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1/*
2 * linux/net/sunrpc/xprt.c
3 *
4 * This is a generic RPC call interface supporting congestion avoidance,
5 * and asynchronous calls.
6 *
7 * The interface works like this:
8 *
9 * - When a process places a call, it allocates a request slot if
10 * one is available. Otherwise, it sleeps on the backlog queue
11 * (xprt_reserve).
12 * - Next, the caller puts together the RPC message, stuffs it into
13 * the request struct, and calls xprt_transmit().
14 * - xprt_transmit sends the message and installs the caller on the
15 * transport's wait list. At the same time, 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 *);
69
70static DEFINE_SPINLOCK(xprt_list_lock);
71static LIST_HEAD(xprt_list);
72
73/*
74 * The transport code maintains an estimate on the maximum number of out-
75 * standing RPC requests, using a smoothed version of the congestion
76 * avoidance implemented in 44BSD. This is basically the Van Jacobson
77 * congestion algorithm: If a retransmit occurs, the congestion window is
78 * halved; otherwise, it is incremented by 1/cwnd when
79 *
80 * - a reply is received and
81 * - a full number of requests are outstanding and
82 * - the congestion window hasn't been updated recently.
83 */
84#define RPC_CWNDSHIFT (8U)
85#define RPC_CWNDSCALE (1U << RPC_CWNDSHIFT)
86#define RPC_INITCWND RPC_CWNDSCALE
87#define RPC_MAXCWND(xprt) ((xprt)->max_reqs << RPC_CWNDSHIFT)
88
89#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
90
91/**
92 * xprt_register_transport - register a transport implementation
93 * @transport: transport to register
94 *
95 * If a transport implementation is loaded as a kernel module, it can
96 * call this interface to make itself known to the RPC client.
97 *
98 * Returns:
99 * 0: transport successfully registered
100 * -EEXIST: transport already registered
101 * -EINVAL: transport module being unloaded
102 */
103int xprt_register_transport(struct xprt_class *transport)
104{
105 struct xprt_class *t;
106 int result;
107
108 result = -EEXIST;
109 spin_lock(&xprt_list_lock);
110 list_for_each_entry(t, &xprt_list, list) {
111 /* don't register the same transport class twice */
112 if (t->ident == transport->ident)
113 goto out;
114 }
115
116 list_add_tail(&transport->list, &xprt_list);
117 printk(KERN_INFO "RPC: Registered %s transport module.\n",
118 transport->name);
119 result = 0;
120
121out:
122 spin_unlock(&xprt_list_lock);
123 return result;
124}
125EXPORT_SYMBOL_GPL(xprt_register_transport);
126
127/**
128 * xprt_unregister_transport - unregister a transport implementation
129 * @transport: transport to unregister
130 *
131 * Returns:
132 * 0: transport successfully unregistered
133 * -ENOENT: transport never registered
134 */
135int xprt_unregister_transport(struct xprt_class *transport)
136{
137 struct xprt_class *t;
138 int result;
139
140 result = 0;
141 spin_lock(&xprt_list_lock);
142 list_for_each_entry(t, &xprt_list, list) {
143 if (t == transport) {
144 printk(KERN_INFO
145 "RPC: Unregistered %s transport module.\n",
146 transport->name);
147 list_del_init(&transport->list);
148 goto out;
149 }
150 }
151 result = -ENOENT;
152
153out:
154 spin_unlock(&xprt_list_lock);
155 return result;
156}
157EXPORT_SYMBOL_GPL(xprt_unregister_transport);
158
159/**
160 * xprt_load_transport - load a transport implementation
161 * @transport_name: transport to load
162 *
163 * Returns:
164 * 0: transport successfully loaded
165 * -ENOENT: transport module not available
166 */
167int xprt_load_transport(const char *transport_name)
168{
169 struct xprt_class *t;
170 int result;
171
172 result = 0;
173 spin_lock(&xprt_list_lock);
174 list_for_each_entry(t, &xprt_list, list) {
175 if (strcmp(t->name, transport_name) == 0) {
176 spin_unlock(&xprt_list_lock);
177 goto out;
178 }
179 }
180 spin_unlock(&xprt_list_lock);
181 result = request_module("xprt%s", transport_name);
182out:
183 return result;
184}
185EXPORT_SYMBOL_GPL(xprt_load_transport);
186
187/**
188 * xprt_reserve_xprt - serialize write access to transports
189 * @task: task that is requesting access to the transport
190 * @xprt: pointer to the target transport
191 *
192 * This prevents mixing the payload of separate requests, and prevents
193 * transport connects from colliding with writes. No congestion control
194 * is provided.
195 */
196int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
197{
198 struct rpc_rqst *req = task->tk_rqstp;
199 int priority;
200
201 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
202 if (task == xprt->snd_task)
203 return 1;
204 goto out_sleep;
205 }
206 xprt->snd_task = task;
207 if (req != NULL) {
208 req->rq_bytes_sent = 0;
209 req->rq_ntrans++;
210 }
211
212 return 1;
213
214out_sleep:
215 dprintk("RPC: %5u failed to lock transport %p\n",
216 task->tk_pid, xprt);
217 task->tk_timeout = 0;
218 task->tk_status = -EAGAIN;
219 if (req == NULL)
220 priority = RPC_PRIORITY_LOW;
221 else if (!req->rq_ntrans)
222 priority = RPC_PRIORITY_NORMAL;
223 else
224 priority = RPC_PRIORITY_HIGH;
225 rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
226 return 0;
227}
228EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
229
230static void xprt_clear_locked(struct rpc_xprt *xprt)
231{
232 xprt->snd_task = NULL;
233 if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state) || xprt->shutdown) {
234 smp_mb__before_clear_bit();
235 clear_bit(XPRT_LOCKED, &xprt->state);
236 smp_mb__after_clear_bit();
237 } else
238 queue_work(rpciod_workqueue, &xprt->task_cleanup);
239}
240
241/*
242 * xprt_reserve_xprt_cong - serialize write access to transports
243 * @task: task that is requesting access to the transport
244 *
245 * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
246 * integrated into the decision of whether a request is allowed to be
247 * woken up and given access to the transport.
248 */
249int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
250{
251 struct rpc_rqst *req = task->tk_rqstp;
252 int priority;
253
254 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
255 if (task == xprt->snd_task)
256 return 1;
257 goto out_sleep;
258 }
259 if (req == NULL) {
260 xprt->snd_task = task;
261 return 1;
262 }
263 if (__xprt_get_cong(xprt, task)) {
264 xprt->snd_task = task;
265 req->rq_bytes_sent = 0;
266 req->rq_ntrans++;
267 return 1;
268 }
269 xprt_clear_locked(xprt);
270out_sleep:
271 dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
272 task->tk_timeout = 0;
273 task->tk_status = -EAGAIN;
274 if (req == NULL)
275 priority = RPC_PRIORITY_LOW;
276 else if (!req->rq_ntrans)
277 priority = RPC_PRIORITY_NORMAL;
278 else
279 priority = RPC_PRIORITY_HIGH;
280 rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
281 return 0;
282}
283EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
284
285static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
286{
287 int retval;
288
289 spin_lock_bh(&xprt->transport_lock);
290 retval = xprt->ops->reserve_xprt(xprt, task);
291 spin_unlock_bh(&xprt->transport_lock);
292 return retval;
293}
294
295static void __xprt_lock_write_next(struct rpc_xprt *xprt)
296{
297 struct rpc_task *task;
298 struct rpc_rqst *req;
299
300 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
301 return;
302
303 task = rpc_wake_up_next(&xprt->sending);
304 if (task == NULL)
305 goto out_unlock;
306
307 req = task->tk_rqstp;
308 xprt->snd_task = task;
309 if (req) {
310 req->rq_bytes_sent = 0;
311 req->rq_ntrans++;
312 }
313 return;
314
315out_unlock:
316 xprt_clear_locked(xprt);
317}
318
319static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
320{
321 struct rpc_task *task;
322 struct rpc_rqst *req;
323
324 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
325 return;
326 if (RPCXPRT_CONGESTED(xprt))
327 goto out_unlock;
328 task = rpc_wake_up_next(&xprt->sending);
329 if (task == NULL)
330 goto out_unlock;
331
332 req = task->tk_rqstp;
333 if (req == NULL) {
334 xprt->snd_task = task;
335 return;
336 }
337 if (__xprt_get_cong(xprt, task)) {
338 xprt->snd_task = task;
339 req->rq_bytes_sent = 0;
340 req->rq_ntrans++;
341 return;
342 }
343out_unlock:
344 xprt_clear_locked(xprt);
345}
346
347/**
348 * xprt_release_xprt - allow other requests to use a transport
349 * @xprt: transport with other tasks potentially waiting
350 * @task: task that is releasing access to the transport
351 *
352 * Note that "task" can be NULL. No congestion control is provided.
353 */
354void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
355{
356 if (xprt->snd_task == task) {
357 xprt_clear_locked(xprt);
358 __xprt_lock_write_next(xprt);
359 }
360}
361EXPORT_SYMBOL_GPL(xprt_release_xprt);
362
363/**
364 * xprt_release_xprt_cong - allow other requests to use a transport
365 * @xprt: transport with other tasks potentially waiting
366 * @task: task that is releasing access to the transport
367 *
368 * Note that "task" can be NULL. Another task is awoken to use the
369 * transport if the transport's congestion window allows it.
370 */
371void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
372{
373 if (xprt->snd_task == task) {
374 xprt_clear_locked(xprt);
375 __xprt_lock_write_next_cong(xprt);
376 }
377}
378EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
379
380static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
381{
382 spin_lock_bh(&xprt->transport_lock);
383 xprt->ops->release_xprt(xprt, task);
384 spin_unlock_bh(&xprt->transport_lock);
385}
386
387/*
388 * Van Jacobson congestion avoidance. Check if the congestion window
389 * overflowed. Put the task to sleep if this is the case.
