[PATCH] w1: Userspace communication protocol over connector.
[linux-2.6/verdex.git] / net / sunrpc / xprt.c
blob4dd5b3cfe7547071b945e47d9ba6ab6e5ef89647
1 /*
2 * linux/net/sunrpc/xprt.c
4 * This is a generic RPC call interface supporting congestion avoidance,
5 * and asynchronous calls.
7 * The interface works like this:
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.
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.
34 * Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
36 * Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
39 #include <linux/module.h>
41 #include <linux/types.h>
42 #include <linux/interrupt.h>
43 #include <linux/workqueue.h>
44 #include <linux/random.h>
46 #include <linux/sunrpc/clnt.h>
47 #include <linux/sunrpc/metrics.h>
50 * Local variables
53 #ifdef RPC_DEBUG
54 # define RPCDBG_FACILITY RPCDBG_XPRT
55 #endif
58 * Local functions
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 *);
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
72 * - a reply is received and
73 * - a full number of requests are outstanding and
74 * - the congestion window hasn't been updated recently.
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)
81 #define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
83 /**
84 * xprt_reserve_xprt - serialize write access to transports
85 * @task: task that is requesting access to the transport
87 * This prevents mixing the payload of separate requests, and prevents
88 * transport connects from colliding with writes. No congestion control
89 * is provided.
91 int xprt_reserve_xprt(struct rpc_task *task)
93 struct rpc_xprt *xprt = task->tk_xprt;
94 struct rpc_rqst *req = task->tk_rqstp;
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;
103 xprt->snd_task = task;
104 if (req) {
105 req->rq_bytes_sent = 0;
106 req->rq_ntrans++;
108 return 1;
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;
122 static void xprt_clear_locked(struct rpc_xprt *xprt)
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);
134 * xprt_reserve_xprt_cong - serialize write access to transports
135 * @task: task that is requesting access to the transport
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.
141 int xprt_reserve_xprt_cong(struct rpc_task *task)
143 struct rpc_xprt *xprt = task->tk_xprt;
144 struct rpc_rqst *req = task->tk_rqstp;
146 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
147 if (task == xprt->snd_task)
148 return 1;
149 goto out_sleep;
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++;
157 return 1;
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;
171 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
173 int retval;
175 spin_lock_bh(&xprt->transport_lock);
176 retval = xprt->ops->reserve_xprt(task);
177 spin_unlock_bh(&xprt->transport_lock);
178 return retval;
181 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
183 struct rpc_task *task;
184 struct rpc_rqst *req;
186 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
187 return;
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;
196 req = task->tk_rqstp;
197 xprt->snd_task = task;
198 if (req) {
199 req->rq_bytes_sent = 0;
200 req->rq_ntrans++;
202 return;
204 out_unlock:
205 xprt_clear_locked(xprt);
208 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
210 struct rpc_task *task;
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;
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++;
229 return;
231 out_unlock:
232 xprt_clear_locked(xprt);
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
240 * Note that "task" can be NULL. No congestion control is provided.
242 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
244 if (xprt->snd_task == task) {
245 xprt_clear_locked(xprt);
246 __xprt_lock_write_next(xprt);
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
255 * Note that "task" can be NULL. Another task is awoken to use the
256 * transport if the transport's congestion window allows it.
258 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
260 if (xprt->snd_task == task) {
261 xprt_clear_locked(xprt);
262 __xprt_lock_write_next_cong(xprt);
266 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
268 spin_lock_bh(&xprt->transport_lock);
269 xprt->ops->release_xprt(xprt, task);
270 spin_unlock_bh(&xprt->transport_lock);
274 * Van Jacobson congestion avoidance. Check if the congestion window
275 * overflowed. Put the task to sleep if this is the case.
277 static int
278 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
280 struct rpc_rqst *req = task->tk_rqstp;
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;
294 * Adjust the congestion window, and wake up the next task
295 * that has been sleeping due to congestion
297 static void
298 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
300 if (!req->rq_cong)
301 return;
302 req->rq_cong = 0;
303 xprt->cong -= RPC_CWNDSCALE;
304 __xprt_lock_write_next_cong(xprt);
308 * xprt_release_rqst_cong - housekeeping when request is complete
309 * @task: RPC request that recently completed
311 * Useful for transports that require congestion control.
313 void xprt_release_rqst_cong(struct rpc_task *task)
315 __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
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
323 * We use a time-smoothed congestion estimator to avoid heavy oscillation.
