Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
[linux-2.6] / 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 /*
66  * The transport code maintains an estimate on the maximum number of out-
67  * standing RPC requests, using a smoothed version of the congestion
68  * avoidance implemented in 44BSD. This is basically the Van Jacobson
69  * congestion algorithm: If a retransmit occurs, the congestion window is
70  * halved; otherwise, it is incremented by 1/cwnd when
71  *
72  *      -       a reply is received and
73  *      -       a full number of requests are outstanding and
74  *      -       the congestion window hasn't been updated recently.
75  */
76 #define RPC_CWNDSHIFT           (8U)
77 #define RPC_CWNDSCALE           (1U << RPC_CWNDSHIFT)
78 #define RPC_INITCWND            RPC_CWNDSCALE
79 #define RPC_MAXCWND(xprt)       ((xprt)->max_reqs << RPC_CWNDSHIFT)
80
81 #define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
82
83 /**
84  * xprt_reserve_xprt - serialize write access to transports
85  * @task: task that is requesting access to the transport
86  *
87  * This prevents mixing the payload of separate requests, and prevents
88  * transport connects from colliding with writes.  No congestion control
89  * is provided.
90  */
91 int xprt_reserve_xprt(struct rpc_task *task)
92 {
93         struct rpc_xprt *xprt = task->tk_xprt;
94         struct rpc_rqst *req = task->tk_rqstp;
95
96         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
97                 if (task == xprt->snd_task)
98                         return 1;
99                 if (task == NULL)
100                         return 0;
101                 goto out_sleep;
102         }
103         xprt->snd_task = task;
104         if (req) {
105                 req->rq_bytes_sent = 0;
106                 req->rq_ntrans++;
107         }
108         return 1;
109
110 out_sleep:
111         dprintk("RPC: %5u failed to lock transport %p\n",
112                         task->tk_pid, xprt);
113         task->tk_timeout = 0;
114         task->tk_status = -EAGAIN;
115         if (req && req->rq_ntrans)
116                 rpc_sleep_on(&xprt->resend, task, NULL, NULL);
117         else
118                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
119         return 0;
120 }
121
122 static void xprt_clear_locked(struct rpc_xprt *xprt)
123 {
124         xprt->snd_task = NULL;
125         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
126                 smp_mb__before_clear_bit();
127                 clear_bit(XPRT_LOCKED, &xprt->state);
128                 smp_mb__after_clear_bit();
129         } else
130                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
131 }
132
133 /*
134  * xprt_reserve_xprt_cong - serialize write access to transports
135  * @task: task that is requesting access to the transport
136  *
137  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
138  * integrated into the decision of whether a request is allowed to be
139  * woken up and given access to the transport.
140  */
141 int xprt_reserve_xprt_cong(struct rpc_task *task)
142 {
143         struct rpc_xprt *xprt = task->tk_xprt;
144         struct rpc_rqst *req = task->tk_rqstp;
145
146         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
147                 if (task == xprt->snd_task)
148                         return 1;
149                 goto out_sleep;
150         }
151         if (__xprt_get_cong(xprt, task)) {
152                 xprt->snd_task = task;
153                 if (req) {
154                         req->rq_bytes_sent = 0;
155                         req->rq_ntrans++;
156                 }
157                 return 1;
158         }
159         xprt_clear_locked(xprt);
160 out_sleep:
161         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
162         task->tk_timeout = 0;
163         task->tk_status = -EAGAIN;
164         if (req && req->rq_ntrans)
165                 rpc_sleep_on(&xprt->resend, task, NULL, NULL);
166         else
167                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
168         return 0;
169 }
170
171 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
172 {
173         int retval;
174
175         spin_lock_bh(&xprt->transport_lock);
176         retval = xprt->ops->reserve_xprt(task);
