mac80211: decrease execution of the associated timer
[linux-2.6.git] / 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         list_add_tail(&transport->list, &xprt_list);
112         printk(KERN_INFO "RPC: Registered %s transport module.\n",
113                transport->name);
114         result = 0;
115
116 out:
117         spin_unlock(&xprt_list_lock);
118         return result;
119 }
120 EXPORT_SYMBOL_GPL(xprt_register_transport);
121
122 /**
123  * xprt_unregister_transport - unregister a transport implementation
124  * @transport: transport to unregister
125  *
126  * Returns:
127  * 0:           transport successfully unregistered
128  * -ENOENT:     transport never registered
129  */
130 int xprt_unregister_transport(struct xprt_class *transport)
131 {
132         struct xprt_class *t;
133         int result;
134
135         result = 0;
136         spin_lock(&xprt_list_lock);
137         list_for_each_entry(t, &xprt_list, list) {
138                 if (t == transport) {
139                         printk(KERN_INFO
140                                 "RPC: Unregistered %s transport module.\n",
141                                 transport->name);
142                         list_del_init(&transport->list);
143                         goto out;
144                 }
145         }
146         result = -ENOENT;
147
148 out:
149         spin_unlock(&xprt_list_lock);
150         return result;
151 }
152 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
153
154 /**
155  * xprt_reserve_xprt - serialize write access to transports
156  * @task: task that is requesting access to the transport
157  *
158  * This prevents mixing the payload of separate requests, and prevents
159  * transport connects from colliding with writes.  No congestion control
160  * is provided.
161  */
162 int xprt_reserve_xprt(struct rpc_task *task)
163 {
164         struct rpc_xprt *xprt = task->tk_xprt;
165         struct rpc_rqst *req = task->tk_rqstp;
166
167         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
168                 if (task == xprt->snd_task)
169                         return 1;
170                 if (task == NULL)
171                         return 0;
172                 goto out_sleep;
173         }
174         xprt->snd_task = task;
175         if (req) {
176                 req->rq_bytes_sent = 0;
177                 req->rq_ntrans++;
178         }
179         return 1;
180
181 out_sleep:
182         dprintk("RPC: %5u failed to lock transport %p\n",
183                         task->tk_pid, xprt);
184         task->tk_timeout = 0;
185         task->tk_status = -EAGAIN;
186         if (req && req->rq_ntrans)
187                 rpc_sleep_on(&xprt->resend, task, NULL);
188         else
189                 rpc_sleep_on(&xprt->sending, task, NULL);
190         return 0;
191 }
192 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
193
194 static void xprt_clear_locked(struct rpc_xprt *xprt)
195 {
196         xprt->snd_task = NULL;
197         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
198                 smp_mb__before_clear_bit();
199                 clear_bit(XPRT_LOCKED, &xprt->state);
200                 smp_mb__after_clear_bit();
201         } else
202                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
203 }
204
205 /*
206  * xprt_reserve_xprt_cong - serialize write access to transports
207  * @task: task that is requesting access to the transport
208  *
209  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
210  * integrated into the decision of whether a request is allowed to be
211  * woken up and given access to the transport.
