Pull pnpacpi into acpica branch
[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/random.h>
45
46 #include <linux/sunrpc/clnt.h>
47
48 /*
49  * Local variables
50  */
51
52 #ifdef RPC_DEBUG
53 # undef  RPC_DEBUG_DATA
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: %4d 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                 schedule_work(&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: %4d 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: %4d xprt_cwnd_limited cong = %ld cwnd = %ld\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 xprt %p\n",
391                                 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                 pprintk("RPC: %lu retrans\n", jiffies);
463         } else {
464                 req->rq_timeout = to->to_initval;
465                 req->rq_retries = 0;
466                 xprt_reset_majortimeo(req);
467                 /* Reset the RTT counters == "slow start" */
468                 spin_lock_bh(&xprt->transport_lock);
469                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
470                 spin_unlock_bh(&xprt->transport_lock);
471                 pprintk("RPC: %lu timeout\n", jiffies);
472                 status = -ETIMEDOUT;
473         }
474
475         if (req->rq_timeout == 0) {
476                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
477                 req->rq_timeout = 5 * HZ;
478         }
479         return status;
480 }
481
482 static void xprt_autoclose(void *args)
483 {
484         struct rpc_xprt *xprt = (struct rpc_xprt *)args;
485
486         xprt_disconnect(xprt);
487         xprt->ops->close(xprt);
488         xprt_release_write(xprt, NULL);
489 }
490
491 /**
492  * xprt_disconnect - mark a transport as disconnected
493  * @xprt: transport to flag for disconnect
494  *
495  */
496 void xprt_disconnect(struct rpc_xprt *xprt)
497 {
498         dprintk("RPC:      disconnected transport %p\n", xprt);
499         spin_lock_bh(&xprt->transport_lock);
500         xprt_clear_connected(xprt);
501         xprt_wake_pending_tasks(xprt, -ENOTCONN);
502         spin_unlock_bh(&xprt->transport_lock);
503 }
504
505 static void
506 xprt_init_autodisconnect(unsigned long data)
507 {
508         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
509
510         spin_lock(&xprt->transport_lock);
511         if (!list_empty(&xprt->recv) || xprt->shutdown)
512                 goto out_abort;
513         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
514                 goto out_abort;
515         spin_unlock(&xprt->transport_lock);
516         if (xprt_connecting(xprt))
517                 xprt_release_write(xprt, NULL);
518         else
519                 schedule_work(&xprt->task_cleanup);
520         return;
521 out_abort:
522         spin_unlock(&xprt->transport_lock);
523 }
524
525 /**
526  * xprt_connect - schedule a transport connect operation
527  * @task: RPC task that is requesting the connect
528  *
529  */
530 void xprt_connect(struct rpc_task *task)
531 {
532         struct rpc_xprt *xprt = task->tk_xprt;
533
534         dprintk("RPC: %4d xprt_connect xprt %p %s connected\n", task->tk_pid,
535                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
536
537         if (!xprt->addr.sin_port) {
538                 task->tk_status = -EIO;
539                 return;
540         }
541         if (!xprt_lock_write(xprt, task))
542                 return;
543         if (xprt_connected(xprt))
544                 xprt_release_write(xprt, task);
545         else {
546                 if (task->tk_rqstp)
547                         task->tk_rqstp->rq_bytes_sent = 0;
548
549                 task->tk_timeout = xprt->connect_timeout;
550                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
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                 dprintk("RPC: %4d xprt_connect_status: connection established\n",
562                                 task->tk_pid);
563                 return;
564         }
565
566         switch (task->tk_status) {
567         case -ECONNREFUSED:
568         case -ECONNRESET:
569                 dprintk("RPC: %4d xprt_connect_status: server %s refused connection\n",
570                                 task->tk_pid, task->tk_client->cl_server);
571                 break;
572         case -ENOTCONN:
573                 dprintk("RPC: %4d xprt_connect_status: connection broken\n",
574                                 task->tk_pid);
575                 break;
576         case -ETIMEDOUT:
577                 dprintk("RPC: %4d xprt_connect_status: connect attempt timed out\n",
578                                 task->tk_pid);
579                 break;
580         default:
581                 dprintk("RPC: %4d xprt_connect_status: error %d connecting to server %s\n",
582                                 task->tk_pid, -task->tk_status, task->tk_client->cl_server);
583                 xprt_release_write(xprt, task);
584                 task->tk_status = -EIO;
585                 return;
586         }
587
588         /* if soft mounted, just cause this RPC to fail */
589         if (RPC_IS_SOFT(task)) {
590                 xprt_release_write(xprt, task);
591                 task->tk_status = -EIO;
592         }
593 }
594
595 /**
596  * xprt_lookup_rqst - find an RPC request corresponding to an XID
597  * @xprt: transport on which the original request was transmitted
598  * @xid: RPC XID of incoming reply
