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         int result;
 170
 171         result = 0;
 172         spin_lock(&xprt_list_lock);
 173         list_for_each_entry(t, &xprt_list, list) {
 174                 if (strcmp(t->name, transport_name) == 0) {
 175                         spin_unlock(&xprt_list_lock);
 176                         goto out;
 177                 }
 178         }
 179         spin_unlock(&xprt_list_lock);
 180         result = request_module("xprt%s", transport_name);
 181 out:
 182         return result;
 183 }
 184 EXPORT_SYMBOL_GPL(xprt_load_transport);
 185
 186 /**
 187  * xprt_reserve_xprt - serialize write access to transports
 188  * @task: task that is requesting access to the transport
 189  *
 190  * This prevents mixing the payload of separate requests, and prevents
 191  * transport connects from colliding with writes.  No congestion control
 192  * is provided.
 193  */
 194 int xprt_reserve_xprt(struct rpc_task *task)
 195 {
 196         struct rpc_rqst *req = task->tk_rqstp;
 197         struct rpc_xprt *xprt = req->rq_xprt;
 198
 199         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 200                 if (task == xprt->snd_task)
 201                         return 1;
 202                 goto out_sleep;
 203         }
 204         xprt->snd_task = task;
 205         req->rq_bytes_sent = 0;
 206         req->rq_ntrans++;
 207
 208         return 1;
 209
 210 out_sleep:
 211         dprintk("RPC: %5u failed to lock transport %p\n",
 212                         task->tk_pid, xprt);
 213         task->tk_timeout = 0;
 214         task->tk_status = -EAGAIN;
 215         if (req->rq_ntrans)
 216                 rpc_sleep_on(&xprt->resend, task, NULL);
 217         else
 218                 rpc_sleep_on(&xprt->sending, task, NULL);
 219         return 0;
 220 }
 221 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
 222
 223 static void xprt_clear_locked(struct rpc_xprt *xprt)
 224 {
 225         xprt->snd_task = NULL;
 226         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
 227                 smp_mb__before_clear_bit();
 228                 clear_bit(XPRT_LOCKED, &xprt->state);
 229                 smp_mb__after_clear_bit();
 230         } else
 231                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 232 }
 233
 234 /*
 235  * xprt_reserve_xprt_cong - serialize write access to transports
 236  * @task: task that is requesting access to the transport
 237  *
 238  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
 239  * integrated into the decision of whether a request is allowed to be
 240  * woken up and given access to the transport.
 241  */
 242 int xprt_reserve_xprt_cong(struct rpc_task *task)
 243 {
 244         struct rpc_xprt *xprt = task->tk_xprt;
 245         struct rpc_rqst *req = task->tk_rqstp;
 246
 247         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
 248                 if (task == xprt->snd_task)
 249                         return 1;
 250                 goto out_sleep;
 251         }
 252         if (__xprt_get_cong(xprt, task)) {
 253                 xprt->snd_task = task;
 254                 if (req) {
 255                         req->rq_bytes_sent = 0;
 256                         req->rq_ntrans++;
 257                 }
 258                 return 1;
 259         }
 260         xprt_clear_locked(xprt);
 261 out_sleep:
 262         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
 263         task->tk_timeout = 0;
 264         task->tk_status = -EAGAIN;
 265         if (req && req->rq_ntrans)
 266                 rpc_sleep_on(&xprt->resend, task, NULL);
 267         else
 268                 rpc_sleep_on(&xprt->sending, task, NULL);
 269         return 0;
 270 }
 271 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
 272
 273 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 274 {
 275         int retval;
 276
 277         spin_lock_bh(&xprt->transport_lock);
 278         retval = xprt->ops->reserve_xprt(task);
 279         spin_unlock_bh(&xprt->transport_lock);
 280         return retval;
 281 }
 282
 283 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
 284 {
 285         struct rpc_task *task;
 286         struct rpc_rqst *req;
 287