212  */
213 int xprt_reserve_xprt_cong(struct rpc_task *task)
214 {
215         struct rpc_xprt *xprt = task->tk_xprt;
216         struct rpc_rqst *req = task->tk_rqstp;
217
218         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
219                 if (task == xprt->snd_task)
220                         return 1;
221                 goto out_sleep;
222         }
223         if (__xprt_get_cong(xprt, task)) {
224                 xprt->snd_task = task;
225                 if (req) {
226                         req->rq_bytes_sent = 0;
227                         req->rq_ntrans++;
228                 }
229                 return 1;
230         }
231         xprt_clear_locked(xprt);
232 out_sleep:
233         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
234         task->tk_timeout = 0;
235         task->tk_status = -EAGAIN;
236         if (req && req->rq_ntrans)
237                 rpc_sleep_on(&xprt->resend, task, NULL);
238         else
239                 rpc_sleep_on(&xprt->sending, task, NULL);
240         return 0;
241 }
242 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
243
244 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
245 {
246         int retval;
247
248         spin_lock_bh(&xprt->transport_lock);
249         retval = xprt->ops->reserve_xprt(task);
250         spin_unlock_bh(&xprt->transport_lock);
251         return retval;
252 }
253
254 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
255 {
256         struct rpc_task *task;
257         struct rpc_rqst *req;
258
259         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
260                 return;
261
262         task = rpc_wake_up_next(&xprt->resend);
263         if (!task) {
264                 task = rpc_wake_up_next(&xprt->sending);
265                 if (!task)
266                         goto out_unlock;
267         }
268
269         req = task->tk_rqstp;
270         xprt->snd_task = task;
271         if (req) {
272                 req->rq_bytes_sent = 0;
273                 req->rq_ntrans++;
274         }
275         return;
276
277 out_unlock:
278         xprt_clear_locked(xprt);
279 }
280
281 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
282 {
283         struct rpc_task *task;
284
285         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
286                 return;
287         if (RPCXPRT_CONGESTED(xprt))
288                 goto out_unlock;
289         task = rpc_wake_up_next(&xprt->resend);
290         if (!task) {
291                 task = rpc_wake_up_next(&xprt->sending);
292                 if (!task)
293                         goto out_unlock;
294         }
295         if (__xprt_get_cong(xprt, task)) {
296                 struct rpc_rqst *req = task->tk_rqstp;
297                 xprt->snd_task = task;
298                 if (req) {
299                         req->rq_bytes_sent = 0;
300                         req->rq_ntrans++;
301                 }
302                 return;
303         }
304 out_unlock:
305         xprt_clear_locked(xprt);
306 }
307
308 /**
309  * xprt_release_xprt - allow other requests to use a transport
310  * @xprt: transport with other tasks potentially waiting
311  * @task: task that is releasing access to the transport
312  *
313  * Note that "task" can be NULL.  No congestion control is provided.
314  */
315 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
316 {
317         if (xprt->snd_task == task) {
318                 xprt_clear_locked(xprt);
319                 __xprt_lock_write_next(xprt);
320         }
321 }
322 EXPORT_SYMBOL_GPL(xprt_release_xprt);
323
324 /**
325  * xprt_release_xprt_cong - allow other requests to use a transport
326  * @xprt: transport with other tasks potentially waiting
327  * @task: task that is releasing access to the transport
328  *
329  * Note that "task" can be NULL.  Another task is awoken to use the
330  * transport if the transport's congestion window allows it.
331  */
332 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
333 {
334         if (xprt->snd_task == task) {
335                 xprt_clear_locked(xprt);
336                 __xprt_lock_write_next_cong(xprt);
337         }
338 }
339 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
340
341 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
342 {
343         spin_lock_bh(&xprt->transport_lock);
344         xprt->ops->release_xprt(xprt, task);
345         spin_unlock_bh(&xprt->transport_lock);
346 }
347
348 /*
349  * Van Jacobson congestion avoidance. Check if the congestion window
350  * overflowed. Put the task to sleep if this is the case.
351  */
352 static int
353 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
354 {
355         struct rpc_rqst *req = task->tk_rqstp;
356
357         if (req->rq_cong)
358                 return 1;
359         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
360                         task->tk_pid, xprt->cong, xprt->cwnd);
361         if (RPCXPRT_CONGESTED(xprt))
362                 return 0;
363         req->rq_cong = 1;
364         xprt->cong += RPC_CWNDSCALE;
365         return 1;
366 }
367
368 /*
369  * Adjust the congestion window, and wake up the next task
370  * that has been sleeping due to congestion
371  */
372 static void
373 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
374 {
375         if (!req->rq_cong)
376                 return;
377         req->rq_cong = 0;
378         xprt->cong -= RPC_CWNDSCALE;
379         __xprt_lock_write_next_cong(xprt);
380 }
381
382 /**
383  * xprt_release_rqst_cong - housekeeping when request is complete
384  * @task: RPC request that recently completed
385  *
386  * Useful for transports that require congestion control.
