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, if a reply is expected,
16 *	it installs a timer that is run after the packet's timeout has
17 *	expired.
18 *  -	When a packet arrives, the data_ready handler walks the list of
19 *	pending requests for that transport. If a matching XID is found, the
20 *	caller is woken up, and the timer removed.
21 *  -	When no reply arrives within the timeout interval, the timer is
22 *	fired by the kernel and runs xprt_timer(). It either adjusts the
23 *	timeout values (minor timeout) or wakes up the caller with a status
24 *	of -ETIMEDOUT.
25 *  -	When the caller receives a notification from RPC that a reply arrived,
26 *	it should release the RPC slot, and process the reply.
27 *	If the call timed out, it may choose to retry the operation by
28 *	adjusting the initial timeout value, and simply calling rpc_call
29 *	again.
30 *
31 *  Support for async RPC is done through a set of RPC-specific scheduling
32 *  primitives that `transparently' work for processes as well as async
33 *  tasks that rely on callbacks.
34 *
35 *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
36 *
37 *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
38 */
39
40#include <linux/module.h>
41
42#include <linux/types.h>
43#include <linux/interrupt.h>
44#include <linux/workqueue.h>
45#include <linux/net.h>
46#include <linux/ktime.h>
47
48#include <linux/sunrpc/clnt.h>
49#include <linux/sunrpc/metrics.h>
50#include <linux/sunrpc/bc_xprt.h>
51
52#include "sunrpc.h"
53
54/*
55 * Local variables
56 */
57
58#ifdef RPC_DEBUG
59# define RPCDBG_FACILITY	RPCDBG_XPRT
60#endif
61
62/*
63 * Local functions
64 */
65static void	 xprt_init(struct rpc_xprt *xprt, struct net *net);
66static void	xprt_request_init(struct rpc_task *, struct rpc_xprt *);
67static void	xprt_connect_status(struct rpc_task *task);
68static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
69static void	 xprt_destroy(struct rpc_xprt *xprt);
70
71static DEFINE_SPINLOCK(xprt_list_lock);
72static LIST_HEAD(xprt_list);
73
74/**
75 * xprt_register_transport - register a transport implementation
76 * @transport: transport to register
77 *
78 * If a transport implementation is loaded as a kernel module, it can
79 * call this interface to make itself known to the RPC client.
80 *
81 * Returns:
82 * 0:		transport successfully registered
83 * -EEXIST:	transport already registered
84 * -EINVAL:	transport module being unloaded
85 */
86int xprt_register_transport(struct xprt_class *transport)
87{
88	struct xprt_class *t;
89	int result;
90
91	result = -EEXIST;
92	spin_lock(&xprt_list_lock);
93	list_for_each_entry(t, &xprt_list, list) {
94		/* don't register the same transport class twice */
95		if (t->ident == transport->ident)
96			goto out;
97	}
98
99	list_add_tail(&transport->list, &xprt_list);
100	printk(KERN_INFO "RPC: Registered %s transport module.\n",
101	       transport->name);
102	result = 0;
103
104out:
105	spin_unlock(&xprt_list_lock);
106	return result;
107}
108EXPORT_SYMBOL_GPL(xprt_register_transport);
109
110/**
111 * xprt_unregister_transport - unregister a transport implementation
112 * @transport: transport to unregister
113 *
114 * Returns:
115 * 0:		transport successfully unregistered
116 * -ENOENT:	transport never registered
117 */
118int xprt_unregister_transport(struct xprt_class *transport)
119{
120	struct xprt_class *t;
121	int result;
122
123	result = 0;
124	spin_lock(&xprt_list_lock);
125	list_for_each_entry(t, &xprt_list, list) {
126		if (t == transport) {
127			printk(KERN_INFO
128				"RPC: Unregistered %s transport module.\n",
129				transport->name);
130			list_del_init(&transport->list);
131			goto out;
132		}
133	}
134	result = -ENOENT;
135
136out:
137	spin_unlock(&xprt_list_lock);
138	return result;
139}
140EXPORT_SYMBOL_GPL(xprt_unregister_transport);
141
142/**
143 * xprt_load_transport - load a transport implementation
144 * @transport_name: transport to load
145 *
146 * Returns:
147 * 0:		transport successfully loaded
148 * -ENOENT:	transport module not available
149 */
150int xprt_load_transport(const char *transport_name)
151{
152	struct xprt_class *t;
153	int result;
154
155	result = 0;
156	spin_lock(&xprt_list_lock);
157	list_for_each_entry(t, &xprt_list, list) {
158		if (strcmp(t->name, transport_name) == 0) {
159			spin_unlock(&xprt_list_lock);
160			goto out;
161		}
162	}
163	spin_unlock(&xprt_list_lock);
164	result = request_module("xprt%s", transport_name);
165out:
166	return result;
167}
168EXPORT_SYMBOL_GPL(xprt_load_transport);
169
170/**
171 * xprt_reserve_xprt - serialize write access to transports
172 * @task: task that is requesting access to the transport
173 * @xprt: pointer to the target transport
174 *
175 * This prevents mixing the payload of separate requests, and prevents
176 * transport connects from colliding with writes.  No congestion control
177 * is provided.
