xprt.c revision 11c556b3d8d481829ab5f9933a25d29b00913b5a
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#include <linux/sunrpc/metrics.h>
48
49/*
50 * Local variables
51 */
52
53#ifdef RPC_DEBUG
54# undef  RPC_DEBUG_DATA
55# define RPCDBG_FACILITY	RPCDBG_XPRT
56#endif
57
58/*
59 * Local functions
60 */
61static void	xprt_request_init(struct rpc_task *, struct rpc_xprt *);
62static inline void	do_xprt_reserve(struct rpc_task *);
63static void	xprt_connect_status(struct rpc_task *task);
64static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
65
66/*
67 * The transport code maintains an estimate on the maximum number of out-
68 * standing RPC requests, using a smoothed version of the congestion
69 * avoidance implemented in 44BSD. This is basically the Van Jacobson
70 * congestion algorithm: If a retransmit occurs, the congestion window is
71 * halved; otherwise, it is incremented by 1/cwnd when
72 *
73 *	-	a reply is received and
74 *	-	a full number of requests are outstanding and
75 *	-	the congestion window hasn't been updated recently.
76 */
77#define RPC_CWNDSHIFT		(8U)
78#define RPC_CWNDSCALE		(1U << RPC_CWNDSHIFT)
79#define RPC_INITCWND		RPC_CWNDSCALE
80#define RPC_MAXCWND(xprt)	((xprt)->max_reqs << RPC_CWNDSHIFT)
81
82#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
83
84/**
85 * xprt_reserve_xprt - serialize write access to transports
86 * @task: task that is requesting access to the transport
87 *
88 * This prevents mixing the payload of separate requests, and prevents
89 * transport connects from colliding with writes.  No congestion control
90 * is provided.
91 */
92int xprt_reserve_xprt(struct rpc_task *task)
93{
94	struct rpc_xprt	*xprt = task->tk_xprt;
95	struct rpc_rqst *req = task->tk_rqstp;
96
97	if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
98		if (task == xprt->snd_task)
99			return 1;
100		if (task == NULL)
101			return 0;
102		goto out_sleep;
103	}
104	xprt->snd_task = task;
105	if (req) {
106		req->rq_bytes_sent = 0;
107		req->rq_ntrans++;
108	}
109	return 1;
110
111out_sleep:
112	dprintk("RPC: %4d failed to lock transport %p\n",
113			task->tk_pid, xprt);
114	task->tk_timeout = 0;
115	task->tk_status = -EAGAIN;
116	if (req && req->rq_ntrans)
117		rpc_sleep_on(&xprt->resend, task, NULL, NULL);
118	else
119		rpc_sleep_on(&xprt->sending, task, NULL, NULL);
120	return 0;
121}
122
123static void xprt_clear_locked(struct rpc_xprt *xprt)
124{
125	xprt->snd_task = NULL;
126	if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
127		smp_mb__before_clear_bit();
128		clear_bit(XPRT_LOCKED, &xprt->state);
129		smp_mb__after_clear_bit();
130	} else
131		schedule_work(&xprt->task_cleanup);
132}
133
134/*
135 * xprt_reserve_xprt_cong - serialize write access to transports
136 * @task: task that is requesting access to the transport
137 *
138 * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
139 * integrated into the decision of whether a request is allowed to be
140 * woken up and given access to the transport.