387  */
388 void xprt_release_rqst_cong(struct rpc_task *task)
389 {
390         __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
391 }
392 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
393
394 /**
395  * xprt_adjust_cwnd - adjust transport congestion window
396  * @task: recently completed RPC request used to adjust window
397  * @result: result code of completed RPC request
398  *
399  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
400  */
401 void xprt_adjust_cwnd(struct rpc_task *task, int result)
402 {
403         struct rpc_rqst *req = task->tk_rqstp;
404         struct rpc_xprt *xprt = task->tk_xprt;
405         unsigned long cwnd = xprt->cwnd;
406
407         if (result >= 0 && cwnd <= xprt->cong) {
408                 /* The (cwnd >> 1) term makes sure
409                  * the result gets rounded properly. */
410                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
411                 if (cwnd > RPC_MAXCWND(xprt))
412                         cwnd = RPC_MAXCWND(xprt);
413                 __xprt_lock_write_next_cong(xprt);
414         } else if (result == -ETIMEDOUT) {
415                 cwnd >>= 1;
416                 if (cwnd < RPC_CWNDSCALE)
417                         cwnd = RPC_CWNDSCALE;
418         }
419         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
420                         xprt->cong, xprt->cwnd, cwnd);
421         xprt->cwnd = cwnd;
422         __xprt_put_cong(xprt, req);
423 }
424 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
425
426 /**
427  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
428  * @xprt: transport with waiting tasks
429  * @status: result code to plant in each task before waking it
430  *
431  */
432 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
433 {
434         if (status < 0)
435                 rpc_wake_up_status(&xprt->pending, status);
436         else
437                 rpc_wake_up(&xprt->pending);
438 }
439 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
440
441 /**
442  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
443  * @task: task to be put to sleep
444  * @action: function pointer to be executed after wait
445  */
446 void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
447 {
448         struct rpc_rqst *req = task->tk_rqstp;
449         struct rpc_xprt *xprt = req->rq_xprt;
450
451         task->tk_timeout = req->rq_timeout;
452         rpc_sleep_on(&xprt->pending, task, action);
453 }
454 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
455
456 /**
457  * xprt_write_space - wake the task waiting for transport output buffer space
458  * @xprt: transport with waiting tasks
459  *
460  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
461  */
462 void xprt_write_space(struct rpc_xprt *xprt)
463 {
464         if (unlikely(xprt->shutdown))
465                 return;
466
467         spin_lock_bh(&xprt->transport_lock);
468         if (xprt->snd_task) {
469                 dprintk("RPC:       write space: waking waiting task on "
470                                 "xprt %p\n", xprt);
471                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
472         }
473         spin_unlock_bh(&xprt->transport_lock);
474 }
475 EXPORT_SYMBOL_GPL(xprt_write_space);
476
477 /**
478  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
479  * @task: task whose timeout is to be set
480  *
481  * Set a request's retransmit timeout based on the transport's
482  * default timeout parameters.  Used by transports that don't adjust
483  * the retransmit timeout based on round-trip time estimation.
484  */
485 void xprt_set_retrans_timeout_def(struct rpc_task *task)
486 {
487         task->tk_timeout = task->tk_rqstp->rq_timeout;
488 }
489 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
490
491 /*
492  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
493  * @task: task whose timeout is to be set
494  *
495  * Set a request's retransmit timeout using the RTT estimator.
496  */
497 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
498 {
499         int timer = task->tk_msg.rpc_proc->p_timer;
500         struct rpc_clnt *clnt = task->tk_client;
501         struct rpc_rtt *rtt = clnt->cl_rtt;
502         struct rpc_rqst *req = task->tk_rqstp;
503         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
504
505         task->tk_timeout = rpc_calc_rto(rtt, timer);
506         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
507         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
508                 task->tk_timeout = max_timeout;
509 }
510 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
511
512 static void xprt_reset_majortimeo(struct rpc_rqst *req)
513 {
514         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
515
516         req->rq_majortimeo = req->rq_timeout;
517         if (to->to_exponential)
518                 req->rq_majortimeo <<= to->to_retries;
519         else
520                 req->rq_majortimeo += to->to_increment * to->to_retries;
521         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
522                 req->rq_majortimeo = to->to_maxval;
523         req->rq_majortimeo += jiffies;
524 }
525
526 /**
527  * xprt_adjust_timeout - adjust timeout values for next retransmit
528  * @req: RPC request containing parameters to use for the adjustment
529  *
530  */
531 int xprt_adjust_timeout(struct rpc_rqst *req)
532 {
533         struct rpc_xprt *xprt = req->rq_xprt;
534         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
535         int status = 0;
536