599  *
600  */
601 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid)
602 {
603         struct list_head *pos;
604         struct rpc_rqst *req = NULL;
605
606         list_for_each(pos, &xprt->recv) {
607                 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
608                 if (entry->rq_xid == xid) {
609                         req = entry;
610                         break;
611                 }
612         }
613         return req;
614 }
615
616 /**
617  * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
618  * @task: RPC request that recently completed
619  *
620  */
621 void xprt_update_rtt(struct rpc_task *task)
622 {
623         struct rpc_rqst *req = task->tk_rqstp;
624         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
625         unsigned timer = task->tk_msg.rpc_proc->p_timer;
626
627         if (timer) {
628                 if (req->rq_ntrans == 1)
629                         rpc_update_rtt(rtt, timer,
630                                         (long)jiffies - req->rq_xtime);
631                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
632         }
633 }
634
635 /**
636  * xprt_complete_rqst - called when reply processing is complete
637  * @task: RPC request that recently completed
638  * @copied: actual number of bytes received from the transport
639  *
640  * Caller holds transport lock.
641  */
642 void xprt_complete_rqst(struct rpc_task *task, int copied)
643 {
644         struct rpc_rqst *req = task->tk_rqstp;
645
646         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
647                         task->tk_pid, ntohl(req->rq_xid), copied);
648
649         list_del_init(&req->rq_list);
650         req->rq_received = req->rq_private_buf.len = copied;
651         rpc_wake_up_task(task);
652 }
653
654 static void xprt_timer(struct rpc_task *task)
655 {
656         struct rpc_rqst *req = task->tk_rqstp;
657         struct rpc_xprt *xprt = req->rq_xprt;
658
659         dprintk("RPC: %4d xprt_timer\n", task->tk_pid);
660
661         spin_lock(&xprt->transport_lock);
662         if (!req->rq_received) {
663                 if (xprt->ops->timer)
664                         xprt->ops->timer(task);
665                 task->tk_status = -ETIMEDOUT;
666         }
667         task->tk_timeout = 0;
668         rpc_wake_up_task(task);
669         spin_unlock(&xprt->transport_lock);
670 }
671
672 /**
673  * xprt_prepare_transmit - reserve the transport before sending a request
674  * @task: RPC task about to send a request
675  *
676  */
677 int xprt_prepare_transmit(struct rpc_task *task)
678 {
679         struct rpc_rqst *req = task->tk_rqstp;
680         struct rpc_xprt *xprt = req->rq_xprt;
681         int err = 0;
682
683         dprintk("RPC: %4d xprt_prepare_transmit\n", task->tk_pid);
684
685         spin_lock_bh(&xprt->transport_lock);
686         if (req->rq_received && !req->rq_bytes_sent) {
687                 err = req->rq_received;
688                 goto out_unlock;
689         }
690         if (!xprt->ops->reserve_xprt(task)) {
691                 err = -EAGAIN;
692                 goto out_unlock;
693         }
694
695         if (!xprt_connected(xprt)) {
696                 err = -ENOTCONN;
697                 goto out_unlock;
698         }
699 out_unlock:
700         spin_unlock_bh(&xprt->transport_lock);
701         return err;
702 }
703
704 void
705 xprt_abort_transmit(struct rpc_task *task)
706 {
707         struct rpc_xprt *xprt = task->tk_xprt;
708
709         xprt_release_write(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: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
725
726         smp_rmb();
727         if (!req->rq_received) {
728                 if (list_empty(&req->rq_list)) {
729                         spin_lock_bh(&xprt->transport_lock);
730                         /* Update the softirq receive buffer */
731                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
732                                         sizeof(req->rq_private_buf));
733                         /* Add request to the receive list */
734                         list_add_tail(&req->rq_list, &xprt->recv);
735                         spin_unlock_bh(&xprt->transport_lock);
736                         xprt_reset_majortimeo(req);
737                         /* Turn off autodisconnect */
738                         del_singleshot_timer_sync(&xprt->timer);
739                 }
740         } else if (!req->rq_bytes_sent)
741                 return;
742
743         status = xprt->ops->send_request(task);
744         if (status == 0) {
745                 dprintk("RPC: %4d xmit complete\n", task->tk_pid);
746                 spin_lock_bh(&xprt->transport_lock);
747                 xprt->ops->set_retrans_timeout(task);
748                 /* Don't race with disconnect */
749                 if (!xprt_connected(xprt))
750                         task->tk_status = -ENOTCONN;
751                 else if (!req->rq_received)
752                         rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
753                 xprt->ops->release_xprt(xprt, task);
754                 spin_unlock_bh(&xprt->transport_lock);
755                 return;
756         }
757
758         /* Note: at this point, task->tk_sleeping has not yet been set,
759          *       hence there is no danger of the waking up task being put on
760          *       schedq, and being picked up by a parallel run of rpciod().
