xref: /linux/net/sunrpc/xprt.c (revision 5860800e8696d2cbbd1a0dd60b433549d176e668)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/net/sunrpc/xprt.c
4  *
5  *  This is a generic RPC call interface supporting congestion avoidance,
6  *  and asynchronous calls.
7  *
8  *  The interface works like this:
9  *
10  *  -	When a process places a call, it allocates a request slot if
11  *	one is available. Otherwise, it sleeps on the backlog queue
12  *	(xprt_reserve).
13  *  -	Next, the caller puts together the RPC message, stuffs it into
14  *	the request struct, and calls xprt_transmit().
15  *  -	xprt_transmit sends the message and installs the caller on the
16  *	transport's wait list. At the same time, if a reply is expected,
17  *	it installs a timer that is run after the packet's timeout has
18  *	expired.
19  *  -	When a packet arrives, the data_ready handler walks the list of
20  *	pending requests for that transport. If a matching XID is found, the
21  *	caller is woken up, and the timer removed.
22  *  -	When no reply arrives within the timeout interval, the timer is
23  *	fired by the kernel and runs xprt_timer(). It either adjusts the
24  *	timeout values (minor timeout) or wakes up the caller with a status
25  *	of -ETIMEDOUT.
26  *  -	When the caller receives a notification from RPC that a reply arrived,
27  *	it should release the RPC slot, and process the reply.
28  *	If the call timed out, it may choose to retry the operation by
29  *	adjusting the initial timeout value, and simply calling rpc_call
30  *	again.
31  *
32  *  Support for async RPC is done through a set of RPC-specific scheduling
33  *  primitives that `transparently' work for processes as well as async
34  *  tasks that rely on callbacks.
35  *
36  *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
37  *
38  *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
39  */
40 
41 #include <linux/module.h>
42 
43 #include <linux/types.h>
44 #include <linux/interrupt.h>
45 #include <linux/workqueue.h>
46 #include <linux/net.h>
47 #include <linux/ktime.h>
48 
49 #include <linux/sunrpc/clnt.h>
50 #include <linux/sunrpc/metrics.h>
51 #include <linux/sunrpc/bc_xprt.h>
52 #include <linux/rcupdate.h>
53 #include <linux/sched/mm.h>
54 
55 #include <trace/events/sunrpc.h>
56 
57 #include "sunrpc.h"
58 #include "sysfs.h"
59 #include "fail.h"
60 
61 /*
62  * Local variables
63  */
64 
65 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
66 # define RPCDBG_FACILITY	RPCDBG_XPRT
67 #endif
68 
69 /*
70  * Local functions
71  */
72 static void	xprt_init(struct rpc_xprt *xprt, struct net *net);
73 static __be32	xprt_alloc_xid(struct rpc_xprt *xprt);
74 static void	xprt_destroy(struct rpc_xprt *xprt);
75 static void	xprt_request_init(struct rpc_task *task);
76 static int	xprt_request_prepare(struct rpc_rqst *req);
77 
78 static DEFINE_SPINLOCK(xprt_list_lock);
79 static LIST_HEAD(xprt_list);
80 
81 static unsigned long xprt_request_timeout(const struct rpc_rqst *req)
82 {
83 	unsigned long timeout = jiffies + req->rq_timeout;
84 
85 	if (time_before(timeout, req->rq_majortimeo))
86 		return timeout;
87 	return req->rq_majortimeo;
88 }
89 
90 /**
91  * xprt_register_transport - register a transport implementation
92  * @transport: transport to register
93  *
94  * If a transport implementation is loaded as a kernel module, it can
95  * call this interface to make itself known to the RPC client.