178 */
179int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
180{
181	struct rpc_rqst *req = task->tk_rqstp;
182	int priority;
183
184	if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
185		if (task == xprt->snd_task)
186			return 1;
187		goto out_sleep;
188	}
189	xprt->snd_task = task;
190	if (req != NULL)
191		req->rq_ntrans++;
192
193	return 1;
194
195out_sleep:
196	dprintk("RPC: %5u failed to lock transport %p\n",
197			task->tk_pid, xprt);
198	task->tk_timeout = 0;
199	task->tk_status = -EAGAIN;
200	if (req == NULL)
201		priority = RPC_PRIORITY_LOW;
202	else if (!req->rq_ntrans)
203		priority = RPC_PRIORITY_NORMAL;
204	else
205		priority = RPC_PRIORITY_HIGH;
206	rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
207	return 0;
208}
209EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
210
211static void xprt_clear_locked(struct rpc_xprt *xprt)
212{
213	xprt->snd_task = NULL;
214	if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
215		smp_mb__before_atomic();
216		clear_bit(XPRT_LOCKED, &xprt->state);
217		smp_mb__after_atomic();
218	} else
219		queue_work(rpciod_workqueue, &xprt->task_cleanup);
220}
221
222/*
223 * xprt_reserve_xprt_cong - serialize write access to transports
224 * @task: task that is requesting access to the transport
225 *
226 * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
227 * integrated into the decision of whether a request is allowed to be
228 * woken up and given access to the transport.
229 */
230int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
231{
232	struct rpc_rqst *req = task->tk_rqstp;
233	int priority;
234
235	if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
236		if (task == xprt->snd_task)
237			return 1;
238		goto out_sleep;
239	}
240	if (req == NULL) {
241		xprt->snd_task = task;
242		return 1;
243	}
244	if (__xprt_get_cong(xprt, task)) {
245		xprt->snd_task = task;
246		req->rq_ntrans++;
247		return 1;
248	}
249	xprt_clear_locked(xprt);
250out_sleep:
251	dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
252	task->tk_timeout = 0;
253	task->tk_status = -EAGAIN;
254	if (req == NULL)
255		priority = RPC_PRIORITY_LOW;
256	else if (!req->rq_ntrans)
257		priority = RPC_PRIORITY_NORMAL;
258	else
259		priority = RPC_PRIORITY_HIGH;
260	rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
261	return 0;
262}
263EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
264
265static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
266{
267	int retval;
268
269	spin_lock_bh(&xprt->transport_lock);
270	retval = xprt->ops->reserve_xprt(xprt, task);
271	spin_unlock_bh(&xprt->transport_lock);
272	return retval;
273}
274
275static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
276{
277	struct rpc_xprt *xprt = data;
278	struct rpc_rqst *req;
279
280	req = task->tk_rqstp;
281	xprt->snd_task = task;
282	if (req)
283		req->rq_ntrans++;
284	return true;
285}
286
287static void __xprt_lock_write_next(struct rpc_xprt *xprt)
288{
289	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
290		return;
291
292	if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_func, xprt))
293		return;
294	xprt_clear_locked(xprt);
295}
296
297static bool __xprt_lock_write_cong_func(struct rpc_task *task, void *data)
298{
299	struct rpc_xprt *xprt = data;
300	struct rpc_rqst *req;
301
302	req = task->tk_rqstp;
303	if (req == NULL) {
304		xprt->snd_task = task;
305		return true;
306	}
307	if (__xprt_get_cong(xprt, task)) {
308		xprt->snd_task = task;
309		req->rq_ntrans++;
310		return true;
311	}
312	return false;
313}
314
315static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
316{
317	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
318		return;
319	if (RPCXPRT_CONGESTED(xprt))
320		goto out_unlock;
321	if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_cong_func, xprt))
322		return;
323out_unlock:
324	xprt_clear_locked(xprt);
325}
326
327/**
328 * xprt_release_xprt - allow other requests to use a transport
329 * @xprt: transport with other tasks potentially waiting
330 * @task: task that is releasing access to the transport
331 *
332 * Note that "task" can be NULL.  No congestion control is provided.
333 */
334void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
335{
336	if (xprt->snd_task == task) {
337		if (task != NULL) {
338			struct rpc_rqst *req = task->tk_rqstp;
339			if (req != NULL)
340				req->rq_bytes_sent = 0;
341		}
342		xprt_clear_locked(xprt);
343		__xprt_lock_write_next(xprt);
344	}
345}
346EXPORT_SYMBOL_GPL(xprt_release_xprt);
347
348/**
349 * xprt_release_xprt_cong - allow other requests to use a transport
350 * @xprt: transport with other tasks potentially waiting
351 * @task: task that is releasing access to the transport
352 *
353 * Note that "task" can be NULL.  Another task is awoken to use the
354 * transport if the transport's congestion window allows it.
355 */
356void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
357{
358	if (xprt->snd_task == task) {
359		if (task != NULL) {
360			struct rpc_rqst *req = task->tk_rqstp;
361			if (req != NULL)
362				req->rq_bytes_sent = 0;
363		}
364		xprt_clear_locked(xprt);
365		__xprt_lock_write_next_cong(xprt);
366	}
367}
368EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
369
370static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
371{
372	spin_lock_bh(&xprt->transport_lock);
373	xprt->ops->release_xprt(xprt, task);
374	spin_unlock_bh(&xprt->transport_lock);
375}
376
377/*
378 * Van Jacobson congestion avoidance. Check if the congestion window
379 * overflowed. Put the task to sleep if this is the case.