537         if (time_before(jiffies, req->rq_majortimeo)) {
538                 if (to->to_exponential)
539                         req->rq_timeout <<= 1;
540                 else
541                         req->rq_timeout += to->to_increment;
542                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
543                         req->rq_timeout = to->to_maxval;
544                 req->rq_retries++;
545         } else {
546                 req->rq_timeout = to->to_initval;
547                 req->rq_retries = 0;
548                 xprt_reset_majortimeo(req);
549                 /* Reset the RTT counters == "slow start" */
550                 spin_lock_bh(&xprt->transport_lock);
551                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
552                 spin_unlock_bh(&xprt->transport_lock);
553                 status = -ETIMEDOUT;
554         }
555
556         if (req->rq_timeout == 0) {
557                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
558                 req->rq_timeout = 5 * HZ;
559         }
560         return status;
561 }
562
563 static void xprt_autoclose(struct work_struct *work)
564 {
565         struct rpc_xprt *xprt =
566                 container_of(work, struct rpc_xprt, task_cleanup);
567
568         xprt->ops->close(xprt);
569         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
570         xprt_release_write(xprt, NULL);
571 }
572
573 /**
574  * xprt_disconnect_done - mark a transport as disconnected
575  * @xprt: transport to flag for disconnect
576  *
577  */
578 void xprt_disconnect_done(struct rpc_xprt *xprt)
579 {
580         dprintk("RPC:       disconnected transport %p\n", xprt);
581         spin_lock_bh(&xprt->transport_lock);
582         xprt_clear_connected(xprt);
583         xprt_wake_pending_tasks(xprt, -ENOTCONN);
584         spin_unlock_bh(&xprt->transport_lock);
585 }
586 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
587
588 /**
589  * xprt_force_disconnect - force a transport to disconnect
590  * @xprt: transport to disconnect
591  *
592  */
593 void xprt_force_disconnect(struct rpc_xprt *xprt)
594 {
595         /* Don't race with the test_bit() in xprt_clear_locked() */
596         spin_lock_bh(&xprt->transport_lock);
597         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
598         /* Try to schedule an autoclose RPC call */
599         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
600                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
601         xprt_wake_pending_tasks(xprt, -ENOTCONN);
602         spin_unlock_bh(&xprt->transport_lock);
603 }
604
605 /**
606  * xprt_conditional_disconnect - force a transport to disconnect
607  * @xprt: transport to disconnect
608  * @cookie: 'connection cookie'
609  *
610  * This attempts to break the connection if and only if 'cookie' matches
611  * the current transport 'connection cookie'. It ensures that we don't
612  * try to break the connection more than once when we need to retransmit
613  * a batch of RPC requests.
614  *
615  */
616 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
617 {
618         /* Don't race with the test_bit() in xprt_clear_locked() */
619         spin_lock_bh(&xprt->transport_lock);
620         if (cookie != xprt->connect_cookie)
621                 goto out;
622         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
623                 goto out;
624         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
625         /* Try to schedule an autoclose RPC call */
626         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
627                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
628         xprt_wake_pending_tasks(xprt, -ENOTCONN);
629 out:
630         spin_unlock_bh(&xprt->transport_lock);
631 }
632
633 static void
634 xprt_init_autodisconnect(unsigned long data)
635 {
636         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
637
638         spin_lock(&xprt->transport_lock);
639         if (!list_empty(&xprt->recv) || xprt->shutdown)
640                 goto out_abort;
641         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
642                 goto out_abort;
643         spin_unlock(&xprt->transport_lock);
644         if (xprt_connecting(xprt))
645                 xprt_release_write(xprt, NULL);
646         else
647                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
648         return;
649 out_abort:
650         spin_unlock(&xprt->transport_lock);
651 }
652
653 /**
654  * xprt_connect - schedule a transport connect operation
655  * @task: RPC task that is requesting the connect
656  *
657  */
658 void xprt_connect(struct rpc_task *task)
659 {
660         struct rpc_xprt *xprt = task->tk_xprt;
661
662         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
663                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
664
665         if (!xprt_bound(xprt)) {
666                 task->tk_status = -EAGAIN;
667                 return;
668         }
669         if (!xprt_lock_write(xprt, task))
670                 return;
671         if (xprt_connected(xprt))
672                 xprt_release_write(xprt, task);
673         else {
674                 if (task->tk_rqstp)
675                         task->tk_rqstp->rq_bytes_sent = 0;
676
677                 task->tk_timeout = xprt->connect_timeout;
678                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
679                 xprt->stat.connect_start = jiffies;
680                 xprt->ops->connect(task);
681         }
682         return;
683 }
684
