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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 /*
123 * xprt_reserve_xprt_cong - serialize write access to transports
124 * @task: task that is requesting access to the transport
125 *
126 * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
127 * integrated into the decision of whether a request is allowed to be
128 * woken up and given access to the transport.
129 */
130 int xprt_reserve_xprt_cong(struct rpc_task *task)
131 {
132 struct rpc_xprt *xprt = task->tk_xprt;
133 struct rpc_rqst *req = task->tk_rqstp;
134
135 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
136 if (task == xprt->snd_task)
137 return 1;
138 goto out_sleep;
139 }
140 if (__xprt_get_cong(xprt, task)) {
141 xprt->snd_task = task;
142 if (req) {
143 req->rq_bytes_sent = 0;
144 req->rq_ntrans++;
145 }
146 return 1;
147 }
148 smp_mb__before_clear_bit();
149 clear_bit(XPRT_LOCKED, &xprt->state);
150 smp_mb__after_clear_bit();
151 out_sleep:
152 dprintk("RPC: %4d failed to lock transport %p\n", task->tk_pid, xprt);
153 task->tk_timeout = 0;
154 task->tk_status = -EAGAIN;
155 if (req && req->rq_ntrans)
156 rpc_sleep_on(&xprt->resend, task, NULL, NULL);
157 else
158 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
159 return 0;
160 }
161
162 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
163 {
164 int retval;
165
166 spin_lock_bh(&xprt->transport_lock);
167 retval = xprt->ops->reserve_xprt(task);
168 spin_unlock_bh(&xprt->transport_lock);
169 return retval;
170 }
171
172 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
173 {
174 struct rpc_task *task;
175 struct rpc_rqst *req;
176
177 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
178 return;
179
180 task = rpc_wake_up_next(&xprt->resend);
181 if (!task) {
182 task = rpc_wake_up_next(&xprt->sending);
183 if (!task)
184 goto out_unlock;
185 }
186
187 req = task->tk_rqstp;
188 xprt->snd_task = task;
189 if (req) {
190 req->rq_bytes_sent = 0;
191 req->rq_ntrans++;
192 }
193 return;
194
195 out_unlock:
196 smp_mb__before_clear_bit();
197 clear_bit(XPRT_LOCKED, &xprt->state);
198 smp_mb__after_clear_bit();
199 }
200
201 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
202 {
203 struct rpc_task *task;
204
205 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
206 return;
207 if (RPCXPRT_CONGESTED(xprt))
208 goto out_unlock;
209 task = rpc_wake_up_next(&xprt->resend);
210 if (!task) {
211 task = rpc_wake_up_next(&xprt->sending);
212 if (!task)
213 goto out_unlock;
214 }
215 if (__xprt_get_cong(xprt, task)) {
216 struct rpc_rqst *req = task->tk_rqstp;
217 xprt->snd_task = task;
218 if (req) {
219 req->rq_bytes_sent = 0;
220 req->rq_ntrans++;
221 }
222 return;
223 }
224 out_unlock:
225 smp_mb__before_clear_bit();
226 clear_bit(XPRT_LOCKED, &xprt->state);
227 smp_mb__after_clear_bit();
228 }
229
230 /**
231 * xprt_release_xprt - allow other requests to use a transport
232 * @xprt: transport with other tasks potentially waiting
233 * @task: task that is releasing access to the transport
234 *
235 * Note that "task" can be NULL. No congestion control is provided.
236 */
237 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
238 {
239 if (xprt->snd_task == task) {
240 xprt->snd_task = NULL;
241 smp_mb__before_clear_bit();
242 clear_bit(XPRT_LOCKED, &xprt->state);
243 smp_mb__after_clear_bit();
244 __xprt_lock_write_next(xprt);
245 }
246 }
247
248 /**
249 * xprt_release_xprt_cong - allow other requests to use a transport
250 * @xprt: transport with other tasks potentially waiting
251 * @task: task that is releasing access to the transport
252 *
253 * Note that "task" can be NULL. Another task is awoken to use the
254 * transport if the transport's congestion window allows it.