177         spin_unlock_bh(&xprt->transport_lock);
178         return retval;
179 }
180
181 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
182 {
183         struct rpc_task *task;
184         struct rpc_rqst *req;
185
186         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
187                 return;
188
189         task = rpc_wake_up_next(&xprt->resend);
190         if (!task) {
191                 task = rpc_wake_up_next(&xprt->sending);
192                 if (!task)
193                         goto out_unlock;
194         }
195
196         req = task->tk_rqstp;
197         xprt->snd_task = task;
198         if (req) {
199                 req->rq_bytes_sent = 0;
200                 req->rq_ntrans++;
201         }
202         return;
203
204 out_unlock:
205         xprt_clear_locked(xprt);
206 }
207
208 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
209 {
210         struct rpc_task *task;
211
212         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
213                 return;
214         if (RPCXPRT_CONGESTED(xprt))
215                 goto out_unlock;
216         task = rpc_wake_up_next(&xprt->resend);
217         if (!task) {
218                 task = rpc_wake_up_next(&xprt->sending);
219                 if (!task)
220                         goto out_unlock;
221         }
222         if (__xprt_get_cong(xprt, task)) {
223                 struct rpc_rqst *req = task->tk_rqstp;
224                 xprt->snd_task = task;
225                 if (req) {
226                         req->rq_bytes_sent = 0;
227                         req->rq_ntrans++;
228                 }
229                 return;
230         }
231 out_unlock:
232         xprt_clear_locked(xprt);
233 }
234
235 /**
236  * xprt_release_xprt - allow other requests to use a transport
237  * @xprt: transport with other tasks potentially waiting
238  * @task: task that is releasing access to the transport
239  *
240  * Note that "task" can be NULL.  No congestion control is provided.
241  */
242 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
243 {
244         if (xprt->snd_task == task) {
245                 xprt_clear_locked(xprt);
246                 __xprt_lock_write_next(xprt);
247         }
248 }
249
250 /**
251  * xprt_release_xprt_cong - allow other requests to use a transport
252  * @xprt: transport with other tasks potentially waiting
253  * @task: task that is releasing access to the transport
254  *
255  * Note that "task" can be NULL.  Another task is awoken to use the
256  * transport if the transport's congestion window allows it.
257  */
258 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
259 {
260         if (xprt->snd_task == task) {
261                 xprt_clear_locked(xprt);
262                 __xprt_lock_write_next_cong(xprt);
263         }
264 }
265
266 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
267 {
268         spin_lock_bh(&xprt->transport_lock);
269         xprt->ops->release_xprt(xprt, task);
270         spin_unlock_bh(&xprt->transport_lock);
271 }
272
273 /*
274  * Van Jacobson congestion avoidance. Check if the congestion window
275  * overflowed. Put the task to sleep if this is the case.
276  */
277 static int
278 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
279 {
280         struct rpc_rqst *req = task->tk_rqstp;
281
282         if (req->rq_cong)
283                 return 1;
284         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
285                         task->tk_pid, xprt->cong, xprt->cwnd);
286         if (RPCXPRT_CONGESTED(xprt))
287                 return 0;
288         req->rq_cong = 1;
289         xprt->cong += RPC_CWNDSCALE;
290         return 1;
291 }
292
293 /*
294  * Adjust the congestion window, and wake up the next task
295  * that has been sleeping due to congestion
296  */
297 static void
298 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
299 {
300         if (!req->rq_cong)
301                 return;
302         req->rq_cong = 0;
303         xprt->cong -= RPC_CWNDSCALE;
304         __xprt_lock_write_next_cong(xprt);
305 }
306
307 /**
308  * xprt_release_rqst_cong - housekeeping when request is complete
309  * @task: RPC request that recently completed
310  *
311  * Useful for transports that require congestion control.
