cd641c8634f044c6bb580c2d725bdb908e97849d
[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         result = -EINVAL;
112         if (try_module_get(THIS_MODULE)) {
113                 list_add_tail(&transport->list, &xprt_list);
114                 printk(KERN_INFO "RPC: Registered %s transport module.\n",
115                         transport->name);
116                 result = 0;
117         }
118
119 out:
120         spin_unlock(&xprt_list_lock);
121         return result;
122 }
123 EXPORT_SYMBOL_GPL(xprt_register_transport);
124
125 /**
126  * xprt_unregister_transport - unregister a transport implementation
127  * transport: transport to unregister
128  *
129  * Returns:
130  * 0:           transport successfully unregistered
131  * -ENOENT:     transport never registered
132  */
133 int xprt_unregister_transport(struct xprt_class *transport)
134 {
135         struct xprt_class *t;
136         int result;
137
138         result = 0;
139         spin_lock(&xprt_list_lock);
140         list_for_each_entry(t, &xprt_list, list) {
141                 if (t == transport) {
142                         printk(KERN_INFO
143                                 "RPC: Unregistered %s transport module.\n",
144                                 transport->name);
145                         list_del_init(&transport->list);
146                         module_put(THIS_MODULE);
147                         goto out;
148                 }
149         }
150         result = -ENOENT;
151
152 out:
153         spin_unlock(&xprt_list_lock);
154         return result;
155 }
156 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
157
158 /**
159  * xprt_reserve_xprt - serialize write access to transports
160  * @task: task that is requesting access to the transport
161  *
162  * This prevents mixing the payload of separate requests, and prevents
163  * transport connects from colliding with writes.  No congestion control
164  * is provided.
165  */
166 int xprt_reserve_xprt(struct rpc_task *task)
167 {
168         struct rpc_xprt *xprt = task->tk_xprt;
169         struct rpc_rqst *req = task->tk_rqstp;
170
171         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
172                 if (task == xprt->snd_task)
173                         return 1;
174                 if (task == NULL)
175                         return 0;
176                 goto out_sleep;
177         }
178         xprt->snd_task = task;
179         if (req) {
180                 req->rq_bytes_sent = 0;
181                 req->rq_ntrans++;
182         }
183         return 1;
184
185 out_sleep:
186         dprintk("RPC: %5u failed to lock transport %p\n",
187                         task->tk_pid, xprt);
188         task->tk_timeout = 0;
189         task->tk_status = -EAGAIN;
190         if (req && req->rq_ntrans)
191                 rpc_sleep_on(&xprt->resend, task, NULL, NULL);
192         else
193                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
194         return 0;
195 }
196 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
197
198 static void xprt_clear_locked(struct rpc_xprt *xprt)
199 {
200         xprt->snd_task = NULL;
201         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
202                 smp_mb__before_clear_bit();
203                 clear_bit(XPRT_LOCKED, &xprt->state);
204                 smp_mb__after_clear_bit();
205         } else
206                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
207 }
208
209 /*
210  * xprt_reserve_xprt_cong - serialize write access to transports
211  * @task: task that is requesting access to the transport
212  *
213  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
214  * integrated into the decision of whether a request is allowed to be
215  * woken up and given access to the transport.