380 */
381static int
382__xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
383{
384	struct rpc_rqst *req = task->tk_rqstp;
385
386	if (req->rq_cong)
387		return 1;
388	dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
389			task->tk_pid, xprt->cong, xprt->cwnd);
390	if (RPCXPRT_CONGESTED(xprt))
391		return 0;
392	req->rq_cong = 1;
393	xprt->cong += RPC_CWNDSCALE;
394	return 1;
395}
396
397/*
398 * Adjust the congestion window, and wake up the next task
399 * that has been sleeping due to congestion
400 */
401static void
402__xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
403{
404	if (!req->rq_cong)
405		return;
406	req->rq_cong = 0;
407	xprt->cong -= RPC_CWNDSCALE;
408	__xprt_lock_write_next_cong(xprt);
409}
410
411/**
412 * xprt_release_rqst_cong - housekeeping when request is complete
413 * @task: RPC request that recently completed
414 *
415 * Useful for transports that require congestion control.
416 */
417void xprt_release_rqst_cong(struct rpc_task *task)
418{
419	struct rpc_rqst *req = task->tk_rqstp;
420
421	__xprt_put_cong(req->rq_xprt, req);
422}
423EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
424
425/**
426 * xprt_adjust_cwnd - adjust transport congestion window
427 * @xprt: pointer to xprt
428 * @task: recently completed RPC request used to adjust window
429 * @result: result code of completed RPC request
430 *
431 * The transport code maintains an estimate on the maximum number of out-
432 * standing RPC requests, using a smoothed version of the congestion
433 * avoidance implemented in 44BSD. This is basically the Van Jacobson
434 * congestion algorithm: If a retransmit occurs, the congestion window is
435 * halved; otherwise, it is incremented by 1/cwnd when
436 *
437 *	-	a reply is received and
438 *	-	a full number of requests are outstanding and
439 *	-	the congestion window hasn't been updated recently.
440 */
441void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
442{
443	struct rpc_rqst *req = task->tk_rqstp;
444	unsigned long cwnd = xprt->cwnd;
445
446	if (result >= 0 && cwnd <= xprt->cong) {
447		/* The (cwnd >> 1) term makes sure
448		 * the result gets rounded properly. */
449		cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
450		if (cwnd > RPC_MAXCWND(xprt))
451			cwnd = RPC_MAXCWND(xprt);
452		__xprt_lock_write_next_cong(xprt);
453	} else if (result == -ETIMEDOUT) {
454		cwnd >>= 1;
455		if (cwnd < RPC_CWNDSCALE)
456			cwnd = RPC_CWNDSCALE;
457	}
458	dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
459			xprt->cong, xprt->cwnd, cwnd);
460	xprt->cwnd = cwnd;
461	__xprt_put_cong(xprt, req);
462}
463EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
464
465/**
466 * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
467 * @xprt: transport with waiting tasks
468 * @status: result code to plant in each task before waking it
469 *
470 */
471void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
472{
473	if (status < 0)
474		rpc_wake_up_status(&xprt->pending, status);
475	else
476		rpc_wake_up(&xprt->pending);
477}
478EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
479
480/**
481 * xprt_wait_for_buffer_space - wait for transport output buffer to clear
482 * @task: task to be put to sleep
483 * @action: function pointer to be executed after wait
484 *
485 * Note that we only set the timer for the case of RPC_IS_SOFT(), since
486 * we don't in general want to force a socket disconnection due to
487 * an incomplete RPC call transmission.
488 */
489void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
490{
491	struct rpc_rqst *req = task->tk_rqstp;
492	struct rpc_xprt *xprt = req->rq_xprt;
493
494	task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
495	rpc_sleep_on(&xprt->pending, task, action);
496}
497EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
498
499/**
500 * xprt_write_space - wake the task waiting for transport output buffer space
501 * @xprt: transport with waiting tasks
502 *
503 * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
504 */
505void xprt_write_space(struct rpc_xprt *xprt)
506{
507	spin_lock_bh(&xprt->transport_lock);
508	if (xprt->snd_task) {
509		dprintk("RPC:       write space: waking waiting task on "
510				"xprt %p\n", xprt);
511		rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
512	}
513	spin_unlock_bh(&xprt->transport_lock);
514}
515EXPORT_SYMBOL_GPL(xprt_write_space);
516
517/**
518 * xprt_set_retrans_timeout_def - set a request's retransmit timeout
519 * @task: task whose timeout is to be set
520 *
521 * Set a request's retransmit timeout based on the transport's
522 * default timeout parameters.  Used by transports that don't adjust
523 * the retransmit timeout based on round-trip time estimation.
524 */
525void xprt_set_retrans_timeout_def(struct rpc_task *task)
526{
527	task->tk_timeout = task->tk_rqstp->rq_timeout;
528}
529EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
530
531/**
532 * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
533 * @task: task whose timeout is to be set
534 *
535 * Set a request's retransmit timeout using the RTT estimator.