96  *
97  * Returns:
98  * 0:		transport successfully registered
99  * -EEXIST:	transport already registered
100  * -EINVAL:	transport module being unloaded
101  */
102 int xprt_register_transport(struct xprt_class *transport)
103 {
104 	struct xprt_class *t;
105 	int result;
106 
107 	result = -EEXIST;
108 	spin_lock(&xprt_list_lock);
109 	list_for_each_entry(t, &xprt_list, list) {
110 		/* don't register the same transport class twice */
111 		if (t->ident == transport->ident)
112 			goto out;
113 	}
114 
115 	list_add_tail(&transport->list, &xprt_list);
116 	printk(KERN_INFO "RPC: Registered %s transport module.\n",
117 	       transport->name);
118 	result = 0;
119 
120 out:
121 	spin_unlock(&xprt_list_lock);
122 	return result;
123 }
124 EXPORT_SYMBOL_GPL(xprt_register_transport);
125 
126 /**
127  * xprt_unregister_transport - unregister a transport implementation
128  * @transport: transport to unregister
129  *
130  * Returns:
131  * 0:		transport successfully unregistered
132  * -ENOENT:	transport never registered
133  */
134 int xprt_unregister_transport(struct xprt_class *transport)
135 {
136 	struct xprt_class *t;
137 	int result;
138 
139 	result = 0;
140 	spin_lock(&xprt_list_lock);
141 	list_for_each_entry(t, &xprt_list, list) {
142 		if (t == transport) {
143 			printk(KERN_INFO
144 				"RPC: Unregistered %s transport module.\n",
145 				transport->name);
146 			list_del_init(&transport->list);
147 			goto out;
148 		}
149 	}
150 	result = -ENOENT;
151 
152 out:
153 	spin_unlock(&xprt_list_lock);
154 	return result;
155 }
156 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
157 
158 static void
159 xprt_class_release(const struct xprt_class *t)
160 {
161 	module_put(t->owner);
162 }
163 
164 static const struct xprt_class *
165 xprt_class_find_by_ident_locked(int ident)
166 {
167 	const struct xprt_class *t;
168 
169 	list_for_each_entry(t, &xprt_list, list) {
170 		if (t->ident != ident)
171 			continue;
172 		if (!try_module_get(t->owner))
173 			continue;
174 		return t;
175 	}
176 	return NULL;
177 }
178 
179 static const struct xprt_class *
180 xprt_class_find_by_ident(int ident)
181 {
182 	const struct xprt_class *t;
183 
184 	spin_lock(&xprt_list_lock);
185 	t = xprt_class_find_by_ident_locked(ident);
186 	spin_unlock(&xprt_list_lock);
187 	return t;
188 }
189 
190 static const struct xprt_class *
191 xprt_class_find_by_netid_locked(const char *netid)
192 {
193 	const struct xprt_class *t;
194 	unsigned int i;
195 
196 	list_for_each_entry(t, &xprt_list, list) {
197 		for (i = 0; t->netid[i][0] != '\0'; i++) {
198 			if (strcmp(t->netid[i], netid) != 0)
199 				continue;
200 			if (!try_module_get(t->owner))
201 				continue;
202 			return t;
203 		}
204 	}
205 	return NULL;
206 }
207 
208 static const struct xprt_class *
209 xprt_class_find_by_netid(const char *netid)
210 {
211 	const struct xprt_class *t;
212 
213 	spin_lock(&xprt_list_lock);
214 	t = xprt_class_find_by_netid_locked(netid);
215 	if (!t) {
216 		spin_unlock(&xprt_list_lock);
217 		request_module("rpc%s", netid);
218 		spin_lock(&xprt_list_lock);
219 		t = xprt_class_find_by_netid_locked(netid);
220 	}
221 	spin_unlock(&xprt_list_lock);
222 	return t;
223 }
224 
225 /**
226  * xprt_find_transport_ident - convert a netid into a transport identifier
227  * @netid: transport to load
228  *
229  * Returns:
230  * > 0:		transport identifier
231  * -ENOENT:	transport module not available
232  */
233 int xprt_find_transport_ident(const char *netid)
234 {
235 	const struct xprt_class *t;
236 	int ret;
237 
238 	t = xprt_class_find_by_netid(netid);
239 	if (!t)
240 		return -ENOENT;
241 	ret = t->ident;
242 	xprt_class_release(t);
243 	return ret;
244 }
245 EXPORT_SYMBOL_GPL(xprt_find_transport_ident);
246 
247 static void xprt_clear_locked(struct rpc_xprt *xprt)
248 {
249 	xprt->snd_task = NULL;
250 	if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state))
251 		clear_bit_unlock(XPRT_LOCKED, &xprt->state);
252 	else
253 		queue_work(xprtiod_workqueue, &xprt->task_cleanup);
254 }
255 
256 /**
257  * xprt_reserve_xprt - serialize write access to transports
258  * @task: task that is requesting access to the transport
259  * @xprt: pointer to the target transport
260  *
261  * This prevents mixing the payload of separate requests, and prevents
262  * transport connects from colliding with writes.  No congestion control
263  * is provided.