216  */
217 int xprt_reserve_xprt_cong(struct rpc_task *task)
218 {
219         struct rpc_xprt *xprt = task->tk_xprt;
220         struct rpc_rqst *req = task->tk_rqstp;
221
222         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
223                 if (task == xprt->snd_task)
224                         return 1;
225                 goto out_sleep;
226         }
227         if (__xprt_get_cong(xprt, task)) {
228                 xprt->snd_task = task;
229                 if (req) {
230                         req->rq_bytes_sent = 0;
231                         req->rq_ntrans++;
232                 }
233                 return 1;
234         }
235         xprt_clear_locked(xprt);
236 out_sleep:
237         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
238         task->tk_timeout = 0;
239         task->tk_status = -EAGAIN;
240         if (req && req->rq_ntrans)
241                 rpc_sleep_on(&xprt->resend, task, NULL, NULL);
242         else
243                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
244         return 0;
245 }
246 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
247
248 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
249 {
250         int retval;
251
252         spin_lock_bh(&xprt->transport_lock);
253         retval = xprt->ops->reserve_xprt(task);
254         spin_unlock_bh(&xprt->transport_lock);
255         return retval;
256 }
257
258 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
259 {
260         struct rpc_task *task;
261         struct rpc_rqst *req;
262
263         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
264                 return;
265
266         task = rpc_wake_up_next(&xprt->resend);
267         if (!task) {
268                 task = rpc_wake_up_next(&xprt->sending);
269                 if (!task)
270                         goto out_unlock;
271         }
272
273         req = task->tk_rqstp;
274         xprt->snd_task = task;
275         if (req) {
276                 req->rq_bytes_sent = 0;
277                 req->rq_ntrans++;
278         }
279         return;
280
281 out_unlock:
282         xprt_clear_locked(xprt);
283 }
284
285 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
286 {
287         struct rpc_task *task;
288
289         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
290                 return;
291         if (RPCXPRT_CONGESTED(xprt))
292                 goto out_unlock;
293         task = rpc_wake_up_next(&xprt->resend);
294         if (!task) {
295                 task = rpc_wake_up_next(&xprt->sending);
296                 if (!task)
297                         goto out_unlock;
298         }
299         if (__xprt_get_cong(xprt, task)) {
300                 struct rpc_rqst *req = task->tk_rqstp;
301                 xprt->snd_task = task;
302                 if (req) {
303                         req->rq_bytes_sent = 0;
304                         req->rq_ntrans++;
305                 }
306                 return;
307         }
308 out_unlock:
309         xprt_clear_locked(xprt);
310 }
311
312 /**
313  * xprt_release_xprt - allow other requests to use a transport
314  * @xprt: transport with other tasks potentially waiting
315  * @task: task that is releasing access to the transport
316  *
317  * Note that "task" can be NULL.  No congestion control is provided.
318  */
319 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
320 {
321         if (xprt->snd_task == task) {
322                 xprt_clear_locked(xprt);
323                 __xprt_lock_write_next(xprt);
324         }
325 }
326 EXPORT_SYMBOL_GPL(xprt_release_xprt);
327
328 /**
329  * xprt_release_xprt_cong - allow other requests to use a transport
330  * @xprt: transport with other tasks potentially waiting
331  * @task: task that is releasing access to the transport
332  *
333  * Note that "task" can be NULL.  Another task is awoken to use the
334  * transport if the transport's congestion window allows it.
335  */
336 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
337 {
338         if (xprt->snd_task == task) {
339                 xprt_clear_locked(xprt);
340                 __xprt_lock_write_next_cong(xprt);
341         }
342 }
343 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
344
345 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
346 {
347         spin_lock_bh(&xprt->transport_lock);
348         xprt->ops->release_xprt(xprt, task);
349         spin_unlock_bh(&xprt->transport_lock);
350 }
351
352 /*
353  * Van Jacobson congestion avoidance. Check if the congestion window
354  * overflowed. Put the task to sleep if this is the case.
355  */
356 static int
357 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
358 {
359         struct rpc_rqst *req = task->tk_rqstp;
360
361         if (req->rq_cong)
362                 return 1;
363         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
364                         task->tk_pid, xprt->cong, xprt->cwnd);
365         if (RPCXPRT_CONGESTED(xprt))
366                 return 0;
367         req->rq_cong = 1;
368         xprt->cong += RPC_CWNDSCALE;
369         return 1;
370 }
371
372 /*
373  * Adjust the congestion window, and wake up the next task
374  * that has been sleeping due to congestion
375  */
376 static void
377 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
378 {
379         if (!req->rq_cong)
380                 return;
381         req->rq_cong = 0;
382         xprt->cong -= RPC_CWNDSCALE;
383         __xprt_lock_write_next_cong(xprt);
384 }
385
386 /**
387  * xprt_release_rqst_cong - housekeeping when request is complete
388  * @task: RPC request that recently completed
389  *
390  * Useful for transports that require congestion control.