536 */
537void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
538{
539	int timer = task->tk_msg.rpc_proc->p_timer;
540	struct rpc_clnt *clnt = task->tk_client;
541	struct rpc_rtt *rtt = clnt->cl_rtt;
542	struct rpc_rqst *req = task->tk_rqstp;
543	unsigned long max_timeout = clnt->cl_timeout->to_maxval;
544
545	task->tk_timeout = rpc_calc_rto(rtt, timer);
546	task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
547	if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
548		task->tk_timeout = max_timeout;
549}
550EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
551
552static void xprt_reset_majortimeo(struct rpc_rqst *req)
553{
554	const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
555
556	req->rq_majortimeo = req->rq_timeout;
557	if (to->to_exponential)
558		req->rq_majortimeo <<= to->to_retries;
559	else
560		req->rq_majortimeo += to->to_increment * to->to_retries;
561	if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
562		req->rq_majortimeo = to->to_maxval;
563	req->rq_majortimeo += jiffies;
564}
565
566/**
567 * xprt_adjust_timeout - adjust timeout values for next retransmit
568 * @req: RPC request containing parameters to use for the adjustment
569 *
570 */
571int xprt_adjust_timeout(struct rpc_rqst *req)
572{
573	struct rpc_xprt *xprt = req->rq_xprt;
574	const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
575	int status = 0;
576
577	if (time_before(jiffies, req->rq_majortimeo)) {
578		if (to->to_exponential)
579			req->rq_timeout <<= 1;
580		else
581			req->rq_timeout += to->to_increment;
582		if (to->to_maxval && req->rq_timeout >= to->to_maxval)
583			req->rq_timeout = to->to_maxval;
584		req->rq_retries++;
585	} else {
586		req->rq_timeout = to->to_initval;
587		req->rq_retries = 0;
588		xprt_reset_majortimeo(req);
589		/* Reset the RTT counters == "slow start" */
590		spin_lock_bh(&xprt->transport_lock);
591		rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
592		spin_unlock_bh(&xprt->transport_lock);
593		status = -ETIMEDOUT;
594	}
595
596	if (req->rq_timeout == 0) {
597		printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
598		req->rq_timeout = 5 * HZ;
599	}
600	return status;
601}
602
603static void xprt_autoclose(struct work_struct *work)
604{
605	struct rpc_xprt *xprt =
606		container_of(work, struct rpc_xprt, task_cleanup);
607
608	xprt->ops->close(xprt);
609	clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
610	xprt_release_write(xprt, NULL);
611}
612
613/**
614 * xprt_disconnect_done - mark a transport as disconnected
615 * @xprt: transport to flag for disconnect
616 *
617 */
618void xprt_disconnect_done(struct rpc_xprt *xprt)
619{
620	dprintk("RPC:       disconnected transport %p\n", xprt);
621	spin_lock_bh(&xprt->transport_lock);
622	xprt_clear_connected(xprt);
623	xprt_wake_pending_tasks(xprt, -EAGAIN);
624	spin_unlock_bh(&xprt->transport_lock);
625}
626EXPORT_SYMBOL_GPL(xprt_disconnect_done);
627
628/**
629 * xprt_force_disconnect - force a transport to disconnect
630 * @xprt: transport to disconnect
631 *
632 */
633void xprt_force_disconnect(struct rpc_xprt *xprt)
634{
635	/* Don't race with the test_bit() in xprt_clear_locked() */
636	spin_lock_bh(&xprt->transport_lock);
637	set_bit(XPRT_CLOSE_WAIT, &xprt->state);
638	/* Try to schedule an autoclose RPC call */
639	if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
640		queue_work(rpciod_workqueue, &xprt->task_cleanup);
641	xprt_wake_pending_tasks(xprt, -EAGAIN);
642	spin_unlock_bh(&xprt->transport_lock);
643}
644
645/**
646 * xprt_conditional_disconnect - force a transport to disconnect
647 * @xprt: transport to disconnect
648 * @cookie: 'connection cookie'
649 *
650 * This attempts to break the connection if and only if 'cookie' matches
651 * the current transport 'connection cookie'. It ensures that we don't
652 * try to break the connection more than once when we need to retransmit
653 * a batch of RPC requests.
654 *
655 */
656void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
657{
658	/* Don't race with the test_bit() in xprt_clear_locked() */
659	spin_lock_bh(&xprt->transport_lock);
660	if (cookie != xprt->connect_cookie)
661		goto out;
662	if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
663		goto out;
664	set_bit(XPRT_CLOSE_WAIT, &xprt->state);
665	/* Try to schedule an autoclose RPC call */
666	if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
667		queue_work(rpciod_workqueue, &xprt->task_cleanup);
668	xprt_wake_pending_tasks(xprt, -EAGAIN);
669out:
670	spin_unlock_bh(&xprt->transport_lock);
671}
672
673static void
674xprt_init_autodisconnect(unsigned long data)
675{
676	struct rpc_xprt *xprt = (struct rpc_xprt *)data;
677
678	spin_lock(&xprt->transport_lock);
679	if (!list_empty(&xprt->recv))
680		goto out_abort;
681	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
682		goto out_abort;
683	spin_unlock(&xprt->transport_lock);
684	set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
685	queue_work(rpciod_workqueue, &xprt->task_cleanup);
686	return;
687out_abort:
688	spin_unlock(&xprt->transport_lock);
689}
690
691/**
692 * xprt_connect - schedule a transport connect operation
693 * @task: RPC task that is requesting the connect
694 *
695 */
696void xprt_connect(struct rpc_task *task)
697{
698	struct rpc_xprt	*xprt = task->tk_rqstp->rq_xprt;
699
700	dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
701			xprt, (xprt_connected(xprt) ? "is" : "is not"));
702
703	if (!xprt_bound(xprt)) {
704		task->tk_status = -EAGAIN;
705		return;
706	}