 288         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 289                 return;
 290
 291         task = rpc_wake_up_next(&xprt->resend);
 292         if (!task) {
 293                 task = rpc_wake_up_next(&xprt->sending);
 294                 if (!task)
 295                         goto out_unlock;
 296         }
 297
 298         req = task->tk_rqstp;
 299         xprt->snd_task = task;
 300         if (req) {
 301                 req->rq_bytes_sent = 0;
 302                 req->rq_ntrans++;
 303         }
 304         return;
 305
 306 out_unlock:
 307         xprt_clear_locked(xprt);
 308 }
 309
 310 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
 311 {
 312         struct rpc_task *task;
 313
 314         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 315                 return;
 316         if (RPCXPRT_CONGESTED(xprt))
 317                 goto out_unlock;
 318         task = rpc_wake_up_next(&xprt->resend);
 319         if (!task) {
 320                 task = rpc_wake_up_next(&xprt->sending);
 321                 if (!task)
 322                         goto out_unlock;
 323         }
 324         if (__xprt_get_cong(xprt, task)) {
 325                 struct rpc_rqst *req = task->tk_rqstp;
 326                 xprt->snd_task = task;
 327                 if (req) {
 328                         req->rq_bytes_sent = 0;
 329                         req->rq_ntrans++;
 330                 }
 331                 return;
 332         }
 333 out_unlock:
 334         xprt_clear_locked(xprt);
 335 }
 336
 337 /**
 338  * xprt_release_xprt - allow other requests to use a transport
 339  * @xprt: transport with other tasks potentially waiting
 340  * @task: task that is releasing access to the transport
 341  *
 342  * Note that "task" can be NULL.  No congestion control is provided.
 343  */
 344 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
 345 {
 346         if (xprt->snd_task == task) {
 347                 xprt_clear_locked(xprt);
 348                 __xprt_lock_write_next(xprt);
 349         }
 350 }
 351 EXPORT_SYMBOL_GPL(xprt_release_xprt);
 352
 353 /**
 354  * xprt_release_xprt_cong - allow other requests to use a transport
 355  * @xprt: transport with other tasks potentially waiting
 356  * @task: task that is releasing access to the transport
 357  *
 358  * Note that "task" can be NULL.  Another task is awoken to use the
 359  * transport if the transport's congestion window allows it.
 360  */
 361 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 362 {
 363         if (xprt->snd_task == task) {
 364                 xprt_clear_locked(xprt);
 365                 __xprt_lock_write_next_cong(xprt);
 366         }
 367 }
 368 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
 369
 370 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
 371 {
 372         spin_lock_bh(&xprt->transport_lock);
 373         xprt->ops->release_xprt(xprt, task);
 374         spin_unlock_bh(&xprt->transport_lock);
 375 }
 376
 377 /*
 378  * Van Jacobson congestion avoidance. Check if the congestion window
 379  * overflowed. Put the task to sleep if this is the case.
 380  */
 381 static int
 382 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
 383 {
 384         struct rpc_rqst *req = task->tk_rqstp;
 385
 386         if (req->rq_cong)
 387                 return 1;
 388         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
 389                         task->tk_pid, xprt->cong, xprt->cwnd);
 390         if (RPCXPRT_CONGESTED(xprt))
 391                 return 0;
 392         req->rq_cong = 1;
 393         xprt->cong += RPC_CWNDSCALE;
 394         return 1;
 395 }
 396
 397 /*
 398  * Adjust the congestion window, and wake up the next task
 399  * that has been sleeping due to congestion
 400  */
 401 static void
 402 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
 403 {
 404         if (!req->rq_cong)
 405                 return;
 406         req->rq_cong = 0;
 407         xprt->cong -= RPC_CWNDSCALE;
 408         __xprt_lock_write_next_cong(xprt);
 409 }
 410
 411 /**
 412  * xprt_release_rqst_cong - housekeeping when request is complete
 413  * @task: RPC request that recently completed
 414  *
 415  * Useful for transports that require congestion control.