390 */
391static int
392__xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
393{
394 struct rpc_rqst *req = task->tk_rqstp;
395
396 if (req->rq_cong)
397 return 1;
398 dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
399 task->tk_pid, xprt->cong, xprt->cwnd);
400 if (RPCXPRT_CONGESTED(xprt))
401 return 0;
402 req->rq_cong = 1;
403 xprt->cong += RPC_CWNDSCALE;
404 return 1;
405}
406
407/*
408 * Adjust the congestion window, and wake up the next task
409 * that has been sleeping due to congestion
410 */
411static void
412__xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
413{
414 if (!req->rq_cong)
415 return;
416 req->rq_cong = 0;
417 xprt->cong -= RPC_CWNDSCALE;
418 __xprt_lock_write_next_cong(xprt);
419}
420
421/**
422 * xprt_release_rqst_cong - housekeeping when request is complete
423 * @task: RPC request that recently completed
424 *
425 * Useful for transports that require congestion control.
426 */
427void xprt_release_rqst_cong(struct rpc_task *task)
428{
429 __xprt_put_cong(task->tk_xprt, task->tk_rqstp);
430}
431EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
432
433/**
434 * xprt_adjust_cwnd - adjust transport congestion window
435 * @task: recently completed RPC request used to adjust window
436 * @result: result code of completed RPC request
437 *
438 * We use a time-smoothed congestion estimator to avoid heavy oscillation.
439 */
440void xprt_adjust_cwnd(struct rpc_task *task, int result)
441{
442 struct rpc_rqst *req = task->tk_rqstp;
443 struct rpc_xprt *xprt = task->tk_xprt;
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 */
485void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
486{
487 struct rpc_rqst *req = task->tk_rqstp;
488 struct rpc_xprt *xprt = req->rq_xprt;
489
490 task->tk_timeout = req->rq_timeout;
491 rpc_sleep_on(&xprt->pending, task, action);
492}
493EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
494
495/**
496 * xprt_write_space - wake the task waiting for transport output buffer space
497 * @xprt: transport with waiting tasks
498 *
499 * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
500 */
501void xprt_write_space(struct rpc_xprt *xprt)
502{
503 if (unlikely(xprt->shutdown))
504 return;
505
506 spin_lock_bh(&xprt->transport_lock);
507 if (xprt->snd_task) {
508 dprintk("RPC: write space: waking waiting task on "
509 "xprt %p\n", xprt);
510 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
511 }
512 spin_unlock_bh(&xprt->transport_lock);
513}
514EXPORT_SYMBOL_GPL(xprt_write_space);
515
516/**
517 * xprt_set_retrans_timeout_def - set a request's retransmit timeout
518 * @task: task whose timeout is to be set
519 *
520 * Set a request's retransmit timeout based on the transport's
521 * default timeout parameters. Used by transports that don't adjust
522 * the retransmit timeout based on round-trip time estimation.
523 */
524void xprt_set_retrans_timeout_def(struct rpc_task *task)
525{
526 task->tk_timeout = task->tk_rqstp->rq_timeout;
527}
528EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
529
530/*
531 * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
532 * @task: task whose timeout is to be set
533 *
534 * Set a request's retransmit timeout using the RTT estimator.
535 */
536void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
537{
538 int timer = task->tk_msg.rpc_proc->p_timer;
539 struct rpc_clnt *clnt = task->tk_client;
540 struct rpc_rtt *rtt = clnt->cl_rtt;
541 struct rpc_rqst *req = task->tk_rqstp;
542 unsigned long max_timeout = clnt->cl_timeout->to_maxval;
543
544 task->tk_timeout = rpc_calc_rto(rtt, timer);
545 task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
546 if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
547 task->tk_timeout = max_timeout;
548}
549EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
550
551static void xprt_reset_majortimeo(struct rpc_rqst *req)
552{
553 const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
554
555 req->rq_majortimeo = req->rq_timeout;
556 if (to->to_exponential)
557 req->rq_majortimeo <<= to->to_retries;
558 else
559 req->rq_majortimeo += to->to_increment * to->to_retries;
560 if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
561 req->rq_majortimeo = to->to_maxval;
562 req->rq_majortimeo += jiffies;
563}
564
565/**
566 * xprt_adjust_timeout - adjust timeout values for next retransmit
567 * @req: RPC request containing parameters to use for the adjustment
568 *
569 */
570int xprt_adjust_timeout(struct rpc_rqst *req)
571{
572 struct rpc_xprt *xprt = req->rq_xprt;
573 const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
574 int status = 0;
575
576 if (time_before(jiffies, req->rq_majortimeo)) {
577 if (to->to_exponential)
578 req->rq_timeout <<= 1;
579 else
580 req->rq_timeout += to->to_increment;
581 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
582 req->rq_timeout = to->to_maxval;
583 req->rq_retries++;
584 } else {
585 req->rq_timeout = to->to_initval;
586 req->rq_retries = 0;
587 xprt_reset_majortimeo(req);
588 /* Reset the RTT counters == "slow start" */
589 spin_lock_bh(&xprt->transport_lock);
590 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
591 spin_unlock_bh(&xprt->transport_lock);
592 status = -ETIMEDOUT;
593 }
594
595 if (req->rq_timeout == 0) {
596 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
597 req->rq_timeout = 5 * HZ;
598 }
599 return status;
600}
601
602static void xprt_autoclose(struct work_struct *work)
603{
604 struct rpc_xprt *xprt =
605 container_of(work, struct rpc_xprt, task_cleanup);
606
607 xprt->ops->close(xprt);
608 clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
609 xprt_release_write(xprt, NULL);
610}
611
612/**
613 * xprt_disconnect_done - mark a transport as disconnected
614 * @xprt: transport to flag for disconnect
615 *
616 */
617void xprt_disconnect_done(struct rpc_xprt *xprt)
618{
619 dprintk("RPC: disconnected transport %p\n", xprt);
620 spin_lock_bh(&xprt->transport_lock);
621 xprt_clear_connected(xprt);
622 xprt_wake_pending_tasks(xprt, -EAGAIN);
623 spin_unlock_bh(&xprt->transport_lock);
624}
625EXPORT_SYMBOL_GPL(xprt_disconnect_done);
626
627/**
628 * xprt_force_disconnect - force a transport to disconnect
629 * @xprt: transport to disconnect
630 *
631 */
632void xprt_force_disconnect(struct rpc_xprt *xprt)
633{
634 /* Don't race with the test_bit() in xprt_clear_locked() */
635 spin_lock_bh(&xprt->transport_lock);
636 set_bit(XPRT_CLOSE_WAIT, &xprt->state);
637 /* Try to schedule an autoclose RPC call */
638 if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
639 queue_work(rpciod_workqueue, &xprt->task_cleanup);
640 xprt_wake_pending_tasks(xprt, -EAGAIN);
641 spin_unlock_bh(&xprt->transport_lock);
642}
643
644/**
645 * xprt_conditional_disconnect - force a transport to disconnect
646 * @xprt: transport to disconnect
647 * @cookie: 'connection cookie'
648 *
649 * This attempts to break the connection if and only if 'cookie' matches
650 * the current transport 'connection cookie'. It ensures that we don't
651 * try to break the connection more than once when we need to retransmit
652 * a batch of RPC requests.
653 *
654 */
655void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
656{
657 /* Don't race with the test_bit() in xprt_clear_locked() */
658 spin_lock_bh(&xprt->transport_lock);
659 if (cookie != xprt->connect_cookie)
660 goto out;
661 if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
662 goto out;
663 set_bit(XPRT_CLOSE_WAIT, &xprt->state);
664 /* Try to schedule an autoclose RPC call */
665 if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
666 queue_work(rpciod_workqueue, &xprt->task_cleanup);
667 xprt_wake_pending_tasks(xprt, -EAGAIN);
668out:
669 spin_unlock_bh(&xprt->transport_lock);
670}
671
672static void
673xprt_init_autodisconnect(unsigned long data)
674{
675 struct rpc_xprt *xprt = (struct rpc_xprt *)data;
676
677 spin_lock(&xprt->transport_lock);
678 if (!list_empty(&xprt->recv) || xprt->shutdown)
679 goto out_abort;
680 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
681 goto out_abort;
682 spin_unlock(&xprt->transport_lock);
683 set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
684 queue_work(rpciod_workqueue, &xprt->task_cleanup);
685 return;
686out_abort:
687 spin_unlock(&xprt->transport_lock);
688}
689
690/**
691 * xprt_connect - schedule a transport connect operation
692 * @task: RPC task that is requesting the connect
693 *
694 */
695void xprt_connect(struct rpc_task *task)
696{
697 struct rpc_xprt *xprt = task->tk_xprt;
698
699 dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
700 xprt, (xprt_connected(xprt) ? "is" : "is not"));
701
702 if (!xprt_bound(xprt)) {
703 task->tk_status = -EAGAIN;
704 return;
705 }
706 if (!xprt_lock_write(xprt, task))
707 return;
708
709 if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
710 xprt->ops->close(xprt);
711
712 if (xprt_connected(xprt))
713 xprt_release_write(xprt, task);
714 else {
715 if (task->tk_rqstp)
716 task->tk_rqstp->rq_bytes_sent = 0;
717
718 task->tk_timeout = task->tk_rqstp->rq_timeout;
719 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
720
721 if (test_bit(XPRT_CLOSING, &xprt->state))
722 return;
723 if (xprt_test_and_set_connecting(xprt))
724 return;
725 xprt->stat.connect_start = jiffies;
726 xprt->ops->connect(task);
727 }
728}
729
730static void xprt_connect_status(struct rpc_task *task)
731{
732 struct rpc_xprt *xprt = task->tk_xprt;
733
734 if (task->tk_status == 0) {
735 xprt->stat.connect_count++;
736 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
737 dprintk("RPC: %5u xprt_connect_status: connection established\n",
738 task->tk_pid);
739 return;
740 }
741
742 switch (task->tk_status) {
743 case -EAGAIN:
744 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
745 break;
746 case -ETIMEDOUT:
747 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
748 "out\n", task->tk_pid);
749 break;
750 default:
751 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
752 "server %s\n", task->tk_pid, -task->tk_status,
753 task->tk_client->cl_server);
754 xprt_release_write(xprt, task);
755 task->tk_status = -EIO;
756 }
757}
758
759/**
760 * xprt_lookup_rqst - find an RPC request corresponding to an XID
761 * @xprt: transport on which the original request was transmitted
762 * @xid: RPC XID of incoming reply
763 *
764 */
765struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
766{
767 struct rpc_rqst *entry;
768
769 list_for_each_entry(entry, &xprt->recv, rq_list)
770 if (entry->rq_xid == xid)
771 return entry;
772
773 dprintk("RPC: xprt_lookup_rqst did not find xid %08x\n",
774 ntohl(xid));
775 xprt->stat.bad_xids++;
776 return NULL;
777}
778EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
779
780static void xprt_update_rtt(struct rpc_task *task)
781{
782 struct rpc_rqst *req = task->tk_rqstp;
783 struct rpc_rtt *rtt = task->tk_client->cl_rtt;
784 unsigned timer = task->tk_msg.rpc_proc->p_timer;
785 long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
786
787 if (timer) {
788 if (req->rq_ntrans == 1)
789 rpc_update_rtt(rtt, timer, m);
790 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
791 }
792}
793
794/**
795 * xprt_complete_rqst - called when reply processing is complete
796 * @task: RPC request that recently completed
797 * @copied: actual number of bytes received from the transport
798 *
799 * Caller holds transport lock.