761          */
762         task->tk_status = status;
763
764         switch (status) {
765         case -ECONNREFUSED:
766                 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
767         case -EAGAIN:
768         case -ENOTCONN:
769                 return;
770         default:
771                 break;
772         }
773         xprt_release_write(xprt, task);
774         return;
775 }
776
777 static inline void do_xprt_reserve(struct rpc_task *task)
778 {
779         struct rpc_xprt *xprt = task->tk_xprt;
780
781         task->tk_status = 0;
782         if (task->tk_rqstp)
783                 return;
784         if (!list_empty(&xprt->free)) {
785                 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
786                 list_del_init(&req->rq_list);
787                 task->tk_rqstp = req;
788                 xprt_request_init(task, xprt);
789                 return;
790         }
791         dprintk("RPC:      waiting for request slot\n");
792         task->tk_status = -EAGAIN;
793         task->tk_timeout = 0;
794         rpc_sleep_on(&xprt->backlog, task, NULL, NULL);
795 }
796
797 /**
798  * xprt_reserve - allocate an RPC request slot
799  * @task: RPC task requesting a slot allocation
800  *
801  * If no more slots are available, place the task on the transport's
802  * backlog queue.
803  */
804 void xprt_reserve(struct rpc_task *task)
805 {
806         struct rpc_xprt *xprt = task->tk_xprt;
807
808         task->tk_status = -EIO;
809         spin_lock(&xprt->reserve_lock);
810         do_xprt_reserve(task);
811         spin_unlock(&xprt->reserve_lock);
812 }
813
814 static inline u32 xprt_alloc_xid(struct rpc_xprt *xprt)
815 {
816         return xprt->xid++;
817 }
818
819 static inline void xprt_init_xid(struct rpc_xprt *xprt)
820 {
821         get_random_bytes(&xprt->xid, sizeof(xprt->xid));
822 }
823
824 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
825 {
826         struct rpc_rqst *req = task->tk_rqstp;
827
828         req->rq_timeout = xprt->timeout.to_initval;
829         req->rq_task    = task;
830         req->rq_xprt    = xprt;
831         req->rq_buffer  = NULL;
832         req->rq_bufsize = 0;
833         req->rq_xid     = xprt_alloc_xid(xprt);
834         req->rq_release_snd_buf = NULL;
835         dprintk("RPC: %4d reserved req %p xid %08x\n", task->tk_pid,
836                         req, ntohl(req->rq_xid));
837 }
838
839 /**
840  * xprt_release - release an RPC request slot
841  * @task: task which is finished with the slot
842  *
843  */
844 void xprt_release(struct rpc_task *task)
845 {
846         struct rpc_xprt *xprt = task->tk_xprt;
847         struct rpc_rqst *req;
848
849         if (!(req = task->tk_rqstp))
850                 return;
851         spin_lock_bh(&xprt->transport_lock);
852         xprt->ops->release_xprt(xprt, task);
853         if (xprt->ops->release_request)
854                 xprt->ops->release_request(task);
855         if (!list_empty(&req->rq_list))
856                 list_del(&req->rq_list);
857         xprt->last_used = jiffies;
858         if (list_empty(&xprt->recv))
859                 mod_timer(&xprt->timer,
860                                 xprt->last_used + xprt->idle_timeout);
861         spin_unlock_bh(&xprt->transport_lock);
862         xprt->ops->buf_free(task);
863         task->tk_rqstp = NULL;
864         if (req->rq_release_snd_buf)
865                 req->rq_release_snd_buf(req);
866         memset(req, 0, sizeof(*req));   /* mark unused */
867
868         dprintk("RPC: %4d release request %p\n", task->tk_pid, req);
869
870         spin_lock(&xprt->reserve_lock);
871         list_add(&req->rq_list, &xprt->free);
872         rpc_wake_up_next(&xprt->backlog);