325 void xprt_adjust_cwnd(struct rpc_task *task, int result)
327 struct rpc_rqst *req = task->tk_rqstp;
328 struct rpc_xprt *xprt = task->tk_xprt;
329 unsigned long cwnd = xprt->cwnd;
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;
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);
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
355 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
357 if (status < 0)
358 rpc_wake_up_status(&xprt->pending, status);
359 else
360 rpc_wake_up(&xprt->pending);
364 * xprt_wait_for_buffer_space - wait for transport output buffer to clear
365 * @task: task to be put to sleep
368 void xprt_wait_for_buffer_space(struct rpc_task *task)
370 struct rpc_rqst *req = task->tk_rqstp;
371 struct rpc_xprt *xprt = req->rq_xprt;
373 task->tk_timeout = req->rq_timeout;
374 rpc_sleep_on(&xprt->pending, task, NULL, NULL);
378 * xprt_write_space - wake the task waiting for transport output buffer space
379 * @xprt: transport with waiting tasks
381 * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
383 void xprt_write_space(struct rpc_xprt *xprt)
385 if (unlikely(xprt->shutdown))
386 return;
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);
394 spin_unlock_bh(&xprt->transport_lock);
398 * xprt_set_retrans_timeout_def - set a request's retransmit timeout
399 * @task: task whose timeout is to be set
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.
405 void xprt_set_retrans_timeout_def(struct rpc_task *task)
407 task->tk_timeout = task->tk_rqstp->rq_timeout;
411 * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
412 * @task: task whose timeout is to be set
414 * Set a request's retransmit timeout using the RTT estimator.
416 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
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;
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;
429 static void xprt_reset_majortimeo(struct rpc_rqst *req)
431 struct rpc_timeout *to = &req->rq_xprt->timeout;
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;
444 * xprt_adjust_timeout - adjust timeout values for next retransmit
445 * @req: RPC request containing parameters to use for the adjustment
448 int xprt_adjust_timeout(struct rpc_rqst *req)
450 struct rpc_xprt *xprt = req->rq_xprt;
451 struct rpc_timeout *to = &xprt->timeout;
452 int status = 0;
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;
475 if (req->rq_timeout == 0) {
476 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
477 req->rq_timeout = 5 * HZ;
479 return status;
482 static void xprt_autoclose(void *args)
484 struct rpc_xprt *xprt = (struct rpc_xprt *)args;
486 xprt_disconnect(xprt);
487 xprt->ops->close(xprt);
488 xprt_release_write(xprt, NULL);
492 * xprt_disconnect - mark a transport as disconnected
493 * @xprt: transport to flag for disconnect
496 void xprt_disconnect(struct rpc_xprt *xprt)
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);
505 static void
506 xprt_init_autodisconnect(unsigned long data)
508 struct rpc_xprt *xprt = (struct rpc_xprt *)data;
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);
526 * xprt_connect - schedule a transport connect operation
527 * @task: RPC task that is requesting the connect
530 void xprt_connect(struct rpc_task *task)
532 struct rpc_xprt *xprt = task->tk_xprt;
534 dprintk("RPC: %4d xprt_connect xprt %p %s connected\n", task->tk_pid,
535 xprt, (xprt_connected(xprt) ? "is" : "is not"));
537 if (!xprt->addr.sin_port) {
538 task->tk_status = -EIO;
539 return;
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;
549 task->tk_timeout = xprt->connect_timeout;
550 rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
551 xprt->stat.connect_start = jiffies;
552 xprt->ops->connect(task);
554 return;
557 static void xprt_connect_status(struct rpc_task *task)
559 struct rpc_xprt *xprt = task->tk_xprt;
561 if (task->tk_status >= 0) {
562 xprt->stat.connect_count++;
563 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
564 dprintk("RPC: %4d xprt_connect_status: connection established\n",