800 */
801void xprt_complete_rqst(struct rpc_task *task, int copied)
802{
803 struct rpc_rqst *req = task->tk_rqstp;
804 struct rpc_xprt *xprt = req->rq_xprt;
805
806 dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
807 task->tk_pid, ntohl(req->rq_xid), copied);
808
809 xprt->stat.recvs++;
810 req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
811 if (xprt->ops->timer != NULL)
812 xprt_update_rtt(task);
813
814 list_del_init(&req->rq_list);
815 req->rq_private_buf.len = copied;
816 /* Ensure all writes are done before we update */
817 /* req->rq_reply_bytes_recvd */
818 smp_wmb();
819 req->rq_reply_bytes_recvd = copied;
820 rpc_wake_up_queued_task(&xprt->pending, task);
821}
822EXPORT_SYMBOL_GPL(xprt_complete_rqst);
823
824static void xprt_timer(struct rpc_task *task)
825{
826 struct rpc_rqst *req = task->tk_rqstp;
827 struct rpc_xprt *xprt = req->rq_xprt;
828
829 if (task->tk_status != -ETIMEDOUT)
830 return;
831 dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
832
833 spin_lock_bh(&xprt->transport_lock);
834 if (!req->rq_reply_bytes_recvd) {
835 if (xprt->ops->timer)
836 xprt->ops->timer(task);
837 } else
838 task->tk_status = 0;
839 spin_unlock_bh(&xprt->transport_lock);
840}
841
842static inline int xprt_has_timer(struct rpc_xprt *xprt)
843{
844 return xprt->idle_timeout != 0;
845}
846
847/**
848 * xprt_prepare_transmit - reserve the transport before sending a request
849 * @task: RPC task about to send a request
850 *
851 */
852int xprt_prepare_transmit(struct rpc_task *task)
853{
854 struct rpc_rqst *req = task->tk_rqstp;
855 struct rpc_xprt *xprt = req->rq_xprt;
856 int err = 0;
857
858 dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
859
860 spin_lock_bh(&xprt->transport_lock);
861 if (req->rq_reply_bytes_recvd && !req->rq_bytes_sent) {
862 err = req->rq_reply_bytes_recvd;
863 goto out_unlock;
864 }
865 if (!xprt->ops->reserve_xprt(xprt, task))
866 err = -EAGAIN;
867out_unlock:
868 spin_unlock_bh(&xprt->transport_lock);
869 return err;
870}
871
872void xprt_end_transmit(struct rpc_task *task)
873{
874 xprt_release_write(task->tk_rqstp->rq_xprt, task);
875}
876
877/**
878 * xprt_transmit - send an RPC request on a transport
879 * @task: controlling RPC task
880 *
881 * We have to copy the iovec because sendmsg fiddles with its contents.
882 */
883void xprt_transmit(struct rpc_task *task)
884{
885 struct rpc_rqst *req = task->tk_rqstp;
886 struct rpc_xprt *xprt = req->rq_xprt;
887 int status;
888
889 dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
890
891 if (!req->rq_reply_bytes_recvd) {
892 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
893 /*
894 * Add to the list only if we're expecting a reply
895 */
896 spin_lock_bh(&xprt->transport_lock);
897 /* Update the softirq receive buffer */
898 memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
899 sizeof(req->rq_private_buf));
900 /* Add request to the receive list */
901 list_add_tail(&req->rq_list, &xprt->recv);
902 spin_unlock_bh(&xprt->transport_lock);
903 xprt_reset_majortimeo(req);
904 /* Turn off autodisconnect */
905 del_singleshot_timer_sync(&xprt->timer);
906 }
907 } else if (!req->rq_bytes_sent)
908 return;
909
910 req->rq_connect_cookie = xprt->connect_cookie;
911 req->rq_xtime = ktime_get();
912 status = xprt->ops->send_request(task);
913 if (status != 0) {
914 task->tk_status = status;
915 return;
916 }
917
918 dprintk("RPC: %5u xmit complete\n", task->tk_pid);
919 task->tk_flags |= RPC_TASK_SENT;
920 spin_lock_bh(&xprt->transport_lock);
921
922 xprt->ops->set_retrans_timeout(task);
923
924 xprt->stat.sends++;
925 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
926 xprt->stat.bklog_u += xprt->backlog.qlen;
927
928 /* Don't race with disconnect */
929 if (!xprt_connected(xprt))
930 task->tk_status = -ENOTCONN;
931 else if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task)) {
932 /*
933 * Sleep on the pending queue since
934 * we're expecting a reply.
935 */
936 rpc_sleep_on(&xprt->pending, task, xprt_timer);
937 }
938 spin_unlock_bh(&xprt->transport_lock);
939}
940
941static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
942{
943 struct rpc_rqst *req = ERR_PTR(-EAGAIN);
944
945 if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
946 goto out;
947 req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
948 if (req != NULL)
949 goto out;
950 atomic_dec(&xprt->num_reqs);
951 req = ERR_PTR(-ENOMEM);
952out:
953 return req;
954}
955
956static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
957{
958 if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
959 kfree(req);
960 return true;
961 }
962 return false;
963}
964
965static void xprt_alloc_slot(struct rpc_task *task)
966{
967 struct rpc_xprt *xprt = task->tk_xprt;
968 struct rpc_rqst *req;
969
970 if (!list_empty(&xprt->free)) {
971 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
972 list_del(&req->rq_list);
973 goto out_init_req;
974 }
975 req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT);
976 if (!IS_ERR(req))
977 goto out_init_req;
978 switch (PTR_ERR(req)) {
979 case -ENOMEM:
980 rpc_delay(task, HZ >> 2);
981 dprintk("RPC: dynamic allocation of request slot "
982 "failed! Retrying\n");
983 break;
984 case -EAGAIN:
985 rpc_sleep_on(&xprt->backlog, task, NULL);
986 dprintk("RPC: waiting for request slot\n");
987 }
988 task->tk_status = -EAGAIN;
989 return;
990out_init_req:
991 task->tk_status = 0;
992 task->tk_rqstp = req;
993 xprt_request_init(task, xprt);
994}
995
996static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
997{
998 if (xprt_dynamic_free_slot(xprt, req))
999 return;
1000
1001 memset(req, 0, sizeof(*req)); /* mark unused */
1002
1003 spin_lock(&xprt->reserve_lock);
1004 list_add(&req->rq_list, &xprt->free);
1005 rpc_wake_up_next(&xprt->backlog);
1006 spin_unlock(&xprt->reserve_lock);
1007}
1008
1009static void xprt_free_all_slots(struct rpc_xprt *xprt)
1010{
1011 struct rpc_rqst *req;
1012 while (!list_empty(&xprt->free)) {
1013 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1014 list_del(&req->rq_list);
1015 kfree(req);
1016 }
1017}
1018
1019struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1020 unsigned int num_prealloc,
1021 unsigned int max_alloc)
1022{
1023 struct rpc_xprt *xprt;
1024 struct rpc_rqst *req;
1025 int i;
1026
1027 xprt = kzalloc(size, GFP_KERNEL);
1028 if (xprt == NULL)
1029 goto out;
1030
1031 xprt_init(xprt, net);
1032
1033 for (i = 0; i < num_prealloc; i++) {
1034 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1035 if (!req)
1036 break;
1037 list_add(&req->rq_list, &xprt->free);
1038 }
1039 if (i < num_prealloc)
1040 goto out_free;
1041 if (max_alloc > num_prealloc)
1042 xprt->max_reqs = max_alloc;
1043 else
1044 xprt->max_reqs = num_prealloc;
1045 xprt->min_reqs = num_prealloc;
1046 atomic_set(&xprt->num_reqs, num_prealloc);
1047
1048 return xprt;
1049
1050out_free:
1051 xprt_free(xprt);
1052out:
1053 return NULL;
1054}
1055EXPORT_SYMBOL_GPL(xprt_alloc);
1056
1057void xprt_free(struct rpc_xprt *xprt)
1058{
1059 put_net(xprt->xprt_net);
1060 xprt_free_all_slots(xprt);
1061 kfree(xprt);
1062}
1063EXPORT_SYMBOL_GPL(xprt_free);
1064
1065/**
1066 * xprt_reserve - allocate an RPC request slot
1067 * @task: RPC task requesting a slot allocation
1068 *
1069 * If no more slots are available, place the task on the transport's
1070 * backlog queue.