391  */
392 void xprt_release_rqst_cong(struct rpc_task *task)
393 {
394         __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
395 }
396 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
397
398 /**
399  * xprt_adjust_cwnd - adjust transport congestion window
400  * @task: recently completed RPC request used to adjust window
401  * @result: result code of completed RPC request
402  *
403  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
404  */
405 void xprt_adjust_cwnd(struct rpc_task *task, int result)
406 {
407         struct rpc_rqst *req = task->tk_rqstp;
408         struct rpc_xprt *xprt = task->tk_xprt;
409         unsigned long cwnd = xprt->cwnd;
410
411         if (result >= 0 && cwnd <= xprt->cong) {
412                 /* The (cwnd >> 1) term makes sure
413                  * the result gets rounded properly. */
414                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
415                 if (cwnd > RPC_MAXCWND(xprt))
416                         cwnd = RPC_MAXCWND(xprt);
417                 __xprt_lock_write_next_cong(xprt);
418         } else if (result == -ETIMEDOUT) {
419                 cwnd >>= 1;
420                 if (cwnd < RPC_CWNDSCALE)
421                         cwnd = RPC_CWNDSCALE;
422         }
423         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
424                         xprt->cong, xprt->cwnd, cwnd);
425         xprt->cwnd = cwnd;
426         __xprt_put_cong(xprt, req);
427 }
428 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
429
430 /**
431  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
432  * @xprt: transport with waiting tasks
433  * @status: result code to plant in each task before waking it
434  *
435  */
436 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
437 {
438         if (status < 0)
439                 rpc_wake_up_status(&xprt->pending, status);
440         else
441                 rpc_wake_up(&xprt->pending);
442 }
443 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
444
445 /**
446  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
447  * @task: task to be put to sleep
448  *
449  */
450 void xprt_wait_for_buffer_space(struct rpc_task *task)
451 {
452         struct rpc_rqst *req = task->tk_rqstp;
453         struct rpc_xprt *xprt = req->rq_xprt;
454
455         task->tk_timeout = req->rq_timeout;
456         rpc_sleep_on(&xprt->pending, task, NULL, NULL);
457 }
458 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
459
460 /**
461  * xprt_write_space - wake the task waiting for transport output buffer space
462  * @xprt: transport with waiting tasks
463  *
464  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
465  */
466 void xprt_write_space(struct rpc_xprt *xprt)
467 {
468         if (unlikely(xprt->shutdown))
469                 return;
470
471         spin_lock_bh(&xprt->transport_lock);
472         if (xprt->snd_task) {
473                 dprintk("RPC:       write space: waking waiting task on "
474                                 "xprt %p\n", xprt);
475                 rpc_wake_up_task(xprt->snd_task);
476         }
477         spin_unlock_bh(&xprt->transport_lock);
478 }
479 EXPORT_SYMBOL_GPL(xprt_write_space);
480
481 /**
482  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
483  * @task: task whose timeout is to be set
484  *
485  * Set a request's retransmit timeout based on the transport's
486  * default timeout parameters.  Used by transports that don't adjust
487  * the retransmit timeout based on round-trip time estimation.
488  */
489 void xprt_set_retrans_timeout_def(struct rpc_task *task)
490 {
491         task->tk_timeout = task->tk_rqstp->rq_timeout;
492 }
493 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
494
495 /*
496  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
497  * @task: task whose timeout is to be set
498  *
499  * Set a request's retransmit timeout using the RTT estimator.