707	if (!xprt_lock_write(xprt, task))
708		return;
709
710	if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
711		xprt->ops->close(xprt);
712
713	if (xprt_connected(xprt))
714		xprt_release_write(xprt, task);
715	else {
716		task->tk_rqstp->rq_bytes_sent = 0;
717		task->tk_timeout = task->tk_rqstp->rq_timeout;
718		rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
719
720		if (test_bit(XPRT_CLOSING, &xprt->state))
721			return;
722		if (xprt_test_and_set_connecting(xprt))
723			return;
724		xprt->stat.connect_start = jiffies;
725		xprt->ops->connect(xprt, task);
726	}
727}
728
729static void xprt_connect_status(struct rpc_task *task)
730{
731	struct rpc_xprt	*xprt = task->tk_rqstp->rq_xprt;
732
733	if (task->tk_status == 0) {
734		xprt->stat.connect_count++;
735		xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
736		dprintk("RPC: %5u xprt_connect_status: connection established\n",
737				task->tk_pid);
738		return;
739	}
740
741	switch (task->tk_status) {
742	case -ECONNREFUSED:
743	case -ECONNRESET:
744	case -ECONNABORTED:
745	case -ENETUNREACH:
746	case -EHOSTUNREACH:
747	case -EPIPE:
748	case -EAGAIN:
749		dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
750		break;
751	case -ETIMEDOUT:
752		dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
753				"out\n", task->tk_pid);
754		break;
755	default:
756		dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
757				"server %s\n", task->tk_pid, -task->tk_status,
758				xprt->servername);
759		xprt_release_write(xprt, task);
760		task->tk_status = -EIO;
761	}
762}
763
764/**
765 * xprt_lookup_rqst - find an RPC request corresponding to an XID
766 * @xprt: transport on which the original request was transmitted
767 * @xid: RPC XID of incoming reply
768 *
769 */
770struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
771{
772	struct rpc_rqst *entry;
773
774	list_for_each_entry(entry, &xprt->recv, rq_list)
775		if (entry->rq_xid == xid)
776			return entry;
777
778	dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
779			ntohl(xid));
780	xprt->stat.bad_xids++;
781	return NULL;
782}
783EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
784
785static void xprt_update_rtt(struct rpc_task *task)
786{
787	struct rpc_rqst *req = task->tk_rqstp;
788	struct rpc_rtt *rtt = task->tk_client->cl_rtt;
789	unsigned int timer = task->tk_msg.rpc_proc->p_timer;
790	long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
791
792	if (timer) {
793		if (req->rq_ntrans == 1)
794			rpc_update_rtt(rtt, timer, m);
795		rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
796	}
797}
798
799/**
800 * xprt_complete_rqst - called when reply processing is complete
801 * @task: RPC request that recently completed
802 * @copied: actual number of bytes received from the transport
803 *
804 * Caller holds transport lock.
805 */
806void xprt_complete_rqst(struct rpc_task *task, int copied)
807{
808	struct rpc_rqst *req = task->tk_rqstp;
809	struct rpc_xprt *xprt = req->rq_xprt;
810
811	dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
812			task->tk_pid, ntohl(req->rq_xid), copied);
813
814	xprt->stat.recvs++;
815	req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
816	if (xprt->ops->timer != NULL)
817		xprt_update_rtt(task);
818
819	list_del_init(&req->rq_list);
820	req->rq_private_buf.len = copied;
821	/* Ensure all writes are done before we update */
822	/* req->rq_reply_bytes_recvd */
823	smp_wmb();
824	req->rq_reply_bytes_recvd = copied;
825	rpc_wake_up_queued_task(&xprt->pending, task);
826}
827EXPORT_SYMBOL_GPL(xprt_complete_rqst);
828
829static void xprt_timer(struct rpc_task *task)
830{
831	struct rpc_rqst *req = task->tk_rqstp;
832	struct rpc_xprt *xprt = req->rq_xprt;
833
834	if (task->tk_status != -ETIMEDOUT)
835		return;
836	dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
837
838	spin_lock_bh(&xprt->transport_lock);
839	if (!req->rq_reply_bytes_recvd) {
840		if (xprt->ops->timer)
841			xprt->ops->timer(xprt, task);
842	} else
843		task->tk_status = 0;
844	spin_unlock_bh(&xprt->transport_lock);
845}
846
847static inline int xprt_has_timer(struct rpc_xprt *xprt)
848{
849	return xprt->idle_timeout != 0;
850}
851
852/**
853 * xprt_prepare_transmit - reserve the transport before sending a request
854 * @task: RPC task about to send a request
855 *
856 */
857bool xprt_prepare_transmit(struct rpc_task *task)
858{
859	struct rpc_rqst	*req = task->tk_rqstp;
860	struct rpc_xprt	*xprt = req->rq_xprt;
861	bool ret = false;
862
863	dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
864
865	spin_lock_bh(&xprt->transport_lock);
866	if (!req->rq_bytes_sent) {
867		if (req->rq_reply_bytes_recvd) {
868			task->tk_status = req->rq_reply_bytes_recvd;
869			goto out_unlock;
870		}
871		if ((task->tk_flags & RPC_TASK_NO_RETRANS_TIMEOUT)
872		    && xprt_connected(xprt)
873		    && req->rq_connect_cookie == xprt->connect_cookie) {
874			xprt->ops->set_retrans_timeout(task);
875			rpc_sleep_on(&xprt->pending, task, xprt_timer);
876			goto out_unlock;
877		}
878	}
879	if (!xprt->ops->reserve_xprt(xprt, task)) {
880		task->tk_status = -EAGAIN;
881		goto out_unlock;
882	}
883	ret = true;
884out_unlock:
885	spin_unlock_bh(&xprt->transport_lock);
886	return ret;
887}
888
889void xprt_end_transmit(struct rpc_task *task)
890{
891	xprt_release_write(task->tk_rqstp->rq_xprt, task);
892}
893
894/**
895 * xprt_transmit - send an RPC request on a transport
896 * @task: controlling RPC task
897 *
898 * We have to copy the iovec because sendmsg fiddles with its contents.