141 */
142int xprt_reserve_xprt_cong(struct rpc_task *task)
143{
144	struct rpc_xprt	*xprt = task->tk_xprt;
145	struct rpc_rqst *req = task->tk_rqstp;
146
147	if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
148		if (task == xprt->snd_task)
149			return 1;
150		goto out_sleep;
151	}
152	if (__xprt_get_cong(xprt, task)) {
153		xprt->snd_task = task;
154		if (req) {
155			req->rq_bytes_sent = 0;
156			req->rq_ntrans++;
157		}
158		return 1;
159	}
160	xprt_clear_locked(xprt);
161out_sleep:
162	dprintk("RPC: %4d failed to lock transport %p\n", task->tk_pid, xprt);
163	task->tk_timeout = 0;
164	task->tk_status = -EAGAIN;
165	if (req && req->rq_ntrans)
166		rpc_sleep_on(&xprt->resend, task, NULL, NULL);
167	else
168		rpc_sleep_on(&xprt->sending, task, NULL, NULL);
169	return 0;
170}
171
172static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
173{
174	int retval;
175
176	spin_lock_bh(&xprt->transport_lock);
177	retval = xprt->ops->reserve_xprt(task);
178	spin_unlock_bh(&xprt->transport_lock);
179	return retval;
180}
181
182static void __xprt_lock_write_next(struct rpc_xprt *xprt)
183{
184	struct rpc_task *task;
185	struct rpc_rqst *req;
186
187	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
188		return;
189
190	task = rpc_wake_up_next(&xprt->resend);
191	if (!task) {
192		task = rpc_wake_up_next(&xprt->sending);
193		if (!task)
194			goto out_unlock;
195	}
196
197	req = task->tk_rqstp;
198	xprt->snd_task = task;
199	if (req) {
200		req->rq_bytes_sent = 0;
201		req->rq_ntrans++;
202	}
203	return;
204
205out_unlock:
206	xprt_clear_locked(xprt);
207}
208
209static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
210{
211	struct rpc_task *task;
212
213	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
214		return;
215	if (RPCXPRT_CONGESTED(xprt))
216		goto out_unlock;
217	task = rpc_wake_up_next(&xprt->resend);
218	if (!task) {
219		task = rpc_wake_up_next(&xprt->sending);
220		if (!task)
221			goto out_unlock;
222	}
223	if (__xprt_get_cong(xprt, task)) {
224		struct rpc_rqst *req = task->tk_rqstp;
225		xprt->snd_task = task;
226		if (req) {
227			req->rq_bytes_sent = 0;
228			req->rq_ntrans++;
229		}
230		return;
231	}
232out_unlock:
233	xprt_clear_locked(xprt);
234}
235
236/**
237 * xprt_release_xprt - allow other requests to use a transport
238 * @xprt: transport with other tasks potentially waiting
239 * @task: task that is releasing access to the transport
240 *
241 * Note that "task" can be NULL.  No congestion control is provided.
242 */
243void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
244{
245	if (xprt->snd_task == task) {
246		xprt_clear_locked(xprt);
247		__xprt_lock_write_next(xprt);
248	}
249}
250
251/**
252 * xprt_release_xprt_cong - allow other requests to use a transport
253 * @xprt: transport with other tasks potentially waiting
254 * @task: task that is releasing access to the transport
255 *
256 * Note that "task" can be NULL.  Another task is awoken to use the
257 * transport if the transport's congestion window allows it.
258 */
259void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
260{
261	if (xprt->snd_task == task) {
262		xprt_clear_locked(xprt);
263		__xprt_lock_write_next_cong(xprt);
264	}
265}
266
267static 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 */
278static 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 */
298static 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 */
314void 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 */
326void 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 */
356void 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 */
369void 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 */
384void 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 */
406void 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 */
417void 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
430static 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 */
449int 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
483static 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 */
497void 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
506static void
507xprt_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;
522out_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 */