500  */
501 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
502 {
503         int timer = task->tk_msg.rpc_proc->p_timer;
504         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
505         struct rpc_rqst *req = task->tk_rqstp;
506         unsigned long max_timeout = req->rq_xprt->timeout.to_maxval;
507
508         task->tk_timeout = rpc_calc_rto(rtt, timer);
509         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
510         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
511                 task->tk_timeout = max_timeout;
512 }
513 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
514
515 static void xprt_reset_majortimeo(struct rpc_rqst *req)
516 {
517         struct rpc_timeout *to = &req->rq_xprt->timeout;
518
519         req->rq_majortimeo = req->rq_timeout;
520         if (to->to_exponential)
521                 req->rq_majortimeo <<= to->to_retries;
522         else
523                 req->rq_majortimeo += to->to_increment * to->to_retries;
524         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
525                 req->rq_majortimeo = to->to_maxval;
526         req->rq_majortimeo += jiffies;
527 }
528
529 /**
530  * xprt_adjust_timeout - adjust timeout values for next retransmit
531  * @req: RPC request containing parameters to use for the adjustment
532  *
533  */
534 int xprt_adjust_timeout(struct rpc_rqst *req)
535 {
536         struct rpc_xprt *xprt = req->rq_xprt;
537         struct rpc_timeout *to = &xprt->timeout;
538         int status = 0;
539
540         if (time_before(jiffies, req->rq_majortimeo)) {
541                 if (to->to_exponential)
542                         req->rq_timeout <<= 1;
543                 else
544                         req->rq_timeout += to->to_increment;
545                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
546                         req->rq_timeout = to->to_maxval;
547                 req->rq_retries++;
548         } else {
549                 req->rq_timeout = to->to_initval;
550                 req->rq_retries = 0;
551                 xprt_reset_majortimeo(req);
552                 /* Reset the RTT counters == "slow start" */
553                 spin_lock_bh(&xprt->transport_lock);
554                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
555                 spin_unlock_bh(&xprt->transport_lock);
556                 status = -ETIMEDOUT;
557         }
558
559         if (req->rq_timeout == 0) {
560                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
561                 req->rq_timeout = 5 * HZ;
562         }
563         return status;
564 }
565
566 static void xprt_autoclose(struct work_struct *work)
567 {
568         struct rpc_xprt *xprt =
569                 container_of(work, struct rpc_xprt, task_cleanup);
570
571         xprt_disconnect(xprt);
572         xprt->ops->close(xprt);
573         xprt_release_write(xprt, NULL);
574 }
575
576 /**
577  * xprt_disconnect - mark a transport as disconnected
578  * @xprt: transport to flag for disconnect
579  *
580  */
581 void xprt_disconnect(struct rpc_xprt *xprt)
582 {
583         dprintk("RPC:       disconnected transport %p\n", xprt);
584         spin_lock_bh(&xprt->transport_lock);
585         xprt_clear_connected(xprt);
586         xprt_wake_pending_tasks(xprt, -ENOTCONN);
587         spin_unlock_bh(&xprt->transport_lock);
588 }
589 EXPORT_SYMBOL_GPL(xprt_disconnect);
590
591 static void
592 xprt_init_autodisconnect(unsigned long data)
593 {
594         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
595
596         spin_lock(&xprt->transport_lock);
597         if (!list_empty(&xprt->recv) || xprt->shutdown)
598                 goto out_abort;
599         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
600                 goto out_abort;
601         spin_unlock(&xprt->transport_lock);
602         if (xprt_connecting(xprt))
603                 xprt_release_write(xprt, NULL);
604         else
605                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
606         return;
607 out_abort:
608         spin_unlock(&xprt->transport_lock);
609 }
610
611 /**
612  * xprt_connect - schedule a transport connect operation
613  * @task: RPC task that is requesting the connect
614  *
615  */
616 void xprt_connect(struct rpc_task *task)
617 {
618         struct rpc_xprt *xprt = task->tk_xprt;
619
620         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
621                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
622
623         if (!xprt_bound(xprt)) {
624                 task->tk_status = -EIO;
625                 return;
626         }
627         if (!xprt_lock_write(xprt, task))
628                 return;
629         if (xprt_connected(xprt))
630                 xprt_release_write(xprt, task);
631         else {
632                 if (task->tk_rqstp)
633                         task->tk_rqstp->rq_bytes_sent = 0;
634
635                 task->tk_timeout = xprt->connect_timeout;
636                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
637                 xprt->stat.connect_start = jiffies;
638                 xprt->ops->connect(task);
639         }
640         return;
641 }
642
643 static void xprt_connect_status(struct rpc_task *task)
644 {
645         struct rpc_xprt *xprt = task->tk_xprt;
646
647         if (task->tk_status >= 0) {
648                 xprt->stat.connect_count++;
649                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