255 */
256 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
257 {
258 if (xprt->snd_task == task) {
259 xprt->snd_task = NULL;
260 smp_mb__before_clear_bit();
261 clear_bit(XPRT_LOCKED, &xprt->state);
262 smp_mb__after_clear_bit();
263 __xprt_lock_write_next_cong(xprt);
264 }
265 }
266
267 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
268 {
269 spin_lock_bh(&xprt->transport_lock);
270 xprt->ops->release_xprt(xprt, task);
271 spin_unlock_bh(&xprt->transport_lock);
272 }
273
274 /*
275 * Van Jacobson congestion avoidance. Check if the congestion window
276 * overflowed. Put the task to sleep if this is the case.
277 */
278 static int
279 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
280 {
281 struct rpc_rqst *req = task->tk_rqstp;
282
283 if (req->rq_cong)
284 return 1;
285 dprintk("RPC: %4d xprt_cwnd_limited cong = %ld cwnd = %ld\n",
286 task->tk_pid, xprt->cong, xprt->cwnd);
287 if (RPCXPRT_CONGESTED(xprt))
288 return 0;
289 req->rq_cong = 1;
290 xprt->cong += RPC_CWNDSCALE;
291 return 1;
292 }
293
294 /*
295 * Adjust the congestion window, and wake up the next task
296 * that has been sleeping due to congestion
297 */
298 static void
299 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
300 {
301 if (!req->rq_cong)
302 return;
303 req->rq_cong = 0;
304 xprt->cong -= RPC_CWNDSCALE;
305 __xprt_lock_write_next_cong(xprt);
306 }
307
308 /**
309 * xprt_release_rqst_cong - housekeeping when request is complete
310 * @task: RPC request that recently completed
311 *
312 * Useful for transports that require congestion control.
313 */
314 void xprt_release_rqst_cong(struct rpc_task *task)
315 {
316 __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
317 }
318
319 /**
320 * xprt_adjust_cwnd - adjust transport congestion window
321 * @task: recently completed RPC request used to adjust window
322 * @result: result code of completed RPC request
323 *
324 * We use a time-smoothed congestion estimator to avoid heavy oscillation.
325 */
326 void xprt_adjust_cwnd(struct rpc_task *task, int result)
327 {
328 struct rpc_rqst *req = task->tk_rqstp;
329 struct rpc_xprt *xprt = task->tk_xprt;
330 unsigned long cwnd = xprt->cwnd;
331
332 if (result >= 0 && cwnd <= xprt->cong) {
333 /* The (cwnd >> 1) term makes sure
334 * the result gets rounded properly. */
335 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
336 if (cwnd > RPC_MAXCWND(xprt))
337 cwnd = RPC_MAXCWND(xprt);
338 __xprt_lock_write_next_cong(xprt);
339 } else if (result == -ETIMEDOUT) {
340 cwnd >>= 1;
341 if (cwnd < RPC_CWNDSCALE)
342 cwnd = RPC_CWNDSCALE;
343 }
344 dprintk("RPC: cong %ld, cwnd was %ld, now %ld\n",
345 xprt->cong, xprt->cwnd, cwnd);
346 xprt->cwnd = cwnd;
347 __xprt_put_cong(xprt, req);
348 }
349
350 /**
351 * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
352 * @xprt: transport with waiting tasks
353 * @status: result code to plant in each task before waking it
354 *
355 */
356 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
357 {
358 if (status < 0)
359 rpc_wake_up_status(&xprt->pending, status);
360 else
361 rpc_wake_up(&xprt->pending);
362 }
363
364 /**
365 * xprt_wait_for_buffer_space - wait for transport output buffer to clear
366 * @task: task to be put to sleep
367 *
368 */
369 void xprt_wait_for_buffer_space(struct rpc_task *task)
370 {
371 struct rpc_rqst *req = task->tk_rqstp;
372 struct rpc_xprt *xprt = req->rq_xprt;
373
374 task->tk_timeout = req->rq_timeout;
375 rpc_sleep_on(&xprt->pending, task, NULL, NULL);
376 }
377
378 /**
379 * xprt_write_space - wake the task waiting for transport output buffer space
380 * @xprt: transport with waiting tasks
381 *
382 * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
383 */
384 void xprt_write_space(struct rpc_xprt *xprt)
385 {
386 if (unlikely(xprt->shutdown))
387 return;
388
389 spin_lock_bh(&xprt->transport_lock);
390 if (xprt->snd_task) {
391 dprintk("RPC: write space: waking waiting task on xprt %p\n",
392 xprt);
393 rpc_wake_up_task(xprt->snd_task);
394 }
395 spin_unlock_bh(&xprt->transport_lock);
396 }
397
398 /**
399 * xprt_set_retrans_timeout_def - set a request's retransmit timeout
400 * @task: task whose timeout is to be set
401 *
402 * Set a request's retransmit timeout based on the transport's
403 * default timeout parameters. Used by transports that don't adjust
404 * the retransmit timeout based on round-trip time estimation.