685 static void xprt_connect_status(struct rpc_task *task)
686 {
687         struct rpc_xprt *xprt = task->tk_xprt;
688
689         if (task->tk_status == 0) {
690                 xprt->stat.connect_count++;
691                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
692                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
693                                 task->tk_pid);
694                 return;
695         }
696
697         switch (task->tk_status) {
698         case -ENOTCONN:
699                 dprintk("RPC: %5u xprt_connect_status: connection broken\n",
700                                 task->tk_pid);
701                 break;
702         case -ETIMEDOUT:
703                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
704                                 "out\n", task->tk_pid);
705                 break;
706         default:
707                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
708                                 "server %s\n", task->tk_pid, -task->tk_status,
709                                 task->tk_client->cl_server);
710                 xprt_release_write(xprt, task);
711                 task->tk_status = -EIO;
712         }
713 }
714
715 /**
716  * xprt_lookup_rqst - find an RPC request corresponding to an XID
717  * @xprt: transport on which the original request was transmitted
718  * @xid: RPC XID of incoming reply
719  *
720  */
721 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
722 {
723         struct list_head *pos;
724
725         list_for_each(pos, &xprt->recv) {
726                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
727                 if (entry->rq_xid == xid)
728                         return entry;
729         }
730
731         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
732                         ntohl(xid));
733         xprt->stat.bad_xids++;
734         return NULL;
735 }
736 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
737
738 /**
739  * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
740  * @task: RPC request that recently completed
741  *
742  */
743 void xprt_update_rtt(struct rpc_task *task)
744 {
745         struct rpc_rqst *req = task->tk_rqstp;
746         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
747         unsigned timer = task->tk_msg.rpc_proc->p_timer;
748
749         if (timer) {
750                 if (req->rq_ntrans == 1)
751                         rpc_update_rtt(rtt, timer,
752                                         (long)jiffies - req->rq_xtime);
753                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
754         }
755 }
756 EXPORT_SYMBOL_GPL(xprt_update_rtt);
757
758 /**
759  * xprt_complete_rqst - called when reply processing is complete
760  * @task: RPC request that recently completed
761  * @copied: actual number of bytes received from the transport
762  *
763  * Caller holds transport lock.
764  */
765 void xprt_complete_rqst(struct rpc_task *task, int copied)
766 {
767         struct rpc_rqst *req = task->tk_rqstp;
768         struct rpc_xprt *xprt = req->rq_xprt;
769
770         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
771                         task->tk_pid, ntohl(req->rq_xid), copied);
772
773         xprt->stat.recvs++;
774         task->tk_rtt = (long)jiffies - req->rq_xtime;
775
776         list_del_init(&req->rq_list);
777         req->rq_private_buf.len = copied;
778         /* Ensure all writes are done before we update req->rq_received */
779         smp_wmb();
780         req->rq_received = copied;
781         rpc_wake_up_queued_task(&xprt->pending, task);
782 }
783 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
784
785 static void xprt_timer(struct rpc_task *task)
786 {
787         struct rpc_rqst *req = task->tk_rqstp;
788         struct rpc_xprt *xprt = req->rq_xprt;
789
790         if (task->tk_status != -ETIMEDOUT)
791                 return;
792         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
793
794         spin_lock_bh(&xprt->transport_lock);
795         if (!req->rq_received) {
796                 if (xprt->ops->timer)
797                         xprt->ops->timer(task);
798         } else
799                 task->tk_status = 0;
800         spin_unlock_bh(&xprt->transport_lock);
801 }
802
803 /**
804  * xprt_prepare_transmit - reserve the transport before sending a request
805  * @task: RPC task about to send a request
806  *
807  */
808 int xprt_prepare_transmit(struct rpc_task *task)
809 {
810         struct rpc_rqst *req = task->tk_rqstp;
811         struct rpc_xprt *xprt = req->rq_xprt;
812         int err = 0;
813
814         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
815
816         spin_lock_bh(&xprt->transport_lock);
817         if (req->rq_received && !req->rq_bytes_sent) {
818                 err = req->rq_received;
819                 goto out_unlock;
820         }
821         if (!xprt->ops->reserve_xprt(task)) {
822                 err = -EAGAIN;
823                 goto out_unlock;
824         }
825
826         if (!xprt_connected(xprt)) {
827                 err = -ENOTCONN;
828                 goto out_unlock;
829         }
830 out_unlock:
831         spin_unlock_bh(&xprt->transport_lock);
832         return err;
833 }
834
835 void xprt_end_transmit(struct rpc_task *task)
836 {
837         xprt_release_write(task->tk_xprt, task);
838 }
839
840 /**
841  * xprt_transmit - send an RPC request on a transport
842  * @task: controlling RPC task
843  *
844  * We have to copy the iovec because sendmsg fiddles with its contents.