650                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
651                                 task->tk_pid);
652                 return;
653         }
654
655         switch (task->tk_status) {
656         case -ECONNREFUSED:
657         case -ECONNRESET:
658                 dprintk("RPC: %5u xprt_connect_status: server %s refused "
659                                 "connection\n", task->tk_pid,
660                                 task->tk_client->cl_server);
661                 break;
662         case -ENOTCONN:
663                 dprintk("RPC: %5u xprt_connect_status: connection broken\n",
664                                 task->tk_pid);
665                 break;
666         case -ETIMEDOUT:
667                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
668                                 "out\n", task->tk_pid);
669                 break;
670         default:
671                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
672                                 "server %s\n", task->tk_pid, -task->tk_status,
673                                 task->tk_client->cl_server);
674                 xprt_release_write(xprt, task);
675                 task->tk_status = -EIO;
676         }
677 }
678
679 /**
680  * xprt_lookup_rqst - find an RPC request corresponding to an XID
681  * @xprt: transport on which the original request was transmitted
682  * @xid: RPC XID of incoming reply
683  *
684  */
685 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
686 {
687         struct list_head *pos;
688
689         list_for_each(pos, &xprt->recv) {
690                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
691                 if (entry->rq_xid == xid)
692                         return entry;
693         }
694
695         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
696                         ntohl(xid));
697         xprt->stat.bad_xids++;
698         return NULL;
699 }
700 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
701
702 /**
703  * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
704  * @task: RPC request that recently completed
705  *
706  */
707 void xprt_update_rtt(struct rpc_task *task)
708 {
709         struct rpc_rqst *req = task->tk_rqstp;
710         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
711         unsigned timer = task->tk_msg.rpc_proc->p_timer;
712
713         if (timer) {
714                 if (req->rq_ntrans == 1)
715                         rpc_update_rtt(rtt, timer,
716                                         (long)jiffies - req->rq_xtime);
717                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
718         }
719 }
720 EXPORT_SYMBOL_GPL(xprt_update_rtt);
721
722 /**
723  * xprt_complete_rqst - called when reply processing is complete
724  * @task: RPC request that recently completed
725  * @copied: actual number of bytes received from the transport
726  *
727  * Caller holds transport lock.
728  */
729 void xprt_complete_rqst(struct rpc_task *task, int copied)
730 {
731         struct rpc_rqst *req = task->tk_rqstp;
732
733         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
734                         task->tk_pid, ntohl(req->rq_xid), copied);
735
736         task->tk_xprt->stat.recvs++;
737         task->tk_rtt = (long)jiffies - req->rq_xtime;
738
739         list_del_init(&req->rq_list);
740         /* Ensure all writes are done before we update req->rq_received */
741         smp_wmb();
742         req->rq_received = req->rq_private_buf.len = copied;
743         rpc_wake_up_task(task);
744 }
745 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
746
747 static void xprt_timer(struct rpc_task *task)
748 {
749         struct rpc_rqst *req = task->tk_rqstp;
750         struct rpc_xprt *xprt = req->rq_xprt;
751
752         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
753
754         spin_lock(&xprt->transport_lock);
755         if (!req->rq_received) {
756                 if (xprt->ops->timer)
757                         xprt->ops->timer(task);
758                 task->tk_status = -ETIMEDOUT;
759         }
760         task->tk_timeout = 0;
761         rpc_wake_up_task(task);
762         spin_unlock(&xprt->transport_lock);
763 }
764
765 /**
766  * xprt_prepare_transmit - reserve the transport before sending a request
767  * @task: RPC task about to send a request
768  *
769  */
770 int xprt_prepare_transmit(struct rpc_task *task)
771 {
772         struct rpc_rqst *req = task->tk_rqstp;
773         struct rpc_xprt *xprt = req->rq_xprt;
774         int err = 0;
775
776         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
777
778         spin_lock_bh(&xprt->transport_lock);
779         if (req->rq_received && !req->rq_bytes_sent) {
780                 err = req->rq_received;
781                 goto out_unlock;
782         }
783         if (!xprt->ops->reserve_xprt(task)) {
784                 err = -EAGAIN;
785                 goto out_unlock;
786         }
787
788         if (!xprt_connected(xprt)) {
789                 err = -ENOTCONN;
790                 goto out_unlock;
791         }
792 out_unlock:
793         spin_unlock_bh(&xprt->transport_lock);
794         return err;
795 }
796
797 void xprt_end_transmit(struct rpc_task *task)
798 {
799         xprt_release_write(task->tk_xprt, task);
800 }
801
802 /**
803  * xprt_transmit - send an RPC request on a transport
804  * @task: controlling RPC task
805  *
806  * We have to copy the iovec because sendmsg fiddles with its contents.