405 */
406 void xprt_set_retrans_timeout_def(struct rpc_task *task)
407 {
408 task->tk_timeout = task->tk_rqstp->rq_timeout;
409 }
410
411 /*
412 * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
413 * @task: task whose timeout is to be set
414 *
415 * Set a request's retransmit timeout using the RTT estimator.
416 */
417 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
418 {
419 int timer = task->tk_msg.rpc_proc->p_timer;
420 struct rpc_rtt *rtt = task->tk_client->cl_rtt;
421 struct rpc_rqst *req = task->tk_rqstp;
422 unsigned long max_timeout = req->rq_xprt->timeout.to_maxval;
423
424 task->tk_timeout = rpc_calc_rto(rtt, timer);
425 task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
426 if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
427 task->tk_timeout = max_timeout;
428 }
429
430 static void xprt_reset_majortimeo(struct rpc_rqst *req)
431 {
432 struct rpc_timeout *to = &req->rq_xprt->timeout;
433
434 req->rq_majortimeo = req->rq_timeout;
435 if (to->to_exponential)
436 req->rq_majortimeo <<= to->to_retries;
437 else
438 req->rq_majortimeo += to->to_increment * to->to_retries;
439 if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
440 req->rq_majortimeo = to->to_maxval;
441 req->rq_majortimeo += jiffies;
442 }
443
444 /**
445 * xprt_adjust_timeout - adjust timeout values for next retransmit
446 * @req: RPC request containing parameters to use for the adjustment
447 *
448 */
449 int xprt_adjust_timeout(struct rpc_rqst *req)
450 {
451 struct rpc_xprt *xprt = req->rq_xprt;
452 struct rpc_timeout *to = &xprt->timeout;
453 int status = 0;
454
455 if (time_before(jiffies, req->rq_majortimeo)) {
456 if (to->to_exponential)
457 req->rq_timeout <<= 1;
458 else
459 req->rq_timeout += to->to_increment;
460 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
461 req->rq_timeout = to->to_maxval;
462 req->rq_retries++;
463 pprintk("RPC: %lu retrans\n", jiffies);
464 } else {
465 req->rq_timeout = to->to_initval;
466 req->rq_retries = 0;
467 xprt_reset_majortimeo(req);
468 /* Reset the RTT counters == "slow start" */
469 spin_lock_bh(&xprt->transport_lock);
470 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
471 spin_unlock_bh(&xprt->transport_lock);
472 pprintk("RPC: %lu timeout\n", jiffies);
473 status = -ETIMEDOUT;
474 }
475
476 if (req->rq_timeout == 0) {
477 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
478 req->rq_timeout = 5 * HZ;
479 }
480 return status;
481 }
482
483 static void xprt_autoclose(void *args)
484 {
485 struct rpc_xprt *xprt = (struct rpc_xprt *)args;
486
487 xprt_disconnect(xprt);
488 xprt->ops->close(xprt);
489 xprt_release_write(xprt, NULL);
490 }
491
492 /**
493 * xprt_disconnect - mark a transport as disconnected
494 * @xprt: transport to flag for disconnect
495 *
496 */
497 void xprt_disconnect(struct rpc_xprt *xprt)
498 {
499 dprintk("RPC: disconnected transport %p\n", xprt);
500 spin_lock_bh(&xprt->transport_lock);
501 xprt_clear_connected(xprt);
502 xprt_wake_pending_tasks(xprt, -ENOTCONN);
503 spin_unlock_bh(&xprt->transport_lock);
504 }
505
506 static void
507 xprt_init_autodisconnect(unsigned long data)
508 {
509 struct rpc_xprt *xprt = (struct rpc_xprt *)data;
510
511 spin_lock(&xprt->transport_lock);
512 if (!list_empty(&xprt->recv) || xprt->shutdown)
513 goto out_abort;
514 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
515 goto out_abort;
516 spin_unlock(&xprt->transport_lock);
517 if (xprt_connecting(xprt))