 416  */
 417 void xprt_release_rqst_cong(struct rpc_task *task)
 418 {
 419         __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
 420 }
 421 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
 422
 423 /**
 424  * xprt_adjust_cwnd - adjust transport congestion window
 425  * @task: recently completed RPC request used to adjust window
 426  * @result: result code of completed RPC request
 427  *
 428  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
 429  */
 430 void xprt_adjust_cwnd(struct rpc_task *task, int result)
 431 {
 432         struct rpc_rqst *req = task->tk_rqstp;
 433         struct rpc_xprt *xprt = task->tk_xprt;
 434         unsigned long cwnd = xprt->cwnd;
 435
 436         if (result >= 0 && cwnd <= xprt->cong) {
 437                 /* The (cwnd >> 1) term makes sure
 438                  * the result gets rounded properly. */
 439                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
 440                 if (cwnd > RPC_MAXCWND(xprt))
 441                         cwnd = RPC_MAXCWND(xprt);
 442                 __xprt_lock_write_next_cong(xprt);
 443         } else if (result == -ETIMEDOUT) {
 444                 cwnd >>= 1;
 445                 if (cwnd < RPC_CWNDSCALE)
 446                         cwnd = RPC_CWNDSCALE;
 447         }
 448         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
 449                         xprt->cong, xprt->cwnd, cwnd);
 450         xprt->cwnd = cwnd;
 451         __xprt_put_cong(xprt, req);
 452 }
 453 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
 454
 455 /**
 456  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
 457  * @xprt: transport with waiting tasks
 458  * @status: result code to plant in each task before waking it
 459  *
 460  */
 461 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
 462 {
 463         if (status < 0)
 464                 rpc_wake_up_status(&xprt->pending, status);
 465         else
 466                 rpc_wake_up(&xprt->pending);
 467 }
 468 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
 469
 470 /**
 471  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
 472  * @task: task to be put to sleep
 473  * @action: function pointer to be executed after wait
 474  */
 475 void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
 476 {
 477         struct rpc_rqst *req = task->tk_rqstp;
 478         struct rpc_xprt *xprt = req->rq_xprt;
 479
 480         task->tk_timeout = req->rq_timeout;
 481         rpc_sleep_on(&xprt->pending, task, action);
 482 }
 483 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
 484
 485 /**
 486  * xprt_write_space - wake the task waiting for transport output buffer space
 487  * @xprt: transport with waiting tasks
 488  *
 489  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
 490  */
 491 void xprt_write_space(struct rpc_xprt *xprt)
 492 {
 493         if (unlikely(xprt->shutdown))
 494                 return;
 495
 496         spin_lock_bh(&xprt->transport_lock);
 497         if (xprt->snd_task) {
 498                 dprintk("RPC:       write space: waking waiting task on "
 499                                 "xprt %p\n", xprt);
 500                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
 501         }
 502         spin_unlock_bh(&xprt->transport_lock);
 503 }
 504 EXPORT_SYMBOL_GPL(xprt_write_space);
 505
 506 /**
 507  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
 508  * @task: task whose timeout is to be set
 509  *
 510  * Set a request's retransmit timeout based on the transport's
 511  * default timeout parameters.  Used by transports that don't adjust
 512  * the retransmit timeout based on round-trip time estimation.
 513  */
 514 void xprt_set_retrans_timeout_def(struct rpc_task *task)
 515 {
 516         task->tk_timeout = task->tk_rqstp->rq_timeout;
 517 }
 518 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
 519
 520 /*
 521  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
 522  * @task: task whose timeout is to be set
 523  *
 524  * Set a request's retransmit timeout using the RTT estimator.