807  */
808 void xprt_transmit(struct rpc_task *task)
809 {
810         struct rpc_rqst *req = task->tk_rqstp;
811         struct rpc_xprt *xprt = req->rq_xprt;
812         int status;
813
814         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
815
816         if (!req->rq_received) {
817                 if (list_empty(&req->rq_list)) {
818                         spin_lock_bh(&xprt->transport_lock);
819                         /* Update the softirq receive buffer */
820                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
821                                         sizeof(req->rq_private_buf));
822                         /* Add request to the receive list */
823                         list_add_tail(&req->rq_list, &xprt->recv);
824                         spin_unlock_bh(&xprt->transport_lock);
825                         xprt_reset_majortimeo(req);
826                         /* Turn off autodisconnect */
827                         del_singleshot_timer_sync(&xprt->timer);
828                 }
829         } else if (!req->rq_bytes_sent)
830                 return;
831
832         status = xprt->ops->send_request(task);
833         if (status == 0) {
834                 dprintk("RPC: %5u xmit complete\n", task->tk_pid);
835                 spin_lock_bh(&xprt->transport_lock);
836
837                 xprt->ops->set_retrans_timeout(task);
838
839                 xprt->stat.sends++;
840                 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
841                 xprt->stat.bklog_u += xprt->backlog.qlen;
842
843                 /* Don't race with disconnect */
844                 if (!xprt_connected(xprt))
845                         task->tk_status = -ENOTCONN;
846                 else if (!req->rq_received)
847                         rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
848                 spin_unlock_bh(&xprt->transport_lock);
849                 return;
850         }
851
852         /* Note: at this point, task->tk_sleeping has not yet been set,
853          *       hence there is no danger of the waking up task being put on
854          *       schedq, and being picked up by a parallel run of rpciod().
855          */
856         task->tk_status = status;
857         if (status == -ECONNREFUSED)
858                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
859 }
860
861 static inline void do_xprt_reserve(struct rpc_task *task)
862 {
863         struct rpc_xprt *xprt = task->tk_xprt;
864
865         task->tk_status = 0;
866         if (task->tk_rqstp)
867                 return;
868         if (!list_empty(&xprt->free)) {
869                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
870                 list_del_init(&req->rq_list);
871                 task->tk_rqstp = req;
872                 xprt_request_init(task, xprt);
873                 return;
874         }
875         dprintk("RPC:       waiting for request slot\n");
876         task->tk_status = -EAGAIN;
877         task->tk_timeout = 0;
878         rpc_sleep_on(&xprt->backlog, task, NULL, NULL);
879 }
880
881 /**
882  * xprt_reserve - allocate an RPC request slot
883  * @task: RPC task requesting a slot allocation
884  *
885  * If no more slots are available, place the task on the transport's
886  * backlog queue.
887  */
888 void xprt_reserve(struct rpc_task *task)
889 {
890         struct rpc_xprt *xprt = task->tk_xprt;
891
892         task->tk_status = -EIO;
893         spin_lock(&xprt->reserve_lock);
894         do_xprt_reserve(task);
895         spin_unlock(&xprt->reserve_lock);
896 }
897
898 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
899 {
900         return xprt->xid++;
901 }
902
903 static inline void xprt_init_xid(struct rpc_xprt *xprt)
904 {
905         xprt->xid = net_random();
906 }
907
908 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
909 {
910         struct rpc_rqst *req = task->tk_rqstp;
911
912         req->rq_timeout = xprt->timeout.to_initval;
913         req->rq_task    = task;
914         req->rq_xprt    = xprt;
915         req->rq_buffer  = NULL;
916         req->rq_xid     = xprt_alloc_xid(xprt);
917         req->rq_release_snd_buf = NULL;
918         xprt_reset_majortimeo(req);
919         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
920                         req, ntohl(req->rq_xid));
921 }
922
923 /**
924  * xprt_release - release an RPC request slot
925  * @task: task which is finished with the slot
926  *
927  */
928 void xprt_release(struct rpc_task *task)
929 {
930         struct rpc_xprt *xprt = task->tk_xprt;
931         struct rpc_rqst *req;
932
933         if (!(req = task->tk_rqstp))
934                 return;
935         rpc_count_iostats(task);