899 */
900void xprt_transmit(struct rpc_task *task)
901{
902	struct rpc_rqst	*req = task->tk_rqstp;
903	struct rpc_xprt	*xprt = req->rq_xprt;
904	int status, numreqs;
905
906	dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
907
908	if (!req->rq_reply_bytes_recvd) {
909		if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
910			/*
911			 * Add to the list only if we're expecting a reply
912			 */
913			spin_lock_bh(&xprt->transport_lock);
914			/* Update the softirq receive buffer */
915			memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
916					sizeof(req->rq_private_buf));
917			/* Add request to the receive list */
918			list_add_tail(&req->rq_list, &xprt->recv);
919			spin_unlock_bh(&xprt->transport_lock);
920			xprt_reset_majortimeo(req);
921			/* Turn off autodisconnect */
922			del_singleshot_timer_sync(&xprt->timer);
923		}
924	} else if (!req->rq_bytes_sent)
925		return;
926
927	req->rq_xtime = ktime_get();
928	status = xprt->ops->send_request(task);
929	if (status != 0) {
930		task->tk_status = status;
931		return;
932	}
933
934	dprintk("RPC: %5u xmit complete\n", task->tk_pid);
935	task->tk_flags |= RPC_TASK_SENT;
936	spin_lock_bh(&xprt->transport_lock);
937
938	xprt->ops->set_retrans_timeout(task);
939
940	numreqs = atomic_read(&xprt->num_reqs);
941	if (numreqs > xprt->stat.max_slots)
942		xprt->stat.max_slots = numreqs;
943	xprt->stat.sends++;
944	xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
945	xprt->stat.bklog_u += xprt->backlog.qlen;
946	xprt->stat.sending_u += xprt->sending.qlen;
947	xprt->stat.pending_u += xprt->pending.qlen;
948
949	/* Don't race with disconnect */
950	if (!xprt_connected(xprt))
951		task->tk_status = -ENOTCONN;
952	else {
953		/*
954		 * Sleep on the pending queue since
955		 * we're expecting a reply.
956		 */
957		if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task))
958			rpc_sleep_on(&xprt->pending, task, xprt_timer);
959		req->rq_connect_cookie = xprt->connect_cookie;
960	}
961	spin_unlock_bh(&xprt->transport_lock);
962}
963
964static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
965{
966	set_bit(XPRT_CONGESTED, &xprt->state);
967	rpc_sleep_on(&xprt->backlog, task, NULL);
968}
969
970static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
971{
972	if (rpc_wake_up_next(&xprt->backlog) == NULL)
973		clear_bit(XPRT_CONGESTED, &xprt->state);
974}
975
976static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
977{
978	bool ret = false;
979
980	if (!test_bit(XPRT_CONGESTED, &xprt->state))
981		goto out;
982	spin_lock(&xprt->reserve_lock);
983	if (test_bit(XPRT_CONGESTED, &xprt->state)) {
984		rpc_sleep_on(&xprt->backlog, task, NULL);
985		ret = true;
986	}
987	spin_unlock(&xprt->reserve_lock);
988out:
989	return ret;
990}
991
992static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
993{
994	struct rpc_rqst *req = ERR_PTR(-EAGAIN);
995
996	if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
997		goto out;
998	req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
999	if (req != NULL)
1000		goto out;
1001	atomic_dec(&xprt->num_reqs);
1002	req = ERR_PTR(-ENOMEM);
1003out:
1004	return req;
1005}
1006
1007static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1008{
1009	if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
1010		kfree(req);
1011		return true;
1012	}
1013	return false;
1014}
1015
1016void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1017{
1018	struct rpc_rqst *req;
1019
1020	spin_lock(&xprt->reserve_lock);
1021	if (!list_empty(&xprt->free)) {
1022		req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1023		list_del(&req->rq_list);
1024		goto out_init_req;
1025	}
1026	req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
1027	if (!IS_ERR(req))
1028		goto out_init_req;
1029	switch (PTR_ERR(req)) {
1030	case -ENOMEM:
1031		dprintk("RPC:       dynamic allocation of request slot "
1032				"failed! Retrying\n");
1033		task->tk_status = -ENOMEM;
1034		break;
1035	case -EAGAIN:
1036		xprt_add_backlog(xprt, task);
1037		dprintk("RPC:       waiting for request slot\n");
1038	default:
1039		task->tk_status = -EAGAIN;
1040	}
1041	spin_unlock(&xprt->reserve_lock);
1042	return;
1043out_init_req:
1044	task->tk_status = 0;
1045	task->tk_rqstp = req;
1046	xprt_request_init(task, xprt);
1047	spin_unlock(&xprt->reserve_lock);
1048}
1049EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1050
1051void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1052{
1053	/* Note: grabbing the xprt_lock_write() ensures that we throttle
1054	 * new slot allocation if the transport is congested (i.e. when
1055	 * reconnecting a stream transport or when out of socket write
1056	 * buffer space).