873         spin_unlock(&xprt->reserve_lock);
874 }
875
876 /**
877  * xprt_set_timeout - set constant RPC timeout
878  * @to: RPC timeout parameters to set up
879  * @retr: number of retries
880  * @incr: amount of increase after each retry
881  *
882  */
883 void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
884 {
885         to->to_initval   = 
886         to->to_increment = incr;
887         to->to_maxval    = to->to_initval + (incr * retr);
888         to->to_retries   = retr;
889         to->to_exponential = 0;
890 }
891
892 static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc_timeout *to)
893 {
894         int result;
895         struct rpc_xprt *xprt;
896         struct rpc_rqst *req;
897
898         if ((xprt = kmalloc(sizeof(struct rpc_xprt), GFP_KERNEL)) == NULL)
899                 return ERR_PTR(-ENOMEM);
900         memset(xprt, 0, sizeof(*xprt)); /* Nnnngh! */
901
902         xprt->addr = *ap;
903
904         switch (proto) {
905         case IPPROTO_UDP:
906                 result = xs_setup_udp(xprt, to);
907                 break;
908         case IPPROTO_TCP:
909                 result = xs_setup_tcp(xprt, to);
910                 break;
911         default:
912                 printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n",
913                                 proto);
914                 result = -EIO;
915                 break;
916         }
917         if (result) {
918                 kfree(xprt);
919                 return ERR_PTR(result);
920         }
921
922         spin_lock_init(&xprt->transport_lock);
923         spin_lock_init(&xprt->reserve_lock);
924
925         INIT_LIST_HEAD(&xprt->free);
926         INIT_LIST_HEAD(&xprt->recv);
927         INIT_WORK(&xprt->task_cleanup, xprt_autoclose, xprt);
928         init_timer(&xprt->timer);
929         xprt->timer.function = xprt_init_autodisconnect;
930         xprt->timer.data = (unsigned long) xprt;
931         xprt->last_used = jiffies;
932         xprt->cwnd = RPC_INITCWND;
933
934         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
935         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
936         rpc_init_wait_queue(&xprt->resend, "xprt_resend");
937         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
938
939         /* initialize free list */
940         for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
941                 list_add(&req->rq_list, &xprt->free);
942
943         xprt_init_xid(xprt);
944
945         dprintk("RPC:      created transport %p with %u slots\n", xprt,
946                         xprt->max_reqs);
947         
948         return xprt;
949 }
950
951 /**
952  * xprt_create_proto - create an RPC client transport
953  * @proto: requested transport protocol
954  * @sap: remote peer's address
955  * @to: timeout parameters for new transport
956  *
957  */
958 struct rpc_xprt *xprt_create_proto(int proto, struct sockaddr_in *sap, struct rpc_timeout *to)
959 {
960         struct rpc_xprt *xprt;
961
962         xprt = xprt_setup(proto, sap, to);
963         if (IS_ERR(xprt))
964                 dprintk("RPC:      xprt_create_proto failed\n");
965         else
966                 dprintk("RPC:      xprt_create_proto created xprt %p\n", xprt);
967         return xprt;
968 }
969
970 /**
971  * xprt_destroy - destroy an RPC transport, killing off all requests.
972  * @xprt: transport to destroy
973  *
974  */
975 int xprt_destroy(struct rpc_xprt *xprt)
976 {
977         dprintk("RPC:      destroying transport %p\n", xprt);
978         xprt->shutdown = 1;
979         del_timer_sync(&xprt->timer);
980         xprt->ops->destroy(xprt);
981         kfree(xprt);
982
983         return 0;
984 }