if (!xprt_connected(xprt)) {
 831                 err = -ENOTCONN;
 832                 goto out_unlock;
 833         }
 834 out_unlock:
 835         spin_unlock_bh(&xprt->transport_lock);
 836         return err;
 837 }
 838
 839 void xprt_end_transmit(struct rpc_task *task)
 840 {
 841         xprt_release_write(task->tk_xprt, task);
 842 }
 843
 844 /**
 845  * xprt_transmit - send an RPC request on a transport
 846  * @task: controlling RPC task
 847  *
 848  * We have to copy the iovec because sendmsg fiddles with its contents.
 849  */
 850 void xprt_transmit(struct rpc_task *task)
 851 {
 852         struct rpc_rqst *req = task->tk_rqstp;
 853         struct rpc_xprt *xprt = req->rq_xprt;
 854         int status;
 855
 856         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 857
 858         if (!req->rq_received) {
 859                 if (list_empty(&req->rq_list)) {
 860                         spin_lock_bh(&xprt->transport_lock);
 861                         /* Update the softirq receive buffer */
 862                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 863                                         sizeof(req->rq_private_buf));
 864                         /* Add request to the receive list */
 865                         list_add_tail(&req->rq_list, &xprt->recv);
 866                         spin_unlock_bh(&xprt->transport_lock);
 867                         xprt_reset_majortimeo(req);
 868                         /* Turn off autodisconnect */
 869                         del_singleshot_timer_sync(&xprt->timer);
 870                 }
 871         } else if (!req->rq_bytes_sent)
 872                 return;
 873
 874         req->rq_connect_cookie = xprt->connect_cookie;
 875         req->rq_xtime = jiffies;
 876         status = xprt->ops->send_request(task);
 877         if (status == 0) {
 878                 dprintk("RPC: %5u xmit complete\n", task->tk_pid);
 879                 spin_lock_bh(&xprt->transport_lock);
 880
 881                 xprt->ops->set_retrans_timeout(task);
 882
 883                 xprt->stat.sends++;
 884                 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
 885                 xprt->stat.bklog_u += xprt->backlog.qlen;
 886
 887                 /* Don't race with disconnect */
 888                 if (!xprt_connected(xprt))
 889                         task->tk_status = -ENOTCONN;
 890                 else if (!req->rq_received)
 891                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
 892                 spin_unlock_bh(&xprt->transport_lock);
 893                 return;
 894         }
 895
 896         /* Note: at this point, task->tk_sleeping has not yet been set,
 897          *       hence there is no danger of the waking up task being put on
 898          *       schedq, and being picked up by a parallel run of rpciod().
 899          */
 900         task->tk_status = status;
 901         if (status == -ECONNREFUSED)
 902                 rpc_sleep_on(&xprt->sending, task, NULL);
 903 }
 904
 905 static inline void do_xprt_reserve(struct rpc_task *task)
 906 {
 907         struct rpc_xprt *xprt = task->tk_xprt;
 908
 909         task->tk_status = 0;
 910         if (task->tk_rqstp)
 911                 return;
 912         if (!list_empty(&xprt->free)) {
 913                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 914                 list_del_init(&req->rq_list);
 915                 task->tk_rqstp = req;
 916                 xprt_request_init(task, xprt);
 917                 return;
 918         }
 919         dprintk("RPC:       waiting for request slot\n");
 920         task->tk_status = -EAGAIN;
 921         task->tk_timeout = 0;
 922         rpc_sleep_on(&xprt->backlog, task, NULL);
 923 }
 924
 925 /**
 926  * xprt_reserve - allocate an RPC request slot
 927  * @task: RPC task requesting a slot allocation
 928  *
 929  * If no more slots are available, place the task on the transport's
 930  * backlog queue.