1071 */
1072void xprt_reserve(struct rpc_task *task)
1073{
1074 struct rpc_xprt *xprt = task->tk_xprt;
1075
1076 task->tk_status = 0;
1077 if (task->tk_rqstp != NULL)
1078 return;
1079
1080 /* Note: grabbing the xprt_lock_write() here is not strictly needed,
1081 * but ensures that we throttle new slot allocation if the transport
1082 * is congested (e.g. if reconnecting or if we're out of socket
1083 * write buffer space).
1084 */
1085 task->tk_timeout = 0;
1086 task->tk_status = -EAGAIN;
1087 if (!xprt_lock_write(xprt, task))
1088 return;
1089
1090 spin_lock(&xprt->reserve_lock);
1091 xprt_alloc_slot(task);
1092 spin_unlock(&xprt->reserve_lock);
1093 xprt_release_write(xprt, task);
1094}
1095
1096static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1097{
1098 return (__force __be32)xprt->xid++;
1099}
1100
1101static inline void xprt_init_xid(struct rpc_xprt *xprt)
1102{
1103 xprt->xid = net_random();
1104}
1105
1106static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1107{
1108 struct rpc_rqst *req = task->tk_rqstp;
1109
1110 INIT_LIST_HEAD(&req->rq_list);
1111 req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1112 req->rq_task = task;
1113 req->rq_xprt = xprt;
1114 req->rq_buffer = NULL;
1115 req->rq_xid = xprt_alloc_xid(xprt);
1116 req->rq_release_snd_buf = NULL;
1117 xprt_reset_majortimeo(req);
1118 dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1119 req, ntohl(req->rq_xid));
1120}
1121
1122/**
1123 * xprt_release - release an RPC request slot
1124 * @task: task which is finished with the slot
1125 *
1126 */
1127void xprt_release(struct rpc_task *task)
1128{
1129 struct rpc_xprt *xprt;
1130 struct rpc_rqst *req;
1131
1132 if (!(req = task->tk_rqstp))
1133 return;
1134
1135 xprt = req->rq_xprt;
1136 rpc_count_iostats(task);
1137 spin_lock_bh(&xprt->transport_lock);
1138 xprt->ops->release_xprt(xprt, task);
1139 if (xprt->ops->release_request)
1140 xprt->ops->release_request(task);
1141 if (!list_empty(&req->rq_list))
1142 list_del(&req->rq_list);
1143 xprt->last_used = jiffies;
1144 if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1145 mod_timer(&xprt->timer,
1146 xprt->last_used + xprt->idle_timeout);
1147 spin_unlock_bh(&xprt->transport_lock);
1148 if (req->rq_buffer)
1149 xprt->ops->buf_free(req->rq_buffer);
1150 if (req->rq_cred != NULL)
1151 put_rpccred(req->rq_cred);
1152 task->tk_rqstp = NULL;
1153 if (req->rq_release_snd_buf)
1154 req->rq_release_snd_buf(req);
1155
1156 dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1157 if (likely(!bc_prealloc(req)))
1158 xprt_free_slot(xprt, req);
1159 else
1160 xprt_free_bc_request(req);
1161}
1162
1163static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1164{
1165 atomic_set(&xprt->count, 1);
1166
1167 spin_lock_init(&xprt->transport_lock);
1168 spin_lock_init(&xprt->reserve_lock);
1169
1170 INIT_LIST_HEAD(&xprt->free);
1171 INIT_LIST_HEAD(&xprt->recv);
1172#if defined(CONFIG_SUNRPC_BACKCHANNEL)
1173 spin_lock_init(&xprt->bc_pa_lock);
1174 INIT_LIST_HEAD(&xprt->bc_pa_list);
1175#endif /* CONFIG_SUNRPC_BACKCHANNEL */
1176
1177 xprt->last_used = jiffies;
1178 xprt->cwnd = RPC_INITCWND;
1179 xprt->bind_index = 0;
1180
1181 rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1182 rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1183 rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1184 rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1185
1186 xprt_init_xid(xprt);
1187
1188 xprt->xprt_net = get_net(net);
1189}
1190
1191/**
1192 * xprt_create_transport - create an RPC transport
1193 * @args: rpc transport creation arguments
1194 *
1195 */
1196struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1197{
1198 struct rpc_xprt *xprt;
1199 struct xprt_class *t;
1200
1201 spin_lock(&xprt_list_lock);
1202 list_for_each_entry(t, &xprt_list, list) {
1203 if (t->ident == args->ident) {
1204 spin_unlock(&xprt_list_lock);
1205 goto found;
1206 }
1207 }
1208 spin_unlock(&xprt_list_lock);
1209 printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1210 return ERR_PTR(-EIO);
1211
1212found:
1213 xprt = t->setup(args);
1214 if (IS_ERR(xprt)) {
1215 dprintk("RPC: xprt_create_transport: failed, %ld\n",
1216 -PTR_ERR(xprt));
1217 goto out;
1218 }
1219 INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1220 if (xprt_has_timer(xprt))
1221 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1222 (unsigned long)xprt);
1223 else
1224 init_timer(&xprt->timer);
1225 dprintk("RPC: created transport %p with %u slots\n", xprt,
1226 xprt->max_reqs);
1227out:
1228 return xprt;
1229}
1230
1231/**
1232 * xprt_destroy - destroy an RPC transport, killing off all requests.
1233 * @xprt: transport to destroy
1234 *
1235 */
1236static void xprt_destroy(struct rpc_xprt *xprt)
1237{
1238 dprintk("RPC: destroying transport %p\n", xprt);
1239 xprt->shutdown = 1;
1240 del_timer_sync(&xprt->timer);
1241
1242 rpc_destroy_wait_queue(&xprt->binding);
1243 rpc_destroy_wait_queue(&xprt->pending);
1244 rpc_destroy_wait_queue(&xprt->sending);
1245 rpc_destroy_wait_queue(&xprt->backlog);
1246 cancel_work_sync(&xprt->task_cleanup);
1247 /*
1248 * Tear down transport state and free the rpc_xprt
1249 */
1250 xprt->ops->destroy(xprt);
1251}
1252
1253/**
1254 * xprt_put - release a reference to an RPC transport.
1255 * @xprt: pointer to the transport
1256 *
1257 */
1258void xprt_put(struct rpc_xprt *xprt)
1259{
1260 if (atomic_dec_and_test(&xprt->count))
1261 xprt_destroy(xprt);
1262}
1263
1264/**
1265 * xprt_get - return a reference to an RPC transport.
1266 * @xprt: pointer to the transport
1267 *
1268 */
1269struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1270{
1271 if (atomic_inc_not_zero(&xprt->count))
1272 return xprt;
1273 return NULL;
1274}
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#include <linux/rcupdate.h>
52
53#include <trace/events/sunrpc.h>
54
55#include "sunrpc.h"
56
57/*
58 * Local variables
59 */
60
61#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
62# define RPCDBG_FACILITY RPCDBG_XPRT
63#endif
64
65/*
66 * Local functions
67 */
68static void xprt_init(struct rpc_xprt *xprt, struct net *net);
69static void xprt_request_init(struct rpc_task *, struct rpc_xprt *);
70static void xprt_connect_status(struct rpc_task *task);
71static int __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
72static void __xprt_put_cong(struct rpc_xprt *, struct rpc_rqst *);
73static void xprt_destroy(struct rpc_xprt *xprt);
74
75static DEFINE_SPINLOCK(xprt_list_lock);
76static LIST_HEAD(xprt_list);
77
78/**
79 * xprt_register_transport - register a transport implementation
80 * @transport: transport to register
81 *
82 * If a transport implementation is loaded as a kernel module, it can
83 * call this interface to make itself known to the RPC client.
84 *
85 * Returns:
86 * 0: transport successfully registered
87 * -EEXIST: transport already registered
88 * -EINVAL: transport module being unloaded
89 */
90int xprt_register_transport(struct xprt_class *transport)
91{
92 struct xprt_class *t;
93 int result;
94
95 result = -EEXIST;
96 spin_lock(&xprt_list_lock);
97 list_for_each_entry(t, &xprt_list, list) {
98 /* don't register the same transport class twice */
99 if (t->ident == transport->ident)
100 goto out;
101 }
102
103 list_add_tail(&transport->list, &xprt_list);
104 printk(KERN_INFO "RPC: Registered %s transport module.\n",
105 transport->name);
106 result = 0;
107
108out:
109 spin_unlock(&xprt_list_lock);
110 return result;
111}
112EXPORT_SYMBOL_GPL(xprt_register_transport);
113
114/**
115 * xprt_unregister_transport - unregister a transport implementation
116 * @transport: transport to unregister
117 *
118 * Returns:
119 * 0: transport successfully unregistered
120 * -ENOENT: transport never registered
121 */
122int xprt_unregister_transport(struct xprt_class *transport)
123{
124 struct xprt_class *t;
125 int result;
126
127 result = 0;
128 spin_lock(&xprt_list_lock);
129 list_for_each_entry(t, &xprt_list, list) {
130 if (t == transport) {
131 printk(KERN_INFO
132 "RPC: Unregistered %s transport module.\n",
133 transport->name);
134 list_del_init(&transport->list);
135 goto out;
136 }
137 }
138 result = -ENOENT;
139
140out:
141 spin_unlock(&xprt_list_lock);
142 return result;
143}
144EXPORT_SYMBOL_GPL(xprt_unregister_transport);
145
146/**
147 * xprt_load_transport - load a transport implementation
148 * @transport_name: transport to load
149 *
150 * Returns:
151 * 0: transport successfully loaded
152 * -ENOENT: transport module not available
153 */
154int xprt_load_transport(const char *transport_name)
155{
156 struct xprt_class *t;
157 int result;
158
159 result = 0;
160 spin_lock(&xprt_list_lock);
161 list_for_each_entry(t, &xprt_list, list) {
162 if (strcmp(t->name, transport_name) == 0) {
163 spin_unlock(&xprt_list_lock);
164 goto out;
165 }
166 }
167 spin_unlock(&xprt_list_lock);
168 result = request_module("xprt%s", transport_name);
169out:
170 return result;
171}
172EXPORT_SYMBOL_GPL(xprt_load_transport);
173
174/**
175 * xprt_reserve_xprt - serialize write access to transports
176 * @task: task that is requesting access to the transport
177 * @xprt: pointer to the target transport
178 *
179 * This prevents mixing the payload of separate requests, and prevents
180 * transport connects from colliding with writes. No congestion control
181 * is provided.