518 xprt_release_write(xprt, NULL);
519 else
520 schedule_work(&xprt->task_cleanup);
521 return;
522 out_abort:
523 spin_unlock(&xprt->transport_lock);
524 }
525
526 /**
527 * xprt_connect - schedule a transport connect operation
528 * @task: RPC task that is requesting the connect
529 *
530 */
531 void xprt_connect(struct rpc_task *task)
532 {
533 struct rpc_xprt *xprt = task->tk_xprt;
534
535 dprintk("RPC: %4d xprt_connect xprt %p %s connected\n", task->tk_pid,
536 xprt, (xprt_connected(xprt) ? "is" : "is not"));
537
538 if (xprt->shutdown) {
539 task->tk_status = -EIO;
540 return;
541 }
542 if (!xprt->addr.sin_port) {
543 task->tk_status = -EIO;
544 return;
545 }
546 if (!xprt_lock_write(xprt, task))
547 return;
548 if (xprt_connected(xprt))
549 xprt_release_write(xprt, task);
550 else {
551 if (task->tk_rqstp)
552 task->tk_rqstp->rq_bytes_sent = 0;
553
554 task->tk_timeout = xprt->connect_timeout;
555 rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
556 xprt->ops->connect(task);
557 }
558 return;
559 }
560
561 static void xprt_connect_status(struct rpc_task *task)
562 {
563 struct rpc_xprt *xprt = task->tk_xprt;
564
565 if (task->tk_status >= 0) {
566 dprintk("RPC: %4d xprt_connect_status: connection established\n",
567 task->tk_pid);
568 return;
569 }
570
571 switch (task->tk_status) {
572 case -ECONNREFUSED:
573 case -ECONNRESET:
574 dprintk("RPC: %4d xprt_connect_status: server %s refused connection\n",
575 task->tk_pid, task->tk_client->cl_server);
576 break;
577 case -ENOTCONN:
578 dprintk("RPC: %4d xprt_connect_status: connection broken\n",
579 task->tk_pid);
580 break;
581 case -ETIMEDOUT:
582 dprintk("RPC: %4d xprt_connect_status: connect attempt timed out\n",
583 task->tk_pid);
584 break;
585 default:
586 dprintk("RPC: %4d xprt_connect_status: error %d connecting to server %s\n",
587 task->tk_pid, -task->tk_status, task->tk_client->cl_server);
588 xprt_release_write(xprt, task);
589 task->tk_status = -EIO;
590 return;
591 }
592
593 /* if soft mounted, just cause this RPC to fail */
594 if (RPC_IS_SOFT(task)) {
595 xprt_release_write(xprt, task);
596 task->tk_status = -EIO;
597 }
598 }
599
600 /**
601 * xprt_lookup_rqst - find an RPC request corresponding to an XID
602 * @xprt: transport on which the original request was transmitted
603 * @xid: RPC XID of incoming reply
604 *
605 */
606 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid)
607 {
608 struct list_head *pos;
609 struct rpc_rqst *req = NULL;
610
611 list_for_each(pos, &xprt->recv) {
612 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
613 if (entry->rq_xid == xid) {
614 req = entry;
615 break;
616 }
617 }
618 return req;
619 }
620
621 /**
622 * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
623 * @task: RPC request that recently completed
624 *
625 */
626 void xprt_update_rtt(struct rpc_task *task)
627 {
628 struct rpc_rqst *req = task->tk_rqstp;
629 struct rpc_rtt *rtt = task->tk_client->cl_rtt;
630 unsigned timer = task->tk_msg.rpc_proc->p_timer;
631
632 if (timer) {
633 if (req->rq_ntrans == 1)
634 rpc_update_rtt(rtt, timer,
635 (long)jiffies - req->rq_xtime);
636 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
637 }
638 }
639
640 /**
641 * xprt_complete_rqst - called when reply processing is complete
642 * @task: RPC request that recently completed
643 * @copied: actual number of bytes received from the transport
644 *
645 * Caller holds transport lock.