 931  */
 932 void xprt_reserve(struct rpc_task *task)
 933 {
 934         struct rpc_xprt *xprt = task->tk_xprt;
 935
 936         task->tk_status = -EIO;
 937         spin_lock(&xprt->reserve_lock);
 938         do_xprt_reserve(task);
 939         spin_unlock(&xprt->reserve_lock);
 940 }
 941
 942 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
 943 {
 944         return xprt->xid++;
 945 }
 946
 947 static inline void xprt_init_xid(struct rpc_xprt *xprt)
 948 {
 949         xprt->xid = net_random();
 950 }
 951
 952 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
 953 {
 954         struct rpc_rqst *req = task->tk_rqstp;
 955
 956         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
 957         req->rq_task    = task;
 958         req->rq_xprt    = xprt;
 959         req->rq_buffer  = NULL;
 960         req->rq_xid     = xprt_alloc_xid(xprt);
 961         req->rq_release_snd_buf = NULL;
 962         xprt_reset_majortimeo(req);
 963         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
 964                         req, ntohl(req->rq_xid));
 965 }
 966
 967 /**
 968  * xprt_release - release an RPC request slot
 969  * @task: task which is finished with the slot
 970  *
 971  */
 972 void xprt_release(struct rpc_task *task)
 973 {
 974         struct rpc_xprt *xprt = task->tk_xprt;
 975         struct rpc_rqst *req;
 976
 977         if (!(req = task->tk_rqstp))
 978                 return;
 979         rpc_count_iostats(task);
 980         spin_lock_bh(&xprt->transport_lock);
 981         xprt->ops->release_xprt(xprt, task);
 982         if (xprt->ops->release_request)
 983                 xprt->ops->release_request(task);
 984         if (!list_empty(&req->rq_list))
 985                 list_del(&req->rq_list);
 986         xprt->last_used = jiffies;
 987         if (list_empty(&xprt->recv))
 988                 mod_timer(&xprt->timer,
 989                                 xprt->last_used + xprt->idle_timeout);
 990         spin_unlock_bh(&xprt->transport_lock);
 991         xprt->ops->buf_free(req->rq_buffer);
 992         task->tk_rqstp = NULL;
 993         if (req->rq_release_snd_buf)
 994                 req->rq_release_snd_buf(req);
 995         memset(req, 0, sizeof(*req));   /* mark unused */
 996
 997         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
 998
 999         spin_lock(&xprt->reserve_lock);
1000         list_add(&req->rq_list, &xprt->free);
1001         rpc_wake_up_next(&xprt->backlog);
1002         spin_unlock(&xprt->reserve_lock);
1003 }
1004
1005 /**
1006  * xprt_create_transport - create an RPC transport
1007  * @args: rpc transport creation arguments
1008  *
1009  */
1010 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1011 {
1012         struct rpc_xprt *xprt;
1013         struct rpc_rqst *req;
1014         struct xprt_class *t;
1015
1016         spin_lock(&xprt_list_lock);
1017         list_for_each_entry(t, &xprt_list, list) {
1018                 if (t->ident == args->ident) {
1019                         spin_unlock(&xprt_list_lock);
1020                         goto found;
1021                 }
1022         }
1023         spin_unlock(&xprt_list_lock);
1024         printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1025         return ERR_PTR(-EIO);
1026
1027 found:
1028         xprt = t->setup(args);
1029         if (IS_ERR(xprt)) {
1030                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1031                                 -PTR_ERR(xprt));
1032                 return xprt;
1033         }
1034
1035         kref_init(&xprt->kref);
1036         spin_lock_init(&xprt->transport_lock);
1037         spin_lock_init(&xprt->reserve_lock);
1038
1039         INIT_LIST_HEAD(&xprt->free);
1040         INIT_LIST_HEAD(&xprt->recv);
1041         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1042         setup_timer(&xprt->timer, xprt_init_autodisconnect,
1043                         (unsigned long)xprt);
1044         xprt->last_used = jiffies;
1045         xprt->cwnd = RPC_INITCWND;
1046         xprt->bind_index = 0;
1047
1048         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1049         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1050         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1051         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
1052         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1053
1054         /* initialize free list */
1055         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
1056                 list_add(&req->rq_list, &xprt->free);
1057
1058         xprt_init_xid(xprt);
1059
1060         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1061                         xprt->max_reqs);
1062
1063         return xprt;
1064 }
1065
1066 /**
1067  * xprt_destroy - destroy an RPC transport, killing off all requests.
1068  * @kref: kref for the transport to destroy
1069  *
1070  */
1071 static void xprt_destroy(struct kref *kref)
1072 {
1073         struct rpc_xprt *xprt = container_of(kref, struct rpc_xprt, kref);
1074
1075         dprintk("RPC:       destroying transport %p\n", xprt);
1076         xprt->shutdown = 1;
1077         del_timer_sync(&xprt->timer);
1078
1079         rpc_destroy_wait_queue(&xprt->binding);
1080         rpc_destroy_wait_queue(&xprt->pending);
1081         rpc_destroy_wait_queue(&xprt->sending);
1082         rpc_destroy_wait_queue(&xprt->resend);
1083         rpc_destroy_wait_queue(&xprt->backlog);
1084         /*
1085          * Tear down transport state and free the rpc_xprt
1086          */
1087         xprt->ops->destroy(xprt);
1088 }
1089
1090 /**
1091  * xprt_put - release a reference to an RPC transport.
1092  * @xprt: pointer to the transport
1093  *
1094  */
1095 void xprt_put(struct rpc_xprt *xprt)
1096 {
1097         kref_put(&xprt->kref, xprt_destroy);
1098 }
1099
1100 /**
1101  * xprt_get - return a reference to an RPC transport.
1102  * @xprt: pointer to the transport
1103  *
1104  */
1105 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1106 {
1107         kref_get(&xprt->kref);
1108         return xprt;
1109 }