312  */
313 void xprt_release_rqst_cong(struct rpc_task *task)
314 {
315         __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
316 }
317
318 /**
319  * xprt_adjust_cwnd - adjust transport congestion window
320  * @task: recently completed RPC request used to adjust window
321  * @result: result code of completed RPC request
322  *
323  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
324  */
325 void xprt_adjust_cwnd(struct rpc_task *task, int result)
326 {
327         struct rpc_rqst *req = task->tk_rqstp;
328         struct rpc_xprt *xprt = task->tk_xprt;
329         unsigned long cwnd = xprt->cwnd;
330
331         if (result >= 0 && cwnd <= xprt->cong) {
332                 /* The (cwnd >> 1) term makes sure
333                  * the result gets rounded properly. */
334                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
335                 if (cwnd > RPC_MAXCWND(xprt))
336                         cwnd = RPC_MAXCWND(xprt);
337                 __xprt_lock_write_next_cong(xprt);
338         } else if (result == -ETIMEDOUT) {
339                 cwnd >>= 1;
340                 if (cwnd < RPC_CWNDSCALE)
341                         cwnd = RPC_CWNDSCALE;
342         }
343         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
344                         xprt->cong, xprt->cwnd, cwnd);
345         xprt->cwnd = cwnd;
346         __xprt_put_cong(xprt, req);
347 }
348
349 /**
350  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
351  * @xprt: transport with waiting tasks
352  * @status: result code to plant in each task before waking it
353  *
354  */
355 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
356 {
357         if (status < 0)
358                 rpc_wake_up_status(&xprt->pending, status);
359         else
360                 rpc_wake_up(&xprt->pending);
361 }
362
363 /**
364  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
365  * @task: task to be put to sleep
366  *
367  */
368 void xprt_wait_for_buffer_space(struct rpc_task *task)
369 {
370         struct rpc_rqst *req = task->tk_rqstp;
371         struct rpc_xprt *xprt = req->rq_xprt;
372
373         task->tk_timeout = req->rq_timeout;
374         rpc_sleep_on(&xprt->pending, task, NULL, NULL);
375 }
376
377 /**
378  * xprt_write_space - wake the task waiting for transport output buffer space
379  * @xprt: transport with waiting tasks
380  *
381  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
382  */
383 void xprt_write_space(struct rpc_xprt *xprt)
384 {
385         if (unlikely(xprt->shutdown))
386                 return;
387
388         spin_lock_bh(&xprt->transport_lock);
389         if (xprt->snd_task) {
390                 dprintk("RPC:       write space: waking waiting task on "
391                                 "xprt %p\n", xprt);
392                 rpc_wake_up_task(xprt->snd_task);
393         }
394         spin_unlock_bh(&xprt->transport_lock);
395 }
396
397 /**
398  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
399  * @task: task whose timeout is to be set
400  *
401  * Set a request's retransmit timeout based on the transport's
402  * default timeout parameters.  Used by transports that don't adjust
403  * the retransmit timeout based on round-trip time estimation.
404  */
405 void xprt_set_retrans_timeout_def(struct rpc_task *task)
406 {
407         task->tk_timeout = task->tk_rqstp->rq_timeout;
408 }
409
410 /*
411  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
412  * @task: task whose timeout is to be set
413  *
414  * Set a request's retransmit timeout using the RTT estimator.
415  */
416 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
417 {
418         int timer = task->tk_msg.rpc_proc->p_timer;
419         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
420         struct rpc_rqst *req = task->tk_rqstp;
421         unsigned long max_timeout = req->rq_xprt->timeout.to_maxval;
422
423         task->tk_timeout = rpc_calc_rto(rtt, timer);
424         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
425         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
426                 task->tk_timeout = max_timeout;
427 }
428
429 static void xprt_reset_majortimeo(struct rpc_rqst *req)
430 {
431         struct rpc_timeout *to = &req->rq_xprt->timeout;
432
433         req->rq_majortimeo = req->rq_timeout;
434         if (to->to_exponential)
435                 req->rq_majortimeo <<= to->to_retries;
436         else
437                 req->rq_majortimeo += to->to_increment * to->to_retries;
438         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
439                 req->rq_majortimeo = to->to_maxval;
440         req->rq_majortimeo += jiffies;
441 }
442
443 /**
444  * xprt_adjust_timeout - adjust timeout values for next retransmit