182 */
183int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
184{
185 struct rpc_rqst *req = task->tk_rqstp;
186 int priority;
187
188 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
189 if (task == xprt->snd_task)
190 return 1;
191 goto out_sleep;
192 }
193 xprt->snd_task = task;
194 if (req != NULL)
195 req->rq_ntrans++;
196
197 return 1;
198
199out_sleep:
200 dprintk("RPC: %5u failed to lock transport %p\n",
201 task->tk_pid, xprt);
202 task->tk_timeout = 0;
203 task->tk_status = -EAGAIN;
204 if (req == NULL)
205 priority = RPC_PRIORITY_LOW;
206 else if (!req->rq_ntrans)
207 priority = RPC_PRIORITY_NORMAL;
208 else
209 priority = RPC_PRIORITY_HIGH;
210 rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
211 return 0;
212}
213EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
214
215static void xprt_clear_locked(struct rpc_xprt *xprt)
216{
217 xprt->snd_task = NULL;
218 if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
219 smp_mb__before_atomic();
220 clear_bit(XPRT_LOCKED, &xprt->state);
221 smp_mb__after_atomic();
222 } else
223 queue_work(rpciod_workqueue, &xprt->task_cleanup);
224}
225
226/*
227 * xprt_reserve_xprt_cong - serialize write access to transports
228 * @task: task that is requesting access to the transport
229 *
230 * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
231 * integrated into the decision of whether a request is allowed to be
232 * woken up and given access to the transport.
233 */
234int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
235{
236 struct rpc_rqst *req = task->tk_rqstp;
237 int priority;
238
239 if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
240 if (task == xprt->snd_task)
241 return 1;
242 goto out_sleep;
243 }
244 if (req == NULL) {
245 xprt->snd_task = task;
246 return 1;
247 }
248 if (__xprt_get_cong(xprt, task)) {
249 xprt->snd_task = task;
250 req->rq_ntrans++;
251 return 1;
252 }
253 xprt_clear_locked(xprt);
254out_sleep:
255 if (req)
256 __xprt_put_cong(xprt, req);
257 dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
258 task->tk_timeout = 0;
259 task->tk_status = -EAGAIN;
260 if (req == NULL)
261 priority = RPC_PRIORITY_LOW;
262 else if (!req->rq_ntrans)
263 priority = RPC_PRIORITY_NORMAL;
264 else
265 priority = RPC_PRIORITY_HIGH;
266 rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
267 return 0;
268}
269EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
270
271static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
272{
273 int retval;
274
275 spin_lock_bh(&xprt->transport_lock);
276 retval = xprt->ops->reserve_xprt(xprt, task);
277 spin_unlock_bh(&xprt->transport_lock);
278 return retval;
279}
280
281static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
282{
283 struct rpc_xprt *xprt = data;
284 struct rpc_rqst *req;
285
286 req = task->tk_rqstp;
287 xprt->snd_task = task;
288 if (req)
289 req->rq_ntrans++;
290 return true;
291}
292
293static void __xprt_lock_write_next(struct rpc_xprt *xprt)
294{
295 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
296 return;
297
298 if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_func, xprt))
299 return;
300 xprt_clear_locked(xprt);
301}
302
303static bool __xprt_lock_write_cong_func(struct rpc_task *task, void *data)
304{
305 struct rpc_xprt *xprt = data;
306 struct rpc_rqst *req;
307
308 req = task->tk_rqstp;
309 if (req == NULL) {
310 xprt->snd_task = task;
311 return true;
312 }
313 if (__xprt_get_cong(xprt, task)) {
314 xprt->snd_task = task;
315 req->rq_ntrans++;
316 return true;
317 }
318 return false;
319}
320
321static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
322{
323 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
324 return;
325 if (RPCXPRT_CONGESTED(xprt))
326 goto out_unlock;
327 if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_cong_func, xprt))
328 return;
329out_unlock:
330 xprt_clear_locked(xprt);
331}
332
333static void xprt_task_clear_bytes_sent(struct rpc_task *task)
334{
335 if (task != NULL) {
336 struct rpc_rqst *req = task->tk_rqstp;
337 if (req != NULL)
338 req->rq_bytes_sent = 0;
339 }
340}
341
342/**
343 * xprt_release_xprt - allow other requests to use a transport
344 * @xprt: transport with other tasks potentially waiting
345 * @task: task that is releasing access to the transport
346 *
347 * Note that "task" can be NULL. No congestion control is provided.
348 */
349void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
350{
351 if (xprt->snd_task == task) {
352 xprt_task_clear_bytes_sent(task);
353 xprt_clear_locked(xprt);
354 __xprt_lock_write_next(xprt);
355 }
356}
357EXPORT_SYMBOL_GPL(xprt_release_xprt);
358
359/**
360 * xprt_release_xprt_cong - allow other requests to use a transport
361 * @xprt: transport with other tasks potentially waiting
362 * @task: task that is releasing access to the transport
363 *
364 * Note that "task" can be NULL. Another task is awoken to use the
365 * transport if the transport's congestion window allows it.
366 */
367void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
368{
369 if (xprt->snd_task == task) {
370 xprt_task_clear_bytes_sent(task);
371 xprt_clear_locked(xprt);
372 __xprt_lock_write_next_cong(xprt);
373 }
374}
375EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
376
377static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
378{
379 spin_lock_bh(&xprt->transport_lock);
380 xprt->ops->release_xprt(xprt, task);
381 spin_unlock_bh(&xprt->transport_lock);
382}
383
384/*
385 * Van Jacobson congestion avoidance. Check if the congestion window
386 * overflowed. Put the task to sleep if this is the case.
387 */
388static int
389__xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
390{
391 struct rpc_rqst *req = task->tk_rqstp;
392
393 if (req->rq_cong)
394 return 1;
395 dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
396 task->tk_pid, xprt->cong, xprt->cwnd);
397 if (RPCXPRT_CONGESTED(xprt))
398 return 0;
399 req->rq_cong = 1;
400 xprt->cong += RPC_CWNDSCALE;
401 return 1;
402}
403
404/*
405 * Adjust the congestion window, and wake up the next task
406 * that has been sleeping due to congestion
407 */
408static void
409__xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
410{
411 if (!req->rq_cong)
412 return;
413 req->rq_cong = 0;
414 xprt->cong -= RPC_CWNDSCALE;
415 __xprt_lock_write_next_cong(xprt);
416}
417
418/**
419 * xprt_release_rqst_cong - housekeeping when request is complete
420 * @task: RPC request that recently completed
421 *
422 * Useful for transports that require congestion control.
423 */
424void xprt_release_rqst_cong(struct rpc_task *task)
425{
426 struct rpc_rqst *req = task->tk_rqstp;
427
428 __xprt_put_cong(req->rq_xprt, req);
429}
430EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
431
432/**
433 * xprt_adjust_cwnd - adjust transport congestion window
434 * @xprt: pointer to xprt
435 * @task: recently completed RPC request used to adjust window
436 * @result: result code of completed RPC request
437 *
438 * The transport code maintains an estimate on the maximum number of out-
439 * standing RPC requests, using a smoothed version of the congestion
440 * avoidance implemented in 44BSD. This is basically the Van Jacobson
441 * congestion algorithm: If a retransmit occurs, the congestion window is
442 * halved; otherwise, it is incremented by 1/cwnd when
443 *
444 * - a reply is received and
445 * - a full number of requests are outstanding and
446 * - the congestion window hasn't been updated recently.
447 */
448void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
449{
450 struct rpc_rqst *req = task->tk_rqstp;
451 unsigned long cwnd = xprt->cwnd;
452
453 if (result >= 0 && cwnd <= xprt->cong) {
454 /* The (cwnd >> 1) term makes sure
455 * the result gets rounded properly. */
456 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
457 if (cwnd > RPC_MAXCWND(xprt))
458 cwnd = RPC_MAXCWND(xprt);
459 __xprt_lock_write_next_cong(xprt);
460 } else if (result == -ETIMEDOUT) {
461 cwnd >>= 1;
462 if (cwnd < RPC_CWNDSCALE)
463 cwnd = RPC_CWNDSCALE;
464 }
465 dprintk("RPC: cong %ld, cwnd was %ld, now %ld\n",
466 xprt->cong, xprt->cwnd, cwnd);
467 xprt->cwnd = cwnd;
468 __xprt_put_cong(xprt, req);
469}
470EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
471
472/**
473 * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
474 * @xprt: transport with waiting tasks
475 * @status: result code to plant in each task before waking it
476 *
477 */
478void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
479{
480 if (status < 0)
481 rpc_wake_up_status(&xprt->pending, status);
482 else
483 rpc_wake_up(&xprt->pending);
484}
485EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
486
487/**
488 * xprt_wait_for_buffer_space - wait for transport output buffer to clear
489 * @task: task to be put to sleep
490 * @action: function pointer to be executed after wait
491 *
492 * Note that we only set the timer for the case of RPC_IS_SOFT(), since
493 * we don't in general want to force a socket disconnection due to
494 * an incomplete RPC call transmission.