565 task->tk_pid);
566 return;
569 switch (task->tk_status) {
570 case -ECONNREFUSED:
571 case -ECONNRESET:
572 dprintk("RPC: %4d xprt_connect_status: server %s refused connection\n",
573 task->tk_pid, task->tk_client->cl_server);
574 break;
575 case -ENOTCONN:
576 dprintk("RPC: %4d xprt_connect_status: connection broken\n",
577 task->tk_pid);
578 break;
579 case -ETIMEDOUT:
580 dprintk("RPC: %4d xprt_connect_status: connect attempt timed out\n",
581 task->tk_pid);
582 break;
583 default:
584 dprintk("RPC: %4d xprt_connect_status: error %d connecting to server %s\n",
585 task->tk_pid, -task->tk_status, task->tk_client->cl_server);
586 xprt_release_write(xprt, task);
587 task->tk_status = -EIO;
588 return;
591 /* if soft mounted, just cause this RPC to fail */
592 if (RPC_IS_SOFT(task)) {
593 xprt_release_write(xprt, task);
594 task->tk_status = -EIO;
599 * xprt_lookup_rqst - find an RPC request corresponding to an XID
600 * @xprt: transport on which the original request was transmitted
601 * @xid: RPC XID of incoming reply
604 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid)
606 struct list_head *pos;
608 list_for_each(pos, &xprt->recv) {
609 struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
610 if (entry->rq_xid == xid)
611 return entry;
613 xprt->stat.bad_xids++;
614 return NULL;
618 * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
619 * @task: RPC request that recently completed
622 void xprt_update_rtt(struct rpc_task *task)
624 struct rpc_rqst *req = task->tk_rqstp;
625 struct rpc_rtt *rtt = task->tk_client->cl_rtt;
626 unsigned timer = task->tk_msg.rpc_proc->p_timer;
628 if (timer) {
629 if (req->rq_ntrans == 1)
630 rpc_update_rtt(rtt, timer,
631 (long)jiffies - req->rq_xtime);
632 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
637 * xprt_complete_rqst - called when reply processing is complete
638 * @task: RPC request that recently completed
639 * @copied: actual number of bytes received from the transport
641 * Caller holds transport lock.
643 void xprt_complete_rqst(struct rpc_task *task, int copied)
645 struct rpc_rqst *req = task->tk_rqstp;
647 dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
648 task->tk_pid, ntohl(req->rq_xid), copied);
650 task->tk_xprt->stat.recvs++;
651 task->tk_rtt = (long)jiffies - req->rq_xtime;
653 list_del_init(&req->rq_list);
654 /* Ensure all writes are done before we update req->rq_received */
655 smp_wmb();
656 req->rq_received = req->rq_private_buf.len = copied;
657 rpc_wake_up_task(task);
660 static void xprt_timer(struct rpc_task *task)
662 struct rpc_rqst *req = task->tk_rqstp;
663 struct rpc_xprt *xprt = req->rq_xprt;
665 dprintk("RPC: %4d xprt_timer\n", task->tk_pid);
667 spin_lock(&xprt->transport_lock);
668 if (!req->rq_received) {
669 if (xprt->ops->timer)
670 xprt->ops->timer(task);
671 task->tk_status = -ETIMEDOUT;
673 task->tk_timeout = 0;
674 rpc_wake_up_task(task);
675 spin_unlock(&xprt->transport_lock);
679 * xprt_prepare_transmit - reserve the transport before sending a request
680 * @task: RPC task about to send a request
683 int xprt_prepare_transmit(struct rpc_task *task)
685 struct rpc_rqst *req = task->tk_rqstp;
686 struct rpc_xprt *xprt = req->rq_xprt;
687 int err = 0;
689 dprintk("RPC: %4d xprt_prepare_transmit\n", task->tk_pid);
691 spin_lock_bh(&xprt->transport_lock);
692 if (req->rq_received && !req->rq_bytes_sent) {
693 err = req->rq_received;
694 goto out_unlock;
696 if (!xprt->ops->reserve_xprt(task)) {
697 err = -EAGAIN;
698 goto out_unlock;
701 if (!xprt_connected(xprt)) {
702 err = -ENOTCONN;
703 goto out_unlock;
705 out_unlock:
706 spin_unlock_bh(&xprt->transport_lock);
707 return err;
710 void
711 xprt_abort_transmit(struct rpc_task *task)
713 struct rpc_xprt *xprt = task->tk_xprt;
715 xprt_release_write(xprt, task);
719 * xprt_transmit - send an RPC request on a transport
720 * @task: controlling RPC task
722 * We have to copy the iovec because sendmsg fiddles with its contents.