264  */
265 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
266 {
267 	struct rpc_rqst *req = task->tk_rqstp;
268 
269 	if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
270 		if (task == xprt->snd_task)
271 			goto out_locked;
272 		goto out_sleep;
273 	}
274 	if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
275 		goto out_unlock;
276 	xprt->snd_task = task;
277 
278 out_locked:
279 	trace_xprt_reserve_xprt(xprt, task);
280 	return 1;
281 
282 out_unlock:
283 	xprt_clear_locked(xprt);
284 out_sleep:
285 	task->tk_status = -EAGAIN;
286 	if  (RPC_IS_SOFT(task))
287 		rpc_sleep_on_timeout(&xprt->sending, task, NULL,
288 				xprt_request_timeout(req));
289 	else
290 		rpc_sleep_on(&xprt->sending, task, NULL);
291 	return 0;
292 }
293 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
294 
295 static bool
296 xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
297 {
298 	return test_bit(XPRT_CWND_WAIT, &xprt->state);
299 }
300 
301 static void
302 xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
303 {
304 	if (!list_empty(&xprt->xmit_queue)) {
305 		/* Peek at head of queue to see if it can make progress */
306 		if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
307 					rq_xmit)->rq_cong)
308 			return;
309 	}
310 	set_bit(XPRT_CWND_WAIT, &xprt->state);
311 }
312 
313 static void
314 xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
315 {
316 	if (!RPCXPRT_CONGESTED(xprt))
317 		clear_bit(XPRT_CWND_WAIT, &xprt->state);
318 }
319 
320 /*
321  * xprt_reserve_xprt_cong - serialize write access to transports
322  * @task: task that is requesting access to the transport
323  *
324  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
325  * integrated into the decision of whether a request is allowed to be
326  * woken up and given access to the transport.
327  * Note that the lock is only granted if we know there are free slots.
328  */
329 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
330 {
331 	struct rpc_rqst *req = task->tk_rqstp;
332 
333 	if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
334 		if (task == xprt->snd_task)
335 			goto out_locked;
336 		goto out_sleep;
337 	}
338 	if (req == NULL) {
339 		xprt->snd_task = task;
340 		goto out_locked;
341 	}
342 	if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
343 		goto out_unlock;
344 	if (!xprt_need_congestion_window_wait(xprt)) {
345 		xprt->snd_task = task;
346 		goto out_locked;
347 	}
348 out_unlock:
349 	xprt_clear_locked(xprt);
350 out_sleep:
351 	task->tk_status = -EAGAIN;
352 	if (RPC_IS_SOFT(task))
353 		rpc_sleep_on_timeout(&xprt->sending, task, NULL,
354 				xprt_request_timeout(req));
355 	else
356 		rpc_sleep_on(&xprt->sending, task, NULL);
357 	return 0;
358 out_locked:
359 	trace_xprt_reserve_cong(xprt, task);
360 	return 1;
361 }
362 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
363 
364 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
365 {
366 	int retval;
367 
368 	if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
369 		return 1;
370 	spin_lock(&xprt->transport_lock);
371 	retval = xprt->ops->reserve_xprt(xprt, task);
372 	spin_unlock(&xprt->transport_lock);
373 	return retval;
374 }
375 
376 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
377 {
378 	struct rpc_xprt *xprt = data;
379 
380 	xprt->snd_task = task;
381 	return true;
382 }
383 
384 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
385 {
386 	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
387 		return;
388 	if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
389 		goto out_unlock;
390 	if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
391 				__xprt_lock_write_func, xprt))
392 		return;
393 out_unlock:
394 	xprt_clear_locked(xprt);
395 }
396 
397 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
398 {
399 	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
400 		return;
401 	if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
402 		goto out_unlock;
403 	if (xprt_need_congestion_window_wait(xprt))
404 		goto out_unlock;
405 	if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
406 				__xprt_lock_write_func, xprt))
407 		return;
408 out_unlock:
409 	xprt_clear_locked(xprt);
410 }
411 
412 /**
413  * xprt_release_xprt - allow other requests to use a transport
414  * @xprt: transport with other tasks potentially waiting
415  * @task: task that is releasing access to the transport
416  *
417  * Note that "task" can be NULL.  No congestion control is provided.