495 */
496void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
497{
498 struct rpc_rqst *req = task->tk_rqstp;
499 struct rpc_xprt *xprt = req->rq_xprt;
500
501 task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
502 rpc_sleep_on(&xprt->pending, task, action);
503}
504EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
505
506/**
507 * xprt_write_space - wake the task waiting for transport output buffer space
508 * @xprt: transport with waiting tasks
509 *
510 * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
511 */
512void xprt_write_space(struct rpc_xprt *xprt)
513{
514 spin_lock_bh(&xprt->transport_lock);
515 if (xprt->snd_task) {
516 dprintk("RPC: write space: waking waiting task on "
517 "xprt %p\n", xprt);
518 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
519 }
520 spin_unlock_bh(&xprt->transport_lock);
521}
522EXPORT_SYMBOL_GPL(xprt_write_space);
523
524/**
525 * xprt_set_retrans_timeout_def - set a request's retransmit timeout
526 * @task: task whose timeout is to be set
527 *
528 * Set a request's retransmit timeout based on the transport's
529 * default timeout parameters. Used by transports that don't adjust
530 * the retransmit timeout based on round-trip time estimation.
531 */
532void xprt_set_retrans_timeout_def(struct rpc_task *task)
533{
534 task->tk_timeout = task->tk_rqstp->rq_timeout;
535}
536EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
537
538/**
539 * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
540 * @task: task whose timeout is to be set
541 *
542 * Set a request's retransmit timeout using the RTT estimator.
543 */
544void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
545{
546 int timer = task->tk_msg.rpc_proc->p_timer;
547 struct rpc_clnt *clnt = task->tk_client;
548 struct rpc_rtt *rtt = clnt->cl_rtt;
549 struct rpc_rqst *req = task->tk_rqstp;
550 unsigned long max_timeout = clnt->cl_timeout->to_maxval;
551
552 task->tk_timeout = rpc_calc_rto(rtt, timer);
553 task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
554 if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
555 task->tk_timeout = max_timeout;
556}
557EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
558
559static void xprt_reset_majortimeo(struct rpc_rqst *req)
560{
561 const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
562
563 req->rq_majortimeo = req->rq_timeout;
564 if (to->to_exponential)
565 req->rq_majortimeo <<= to->to_retries;
566 else
567 req->rq_majortimeo += to->to_increment * to->to_retries;
568 if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
569 req->rq_majortimeo = to->to_maxval;
570 req->rq_majortimeo += jiffies;
571}
572
573/**
574 * xprt_adjust_timeout - adjust timeout values for next retransmit
575 * @req: RPC request containing parameters to use for the adjustment
576 *
577 */
578int xprt_adjust_timeout(struct rpc_rqst *req)
579{
580 struct rpc_xprt *xprt = req->rq_xprt;
581 const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
582 int status = 0;
583
584 if (time_before(jiffies, req->rq_majortimeo)) {
585 if (to->to_exponential)
586 req->rq_timeout <<= 1;
587 else
588 req->rq_timeout += to->to_increment;
589 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
590 req->rq_timeout = to->to_maxval;
591 req->rq_retries++;
592 } else {
593 req->rq_timeout = to->to_initval;
594 req->rq_retries = 0;
595 xprt_reset_majortimeo(req);
596 /* Reset the RTT counters == "slow start" */
597 spin_lock_bh(&xprt->transport_lock);
598 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
599 spin_unlock_bh(&xprt->transport_lock);
600 status = -ETIMEDOUT;
601 }
602
603 if (req->rq_timeout == 0) {
604 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
605 req->rq_timeout = 5 * HZ;
606 }
607 return status;
608}
609
610static void xprt_autoclose(struct work_struct *work)
611{
612 struct rpc_xprt *xprt =
613 container_of(work, struct rpc_xprt, task_cleanup);
614
615 clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
616 xprt->ops->close(xprt);
617 xprt_release_write(xprt, NULL);
618 wake_up_bit(&xprt->state, XPRT_LOCKED);
619}
620
621/**
622 * xprt_disconnect_done - mark a transport as disconnected
623 * @xprt: transport to flag for disconnect
624 *
625 */
626void xprt_disconnect_done(struct rpc_xprt *xprt)
627{
628 dprintk("RPC: disconnected transport %p\n", xprt);
629 spin_lock_bh(&xprt->transport_lock);
630 xprt_clear_connected(xprt);
631 xprt_wake_pending_tasks(xprt, -EAGAIN);
632 spin_unlock_bh(&xprt->transport_lock);
633}
634EXPORT_SYMBOL_GPL(xprt_disconnect_done);
635
636/**
637 * xprt_force_disconnect - force a transport to disconnect
638 * @xprt: transport to disconnect
639 *
640 */
641void xprt_force_disconnect(struct rpc_xprt *xprt)
642{
643 /* Don't race with the test_bit() in xprt_clear_locked() */
644 spin_lock_bh(&xprt->transport_lock);
645 set_bit(XPRT_CLOSE_WAIT, &xprt->state);
646 /* Try to schedule an autoclose RPC call */
647 if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
648 queue_work(rpciod_workqueue, &xprt->task_cleanup);
649 xprt_wake_pending_tasks(xprt, -EAGAIN);
650 spin_unlock_bh(&xprt->transport_lock);
651}
652
653/**
654 * xprt_conditional_disconnect - force a transport to disconnect
655 * @xprt: transport to disconnect
656 * @cookie: 'connection cookie'
657 *
658 * This attempts to break the connection if and only if 'cookie' matches
659 * the current transport 'connection cookie'. It ensures that we don't
660 * try to break the connection more than once when we need to retransmit
661 * a batch of RPC requests.
662 *
663 */
664void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
665{
666 /* Don't race with the test_bit() in xprt_clear_locked() */
667 spin_lock_bh(&xprt->transport_lock);
668 if (cookie != xprt->connect_cookie)
669 goto out;
670 if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
671 goto out;
672 set_bit(XPRT_CLOSE_WAIT, &xprt->state);
673 /* Try to schedule an autoclose RPC call */
674 if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
675 queue_work(rpciod_workqueue, &xprt->task_cleanup);
676 xprt_wake_pending_tasks(xprt, -EAGAIN);
677out:
678 spin_unlock_bh(&xprt->transport_lock);
679}
680
681static void
682xprt_init_autodisconnect(unsigned long data)
683{
684 struct rpc_xprt *xprt = (struct rpc_xprt *)data;
685
686 spin_lock(&xprt->transport_lock);
687 if (!list_empty(&xprt->recv))
688 goto out_abort;
689 if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
690 goto out_abort;
691 spin_unlock(&xprt->transport_lock);
692 queue_work(rpciod_workqueue, &xprt->task_cleanup);
693 return;
694out_abort:
695 spin_unlock(&xprt->transport_lock);
696}
697
698bool xprt_lock_connect(struct rpc_xprt *xprt,
699 struct rpc_task *task,
700 void *cookie)
701{
702 bool ret = false;
703
704 spin_lock_bh(&xprt->transport_lock);
705 if (!test_bit(XPRT_LOCKED, &xprt->state))
706 goto out;
707 if (xprt->snd_task != task)
708 goto out;
709 xprt_task_clear_bytes_sent(task);
710 xprt->snd_task = cookie;
711 ret = true;
712out:
713 spin_unlock_bh(&xprt->transport_lock);
714 return ret;
715}
716
717void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
718{
719 spin_lock_bh(&xprt->transport_lock);
720 if (xprt->snd_task != cookie)
721 goto out;
722 if (!test_bit(XPRT_LOCKED, &xprt->state))
723 goto out;
724 xprt->snd_task =NULL;
725 xprt->ops->release_xprt(xprt, NULL);
726out:
727 spin_unlock_bh(&xprt->transport_lock);
728 wake_up_bit(&xprt->state, XPRT_LOCKED);
729}
730
731/**
732 * xprt_connect - schedule a transport connect operation
733 * @task: RPC task that is requesting the connect
734 *
735 */
736void xprt_connect(struct rpc_task *task)
737{
738 struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
739
740 dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
741 xprt, (xprt_connected(xprt) ? "is" : "is not"));
742
743 if (!xprt_bound(xprt)) {
744 task->tk_status = -EAGAIN;
745 return;
746 }
747 if (!xprt_lock_write(xprt, task))
748 return;
749
750 if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
751 xprt->ops->close(xprt);
752
753 if (!xprt_connected(xprt)) {
754 task->tk_rqstp->rq_bytes_sent = 0;
755 task->tk_timeout = task->tk_rqstp->rq_timeout;
756 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
757
758 if (test_bit(XPRT_CLOSING, &xprt->state))
759 return;
760 if (xprt_test_and_set_connecting(xprt))
761 return;
762 xprt->stat.connect_start = jiffies;
763 xprt->ops->connect(xprt, task);
764 }
765 xprt_release_write(xprt, task);
766}
767
768static void xprt_connect_status(struct rpc_task *task)
769{
770 struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
771
772 if (task->tk_status == 0) {
773 xprt->stat.connect_count++;
774 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
775 dprintk("RPC: %5u xprt_connect_status: connection established\n",
776 task->tk_pid);
777 return;
778 }
779
780 switch (task->tk_status) {
781 case -ECONNREFUSED:
782 case -ECONNRESET:
783 case -ECONNABORTED:
784 case -ENETUNREACH:
785 case -EHOSTUNREACH:
786 case -EPIPE:
787 case -EAGAIN:
788 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
789 break;
790 case -ETIMEDOUT:
791 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
792 "out\n", task->tk_pid);
793 break;
794 default:
795 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
796 "server %s\n", task->tk_pid, -task->tk_status,
797 xprt->servername);
798 task->tk_status = -EIO;
799 }
800}
801
802/**
803 * xprt_lookup_rqst - find an RPC request corresponding to an XID
804 * @xprt: transport on which the original request was transmitted
805 * @xid: RPC XID of incoming reply
806 *
807 */
808struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
809{
810 struct rpc_rqst *entry;
811
812 list_for_each_entry(entry, &xprt->recv, rq_list)
813 if (entry->rq_xid == xid) {
814 trace_xprt_lookup_rqst(xprt, xid, 0);
815 return entry;
816 }
817
818 dprintk("RPC: xprt_lookup_rqst did not find xid %08x\n",
819 ntohl(xid));
820 trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
821 xprt->stat.bad_xids++;
822 return NULL;
823}
824EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
825
826static void xprt_update_rtt(struct rpc_task *task)
827{
828 struct rpc_rqst *req = task->tk_rqstp;
829 struct rpc_rtt *rtt = task->tk_client->cl_rtt;
830 unsigned int timer = task->tk_msg.rpc_proc->p_timer;
831 long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
832
833 if (timer) {
834 if (req->rq_ntrans == 1)
835 rpc_update_rtt(rtt, timer, m);
836 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
837 }
838}
839
840/**
841 * xprt_complete_rqst - called when reply processing is complete
842 * @task: RPC request that recently completed
843 * @copied: actual number of bytes received from the transport
844 *
845 * Caller holds transport lock.