531void 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->addr.sin_port) {
539		task->tk_status = -EIO;
540		return;
541	}
542	if (!xprt_lock_write(xprt, task))
543		return;
544	if (xprt_connected(xprt))
545		xprt_release_write(xprt, task);
546	else {
547		if (task->tk_rqstp)
548			task->tk_rqstp->rq_bytes_sent = 0;
549
550		task->tk_timeout = xprt->connect_timeout;
551		rpc_sleep_on(&xprt->pending, task, xprt_connect_status, NULL);
552		xprt->stat.connect_start = jiffies;
553		xprt->ops->connect(task);
554	}
555	return;
556}
557
558static void xprt_connect_status(struct rpc_task *task)
559{
560	struct rpc_xprt	*xprt = task->tk_xprt;
561
562	if (task->tk_status >= 0) {
563		xprt->stat.connect_count++;
564		xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
565		dprintk("RPC: %4d xprt_connect_status: connection established\n",
566				task->tk_pid);
567		return;
568	}
569
570	switch (task->tk_status) {
571	case -ECONNREFUSED:
572	case -ECONNRESET:
573		dprintk("RPC: %4d xprt_connect_status: server %s refused connection\n",
574				task->tk_pid, task->tk_client->cl_server);
575		break;
576	case -ENOTCONN:
577		dprintk("RPC: %4d xprt_connect_status: connection broken\n",
578				task->tk_pid);
579		break;
580	case -ETIMEDOUT:
581		dprintk("RPC: %4d xprt_connect_status: connect attempt timed out\n",
582				task->tk_pid);
583		break;
584	default:
585		dprintk("RPC: %4d xprt_connect_status: error %d connecting to server %s\n",
586				task->tk_pid, -task->tk_status, task->tk_client->cl_server);
587		xprt_release_write(xprt, task);
588		task->tk_status = -EIO;
589		return;
590	}
591
592	/* if soft mounted, just cause this RPC to fail */
593	if (RPC_IS_SOFT(task)) {
594		xprt_release_write(xprt, task);
595		task->tk_status = -EIO;
596	}
597}
598
599/**
600 * xprt_lookup_rqst - find an RPC request corresponding to an XID
601 * @xprt: transport on which the original request was transmitted
602 * @xid: RPC XID of incoming reply
603 *
604 */
605struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, u32 xid)
606{
607	struct list_head *pos;
608
609	list_for_each(pos, &xprt->recv) {
610		struct rpc_rqst *entry = list_entry(pos, struct rpc_rqst, rq_list);
611		if (entry->rq_xid == xid)
612			return entry;
613	}
614	xprt->stat.bad_xids++;
615	return NULL;
616}
617
618/**
619 * xprt_update_rtt - update an RPC client's RTT state after receiving a reply
620 * @task: RPC request that recently completed
621 *
622 */
623void xprt_update_rtt(struct rpc_task *task)
624{
625	struct rpc_rqst *req = task->tk_rqstp;
626	struct rpc_rtt *rtt = task->tk_client->cl_rtt;
627	unsigned timer = task->tk_msg.rpc_proc->p_timer;
628
629	if (timer) {
630		if (req->rq_ntrans == 1)
631			rpc_update_rtt(rtt, timer,
632					(long)jiffies - req->rq_xtime);
633		rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
634	}
635}
636
637/**
638 * xprt_complete_rqst - called when reply processing is complete
639 * @task: RPC request that recently completed
640 * @copied: actual number of bytes received from the transport
641 *
642 * Caller holds transport lock.
643 */
644void xprt_complete_rqst(struct rpc_task *task, int copied)
645{
646	struct rpc_rqst *req = task->tk_rqstp;
647
648	dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
649			task->tk_pid, ntohl(req->rq_xid), copied);
650
651	task->tk_xprt->stat.recvs++;
652	task->tk_rtt = (long)jiffies - req->rq_xtime;
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
659static 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 */
682int 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	spin_lock_bh(&xprt->transport_lock);
691	if (req->rq_received && !req->rq_bytes_sent) {
692		err = req->rq_received;
693		goto out_unlock;
694	}
695	if (!xprt->ops->reserve_xprt(task)) {
696		err = -EAGAIN;
697		goto out_unlock;
698	}
699
700	if (!xprt_connected(xprt)) {
701		err = -ENOTCONN;
702		goto out_unlock;
703	}
704out_unlock:
705	spin_unlock_bh(&xprt->transport_lock);
706	return err;
707}
708
709void
710xprt_abort_transmit(struct rpc_task *task)
711{
712	struct rpc_xprt	*xprt = task->tk_xprt;
713
714	xprt_release_write(xprt, task);
715}
716
717/**
718 * xprt_transmit - send an RPC request on a transport
719 * @task: controlling RPC task
720 *
721 * We have to copy the iovec because sendmsg fiddles with its contents.