445  * @req: RPC request containing parameters to use for the adjustment
446  *
447  */
448 int xprt_adjust_timeout(struct rpc_rqst *req)
449 {
450         struct rpc_xprt *xprt = req->rq_xprt;
451         struct rpc_timeout *to = &xprt->timeout;
452         int status = 0;
453
454         if (time_before(jiffies, req->rq_majortimeo)) {
455                 if (to->to_exponential)
456                         req->rq_timeout <<= 1;
457                 else
458                         req->rq_timeout += to->to_increment;
459                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
460                         req->rq_timeout = to->to_maxval;
461                 req->rq_retries++;
462         } else {
463                 req->rq_timeout = to->to_initval;
464                 req->rq_retries = 0;
465                 xprt_reset_majortimeo(req);
466                 /* Reset the RTT counters == "slow start" */
467                 spin_lock_bh(&xprt->transport_lock);
468                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
469                 spin_unlock_bh(&xprt->transport_lock);
470                 status = -ETIMEDOUT;
471         }
472
473         if (req->rq_timeout == 0) {
474                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
475                 req->rq_timeout = 5 * HZ;
476         }
477         return status;
478 }
479
480 static void xprt_autoclose(struct work_struct *work)
481 {
482         struct rpc_xprt *xprt =
483                 container_of(work, struct rpc_xprt, task_cleanup);
484
485         xprt_disconnect(xprt);
486         xprt->ops->close(xprt);
487         xprt_release_write(xprt, NULL);
488 }
489
490 /**
491  * xprt_disconnect - mark a transport as disconnected
492  * @xprt: transport to flag for disconnect
493  *
494  */
495 void xprt_disconnect(struct rpc_xprt *xprt)
496 {
497         dprintk("RPC:       disconnected transport %p\n", xprt);
498         spin_lock_bh(&xprt->transport_lock);
499         xprt_clear_connected(xprt);
500         xprt_wake_pending_tasks(xprt, -ENOTCONN);
501         spin_unlock_bh(&xprt->transport_lock);
502 }
503
504 static void
505 xprt_init_autodisconnect(unsigned long data)
506 {
507         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
508
509         spin_lock(&xprt->transport_lock);
510         if (!list_empty(&xprt->recv) || xprt->shutdown)
511                 goto out_abort;
512         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
513                 goto out_abort;
514         spin_unlock(&xprt->transport_lock);
515         if (xprt_connecting(xprt))
516                 xprt_release_write(xprt, NULL);
517         else
518                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
519         return;
520 out_abort:
521         spin_unlock(&xprt->transport_lock);
522 }
523
524 /**
525  * xprt_connect - schedule a transport connect operation
526  * @task: RPC task that is requesting the connect
527  *
528  */
529 void xprt_connect(struct rpc_task *task)
530 {
531         struct rpc_xprt *xprt = task->tk_xprt;
532
533         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
534                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
535
536         if (!xprt_bound(xprt)) {
537                 task->tk_status = -EIO;
538                 return;
539         }
540         if (!xprt_lock_write(xprt, task))
541                 return;
542         if (xprt_connected(xprt))
543                 xprt_release_write(xprt, task);
544         else {
545                 if (task->tk_rqstp)
546                         task->tk_rqstp->rq_bytes_sent = 0;
547
548                 task->tk_timeout = xprt->connect_timeout;
549                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
550                 xprt->stat.connect_start = jiffies;
551                 xprt->ops->connect(task);
552         }
553         return;
554 }
555
556 static void xprt_connect_status(struct rpc_task *task)
557 {
558         struct rpc_xprt *xprt = task->tk_xprt;
559
560         if (task->tk_status >= 0) {
561                 xprt->stat.connect_count++;
562                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
563                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
564                                 task->tk_pid);
565                 return;
566         }
567
568         switch (task->tk_status) {
569         case -ECONNREFUSED:
570         case -ECONNRESET:
571                 dprintk("RPC: %5u xprt_connect_status: server %s refused "
572                                 "connection\n", task->tk_pid,
573                                 task->tk_client->cl_server);
574                 break;
575         case -ENOTCONN:
576                 dprintk("RPC: %5u xprt_connect_status: connection broken\n",