846 */
847void xprt_complete_rqst(struct rpc_task *task, int copied)
848{
849 struct rpc_rqst *req = task->tk_rqstp;
850 struct rpc_xprt *xprt = req->rq_xprt;
851
852 dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
853 task->tk_pid, ntohl(req->rq_xid), copied);
854 trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
855
856 xprt->stat.recvs++;
857 req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
858 if (xprt->ops->timer != NULL)
859 xprt_update_rtt(task);
860
861 list_del_init(&req->rq_list);
862 req->rq_private_buf.len = copied;
863 /* Ensure all writes are done before we update */
864 /* req->rq_reply_bytes_recvd */
865 smp_wmb();
866 req->rq_reply_bytes_recvd = copied;
867 rpc_wake_up_queued_task(&xprt->pending, task);
868}
869EXPORT_SYMBOL_GPL(xprt_complete_rqst);
870
871static void xprt_timer(struct rpc_task *task)
872{
873 struct rpc_rqst *req = task->tk_rqstp;
874 struct rpc_xprt *xprt = req->rq_xprt;
875
876 if (task->tk_status != -ETIMEDOUT)
877 return;
878 dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
879
880 spin_lock_bh(&xprt->transport_lock);
881 if (!req->rq_reply_bytes_recvd) {
882 if (xprt->ops->timer)
883 xprt->ops->timer(xprt, task);
884 } else
885 task->tk_status = 0;
886 spin_unlock_bh(&xprt->transport_lock);
887}
888
889static inline int xprt_has_timer(struct rpc_xprt *xprt)
890{
891 return xprt->idle_timeout != 0;
892}
893
894/**
895 * xprt_prepare_transmit - reserve the transport before sending a request
896 * @task: RPC task about to send a request
897 *
898 */
899bool xprt_prepare_transmit(struct rpc_task *task)
900{
901 struct rpc_rqst *req = task->tk_rqstp;
902 struct rpc_xprt *xprt = req->rq_xprt;
903 bool ret = false;
904
905 dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
906
907 spin_lock_bh(&xprt->transport_lock);
908 if (!req->rq_bytes_sent) {
909 if (req->rq_reply_bytes_recvd) {
910 task->tk_status = req->rq_reply_bytes_recvd;
911 goto out_unlock;
912 }
913 if ((task->tk_flags & RPC_TASK_NO_RETRANS_TIMEOUT)
914 && xprt_connected(xprt)
915 && req->rq_connect_cookie == xprt->connect_cookie) {
916 xprt->ops->set_retrans_timeout(task);
917 rpc_sleep_on(&xprt->pending, task, xprt_timer);
918 goto out_unlock;
919 }
920 }
921 if (!xprt->ops->reserve_xprt(xprt, task)) {
922 task->tk_status = -EAGAIN;
923 goto out_unlock;
924 }
925 ret = true;
926out_unlock:
927 spin_unlock_bh(&xprt->transport_lock);
928 return ret;
929}
930
931void xprt_end_transmit(struct rpc_task *task)
932{
933 xprt_release_write(task->tk_rqstp->rq_xprt, task);
934}
935
936/**
937 * xprt_transmit - send an RPC request on a transport
938 * @task: controlling RPC task
939 *
940 * We have to copy the iovec because sendmsg fiddles with its contents.
941 */
942void xprt_transmit(struct rpc_task *task)
943{
944 struct rpc_rqst *req = task->tk_rqstp;
945 struct rpc_xprt *xprt = req->rq_xprt;
946 int status, numreqs;
947
948 dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
949
950 if (!req->rq_reply_bytes_recvd) {
951 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
952 /*
953 * Add to the list only if we're expecting a reply
954 */
955 spin_lock_bh(&xprt->transport_lock);
956 /* Update the softirq receive buffer */
957 memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
958 sizeof(req->rq_private_buf));
959 /* Add request to the receive list */
960 list_add_tail(&req->rq_list, &xprt->recv);
961 spin_unlock_bh(&xprt->transport_lock);
962 xprt_reset_majortimeo(req);
963 /* Turn off autodisconnect */
964 del_singleshot_timer_sync(&xprt->timer);
965 }
966 } else if (!req->rq_bytes_sent)
967 return;
968
969 req->rq_xtime = ktime_get();
970 status = xprt->ops->send_request(task);
971 trace_xprt_transmit(xprt, req->rq_xid, status);
972 if (status != 0) {
973 task->tk_status = status;
974 return;
975 }
976 xprt_inject_disconnect(xprt);
977
978 dprintk("RPC: %5u xmit complete\n", task->tk_pid);
979 task->tk_flags |= RPC_TASK_SENT;
980 spin_lock_bh(&xprt->transport_lock);
981
982 xprt->ops->set_retrans_timeout(task);
983
984 numreqs = atomic_read(&xprt->num_reqs);
985 if (numreqs > xprt->stat.max_slots)
986 xprt->stat.max_slots = numreqs;
987 xprt->stat.sends++;
988 xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
989 xprt->stat.bklog_u += xprt->backlog.qlen;
990 xprt->stat.sending_u += xprt->sending.qlen;
991 xprt->stat.pending_u += xprt->pending.qlen;
992
993 /* Don't race with disconnect */
994 if (!xprt_connected(xprt))
995 task->tk_status = -ENOTCONN;
996 else {
997 /*
998 * Sleep on the pending queue since
999 * we're expecting a reply.
1000 */
1001 if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task))
1002 rpc_sleep_on(&xprt->pending, task, xprt_timer);
1003 req->rq_connect_cookie = xprt->connect_cookie;
1004 }
1005 spin_unlock_bh(&xprt->transport_lock);
1006}
1007
1008static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1009{
1010 set_bit(XPRT_CONGESTED, &xprt->state);
1011 rpc_sleep_on(&xprt->backlog, task, NULL);
1012}
1013
1014static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
1015{
1016 if (rpc_wake_up_next(&xprt->backlog) == NULL)
1017 clear_bit(XPRT_CONGESTED, &xprt->state);
1018}
1019
1020static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1021{
1022 bool ret = false;
1023
1024 if (!test_bit(XPRT_CONGESTED, &xprt->state))
1025 goto out;
1026 spin_lock(&xprt->reserve_lock);
1027 if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1028 rpc_sleep_on(&xprt->backlog, task, NULL);
1029 ret = true;
1030 }
1031 spin_unlock(&xprt->reserve_lock);
1032out:
1033 return ret;
1034}
1035
1036static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
1037{
1038 struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1039
1040 if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
1041 goto out;
1042 req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
1043 if (req != NULL)
1044 goto out;
1045 atomic_dec(&xprt->num_reqs);
1046 req = ERR_PTR(-ENOMEM);
1047out:
1048 return req;
1049}
1050
1051static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1052{
1053 if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
1054 kfree(req);
1055 return true;
1056 }
1057 return false;
1058}
1059
1060void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1061{
1062 struct rpc_rqst *req;
1063
1064 spin_lock(&xprt->reserve_lock);
1065 if (!list_empty(&xprt->free)) {
1066 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1067 list_del(&req->rq_list);
1068 goto out_init_req;
1069 }
1070 req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
1071 if (!IS_ERR(req))
1072 goto out_init_req;
1073 switch (PTR_ERR(req)) {
1074 case -ENOMEM:
1075 dprintk("RPC: dynamic allocation of request slot "
1076 "failed! Retrying\n");
1077 task->tk_status = -ENOMEM;
1078 break;
1079 case -EAGAIN:
1080 xprt_add_backlog(xprt, task);
1081 dprintk("RPC: waiting for request slot\n");
1082 default:
1083 task->tk_status = -EAGAIN;
1084 }
1085 spin_unlock(&xprt->reserve_lock);
1086 return;
1087out_init_req:
1088 task->tk_status = 0;
1089 task->tk_rqstp = req;
1090 xprt_request_init(task, xprt);
1091 spin_unlock(&xprt->reserve_lock);
1092}
1093EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1094
1095void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1096{
1097 /* Note: grabbing the xprt_lock_write() ensures that we throttle
1098 * new slot allocation if the transport is congested (i.e. when
1099 * reconnecting a stream transport or when out of socket write
1100 * buffer space).