722 */
723void xprt_transmit(struct rpc_task *task)
724{
725	struct rpc_rqst	*req = task->tk_rqstp;
726	struct rpc_xprt	*xprt = req->rq_xprt;
727	int status;
728
729	dprintk("RPC: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
730
731	smp_rmb();
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);
744		}
745	} else if (!req->rq_bytes_sent)
746		return;
747
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);
752
753		xprt->ops->set_retrans_timeout(task);
754
755		xprt->stat.sends++;
756		xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
757		xprt->stat.bklog_u += xprt->backlog.qlen;
758
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);
764
765		xprt->ops->release_xprt(xprt, task);
766		spin_unlock_bh(&xprt->transport_lock);
767		return;
768	}
769
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().
773	 */
774	task->tk_status = status;
775
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;
784	}
785	xprt_release_write(xprt, task);
786	return;
787}
788
789static inline void do_xprt_reserve(struct rpc_task *task)
790{
791	struct rpc_xprt	*xprt = task->tk_xprt;
792
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;
802	}
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);
807}
808
809/**
810 * xprt_reserve - allocate an RPC request slot
811 * @task: RPC task requesting a slot allocation
812 *
813 * If no more slots are available, place the task on the transport's
814 * backlog queue.
815 */
816void xprt_reserve(struct rpc_task *task)
817{
818	struct rpc_xprt	*xprt = task->tk_xprt;
819
820	task->tk_status = -EIO;
821	spin_lock(&xprt->reserve_lock);
822	do_xprt_reserve(task);
823	spin_unlock(&xprt->reserve_lock);
824}
825
826static inline u32 xprt_alloc_xid(struct rpc_xprt *xprt)
827{
828	return xprt->xid++;
829}
830
831static inline void xprt_init_xid(struct rpc_xprt *xprt)
832{
833	get_random_bytes(&xprt->xid, sizeof(xprt->xid));
834}
835
836static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
837{
838	struct rpc_rqst	*req = task->tk_rqstp;
839
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));
849}
850
851/**
852 * xprt_release - release an RPC request slot
853 * @task: task which is finished with the slot
854 *
855 */
856void xprt_release(struct rpc_task *task)
857{
858	struct rpc_xprt	*xprt = task->tk_xprt;
859	struct rpc_rqst	*req;
860
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 */
880
881	dprintk("RPC: %4d release request %p\n", task->tk_pid, req);
882
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);
887}
888
889/**
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
894 *
895 */
896void xprt_set_timeout(struct rpc_timeout *to, unsigned int retr, unsigned long incr)
897{
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;
903}
904
905static struct rpc_xprt *xprt_setup(int proto, struct sockaddr_in *ap, struct rpc_timeout *to)
906{
907	int result;
908	struct rpc_xprt	*xprt;
909	struct rpc_rqst	*req;
910
911	if ((xprt = kmalloc(sizeof(struct rpc_xprt), GFP_KERNEL)) == NULL)
912		return ERR_PTR(-ENOMEM);
913	memset(xprt, 0, sizeof(*xprt)); /* Nnnngh! */
914
915	xprt->addr = *ap;
916
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;
929	}
930	if (result) {
931		kfree(xprt);
932		return ERR_PTR(result);
933	}
934
935	spin_lock_init(&xprt->transport_lock);
936	spin_lock_init(&xprt->reserve_lock);
937
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;
946
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");
951
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);
955
956	xprt_init_xid(xprt);
957
958	dprintk("RPC:      created transport %p with %u slots\n", xprt,
959			xprt->max_reqs);
960
961	return xprt;
962}
963
964/**
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
969 *
970 */
971struct rpc_xprt *xprt_create_proto(int proto, struct sockaddr_in *sap, struct rpc_timeout *to)
972{
973	struct rpc_xprt	*xprt;
974
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;
981}
982
983/**
984 * xprt_destroy - destroy an RPC transport, killing off all requests.
985 * @xprt: transport to destroy
986 *
987 */
988int xprt_destroy(struct rpc_xprt *xprt)
989{
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);
995
996	return 0;
997}
998