577                                 task->tk_pid);
578                 break;
579         case -ETIMEDOUT:
580                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
581                                 "out\n", task->tk_pid);
582                 break;
583         default:
584                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
585                                 "server %s\n", task->tk_pid, -task->tk_status,
586                                 task->tk_client->cl_server);
587                 xprt_release_write(xprt, task);
588                 task->tk_status = -EIO;
589         }
590 }
591
592 /**
593  * xprt_lookup_rqst - find an RPC request corresponding to an XID
594  * @xprt: transport on which the original request was transmitted
595  * @xid: RPC XID of incoming reply
596  *
597  */
598 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
599 {
600         struct list_head *pos;
601
602         list_for_each(pos, &xprt->recv) {
603                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
604                 if (entry->rq_xid == xid)
605                         return entry;
606         }
607
608         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
609                         ntohl(xid));
610         xprt->stat.bad_xids++;
611         return NULL;
612 }
613
614 /**
615  * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
616  * @task: RPC request that recently completed
617  *
618  */
619 void xprt_update_rtt(struct rpc_task *task)
620 {
621         struct rpc_rqst *req = task->tk_rqstp;
622         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
623         unsigned timer = task->tk_msg.rpc_proc->p_timer;
624
625         if (timer) {
626                 if (req->rq_ntrans == 1)
627                         rpc_update_rtt(rtt, timer,
628                                         (long)jiffies - req->rq_xtime);
629                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
630         }
631 }
632
633 /**
634  * xprt_complete_rqst - called when reply processing is complete
635  * @task: RPC request that recently completed
636  * @copied: actual number of bytes received from the transport
637  *
638  * Caller holds transport lock.
639  */
640 void xprt_complete_rqst(struct rpc_task *task, int copied)
641 {
642         struct rpc_rqst *req = task->tk_rqstp;
643
644         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
645                         task->tk_pid, ntohl(req->rq_xid), copied);
646
647         task->tk_xprt->stat.recvs++;
648         task->tk_rtt = (long)jiffies - req->rq_xtime;
649
650         list_del_init(&req->rq_list);
651         /* Ensure all writes are done before we update req->rq_received */
652         smp_wmb();
653         req->rq_received = req->rq_private_buf.len = copied;
654         rpc_wake_up_task(task);
655 }
656
657 static void xprt_timer(struct rpc_task *task)
658 {
659         struct rpc_rqst *req = task->tk_rqstp;
660         struct rpc_xprt *xprt = req->rq_xprt;
661
662         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
663
664         spin_lock(&xprt->transport_lock);
665         if (!req->rq_received) {
666                 if (xprt->ops->timer)
667                         xprt->ops->timer(task);
668                 task->tk_status = -ETIMEDOUT;
669         }
670         task->tk_timeout = 0;
671         rpc_wake_up_task(task);
672         spin_unlock(&xprt->transport_lock);
673 }
674
675 /**
676  * xprt_prepare_transmit - reserve the transport before sending a request
677  * @task: RPC task about to send a request
678  *
679  */
680 int xprt_prepare_transmit(struct rpc_task *task)
681 {
682         struct rpc_rqst *req = task->tk_rqstp;
683         struct rpc_xprt *xprt = req->rq_xprt;
684         int err = 0;
685
686         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
687
688         spin_lock_bh(&xprt->transport_lock);
689         if (req->rq_received && !req->rq_bytes_sent) {
690                 err = req->rq_received;
691                 goto out_unlock;
692         }
693         if (!xprt->ops->reserve_xprt(task)) {
694                 err = -EAGAIN;
695                 goto out_unlock;
696         }
697
698         if (!xprt_connected(xprt)) {
699                 err = -ENOTCONN;
700                 goto out_unlock;
701         }
702 out_unlock:
703         spin_unlock_bh(&xprt->transport_lock);
704         return err;
705 }
706
707 void xprt_end_transmit(struct rpc_task *task)
708 {
709         xprt_release_write(task->tk_xprt, task);
710 }
711
712 /**
713  * xprt_transmit - send an RPC request on a transport
714  * @task: controlling RPC task
715  *
716  * We have to copy the iovec because sendmsg fiddles with its contents.