 525  */
 526 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
 527 {
 528         int timer = task->tk_msg.rpc_proc->p_timer;
 529         struct rpc_clnt *clnt = task->tk_client;
 530         struct rpc_rtt *rtt = clnt->cl_rtt;
 531         struct rpc_rqst *req = task->tk_rqstp;
 532         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
 533
 534         task->tk_timeout = rpc_calc_rto(rtt, timer);
 535         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
 536         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
 537                 task->tk_timeout = max_timeout;
 538 }
 539 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
 540
 541 static void xprt_reset_majortimeo(struct rpc_rqst *req)
 542 {
 543         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 544
 545         req->rq_majortimeo = req->rq_timeout;
 546         if (to->to_exponential)
 547                 req->rq_majortimeo <<= to->to_retries;
 548         else
 549                 req->rq_majortimeo += to->to_increment * to->to_retries;
 550         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
 551                 req->rq_majortimeo = to->to_maxval;
 552         req->rq_majortimeo += jiffies;
 553 }
 554
 555 /**
 556  * xprt_adjust_timeout - adjust timeout values for next retransmit
 557  * @req: RPC request containing parameters to use for the adjustment
 558  *
 559  */
 560 int xprt_adjust_timeout(struct rpc_rqst *req)
 561 {
 562         struct rpc_xprt *xprt = req->rq_xprt;
 563         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
 564         int status = 0;
 565
 566         if (time_before(jiffies, req->rq_majortimeo)) {
 567                 if (to->to_exponential)
 568                         req->rq_timeout <<= 1;
 569                 else
 570                         req->rq_timeout += to->to_increment;
 571                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
 572                         req->rq_timeout = to->to_maxval;
 573                 req->rq_retries++;
 574         } else {
 575                 req->rq_timeout = to->to_initval;
 576                 req->rq_retries = 0;
 577                 xprt_reset_majortimeo(req);
 578                 /* Reset the RTT counters == "slow start" */
 579                 spin_lock_bh(&xprt->transport_lock);
 580                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
 581                 spin_unlock_bh(&xprt->transport_lock);
 582                 status = -ETIMEDOUT;
 583         }
 584
 585         if (req->rq_timeout == 0) {
 586                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
 587                 req->rq_timeout = 5 * HZ;
 588         }
 589         return status;
 590 }
 591
 592 static void xprt_autoclose(struct work_struct *work)
 593 {
 594         struct rpc_xprt *xprt =
 595                 container_of(work, struct rpc_xprt, task_cleanup);
 596
 597         xprt->ops->close(xprt);
 598         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
 599         xprt_release_write(xprt, NULL);
 600 }
 601
 602 /**
 603  * xprt_disconnect_done - mark a transport as disconnected
 604  * @xprt: transport to flag for disconnect
 605  *
 606  */
 607 void xprt_disconnect_done(struct rpc_xprt *xprt)
 608 {
 609         dprintk("RPC:       disconnected transport %p\n", xprt);
 610         spin_lock_bh(&xprt->transport_lock);
 611         xprt_clear_connected(xprt);
 612         xprt_wake_pending_tasks(xprt, -EAGAIN);
 613         spin_unlock_bh(&xprt->transport_lock);
 614 }
 615 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
 616
 617 /**
 618  * xprt_force_disconnect - force a transport to disconnect
 619  * @xprt: transport to disconnect
 620  *
 621  */
 622 void xprt_force_disconnect(struct rpc_xprt *xprt)
 623 {
 624         /* Don't race with the test_bit() in xprt_clear_locked() */
 625         spin_lock_bh(&xprt->transport_lock);
 626         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 627         /* Try to schedule an autoclose RPC call */
 628         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 629                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 630         xprt_wake_pending_tasks(xprt, -EAGAIN);
 631         spin_unlock_bh(&xprt->transport_lock);
 632 }
 633
 634 /**
 635  * xprt_conditional_disconnect - force a transport to disconnect
 636  * @xprt: transport to disconnect
 637  * @cookie: 'connection cookie'
 638  *
 639  * This attempts to break the connection if and only if 'cookie' matches
 640  * the current transport 'connection cookie'. It ensures that we don't
 641  * try to break the connection more than once when we need to retransmit
 642  * a batch of RPC requests.