1057	 */
1058	if (xprt_lock_write(xprt, task)) {
1059		xprt_alloc_slot(xprt, task);
1060		xprt_release_write(xprt, task);
1061	}
1062}
1063EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1064
1065static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1066{
1067	spin_lock(&xprt->reserve_lock);
1068	if (!xprt_dynamic_free_slot(xprt, req)) {
1069		memset(req, 0, sizeof(*req));	/* mark unused */
1070		list_add(&req->rq_list, &xprt->free);
1071	}
1072	xprt_wake_up_backlog(xprt);
1073	spin_unlock(&xprt->reserve_lock);
1074}
1075
1076static void xprt_free_all_slots(struct rpc_xprt *xprt)
1077{
1078	struct rpc_rqst *req;
1079	while (!list_empty(&xprt->free)) {
1080		req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1081		list_del(&req->rq_list);
1082		kfree(req);
1083	}
1084}
1085
1086struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1087		unsigned int num_prealloc,
1088		unsigned int max_alloc)
1089{
1090	struct rpc_xprt *xprt;
1091	struct rpc_rqst *req;
1092	int i;
1093
1094	xprt = kzalloc(size, GFP_KERNEL);
1095	if (xprt == NULL)
1096		goto out;
1097
1098	xprt_init(xprt, net);
1099
1100	for (i = 0; i < num_prealloc; i++) {
1101		req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1102		if (!req)
1103			goto out_free;
1104		list_add(&req->rq_list, &xprt->free);
1105	}
1106	if (max_alloc > num_prealloc)
1107		xprt->max_reqs = max_alloc;
1108	else
1109		xprt->max_reqs = num_prealloc;
1110	xprt->min_reqs = num_prealloc;
1111	atomic_set(&xprt->num_reqs, num_prealloc);
1112
1113	return xprt;
1114
1115out_free:
1116	xprt_free(xprt);
1117out:
1118	return NULL;
1119}
1120EXPORT_SYMBOL_GPL(xprt_alloc);
1121
1122void xprt_free(struct rpc_xprt *xprt)
1123{
1124	put_net(xprt->xprt_net);
1125	xprt_free_all_slots(xprt);
1126	kfree(xprt);
1127}
1128EXPORT_SYMBOL_GPL(xprt_free);
1129
1130/**
1131 * xprt_reserve - allocate an RPC request slot
1132 * @task: RPC task requesting a slot allocation
1133 *
1134 * If the transport is marked as being congested, or if no more
1135 * slots are available, place the task on the transport's
1136 * backlog queue.
1137 */
1138void xprt_reserve(struct rpc_task *task)
1139{
1140	struct rpc_xprt	*xprt;
1141
1142	task->tk_status = 0;
1143	if (task->tk_rqstp != NULL)
1144		return;
1145
1146	task->tk_timeout = 0;
1147	task->tk_status = -EAGAIN;
1148	rcu_read_lock();
1149	xprt = rcu_dereference(task->tk_client->cl_xprt);
1150	if (!xprt_throttle_congested(xprt, task))
1151		xprt->ops->alloc_slot(xprt, task);
1152	rcu_read_unlock();
1153}
1154
1155/**
1156 * xprt_retry_reserve - allocate an RPC request slot
1157 * @task: RPC task requesting a slot allocation
1158 *
1159 * If no more slots are available, place the task on the transport's
1160 * backlog queue.
1161 * Note that the only difference with xprt_reserve is that we now
1162 * ignore the value of the XPRT_CONGESTED flag.
1163 */
1164void xprt_retry_reserve(struct rpc_task *task)
1165{
1166	struct rpc_xprt	*xprt;
1167
1168	task->tk_status = 0;
1169	if (task->tk_rqstp != NULL)
1170		return;
1171
1172	task->tk_timeout = 0;
1173	task->tk_status = -EAGAIN;
1174	rcu_read_lock();
1175	xprt = rcu_dereference(task->tk_client->cl_xprt);
1176	xprt->ops->alloc_slot(xprt, task);
1177	rcu_read_unlock();
1178}
1179
1180static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1181{
1182	return (__force __be32)xprt->xid++;
1183}
1184
1185static inline void xprt_init_xid(struct rpc_xprt *xprt)
1186{
1187	xprt->xid = prandom_u32();
1188}
1189
1190static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1191{
1192	struct rpc_rqst	*req = task->tk_rqstp;
1193
1194	INIT_LIST_HEAD(&req->rq_list);
1195	req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1196	req->rq_task	= task;
1197	req->rq_xprt    = xprt;
1198	req->rq_buffer  = NULL;
1199	req->rq_xid     = xprt_alloc_xid(xprt);
1200	req->rq_connect_cookie = xprt->connect_cookie - 1;
1201	req->rq_bytes_sent = 0;
1202	req->rq_snd_buf.len = 0;
1203	req->rq_snd_buf.buflen = 0;
1204	req->rq_rcv_buf.len = 0;
1205	req->rq_rcv_buf.buflen = 0;
1206	req->rq_release_snd_buf = NULL;
1207	xprt_reset_majortimeo(req);
1208	dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1209			req, ntohl(req->rq_xid));
1210}
1211
1212/**
1213 * xprt_release - release an RPC request slot
1214 * @task: task which is finished with the slot
1215 *
1216 */
1217void xprt_release(struct rpc_task *task)
1218{
1219	struct rpc_xprt	*xprt;
1220	struct rpc_rqst	*req = task->tk_rqstp;
1221
1222	if (req == NULL) {
1223		if (task->tk_client) {
1224			rcu_read_lock();