845  */
846 void xprt_transmit(struct rpc_task *task)
847 {
848         struct rpc_rqst *req = task->tk_rqstp;
849         struct rpc_xprt *xprt = req->rq_xprt;
850         int status;
851
852         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
853
854         if (!req->rq_received) {
855                 if (list_empty(&req->rq_list)) {
856                         spin_lock_bh(&xprt->transport_lock);
857                         /* Update the softirq receive buffer */
858                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
859                                         sizeof(req->rq_private_buf));
860                         /* Add request to the receive list */
861                         list_add_tail(&req->rq_list, &xprt->recv);
862                         spin_unlock_bh(&xprt->transport_lock);
863                         xprt_reset_majortimeo(req);
864                         /* Turn off autodisconnect */
865                         del_singleshot_timer_sync(&xprt->timer);
866                 }
867         } else if (!req->rq_bytes_sent)
868                 return;
869
870         req->rq_connect_cookie = xprt->connect_cookie;
871         req->rq_xtime = jiffies;
872         status = xprt->ops->send_request(task);
873         if (status == 0) {
874                 dprintk("RPC: %5u xmit complete\n", task->tk_pid);
875                 spin_lock_bh(&xprt->transport_lock);
876
877                 xprt->ops->set_retrans_timeout(task);
878
879                 xprt->stat.sends++;
880                 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
881                 xprt->stat.bklog_u += xprt->backlog.qlen;
882
883                 /* Don't race with disconnect */
884                 if (!xprt_connected(xprt))
885                         task->tk_status = -ENOTCONN;
886                 else if (!req->rq_received)
887                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
888                 spin_unlock_bh(&xprt->transport_lock);
889                 return;
890         }
891
892         /* Note: at this point, task->tk_sleeping has not yet been set,
893          *       hence there is no danger of the waking up task being put on
894          *       schedq, and being picked up by a parallel run of rpciod().
895          */
896         task->tk_status = status;
897         if (status == -ECONNREFUSED)
898                 rpc_sleep_on(&xprt->sending, task, NULL);
899 }
900
901 static inline void do_xprt_reserve(struct rpc_task *task)
902 {
903         struct rpc_xprt *xprt = task->tk_xprt;
904
905         task->tk_status = 0;
906         if (task->tk_rqstp)
907                 return;
908         if (!list_empty(&xprt->free)) {
909                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
910                 list_del_init(&req->rq_list);
911                 task->tk_rqstp = req;
912                 xprt_request_init(task, xprt);
913                 return;
914         }
915         dprintk("RPC:       waiting for request slot\n");
916         task->tk_status = -EAGAIN;
917         task->tk_timeout = 0;
918         rpc_sleep_on(&xprt->backlog, task, NULL);
919 }
920
921 /**
922  * xprt_reserve - allocate an RPC request slot
923  * @task: RPC task requesting a slot allocation
924  *
925  * If no more slots are available, place the task on the transport's
926  * backlog queue.