724 void xprt_transmit(struct rpc_task *task)
726 struct rpc_rqst *req = task->tk_rqstp;
727 struct rpc_xprt *xprt = req->rq_xprt;
728 int status;
730 dprintk("RPC: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
732 if (!req->rq_received) {
733 if (list_empty(&req->rq_list)) {
734 spin_lock_bh(&xprt->transport_lock);
735 /* Update the softirq receive buffer */
736 memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
737 sizeof(req->rq_private_buf));
738 /* Add request to the receive list */
739 list_add_tail(&req->rq_list, &xprt->recv);
740 spin_unlock_bh(&xprt->transport_lock);
741 xprt_reset_majortimeo(req);
742 /* Turn off autodisconnect */
743 del_singleshot_timer_sync(&xprt->timer);
745 } else if (!req->rq_bytes_sent)
746 return;
748 status = xprt->ops->send_request(task);
749 if (status == 0) {
750 dprintk("RPC: %4d xmit complete\n", task->tk_pid);
751 spin_lock_bh(&xprt->transport_lock);
753 xprt->ops->set_retrans_timeout(task);
755 xprt->stat.sends++;
756 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
757 xprt->stat.bklog_u += xprt->backlog.qlen;
759 /* Don't race with disconnect */
760 if (!xprt_connected(xprt))
761 task->tk_status = -ENOTCONN;
762 else if (!req->rq_received)
763 rpc_sleep_on(&xprt->pending, task, NULL, xprt_timer);
765 xprt->ops->release_xprt(xprt, task);
766 spin_unlock_bh(&xprt->transport_lock);
767 return;
770 /* Note: at this point, task->tk_sleeping has not yet been set,
771 * hence there is no danger of the waking up task being put on
772 * schedq, and being picked up by a parallel run of rpciod().
774 task->tk_status = status;
776 switch (status) {
777 case -ECONNREFUSED:
778 rpc_sleep_on(&xprt->sending, task, NULL, NULL);
779 case -EAGAIN:
780 case -ENOTCONN:
781 return;
782 default:
783 break;
785 xprt_release_write(xprt, task);
786 return;
789 static inline void do_xprt_reserve(struct rpc_task *task)
791 struct rpc_xprt *xprt = task->tk_xprt;
793 task->tk_status = 0;
794 if (task->tk_rqstp)
795 return;
796 if (!list_empty(&xprt->free)) {
797 struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
798 list_del_init(&req->rq_list);
799 task->tk_rqstp = req;
800 xprt_request_init(task, xprt);
801 return;
803 dprintk("RPC: waiting for request slot\n");
804 task->tk_status = -EAGAIN;
805 task->tk_timeout = 0;
806 rpc_sleep_on(&xprt->backlog, task, NULL, NULL);
810 * xprt_reserve - allocate an RPC request slot
811 * @task: RPC task requesting a slot allocation
813 * If no more slots are available, place the task on the transport's
814 * backlog queue.
816 void xprt_reserve(struct rpc_task *task)
818 struct rpc_xprt *xprt = task->tk_xprt;
820 task->tk_status = -EIO;
821 spin_lock(&xprt->reserve_lock);
822 do_xprt_reserve(task);
823 spin_unlock(&xprt->reserve_lock);
826 static inline u32 xprt_alloc_xid(struct rpc_xprt *xprt)
828 return xprt->xid++;
831 static inline void xprt_init_xid(struct rpc_xprt *xprt)
833 get_random_bytes(&xprt->xid, sizeof(xprt->xid));
836 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
838 struct rpc_rqst *req = task->tk_rqstp;
840 req->rq_timeout = xprt->timeout.to_initval;
841 req->rq_task = task;
842 req->rq_xprt = xprt;
843 req->rq_buffer = NULL;
844 req->rq_bufsize = 0;
845 req->rq_xid = xprt_alloc_xid(xprt);
846 req->rq_release_snd_buf = NULL;
847 dprintk("RPC: %4d reserved req %p xid %08x\n", task->tk_pid,
848 req, ntohl(req->rq_xid));
852 * xprt_release - release an RPC request slot
853 * @task: task which is finished with the slot
856 void xprt_release(struct rpc_task *task)
858 struct rpc_xprt *xprt = task->tk_xprt;
859 struct rpc_rqst *req;
861 if (!(req = task->tk_rqstp))