 643  *
 644  */
 645 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
 646 {
 647         /* Don't race with the test_bit() in xprt_clear_locked() */
 648         spin_lock_bh(&xprt->transport_lock);
 649         if (cookie != xprt->connect_cookie)
 650                 goto out;
 651         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
 652                 goto out;
 653         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
 654         /* Try to schedule an autoclose RPC call */
 655         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 656                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
 657         xprt_wake_pending_tasks(xprt, -EAGAIN);
 658 out:
 659         spin_unlock_bh(&xprt->transport_lock);
 660 }
 661
 662 static void
 663 xprt_init_autodisconnect(unsigned long data)
 664 {
 665         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
 666
 667         spin_lock(&xprt->transport_lock);
 668         if (!list_empty(&xprt->recv) || xprt->shutdown)
 669                 goto out_abort;
 670         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
 671                 goto out_abort;
 672         spin_unlock(&xprt->transport_lock);
 673         set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
 674         queue_work(rpciod_workqueue, &xprt->task_cleanup);
 675         return;
 676 out_abort:
 677         spin_unlock(&xprt->transport_lock);
 678 }
 679
 680 /**
 681  * xprt_connect - schedule a transport connect operation
 682  * @task: RPC task that is requesting the connect
 683  *
 684  */
 685 void xprt_connect(struct rpc_task *task)
 686 {
 687         struct rpc_xprt *xprt = task->tk_xprt;
 688
 689         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
 690                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
 691
 692         if (!xprt_bound(xprt)) {
 693                 task->tk_status = -EAGAIN;
 694                 return;
 695         }
 696         if (!xprt_lock_write(xprt, task))
 697                 return;
 698
 699         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
 700                 xprt->ops->close(xprt);
 701
 702         if (xprt_connected(xprt))
 703                 xprt_release_write(xprt, task);
 704         else {
 705                 if (task->tk_rqstp)
 706                         task->tk_rqstp->rq_bytes_sent = 0;
 707
 708                 task->tk_timeout = task->tk_rqstp->rq_timeout;
 709                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
 710
 711                 if (test_bit(XPRT_CLOSING, &xprt->state))
 712                         return;
 713                 if (xprt_test_and_set_connecting(xprt))
 714                         return;
 715                 xprt->stat.connect_start = jiffies;
 716                 xprt->ops->connect(task);
 717         }
 718 }
 719
 720 static void xprt_connect_status(struct rpc_task *task)
 721 {
 722         struct rpc_xprt *xprt = task->tk_xprt;
 723
 724         if (task->tk_status == 0) {
 725                 xprt->stat.connect_count++;
 726                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
 727                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
 728                                 task->tk_pid);
 729                 return;
 730         }
 731
 732         switch (task->tk_status) {
 733         case -EAGAIN:
 734                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
 735                 break;
 736         case -ETIMEDOUT:
 737                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
 738                                 "out\n", task->tk_pid);
 739                 break;
 740         default:
 741                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
 742                                 "server %s\n", task->tk_pid, -task->tk_status,
 743                                 task->tk_client->cl_server);
 744                 xprt_release_write(xprt, task);
 745                 task->tk_status = -EIO;
 746         }
 747 }
 748
 749 /**
 750  * xprt_lookup_rqst - find an RPC request corresponding to an XID
 751  * @xprt: transport on which the original request was transmitted
 752  * @xid: RPC XID of incoming reply
 753  *
 754  */
 755 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
 756 {
 757         struct rpc_rqst *entry;
 758
 759         list_for_each_entry(entry, &xprt->recv, rq_list)
 760                 if (entry->rq_xid == xid)
 761                         return entry;
 762
 763         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
 764                         ntohl(xid));
 765         xprt->stat.bad_xids++;
 766         return NULL;
 767 }
 768 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
 769
 770 static void xprt_update_rtt(struct rpc_task *task)
 771 {
 772         struct rpc_rqst *req = task->tk_rqstp;
 773         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
 774         unsigned timer = task->tk_msg.rpc_proc->p_timer;
 775         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
 776
 777         if (timer) {
 778                 if (req->rq_ntrans == 1)
 779                         rpc_update_rtt(rtt, timer, m);
 780                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
 781         }
 782 }
 783
 784 /**
 785  * xprt_complete_rqst - called when reply processing is complete
 786  * @task: RPC request that recently completed
 787  * @copied: actual number of bytes received from the transport
 788  *
 789  * Caller holds transport lock.