717  */
718 void xprt_transmit(struct rpc_task *task)
719 {
720         struct rpc_rqst *req = task->tk_rqstp;
721         struct rpc_xprt *xprt = req->rq_xprt;
722         int status;
723
724         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
725
726         if (!req->rq_received) {
727                 if (list_empty(&req->rq_list)) {
728                         spin_lock_bh(&xprt->transport_lock);
729                         /* Update the softirq receive buffer */
730                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
731                                         sizeof(req->rq_private_buf));
732                         /* Add request to the receive list */
733                         list_add_tail(&req->rq_list, &xprt->recv);
734                         spin_unlock_bh(&xprt->transport_lock);
735                         xprt_reset_majortimeo(req);
736                         /* Turn off autodisconnect */
737                         del_singleshot_timer_sync(&xprt->timer);
738                 }
739         } else if (!req->rq_bytes_sent)
740                 return;
741
742         status = xprt->ops->send_request(task);
743         if (status == 0) {
744                 dprintk("RPC: %5u xmit complete\n", task->tk_pid);
745                 spin_lock_bh(&xprt->transport_lock);
746
747                 xprt->ops->set_retrans_timeout(task);
748
749                 xprt->stat.sends++;
750                 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
751                 xprt->stat.bklog_u += xprt->backlog.qlen;
752
753                 /* Don't race with disconnect */
754                 if (!xprt_connected(xprt))
755                         task->tk_status = -ENOTCONN;
756                 else if (!req->rq_received)
757                         rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
758                 spin_unlock_bh(&xprt->transport_lock);
759                 return;
760         }
761
762         /* Note: at this point, task->tk_sleeping has not yet been set,
763          *       hence there is no danger of the waking up task being put on
764          *       schedq, and being picked up by a parallel run of rpciod().
765          */
766         task->tk_status = status;
767         if (status == -ECONNREFUSED)
768                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
769 }
770
771 static inline void do_xprt_reserve(struct rpc_task *task)
772 {
773         struct rpc_xprt *xprt = task->tk_xprt;
774
775         task->tk_status = 0;
776         if (task->tk_rqstp)
777                 return;
778         if (!list_empty(&xprt->free)) {
779                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
780                 list_del_init(&req->rq_list);
781                 task->tk_rqstp = req;
782                 xprt_request_init(task, xprt);
783                 return;
784         }
785         dprintk("RPC:       waiting for request slot\n");
786         task->tk_status = -EAGAIN;
787         task->tk_timeout = 0;
788         rpc_sleep_on(&xprt->backlog, task, NULL, NULL);
789 }
790
791 /**
792  * xprt_reserve - allocate an RPC request slot
793  * @task: RPC task requesting a slot allocation
794  *
795  * If no more slots are available, place the task on the transport's
796  * backlog queue.
797  */
798 void xprt_reserve(struct rpc_task *task)
799 {
800         struct rpc_xprt *xprt = task->tk_xprt;
801
802         task->tk_status = -EIO;
803         spin_lock(&xprt->reserve_lock);
804         do_xprt_reserve(task);
805         spin_unlock(&xprt->reserve_lock);
806 }
807
808 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
809 {
810         return xprt->xid++;
811 }
812
813 static inline void xprt_init_xid(struct rpc_xprt *xprt)
814 {
815         xprt->xid = net_random();
816 }
817
818 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
819 {
820         struct rpc_rqst *req = task->tk_rqstp;
821
822         req->rq_timeout = xprt->timeout.to_initval;
823         req->rq_task    = task;
824         req->rq_xprt    = xprt;
825         req->rq_buffer  = NULL;
826         req->rq_xid     = xprt_alloc_xid(xprt);
827         req->rq_release_snd_buf = NULL;
828         xprt_reset_majortimeo(req);
829         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
830                         req, ntohl(req->rq_xid));
831 }
832
833 /**
834  * xprt_release - release an RPC request slot
835  * @task: task which is finished with the slot
836  *
837  */
838 void xprt_release(struct rpc_task *task)
839 {
840         struct rpc_xprt *xprt = task->tk_xprt;
841         struct rpc_rqst *req;
842
843         if (!(req = task->tk_rqstp))
844                 return;
845         rpc_count_iostats(task);