927  */
928 void xprt_reserve(struct rpc_task *task)
929 {
930         struct rpc_xprt *xprt = task->tk_xprt;
931
932         task->tk_status = -EIO;
933         spin_lock(&xprt->reserve_lock);
934         do_xprt_reserve(task);
935         spin_unlock(&xprt->reserve_lock);
936 }
937
938 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
939 {
940         return xprt->xid++;
941 }
942
943 static inline void xprt_init_xid(struct rpc_xprt *xprt)
944 {
945         xprt->xid = net_random();
946 }
947
948 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
949 {
950         struct rpc_rqst *req = task->tk_rqstp;
951
952         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
953         req->rq_task    = task;
954         req->rq_xprt    = xprt;
955         req->rq_buffer  = NULL;
956         req->rq_xid     = xprt_alloc_xid(xprt);
957         req->rq_release_snd_buf = NULL;
958         xprt_reset_majortimeo(req);
959         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
960                         req, ntohl(req->rq_xid));
961 }
962
963 /**
964  * xprt_release - release an RPC request slot
965  * @task: task which is finished with the slot
966  *
967  */
968 void xprt_release(struct rpc_task *task)
969 {
970         struct rpc_xprt *xprt = task->tk_xprt;
971         struct rpc_rqst *req;
972
973         if (!(req = task->tk_rqstp))
974                 return;
975         rpc_count_iostats(task);
976         spin_lock_bh(&xprt->transport_lock);
977         xprt->ops->release_xprt(xprt, task);
978         if (xprt->ops->release_request)
979                 xprt->ops->release_request(task);
980         if (!list_empty(&req->rq_list))
981                 list_del(&req->rq_list);
982         xprt->last_used = jiffies;
983         if (list_empty(&xprt->recv))
984                 mod_timer(&xprt->timer,
985                                 xprt->last_used + xprt->idle_timeout);
986         spin_unlock_bh(&xprt->transport_lock);
987         xprt->ops->buf_free(req->rq_buffer);
988         task->tk_rqstp = NULL;
989         if (req->rq_release_snd_buf)
990                 req->rq_release_snd_buf(req);
991         memset(req, 0, sizeof(*req));   /* mark unused */
992
993         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
994
995         spin_lock(&xprt->reserve_lock);
996         list_add(&req->rq_list, &xprt->free);
997         rpc_wake_up_next(&xprt->backlog);
998         spin_unlock(&xprt->reserve_lock);
999 }
1000
1001 /**
1002  * xprt_create_transport - create an RPC transport
1003  * @args: rpc transport creation arguments
1004  *
1005  */
1006 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1007 {
1008         struct rpc_xprt *xprt;
1009         struct rpc_rqst *req;
1010         struct xprt_class *t;
1011
1012         spin_lock(&xprt_list_lock);
1013         list_for_each_entry(t, &xprt_list, list) {
1014                 if (t->ident == args->ident) {
1015                         spin_unlock(&xprt_list_lock);
1016                         goto found;
1017                 }
1018         }
1019         spin_unlock(&xprt_list_lock);
1020         printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1021         return ERR_PTR(-EIO);
1022
1023 found:
1024         xprt = t->setup(args);
1025         if (IS_ERR(xprt)) {
1026                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1027                                 -PTR_ERR(xprt));
1028                 return xprt;
1029         }
1030
1031         kref_init(&xprt->kref);
1032         spin_lock_init(&xprt->transport_lock);
1033         spin_lock_init(&xprt->reserve_lock);
1034
1035         INIT_LIST_HEAD(&xprt->free);
1036         INIT_LIST_HEAD(&xprt->recv);
1037         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1038         setup_timer(&xprt->timer, xprt_init_autodisconnect,
1039                         (unsigned long)xprt);
1040         xprt->last_used = jiffies;
1041         xprt->cwnd = RPC_INITCWND;
1042         xprt->bind_index = 0;
1043
1044         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1045         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1046         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1047         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
1048         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1049
1050         /* initialize free list */
1051         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
1052                 list_add(&req->rq_list, &xprt->free);
1053
1054         xprt_init_xid(xprt);
1055
1056         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1057                         xprt->max_reqs);
1058
1059         return xprt;
1060 }
1061
1062 /**
1063  * xprt_destroy - destroy an RPC transport, killing off all requests.
1064  * @kref: kref for the transport to destroy
1065  *
1066  */
1067 static void xprt_destroy(struct kref *kref)
1068 {
1069         struct rpc_xprt *xprt = container_of(kref, struct rpc_xprt, kref);
1070
1071         dprintk("RPC:       destroying transport %p\n", xprt);
1072         xprt->shutdown = 1;
1073         del_timer_sync(&xprt->timer);
1074
1075         rpc_destroy_wait_queue(&xprt->binding);
1076         rpc_destroy_wait_queue(&xprt->pending);
1077         rpc_destroy_wait_queue(&xprt->sending);
1078         rpc_destroy_wait_queue(&xprt->resend);
1079         rpc_destroy_wait_queue(&xprt->backlog);
1080         /*
1081          * Tear down transport state and free the rpc_xprt
1082          */
1083         xprt->ops->destroy(xprt);
1084 }
1085
1086 /**
1087  * xprt_put - release a reference to an RPC transport.
1088  * @xprt: pointer to the transport
1089  *
1090  */
1091 void xprt_put(struct rpc_xprt *xprt)
1092 {
1093         kref_put(&xprt->kref, xprt_destroy);
1094 }
1095
1096 /**
1097  * xprt_get - return a reference to an RPC transport.
1098  * @xprt: pointer to the transport
1099  *
1100  */
1101 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1102 {
1103         kref_get(&xprt->kref);
1104         return xprt;
1105 }