 790  */
 791 void xprt_complete_rqst(struct rpc_task *task, int copied)
 792 {
 793         struct rpc_rqst *req = task->tk_rqstp;
 794         struct rpc_xprt *xprt = req->rq_xprt;
 795
 796         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
 797                         task->tk_pid, ntohl(req->rq_xid), copied);
 798
 799         xprt->stat.recvs++;
 800         req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
 801         if (xprt->ops->timer != NULL)
 802                 xprt_update_rtt(task);
 803
 804         list_del_init(&req->rq_list);
 805         req->rq_private_buf.len = copied;
 806         /* Ensure all writes are done before we update */
 807         /* req->rq_reply_bytes_recvd */
 808         smp_wmb();
 809         req->rq_reply_bytes_recvd = copied;
 810         rpc_wake_up_queued_task(&xprt->pending, task);
 811 }
 812 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
 813
 814 static void xprt_timer(struct rpc_task *task)
 815 {
 816         struct rpc_rqst *req = task->tk_rqstp;
 817         struct rpc_xprt *xprt = req->rq_xprt;
 818
 819         if (task->tk_status != -ETIMEDOUT)
 820                 return;
 821         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
 822
 823         spin_lock_bh(&xprt->transport_lock);
 824         if (!req->rq_reply_bytes_recvd) {
 825                 if (xprt->ops->timer)
 826                         xprt->ops->timer(task);
 827         } else
 828                 task->tk_status = 0;
 829         spin_unlock_bh(&xprt->transport_lock);
 830 }
 831
 832 static inline int xprt_has_timer(struct rpc_xprt *xprt)
 833 {
 834         return xprt->idle_timeout != 0;
 835 }
 836
 837 /**
 838  * xprt_prepare_transmit - reserve the transport before sending a request
 839  * @task: RPC task about to send a request
 840  *
 841  */
 842 int xprt_prepare_transmit(struct rpc_task *task)
 843 {
 844         struct rpc_rqst *req = task->tk_rqstp;
 845         struct rpc_xprt *xprt = req->rq_xprt;
 846         int err = 0;
 847
 848         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
 849
 850         spin_lock_bh(&xprt->transport_lock);
 851         if (req->rq_reply_bytes_recvd && !req->rq_bytes_sent) {
 852                 err = req->rq_reply_bytes_recvd;
 853                 goto out_unlock;
 854         }
 855         if (!xprt->ops->reserve_xprt(task))
 856                 err = -EAGAIN;
 857 out_unlock:
 858         spin_unlock_bh(&xprt->transport_lock);
 859         return err;
 860 }
 861
 862 void xprt_end_transmit(struct rpc_task *task)
 863 {
 864         xprt_release_write(task->tk_rqstp->rq_xprt, task);
 865 }
 866
 867 /**
 868  * xprt_transmit - send an RPC request on a transport
 869  * @task: controlling RPC task
 870  *
 871  * We have to copy the iovec because sendmsg fiddles with its contents.
 872  */
 873 void xprt_transmit(struct rpc_task *task)
 874 {
 875         struct rpc_rqst *req = task->tk_rqstp;
 876         struct rpc_xprt *xprt = req->rq_xprt;
 877         int status;
 878
 879         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 880
 881         if (!req->rq_reply_bytes_recvd) {
 882                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
 883                         /*
 884                          * Add to the list only if we're expecting a reply
 885                          */
 886                         spin_lock_bh(&xprt->transport_lock);
 887                         /* Update the softirq receive buffer */
 888                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
 889                                         sizeof(req->rq_private_buf));
 890                         /* Add request to the receive list */
 891                         list_add_tail(&req->rq_list, &xprt->recv);
 892                         spin_unlock_bh(&xprt->transport_lock);
 893                         xprt_reset_majortimeo(req);
 894                         /* Turn off autodisconnect */
 895                         del_singleshot_timer_sync(&xprt->timer);
 896                 }
 897         } else if (!req->rq_bytes_sent)
 898                 return;
 899
 900         req->rq_connect_cookie = xprt->connect_cookie;
 901         req->rq_xtime = ktime_get();
 902         status = xprt->ops->send_request(task);
 903         if (status != 0) {
 904                 task->tk_status = status;
 905                 return;
 906         }
 907
 908         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
 909         task->tk_flags |= RPC_TASK_SENT;
 910         spin_lock_bh(&xprt->transport_lock);
 911
 912         xprt->ops->set_retrans_timeout(task);
 913
 914         xprt->stat.sends++;
 915         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
 916         xprt->stat.bklog_u += xprt->backlog.qlen;
 917
 918         /* Don't race with disconnect */
 919         if (!xprt_connected(xprt))
 920                 task->tk_status = -ENOTCONN;
 921         else if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task)) {
 922                 /*
 923                  * Sleep on the pending queue since
 924                  * we're expecting a reply.