936         spin_lock_bh(&xprt->transport_lock);
937         xprt->ops->release_xprt(xprt, task);
938         if (xprt->ops->release_request)
939                 xprt->ops->release_request(task);
940         if (!list_empty(&req->rq_list))
941                 list_del(&req->rq_list);
942         xprt->last_used = jiffies;
943         if (list_empty(&xprt->recv))
944                 mod_timer(&xprt->timer,
945                                 xprt->last_used + xprt->idle_timeout);
946         spin_unlock_bh(&xprt->transport_lock);
947         xprt->ops->buf_free(req->rq_buffer);
948         task->tk_rqstp = NULL;
949         if (req->rq_release_snd_buf)
950                 req->rq_release_snd_buf(req);
951         memset(req, 0, sizeof(*req));   /* mark unused */
952
953         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
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 /**
962  * xprt_set_timeout - set constant RPC timeout
963  * @to: RPC timeout parameters to set up
964  * @retr: number of retries
965  * @incr: amount of increase after each retry
966  *
967  */
968 void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
969 {
970         to->to_initval   =
971         to->to_increment = incr;
972         to->to_maxval    = to->to_initval + (incr * retr);
973         to->to_retries   = retr;
974         to->to_exponential = 0;
975 }
976
977 /**
978  * xprt_create_transport - create an RPC transport
979  * @args: rpc transport creation arguments
980  *
981  */
982 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
983 {
984         struct rpc_xprt *xprt;
985         struct rpc_rqst *req;
986         struct xprt_class *t;
987
988         spin_lock(&xprt_list_lock);
989         list_for_each_entry(t, &xprt_list, list) {
990                 if (t->ident == args->ident) {
991                         spin_unlock(&xprt_list_lock);
992                         goto found;
993                 }
994         }
995         spin_unlock(&xprt_list_lock);
996         printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
997         return ERR_PTR(-EIO);
998
999 found:
1000         xprt = t->setup(args);
1001         if (IS_ERR(xprt)) {
1002                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1003                                 -PTR_ERR(xprt));
1004                 return xprt;
1005         }
1006
1007         kref_init(&xprt->kref);
1008         spin_lock_init(&xprt->transport_lock);
1009         spin_lock_init(&xprt->reserve_lock);
1010
1011         INIT_LIST_HEAD(&xprt->free);
1012         INIT_LIST_HEAD(&xprt->recv);
1013         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1014         init_timer(&xprt->timer);
1015         xprt->timer.function = xprt_init_autodisconnect;
1016         xprt->timer.data = (unsigned long) xprt;
1017         xprt->last_used = jiffies;
1018         xprt->cwnd = RPC_INITCWND;
1019         xprt->bind_index = 0;
1020
1021         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1022         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1023         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1024         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
1025         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1026
1027         /* initialize free list */
1028         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
1029                 list_add(&req->rq_list, &xprt->free);
1030
1031         xprt_init_xid(xprt);
1032
1033         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1034                         xprt->max_reqs);
1035
1036         return xprt;
1037 }
1038
1039 /**
1040  * xprt_destroy - destroy an RPC transport, killing off all requests.
1041  * @kref: kref for the transport to destroy
1042  *
1043  */
1044 static void xprt_destroy(struct kref *kref)
1045 {
1046         struct rpc_xprt *xprt = container_of(kref, struct rpc_xprt, kref);
1047
1048         dprintk("RPC:       destroying transport %p\n", xprt);
1049         xprt->shutdown = 1;
1050         del_timer_sync(&xprt->timer);
1051
1052         /*
1053          * Tear down transport state and free the rpc_xprt
1054          */
1055         xprt->ops->destroy(xprt);
1056 }
1057
1058 /**
1059  * xprt_put - release a reference to an RPC transport.
1060  * @xprt: pointer to the transport
1061  *
1062  */
1063 void xprt_put(struct rpc_xprt *xprt)
1064 {
1065         kref_put(&xprt->kref, xprt_destroy);
1066 }
1067
1068 /**
1069  * xprt_get - return a reference to an RPC transport.
1070  * @xprt: pointer to the transport
1071  *
1072  */
1073 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1074 {
1075         kref_get(&xprt->kref);
1076         return xprt;
1077 }