1225			xprt = rcu_dereference(task->tk_client->cl_xprt);
1226			if (xprt->snd_task == task)
1227				xprt_release_write(xprt, task);
1228			rcu_read_unlock();
1229		}
1230		return;
1231	}
1232
1233	xprt = req->rq_xprt;
1234	if (task->tk_ops->rpc_count_stats != NULL)
1235		task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1236	else if (task->tk_client)
1237		rpc_count_iostats(task, task->tk_client->cl_metrics);
1238	spin_lock_bh(&xprt->transport_lock);
1239	xprt->ops->release_xprt(xprt, task);
1240	if (xprt->ops->release_request)
1241		xprt->ops->release_request(task);
1242	if (!list_empty(&req->rq_list))
1243		list_del(&req->rq_list);
1244	xprt->last_used = jiffies;
1245	if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1246		mod_timer(&xprt->timer,
1247				xprt->last_used + xprt->idle_timeout);
1248	spin_unlock_bh(&xprt->transport_lock);
1249	if (req->rq_buffer)
1250		xprt->ops->buf_free(req->rq_buffer);
1251	if (req->rq_cred != NULL)
1252		put_rpccred(req->rq_cred);
1253	task->tk_rqstp = NULL;
1254	if (req->rq_release_snd_buf)
1255		req->rq_release_snd_buf(req);
1256
1257	dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1258	if (likely(!bc_prealloc(req)))
1259		xprt_free_slot(xprt, req);
1260	else
1261		xprt_free_bc_request(req);
1262}
1263
1264static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1265{
1266	atomic_set(&xprt->count, 1);
1267
1268	spin_lock_init(&xprt->transport_lock);
1269	spin_lock_init(&xprt->reserve_lock);
1270
1271	INIT_LIST_HEAD(&xprt->free);
1272	INIT_LIST_HEAD(&xprt->recv);
1273#if defined(CONFIG_SUNRPC_BACKCHANNEL)
1274	spin_lock_init(&xprt->bc_pa_lock);
1275	INIT_LIST_HEAD(&xprt->bc_pa_list);
1276#endif /* CONFIG_SUNRPC_BACKCHANNEL */
1277
1278	xprt->last_used = jiffies;
1279	xprt->cwnd = RPC_INITCWND;
1280	xprt->bind_index = 0;
1281
1282	rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1283	rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1284	rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1285	rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1286
1287	xprt_init_xid(xprt);
1288
1289	xprt->xprt_net = get_net(net);
1290}
1291
1292/**
1293 * xprt_create_transport - create an RPC transport
1294 * @args: rpc transport creation arguments
1295 *
1296 */
1297struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1298{
1299	struct rpc_xprt	*xprt;
1300	struct xprt_class *t;
1301
1302	spin_lock(&xprt_list_lock);
1303	list_for_each_entry(t, &xprt_list, list) {
1304		if (t->ident == args->ident) {
1305			spin_unlock(&xprt_list_lock);
1306			goto found;
1307		}
1308	}
1309	spin_unlock(&xprt_list_lock);
1310	dprintk("RPC: transport (%d) not supported\n", args->ident);
1311	return ERR_PTR(-EIO);
1312
1313found:
1314	xprt = t->setup(args);
1315	if (IS_ERR(xprt)) {
1316		dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1317				-PTR_ERR(xprt));
1318		goto out;
1319	}
1320	if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1321		xprt->idle_timeout = 0;
1322	INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1323	if (xprt_has_timer(xprt))
1324		setup_timer(&xprt->timer, xprt_init_autodisconnect,
1325			    (unsigned long)xprt);
1326	else
1327		init_timer(&xprt->timer);
1328
1329	if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1330		xprt_destroy(xprt);
1331		return ERR_PTR(-EINVAL);
1332	}
1333	xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1334	if (xprt->servername == NULL) {
1335		xprt_destroy(xprt);
1336		return ERR_PTR(-ENOMEM);
1337	}
1338
1339	dprintk("RPC:       created transport %p with %u slots\n", xprt,
1340			xprt->max_reqs);
1341out:
1342	return xprt;
1343}
1344
1345/**
1346 * xprt_destroy - destroy an RPC transport, killing off all requests.
1347 * @xprt: transport to destroy
1348 *
1349 */
1350static void xprt_destroy(struct rpc_xprt *xprt)
1351{
1352	dprintk("RPC:       destroying transport %p\n", xprt);
1353	del_timer_sync(&xprt->timer);
1354
1355	rpc_destroy_wait_queue(&xprt->binding);
1356	rpc_destroy_wait_queue(&xprt->pending);
1357	rpc_destroy_wait_queue(&xprt->sending);
1358	rpc_destroy_wait_queue(&xprt->backlog);
1359	cancel_work_sync(&xprt->task_cleanup);
1360	kfree(xprt->servername);
1361	/*
1362	 * Tear down transport state and free the rpc_xprt
1363	 */
1364	xprt->ops->destroy(xprt);
1365}
1366
1367/**
1368 * xprt_put - release a reference to an RPC transport.
1369 * @xprt: pointer to the transport
1370 *
1371 */
1372void xprt_put(struct rpc_xprt *xprt)
1373{
1374	if (atomic_dec_and_test(&xprt->count))
1375		xprt_destroy(xprt);
1376}
1377