 925                  */
 926                 rpc_sleep_on(&xprt->pending, task, xprt_timer);
 927         }
 928         spin_unlock_bh(&xprt->transport_lock);
 929 }
 930
 931 static void xprt_alloc_slot(struct rpc_task *task)
 932 {
 933         struct rpc_xprt *xprt = task->tk_xprt;
 934
 935         task->tk_status = 0;
 936         if (task->tk_rqstp)
 937                 return;
 938         if (!list_empty(&xprt->free)) {
 939                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 940                 list_del_init(&req->rq_list);
 941                 task->tk_rqstp = req;
 942                 xprt_request_init(task, xprt);
 943                 return;
 944         }
 945         dprintk("RPC:       waiting for request slot\n");
 946         task->tk_status = -EAGAIN;
 947         task->tk_timeout = 0;
 948         rpc_sleep_on(&xprt->backlog, task, NULL);
 949 }
 950
 951 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
 952 {
 953         memset(req, 0, sizeof(*req));   /* mark unused */
 954
 955         spin_lock(&xprt->reserve_lock);
 956         list_add(&req->rq_list, &xprt->free);
 957         rpc_wake_up_next(&xprt->backlog);
 958         spin_unlock(&xprt->reserve_lock);
 959 }
 960
 961 struct rpc_xprt *xprt_alloc(struct net *net, int size, int max_req)
 962 {
 963         struct rpc_xprt *xprt;
 964
 965         xprt = kzalloc(size, GFP_KERNEL);
 966         if (xprt == NULL)
 967                 goto out;
 968         atomic_set(&xprt->count, 1);
 969
 970         xprt->max_reqs = max_req;
 971         xprt->slot = kcalloc(max_req, sizeof(struct rpc_rqst), GFP_KERNEL);
 972         if (xprt->slot == NULL)
 973                 goto out_free;
 974
 975         xprt->xprt_net = get_net(net);
 976         return xprt;
 977
 978 out_free:
 979         kfree(xprt);
 980 out:
 981         return NULL;
 982 }
 983 EXPORT_SYMBOL_GPL(xprt_alloc);
 984
 985 void xprt_free(struct rpc_xprt *xprt)
 986 {
 987         put_net(xprt->xprt_net);
 988         kfree(xprt->slot);
 989         kfree(xprt);
 990 }
 991 EXPORT_SYMBOL_GPL(xprt_free);
 992
 993 /**
 994  * xprt_reserve - allocate an RPC request slot
 995  * @task: RPC task requesting a slot allocation
 996  *
 997  * If no more slots are available, place the task on the transport's
 998  * backlog queue.
 999  */
1000 void xprt_reserve(struct rpc_task *task)
1001 {
1002         struct rpc_xprt *xprt = task->tk_xprt;
1003
1004         task->tk_status = -EIO;
1005         spin_lock(&xprt->reserve_lock);
1006         xprt_alloc_slot(task);
1007         spin_unlock(&xprt->reserve_lock);
1008 }
1009
1010 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1011 {
1012         return (__force __be32)xprt->xid++;
1013 }
1014
1015 static inline void xprt_init_xid(struct rpc_xprt *xprt)
1016 {
1017         xprt->xid = net_random();
1018 }
1019
1020 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1021 {
1022         struct rpc_rqst *req = task->tk_rqstp;
1023
1024         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1025         req->rq_task    = task;
1026         req->rq_xprt    = xprt;
1027         req->rq_buffer  = NULL;
1028         req->rq_xid     = xprt_alloc_xid(xprt);
1029         req->rq_release_snd_buf = NULL;
1030         xprt_reset_majortimeo(req);
1031         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1032                         req, ntohl(req->rq_xid));
1033 }
1034
1035 /**
1036  * xprt_release - release an RPC request slot
1037  * @task: task which is finished with the slot
1038  *
1039  */
1040 void xprt_release(struct rpc_task *task)
1041 {
1042         struct rpc_xprt *xprt;
1043         struct rpc_rqst *req;
1044
1045         if (!(req = task->tk_rqstp))
1046                 return;
1047
1048         xprt = req->rq_xprt;
1049         rpc_count_iostats(task);
1050         spin_lock_bh(&xprt->transport_lock);
1051         xprt->ops->release_xprt(xprt, task);
1052         if (xprt->ops->release_request)
1053                 xprt->ops->release_request(task);
1054         if (!list_empty(&req->rq_list))
1055                 list_del(&req->rq_list);
1056         xprt->last_used = jiffies;
1057         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1058                 mod_timer(&xprt->timer,
1059                                 xprt->last_used + xprt->idle_timeout);
1060         spin_unlock_bh(&xprt->transport_lock);
1061         if (req->rq_buffer)
1062                 xprt->ops->buf_free(req->rq_buffer);