646 */
647 void xprt_complete_rqst(struct rpc_task *task, int copied)
648 {
649 struct rpc_rqst *req = task->tk_rqstp;
650
651 dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
652 task->tk_pid, ntohl(req->rq_xid), copied);
653
654 list_del_init(&req->rq_list);
655 req->rq_received = req->rq_private_buf.len = copied;
656 rpc_wake_up_task(task);
657 }
658
659 static void xprt_timer(struct rpc_task *task)
660 {
661 struct rpc_rqst *req = task->tk_rqstp;
662 struct rpc_xprt *xprt = req->rq_xprt;
663
664 dprintk("RPC: %4d xprt_timer\n", task->tk_pid);
665
666 spin_lock(&xprt->transport_lock);
667 if (!req->rq_received) {
668 if (xprt->ops->timer)
669 xprt->ops->timer(task);
670 task->tk_status = -ETIMEDOUT;
671 }
672 task->tk_timeout = 0;
673 rpc_wake_up_task(task);
674 spin_unlock(&xprt->transport_lock);
675 }
676
677 /**
678 * xprt_prepare_transmit - reserve the transport before sending a request
679 * @task: RPC task about to send a request
680 *
681 */
682 int xprt_prepare_transmit(struct rpc_task *task)
683 {
684 struct rpc_rqst *req = task->tk_rqstp;
685 struct rpc_xprt *xprt = req->rq_xprt;
686 int err = 0;
687
688 dprintk("RPC: %4d xprt_prepare_transmit\n", task->tk_pid);
689
690 if (xprt->shutdown)
691 return -EIO;
692
693 spin_lock_bh(&xprt->transport_lock);
694 if (req->rq_received && !req->rq_bytes_sent) {
695 err = req->rq_received;
696 goto out_unlock;
697 }
698 if (!xprt->ops->reserve_xprt(task)) {
699 err = -EAGAIN;
700 goto out_unlock;
701 }
702
703 if (!xprt_connected(xprt)) {
704 err = -ENOTCONN;
705 goto out_unlock;
706 }
707 out_unlock:
708 spin_unlock_bh(&xprt->transport_lock);
709 return err;
710 }
711
712 void
713 xprt_abort_transmit(struct rpc_task *task)
714 {
715 struct rpc_xprt *xprt = task->tk_xprt;
716
717 xprt_release_write(xprt, task);
718 }
719
720 /**
721 * xprt_transmit - send an RPC request on a transport
722 * @task: controlling RPC task
723 *
724 * We have to copy the iovec because sendmsg fiddles with its contents.
725 */
726 void xprt_transmit(struct rpc_task *task)
727 {
728 struct rpc_rqst *req = task->tk_rqstp;
729 struct rpc_xprt *xprt = req->rq_xprt;
730 int status;
731
732 dprintk("RPC: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
733
734 smp_rmb();
735 if (!req->rq_received) {
736 if (list_empty(&req->rq_list)) {
737 spin_lock_bh(&xprt->transport_lock);
738 /* Update the softirq receive buffer */
739 memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
740 sizeof(req->rq_private_buf));
741 /* Add request to the receive list */
742 list_add_tail(&req->rq_list, &xprt->recv);
743 spin_unlock_bh(&xprt->transport_lock);
744 xprt_reset_majortimeo(req);
745 /* Turn off autodisconnect */
746 del_singleshot_timer_sync(&xprt->timer);
747 }
748 } else if (!req->rq_bytes_sent)
749 return;
750
751 status = xprt->ops->send_request(task);
752 if (status == 0) {
753 dprintk("RPC: %4d xmit complete\n", task->tk_pid);
754 spin_lock_bh(&xprt->transport_lock);
755 xprt->ops->set_retrans_timeout(task);
756 /* Don't race with disconnect */
757 if (!xprt_connected(xprt))
758 task->tk_status = -ENOTCONN;
759 else if (!req->rq_received)
760 rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
761 xprt->ops->release_xprt(xprt, task);
762 spin_unlock_bh(&xprt->transport_lock);
763 return;
764 }
765
766 /* Note: at this point, task->tk_sleeping has not yet been set,
767 * hence there is no danger of the waking up task being put on
768 * schedq, and being picked up by a parallel run of rpciod().