862 return;
863 rpc_count_iostats(task);
864 spin_lock_bh(&xprt->transport_lock);
865 xprt->ops->release_xprt(xprt, task);
866 if (xprt->ops->release_request)
867 xprt->ops->release_request(task);
868 if (!list_empty(&req->rq_list))
869 list_del(&req->rq_list);
870 xprt->last_used = jiffies;
871 if (list_empty(&xprt->recv))
872 mod_timer(&xprt->timer,
873 xprt->last_used + xprt->idle_timeout);
874 spin_unlock_bh(&xprt->transport_lock);
875 xprt->ops->buf_free(task);
876 task->tk_rqstp = NULL;
877 if (req->rq_release_snd_buf)
878 req->rq_release_snd_buf(req);
879 memset(req, 0, sizeof(*req)); /* mark unused */
881 dprintk("RPC: %4d release request %p\n", task->tk_pid, req);
883 spin_lock(&xprt->reserve_lock);
884 list_add(&req->rq_list, &xprt->free);
885 rpc_wake_up_next(&xprt->backlog);
886 spin_unlock(&xprt->reserve_lock);
890 * xprt_set_timeout - set constant RPC timeout
891 * @to: RPC timeout parameters to set up
892 * @retr: number of retries
893 * @incr: amount of increase after each retry
896 void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
898 to->to_initval =
899 to->to_increment = incr;
900 to->to_maxval = to->to_initval + (incr * retr);
901 to->to_retries = retr;
902 to->to_exponential = 0;
905 static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc_timeout *to)
907 int result;
908 struct rpc_xprt *xprt;
909 struct rpc_rqst *req;
911 if ((xprt = kmalloc(sizeof(struct rpc_xprt), GFP_KERNEL)) == NULL)
912 return ERR_PTR(-ENOMEM);
913 memset(xprt, 0, sizeof(*xprt)); /* Nnnngh! */
915 xprt->addr = *ap;
917 switch (proto) {
918 case IPPROTO_UDP:
919 result = xs_setup_udp(xprt, to);
920 break;
921 case IPPROTO_TCP:
922 result = xs_setup_tcp(xprt, to);
923 break;
924 default:
925 printk(KERN_ERR "RPC: unrecognized transport protocol: %d\n",
926 proto);
927 result = -EIO;
928 break;
930 if (result) {
931 kfree(xprt);
932 return ERR_PTR(result);
935 spin_lock_init(&xprt->transport_lock);
936 spin_lock_init(&xprt->reserve_lock);
938 INIT_LIST_HEAD(&xprt->free);
939 INIT_LIST_HEAD(&xprt->recv);
940 INIT_WORK(&xprt->task_cleanup, xprt_autoclose, xprt);
941 init_timer(&xprt->timer);
942 xprt->timer.function = xprt_init_autodisconnect;
943 xprt->timer.data = (unsigned long) xprt;
944 xprt->last_used = jiffies;
945 xprt->cwnd = RPC_INITCWND;
947 rpc_init_wait_queue(&xprt->pending, "xprt_pending");
948 rpc_init_wait_queue(&xprt->sending, "xprt_sending");
949 rpc_init_wait_queue(&xprt->resend, "xprt_resend");
950 rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
952 /* initialize free list */
953 for (req = &xprt->slot[xprt->max_reqs-1]; req >= &xprt->slot[0]; req--)
954 list_add(&req->rq_list, &xprt->free);
956 xprt_init_xid(xprt);
958 dprintk("RPC: created transport %p with %u slots\n", xprt,
959 xprt->max_reqs);
961 return xprt;
965 * xprt_create_proto - create an RPC client transport
966 * @proto: requested transport protocol
967 * @sap: remote peer's address
968 * @to: timeout parameters for new transport
971 struct rpc_xprt *xprt_create_proto(int proto, struct sockaddr_in *sap, struct rpc_timeout *to)
973 struct rpc_xprt *xprt;
975 xprt = xprt_setup(proto, sap, to);
976 if (IS_ERR(xprt))
977 dprintk("RPC: xprt_create_proto failed\n");
978 else
979 dprintk("RPC: xprt_create_proto created xprt %p\n", xprt);
980 return xprt;
984 * xprt_destroy - destroy an RPC transport, killing off all requests.
985 * @xprt: transport to destroy
988 int xprt_destroy(struct rpc_xprt *xprt)
990 dprintk("RPC: destroying transport %p\n", xprt);
991 xprt->shutdown = 1;
992 del_timer_sync(&xprt->timer);
993 xprt->ops->destroy(xprt);
994 kfree(xprt);
996 return 0;