1063         if (req->rq_cred != NULL)
1064                 put_rpccred(req->rq_cred);
1065         task->tk_rqstp = NULL;
1066         if (req->rq_release_snd_buf)
1067                 req->rq_release_snd_buf(req);
1068
1069         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1070         if (likely(!bc_prealloc(req)))
1071                 xprt_free_slot(xprt, req);
1072         else
1073                 xprt_free_bc_request(req);
1074 }
1075
1076 /**
1077  * xprt_create_transport - create an RPC transport
1078  * @args: rpc transport creation arguments
1079  *
1080  */
1081 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1082 {
1083         struct rpc_xprt *xprt;
1084         struct rpc_rqst *req;
1085         struct xprt_class *t;
1086
1087         spin_lock(&xprt_list_lock);
1088         list_for_each_entry(t, &xprt_list, list) {
1089                 if (t->ident == args->ident) {
1090                         spin_unlock(&xprt_list_lock);
1091                         goto found;
1092                 }
1093         }
1094         spin_unlock(&xprt_list_lock);
1095         printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1096         return ERR_PTR(-EIO);
1097
1098 found:
1099         xprt = t->setup(args);
1100         if (IS_ERR(xprt)) {
1101                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1102                                 -PTR_ERR(xprt));
1103                 return xprt;
1104         }
1105         if (test_and_set_bit(XPRT_INITIALIZED, &xprt->state))
1106                 /* ->setup returned a pre-initialized xprt: */
1107                 return xprt;
1108
1109         spin_lock_init(&xprt->transport_lock);
1110         spin_lock_init(&xprt->reserve_lock);
1111
1112         INIT_LIST_HEAD(&xprt->free);
1113         INIT_LIST_HEAD(&xprt->recv);
1114 #if defined(CONFIG_NFS_V4_1)
1115         spin_lock_init(&xprt->bc_pa_lock);
1116         INIT_LIST_HEAD(&xprt->bc_pa_list);
1117 #endif /* CONFIG_NFS_V4_1 */
1118
1119         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1120         if (xprt_has_timer(xprt))
1121                 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1122                             (unsigned long)xprt);
1123         else
1124                 init_timer(&xprt->timer);
1125         xprt->last_used = jiffies;
1126         xprt->cwnd = RPC_INITCWND;
1127         xprt->bind_index = 0;
1128
1129         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1130         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1131         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1132         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
1133         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1134
1135         /* initialize free list */
1136         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
1137                 list_add(&req->rq_list, &xprt->free);
1138
1139         xprt_init_xid(xprt);
1140
1141         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1142                         xprt->max_reqs);
1143         return xprt;
1144 }
1145
1146 /**
1147  * xprt_destroy - destroy an RPC transport, killing off all requests.
1148  * @xprt: transport to destroy
1149  *
1150  */
1151 static void xprt_destroy(struct rpc_xprt *xprt)
1152 {
1153         dprintk("RPC:       destroying transport %p\n", xprt);
1154         xprt->shutdown = 1;
1155         del_timer_sync(&xprt->timer);
1156
1157         rpc_destroy_wait_queue(&xprt->binding);
1158         rpc_destroy_wait_queue(&xprt->pending);
1159         rpc_destroy_wait_queue(&xprt->sending);
1160         rpc_destroy_wait_queue(&xprt->resend);
1161         rpc_destroy_wait_queue(&xprt->backlog);
1162         cancel_work_sync(&xprt->task_cleanup);
1163         /*
1164          * Tear down transport state and free the rpc_xprt
1165          */
1166         xprt->ops->destroy(xprt);
1167 }
1168
1169 /**
1170  * xprt_put - release a reference to an RPC transport.
1171  * @xprt: pointer to the transport
1172  *
1173  */
1174 void xprt_put(struct rpc_xprt *xprt)
1175 {
1176         if (atomic_dec_and_test(&xprt->count))
1177                 xprt_destroy(xprt);
1178 }
1179
1180 /**
1181  * xprt_get - return a reference to an RPC transport.
1182  * @xprt: pointer to the transport
1183  *
1184  */
1185 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1186 {
1187         if (atomic_inc_not_zero(&xprt->count))
1188                 return xprt;
1189         return NULL;
1190 }