769 */
770 task->tk_status = status;
771
772 switch (status) {
773 case -ECONNREFUSED:
774 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
775 case -EAGAIN:
776 case -ENOTCONN:
777 return;
778 default:
779 break;
780 }
781 xprt_release_write(xprt, task);
782 return;
783 }
784
785 static inline void do_xprt_reserve(struct rpc_task *task)
786 {
787 struct rpc_xprt *xprt = task->tk_xprt;
788
789 task->tk_status = 0;
790 if (task->tk_rqstp)
791 return;
792 if (!list_empty(&xprt->free)) {
793 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
794 list_del_init(&req->rq_list);
795 task->tk_rqstp = req;
796 xprt_request_init(task, xprt);
797 return;
798 }
799 dprintk("RPC: waiting for request slot\n");
800 task->tk_status = -EAGAIN;
801 task->tk_timeout = 0;
802 rpc_sleep_on(&xprt->backlog, task, NULL, NULL);
803 }
804
805 /**
806 * xprt_reserve - allocate an RPC request slot
807 * @task: RPC task requesting a slot allocation
808 *
809 * If no more slots are available, place the task on the transport's
810 * backlog queue.
811 */
812 void xprt_reserve(struct rpc_task *task)
813 {
814 struct rpc_xprt *xprt = task->tk_xprt;
815
816 task->tk_status = -EIO;
817 if (!xprt->shutdown) {
818 spin_lock(&xprt->reserve_lock);
819 do_xprt_reserve(task);
820 spin_unlock(&xprt->reserve_lock);
821 }
822 }
823
824 static inline u32 xprt_alloc_xid(struct rpc_xprt *xprt)
825 {
826 return xprt->xid++;
827 }
828
829 static inline void xprt_init_xid(struct rpc_xprt *xprt)
830 {
831 get_random_bytes(&xprt->xid, sizeof(xprt->xid));
832 }
833
834 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
835 {
836 struct rpc_rqst *req = task->tk_rqstp;
837
838 req->rq_timeout = xprt->timeout.to_initval;
839 req->rq_task = task;
840 req->rq_xprt = xprt;
841 req->rq_xid = xprt_alloc_xid(xprt);
842 req->rq_release_snd_buf = NULL;
843 dprintk("RPC: %4d reserved req %p xid %08x\n", task->tk_pid,
844 req, ntohl(req->rq_xid));
845 }
846
847 /**
848 * xprt_release - release an RPC request slot
849 * @task: task which is finished with the slot
850 *
851 */
852 void xprt_release(struct rpc_task *task)
853 {
854 struct rpc_xprt *xprt = task->tk_xprt;
855 struct rpc_rqst *req;
856
857 if (!(req = task->tk_rqstp))
858 return;
859 spin_lock_bh(&xprt->transport_lock);
860 xprt->ops->release_xprt(xprt, task);
861 if (xprt->ops->release_request)
862 xprt->ops->release_request(task);
863 if (!list_empty(&req->rq_list))
864 list_del(&req->rq_list);
865 xprt->last_used = jiffies;
866 if (list_empty(&xprt->recv) && !xprt->shutdown)
867 mod_timer(&xprt->timer,
868 xprt->last_used + xprt->idle_timeout);
869 spin_unlock_bh(&xprt->transport_lock);
870 task->tk_rqstp = NULL;
871 if (req->rq_release_snd_buf)
872 req->rq_release_snd_buf(req);
873 memset(req, 0, sizeof(*req)); /* mark unused */
874
875 dprintk("RPC: %4d release request %p\n", task->tk_pid, req);
876
877 spin_lock(&xprt->reserve_lock);
878 list_add(&req->rq_list, &xprt->free);
879 rpc_wake_up_next(&xprt->backlog);
880 spin_unlock(&xprt->reserve_lock);
881 }
882
883 /**
884 * xprt_set_timeout - set constant RPC timeout
885 * @to: RPC timeout parameters to set up