846         spin_lock_bh(&xprt->transport_lock);
847         xprt->ops->release_xprt(xprt, task);
848         if (xprt->ops->release_request)
849                 xprt->ops->release_request(task);
850         if (!list_empty(&req->rq_list))
851                 list_del(&req->rq_list);
852         xprt->last_used = jiffies;
853         if (list_empty(&xprt->recv))
854                 mod_timer(&xprt->timer,
855                                 xprt->last_used + xprt->idle_timeout);
856         spin_unlock_bh(&xprt->transport_lock);
857         xprt->ops->buf_free(req->rq_buffer);
858         task->tk_rqstp = NULL;
859         if (req->rq_release_snd_buf)
860                 req->rq_release_snd_buf(req);
861         memset(req, 0, sizeof(*req));   /* mark unused */
862
863         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
864
865         spin_lock(&xprt->reserve_lock);
866         list_add(&req->rq_list, &xprt->free);
867         rpc_wake_up_next(&xprt->backlog);
868         spin_unlock(&xprt->reserve_lock);
869 }
870
871 /**
872  * xprt_set_timeout - set constant RPC timeout
873  * @to: RPC timeout parameters to set up
874  * @retr: number of retries
875  * @incr: amount of increase after each retry
876  *
877  */
878 void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
879 {
880         to->to_initval   =
881         to->to_increment = incr;
882         to->to_maxval    = to->to_initval + (incr * retr);
883         to->to_retries   = retr;
884         to->to_exponential = 0;
885 }
886
887 /**
888  * xprt_create_transport - create an RPC transport
889  * @args: rpc transport creation arguments
890  *
891  */
892 struct rpc_xprt *xprt_create_transport(struct rpc_xprtsock_create *args)
893 {
894         struct rpc_xprt *xprt;
895         struct rpc_rqst *req;
896
897         switch (args->proto) {
898         case IPPROTO_UDP:
899                 xprt = xs_setup_udp(args);
900                 break;
901         case IPPROTO_TCP:
902                 xprt = xs_setup_tcp(args);
903                 break;
904         default:
905                 printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n",
906                                 args->proto);
907                 return ERR_PTR(-EIO);
908         }
909         if (IS_ERR(xprt)) {
910                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
911                                 -PTR_ERR(xprt));
912                 return xprt;
913         }
914
915         kref_init(&xprt->kref);
916         spin_lock_init(&xprt->transport_lock);
917         spin_lock_init(&xprt->reserve_lock);
918
919         INIT_LIST_HEAD(&xprt->free);
920         INIT_LIST_HEAD(&xprt->recv);
921         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
922         init_timer(&xprt->timer);
923         xprt->timer.function = xprt_init_autodisconnect;
924         xprt->timer.data = (unsigned long) xprt;
925         xprt->last_used = jiffies;
926         xprt->cwnd = RPC_INITCWND;
927         xprt->bind_index = 0;
928
929         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
930         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
931         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
932         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
933         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
934
935         /* initialize free list */
936         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
937                 list_add(&req->rq_list, &xprt->free);
938
939         xprt_init_xid(xprt);
940
941         dprintk("RPC:       created transport %p with %u slots\n", xprt,
942                         xprt->max_reqs);
943
944         return xprt;
945 }
946
947 /**
948  * xprt_destroy - destroy an RPC transport, killing off all requests.
949  * @kref: kref for the transport to destroy
950  *
951  */
952 static void xprt_destroy(struct kref *kref)
953 {
954         struct rpc_xprt *xprt = container_of(kref, struct rpc_xprt, kref);
955
956         dprintk("RPC:       destroying transport %p\n", xprt);
957         xprt->shutdown = 1;
958         del_timer_sync(&xprt->timer);
959
960         /*
961          * Tear down transport state and free the rpc_xprt
962          */
963         xprt->ops->destroy(xprt);
964 }
965
966 /**
967  * xprt_put - release a reference to an RPC transport.
968  * @xprt: pointer to the transport
969  *
970  */
971 void xprt_put(struct rpc_xprt *xprt)
972 {
973         kref_put(&xprt->kref, xprt_destroy);
974 }
975
976 /**
977  * xprt_get - return a reference to an RPC transport.
978  * @xprt: pointer to the transport
979  *
980  */
981 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
982 {
983         kref_get(&xprt->kref);
984         return xprt;
985 }