1101 */
1102 if (xprt_lock_write(xprt, task)) {
1103 xprt_alloc_slot(xprt, task);
1104 xprt_release_write(xprt, task);
1105 }
1106}
1107EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1108
1109static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1110{
1111 spin_lock(&xprt->reserve_lock);
1112 if (!xprt_dynamic_free_slot(xprt, req)) {
1113 memset(req, 0, sizeof(*req)); /* mark unused */
1114 list_add(&req->rq_list, &xprt->free);
1115 }
1116 xprt_wake_up_backlog(xprt);
1117 spin_unlock(&xprt->reserve_lock);
1118}
1119
1120static void xprt_free_all_slots(struct rpc_xprt *xprt)
1121{
1122 struct rpc_rqst *req;
1123 while (!list_empty(&xprt->free)) {
1124 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1125 list_del(&req->rq_list);
1126 kfree(req);
1127 }
1128}
1129
1130struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1131 unsigned int num_prealloc,
1132 unsigned int max_alloc)
1133{
1134 struct rpc_xprt *xprt;
1135 struct rpc_rqst *req;
1136 int i;
1137
1138 xprt = kzalloc(size, GFP_KERNEL);
1139 if (xprt == NULL)
1140 goto out;
1141
1142 xprt_init(xprt, net);
1143
1144 for (i = 0; i < num_prealloc; i++) {
1145 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1146 if (!req)
1147 goto out_free;
1148 list_add(&req->rq_list, &xprt->free);
1149 }
1150 if (max_alloc > num_prealloc)
1151 xprt->max_reqs = max_alloc;
1152 else
1153 xprt->max_reqs = num_prealloc;
1154 xprt->min_reqs = num_prealloc;
1155 atomic_set(&xprt->num_reqs, num_prealloc);
1156
1157 return xprt;
1158
1159out_free:
1160 xprt_free(xprt);
1161out:
1162 return NULL;
1163}
1164EXPORT_SYMBOL_GPL(xprt_alloc);
1165
1166void xprt_free(struct rpc_xprt *xprt)
1167{
1168 put_net(xprt->xprt_net);
1169 xprt_free_all_slots(xprt);
1170 kfree_rcu(xprt, rcu);
1171}
1172EXPORT_SYMBOL_GPL(xprt_free);
1173
1174/**
1175 * xprt_reserve - allocate an RPC request slot
1176 * @task: RPC task requesting a slot allocation
1177 *
1178 * If the transport is marked as being congested, or if no more
1179 * slots are available, place the task on the transport's
1180 * backlog queue.
1181 */
1182void xprt_reserve(struct rpc_task *task)
1183{
1184 struct rpc_xprt *xprt = task->tk_xprt;
1185
1186 task->tk_status = 0;
1187 if (task->tk_rqstp != NULL)
1188 return;
1189
1190 task->tk_timeout = 0;
1191 task->tk_status = -EAGAIN;
1192 if (!xprt_throttle_congested(xprt, task))
1193 xprt->ops->alloc_slot(xprt, task);
1194}
1195
1196/**
1197 * xprt_retry_reserve - allocate an RPC request slot
1198 * @task: RPC task requesting a slot allocation
1199 *
1200 * If no more slots are available, place the task on the transport's
1201 * backlog queue.
1202 * Note that the only difference with xprt_reserve is that we now
1203 * ignore the value of the XPRT_CONGESTED flag.
1204 */
1205void xprt_retry_reserve(struct rpc_task *task)
1206{
1207 struct rpc_xprt *xprt = task->tk_xprt;
1208
1209 task->tk_status = 0;
1210 if (task->tk_rqstp != NULL)
1211 return;
1212
1213 task->tk_timeout = 0;
1214 task->tk_status = -EAGAIN;
1215 xprt->ops->alloc_slot(xprt, task);
1216}
1217
1218static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1219{
1220 return (__force __be32)xprt->xid++;
1221}
1222
1223static inline void xprt_init_xid(struct rpc_xprt *xprt)
1224{
1225 xprt->xid = prandom_u32();
1226}
1227
1228static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1229{
1230 struct rpc_rqst *req = task->tk_rqstp;
1231
1232 INIT_LIST_HEAD(&req->rq_list);
1233 req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1234 req->rq_task = task;
1235 req->rq_xprt = xprt;
1236 req->rq_buffer = NULL;
1237 req->rq_xid = xprt_alloc_xid(xprt);
1238 req->rq_connect_cookie = xprt->connect_cookie - 1;
1239 req->rq_bytes_sent = 0;
1240 req->rq_snd_buf.len = 0;
1241 req->rq_snd_buf.buflen = 0;
1242 req->rq_rcv_buf.len = 0;
1243 req->rq_rcv_buf.buflen = 0;
1244 req->rq_release_snd_buf = NULL;
1245 xprt_reset_majortimeo(req);
1246 dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1247 req, ntohl(req->rq_xid));
1248}
1249
1250/**
1251 * xprt_release - release an RPC request slot
1252 * @task: task which is finished with the slot
1253 *
1254 */
1255void xprt_release(struct rpc_task *task)
1256{
1257 struct rpc_xprt *xprt;
1258 struct rpc_rqst *req = task->tk_rqstp;
1259
1260 if (req == NULL) {
1261 if (task->tk_client) {
1262 xprt = task->tk_xprt;
1263 if (xprt->snd_task == task)
1264 xprt_release_write(xprt, task);
1265 }
1266 return;
1267 }
1268
1269 xprt = req->rq_xprt;
1270 if (task->tk_ops->rpc_count_stats != NULL)
1271 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1272 else if (task->tk_client)
1273 rpc_count_iostats(task, task->tk_client->cl_metrics);
1274 spin_lock_bh(&xprt->transport_lock);
1275 xprt->ops->release_xprt(xprt, task);
1276 if (xprt->ops->release_request)
1277 xprt->ops->release_request(task);
1278 if (!list_empty(&req->rq_list))
1279 list_del(&req->rq_list);
1280 xprt->last_used = jiffies;
1281 if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1282 mod_timer(&xprt->timer,
1283 xprt->last_used + xprt->idle_timeout);
1284 spin_unlock_bh(&xprt->transport_lock);
1285 if (req->rq_buffer)
1286 xprt->ops->buf_free(req->rq_buffer);
1287 xprt_inject_disconnect(xprt);
1288 if (req->rq_cred != NULL)
1289 put_rpccred(req->rq_cred);
1290 task->tk_rqstp = NULL;
1291 if (req->rq_release_snd_buf)
1292 req->rq_release_snd_buf(req);
1293
1294 dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1295 if (likely(!bc_prealloc(req)))
1296 xprt_free_slot(xprt, req);
1297 else
1298 xprt_free_bc_request(req);
1299}
1300
1301static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1302{
1303 kref_init(&xprt->kref);
1304
1305 spin_lock_init(&xprt->transport_lock);
1306 spin_lock_init(&xprt->reserve_lock);
1307
1308 INIT_LIST_HEAD(&xprt->free);
1309 INIT_LIST_HEAD(&xprt->recv);
1310#if defined(CONFIG_SUNRPC_BACKCHANNEL)
1311 spin_lock_init(&xprt->bc_pa_lock);
1312 INIT_LIST_HEAD(&xprt->bc_pa_list);
1313#endif /* CONFIG_SUNRPC_BACKCHANNEL */
1314 INIT_LIST_HEAD(&xprt->xprt_switch);
1315
1316 xprt->last_used = jiffies;
1317 xprt->cwnd = RPC_INITCWND;
1318 xprt->bind_index = 0;
1319
1320 rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1321 rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1322 rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1323 rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1324
1325 xprt_init_xid(xprt);
1326
1327 xprt->xprt_net = get_net(net);
1328}
1329
1330/**
1331 * xprt_create_transport - create an RPC transport
1332 * @args: rpc transport creation arguments
1333 *
1334 */
1335struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1336{
1337 struct rpc_xprt *xprt;
1338 struct xprt_class *t;
1339
1340 spin_lock(&xprt_list_lock);
1341 list_for_each_entry(t, &xprt_list, list) {
1342 if (t->ident == args->ident) {
1343 spin_unlock(&xprt_list_lock);
1344 goto found;
1345 }
1346 }
1347 spin_unlock(&xprt_list_lock);
1348 dprintk("RPC: transport (%d) not supported\n", args->ident);
1349 return ERR_PTR(-EIO);
1350
1351found:
1352 xprt = t->setup(args);
1353 if (IS_ERR(xprt)) {
1354 dprintk("RPC: xprt_create_transport: failed, %ld\n",
1355 -PTR_ERR(xprt));
1356 goto out;
1357 }
1358 if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1359 xprt->idle_timeout = 0;
1360 INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1361 if (xprt_has_timer(xprt))
1362 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1363 (unsigned long)xprt);
1364 else
1365 init_timer(&xprt->timer);
1366
1367 if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1368 xprt_destroy(xprt);
1369 return ERR_PTR(-EINVAL);
1370 }
1371 xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1372 if (xprt->servername == NULL) {
1373 xprt_destroy(xprt);
1374 return ERR_PTR(-ENOMEM);
1375 }
1376
1377 rpc_xprt_debugfs_register(xprt);
1378
1379 dprintk("RPC: created transport %p with %u slots\n", xprt,
1380 xprt->max_reqs);
1381out:
1382 return xprt;
1383}
1384
1385/**
1386 * xprt_destroy - destroy an RPC transport, killing off all requests.
1387 * @xprt: transport to destroy
1388 *
1389 */
1390static void xprt_destroy(struct rpc_xprt *xprt)
1391{
1392 dprintk("RPC: destroying transport %p\n", xprt);
1393
1394 /* Exclude transport connect/disconnect handlers */
1395 wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
1396
1397 del_timer_sync(&xprt->timer);
1398
1399 rpc_xprt_debugfs_unregister(xprt);
1400 rpc_destroy_wait_queue(&xprt->binding);
1401 rpc_destroy_wait_queue(&xprt->pending);
1402 rpc_destroy_wait_queue(&xprt->sending);
1403 rpc_destroy_wait_queue(&xprt->backlog);
1404 cancel_work_sync(&xprt->task_cleanup);
1405 kfree(xprt->servername);
1406 /*
1407 * Tear down transport state and free the rpc_xprt
1408 */
1409 xprt->ops->destroy(xprt);
1410}
1411
1412static void xprt_destroy_kref(struct kref *kref)
1413{
1414 xprt_destroy(container_of(kref, struct rpc_xprt, kref));
1415}
1416
1417/**
1418 * xprt_get - return a reference to an RPC transport.
1419 * @xprt: pointer to the transport
1420 *
1421 */
1422struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1423{
1424 if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
1425 return xprt;
1426 return NULL;
1427}
1428EXPORT_SYMBOL_GPL(xprt_get);
1429
1430/**
1431 * xprt_put - release a reference to an RPC transport.
1432 * @xprt: pointer to the transport
1433 *
1434 */
1435void xprt_put(struct rpc_xprt *xprt)
1436{
1437 if (xprt != NULL)
1438 kref_put(&xprt->kref, xprt_destroy_kref);
1439}
1440EXPORT_SYMBOL_GPL(xprt_put);