886 * @retr: number of retries
887 * @incr: amount of increase after each retry
888 *
889 */
890 void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
891 {
892 to->to_initval =
893 to->to_increment = incr;
894 to->to_maxval = to->to_initval + (incr * retr);
895 to->to_retries = retr;
896 to->to_exponential = 0;
897 }
898
899 static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc_timeout *to)
900 {
901 int result;
902 struct rpc_xprt *xprt;
903 struct rpc_rqst *req;
904
905 if ((xprt = kmalloc(sizeof(struct rpc_xprt), GFP_KERNEL)) == NULL)
906 return ERR_PTR(-ENOMEM);
907 memset(xprt, 0, sizeof(*xprt)); /* Nnnngh! */
908
909 xprt->addr = *ap;
910
911 switch (proto) {
912 case IPPROTO_UDP:
913 result = xs_setup_udp(xprt, to);
914 break;
915 case IPPROTO_TCP:
916 result = xs_setup_tcp(xprt, to);
917 break;
918 default:
919 printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n",
920 proto);
921 result = -EIO;
922 break;
923 }
924 if (result) {
925 kfree(xprt);
926 return ERR_PTR(result);
927 }
928
929 spin_lock_init(&xprt->transport_lock);
930 spin_lock_init(&xprt->reserve_lock);
931
932 INIT_LIST_HEAD(&xprt->free);
933 INIT_LIST_HEAD(&xprt->recv);
934 INIT_WORK(&xprt->task_cleanup, xprt_autoclose, xprt);
935 init_timer(&xprt->timer);
936 xprt->timer.function = xprt_init_autodisconnect;
937 xprt->timer.data = (unsigned long) xprt;
938 xprt->last_used = jiffies;
939 xprt->cwnd = RPC_INITCWND;
940
941 rpc_init_wait_queue(&xprt->pending, "xprt_pending");
942 rpc_init_wait_queue(&xprt->sending, "xprt_sending");
943 rpc_init_wait_queue(&xprt->resend, "xprt_resend");
944 rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
945
946 /* initialize free list */
947 for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
948 list_add(&req->rq_list, &xprt->free);
949
950 xprt_init_xid(xprt);
951
952 dprintk("RPC: created transport %p with %u slots\n", xprt,
953 xprt->max_reqs);
954
955 return xprt;
956 }
957
958 /**
959 * xprt_create_proto - create an RPC client transport
960 * @proto: requested transport protocol
961 * @sap: remote peer's address
962 * @to: timeout parameters for new transport
963 *
964 */
965 struct rpc_xprt *xprt_create_proto(int proto, struct sockaddr_in *sap, struct rpc_timeout *to)
966 {
967 struct rpc_xprt *xprt;
968
969 xprt = xprt_setup(proto, sap, to);
970 if (IS_ERR(xprt))
971 dprintk("RPC: xprt_create_proto failed\n");
972 else
973 dprintk("RPC: xprt_create_proto created xprt %p\n", xprt);
974 return xprt;
975 }
976
977 static void xprt_shutdown(struct rpc_xprt *xprt)
978 {
979 xprt->shutdown = 1;
980 rpc_wake_up(&xprt->sending);
981 rpc_wake_up(&xprt->resend);
982 xprt_wake_pending_tasks(xprt, -EIO);
983 rpc_wake_up(&xprt->backlog);
984 del_timer_sync(&xprt->timer);
985 }
986
987 /**
988 * xprt_destroy - destroy an RPC transport, killing off all requests.
989 * @xprt: transport to destroy
990 *
991 */
992 int xprt_destroy(struct rpc_xprt *xprt)
993 {
994 dprintk("RPC: destroying transport %p\n", xprt);
995 xprt_shutdown(xprt);
996 xprt->ops->destroy(xprt);
997 kfree(xprt);
998
999 return 0;
1000 }