418  */
419 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
420 {
421 	if (xprt->snd_task == task) {
422 		xprt_clear_locked(xprt);
423 		__xprt_lock_write_next(xprt);
424 	}
425 	trace_xprt_release_xprt(xprt, task);
426 }
427 EXPORT_SYMBOL_GPL(xprt_release_xprt);
428 
429 /**
430  * xprt_release_xprt_cong - allow other requests to use a transport
431  * @xprt: transport with other tasks potentially waiting
432  * @task: task that is releasing access to the transport
433  *
434  * Note that "task" can be NULL.  Another task is awoken to use the
435  * transport if the transport's congestion window allows it.
436  */
437 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
438 {
439 	if (xprt->snd_task == task) {
440 		xprt_clear_locked(xprt);
441 		__xprt_lock_write_next_cong(xprt);
442 	}
443 	trace_xprt_release_cong(xprt, task);
444 }
445 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
446 
447 void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
448 {
449 	if (xprt->snd_task != task)
450 		return;
451 	spin_lock(&xprt->transport_lock);
452 	xprt->ops->release_xprt(xprt, task);
453 	spin_unlock(&xprt->transport_lock);
454 }
455 
456 /*
457  * Van Jacobson congestion avoidance. Check if the congestion window
458  * overflowed. Put the task to sleep if this is the case.
459  */
460 static int
461 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
462 {
463 	if (req->rq_cong)
464 		return 1;
465 	trace_xprt_get_cong(xprt, req->rq_task);
466 	if (RPCXPRT_CONGESTED(xprt)) {
467 		xprt_set_congestion_window_wait(xprt);
468 		return 0;
469 	}
470 	req->rq_cong = 1;
471 	xprt->cong += RPC_CWNDSCALE;
472 	return 1;
473 }
474 
475 /*
476  * Adjust the congestion window, and wake up the next task
477  * that has been sleeping due to congestion
478  */
479 static void
480 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
481 {
482 	if (!req->rq_cong)
483 		return;
484 	req->rq_cong = 0;
485 	xprt->cong -= RPC_CWNDSCALE;
486 	xprt_test_and_clear_congestion_window_wait(xprt);
487 	trace_xprt_put_cong(xprt, req->rq_task);
488 	__xprt_lock_write_next_cong(xprt);
489 }
490 
491 /**
492  * xprt_request_get_cong - Request congestion control credits
493  * @xprt: pointer to transport
494  * @req: pointer to RPC request
495  *
496  * Useful for transports that require congestion control.
497  */
498 bool
499 xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
500 {
501 	bool ret = false;
502 
503 	if (req->rq_cong)
504 		return true;
505 	spin_lock(&xprt->transport_lock);
506 	ret = __xprt_get_cong(xprt, req) != 0;
507 	spin_unlock(&xprt->transport_lock);
508 	return ret;
509 }
510 EXPORT_SYMBOL_GPL(xprt_request_get_cong);
511 
512 /**
513  * xprt_release_rqst_cong - housekeeping when request is complete
514  * @task: RPC request that recently completed
515  *
516  * Useful for transports that require congestion control.
517  */
518 void xprt_release_rqst_cong(struct rpc_task *task)
519 {
520 	struct rpc_rqst *req = task->tk_rqstp;
521 
522 	__xprt_put_cong(req->rq_xprt, req);
523 }
524 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
525 
526 static void xprt_clear_congestion_window_wait_locked(struct rpc_xprt *xprt)
527 {
528 	if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state))
529 		__xprt_lock_write_next_cong(xprt);
530 }
531 
532 /*
533  * Clear the congestion window wait flag and wake up the next
534  * entry on xprt->sending
535  */
536 static void
537 xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
538 {
539 	if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
540 		spin_lock(&xprt->transport_lock);
541 		__xprt_lock_write_next_cong(xprt);
542 		spin_unlock(&xprt->transport_lock);
543 	}
544 }
545 
546 /**
547  * xprt_adjust_cwnd - adjust transport congestion window
548  * @xprt: pointer to xprt
549  * @task: recently completed RPC request used to adjust window
550  * @result: result code of completed RPC request
551  *
552  * The transport code maintains an estimate on the maximum number of out-
553  * standing RPC requests, using a smoothed version of the congestion
554  * avoidance implemented in 44BSD. This is basically the Van Jacobson
555  * congestion algorithm: If a retransmit occurs, the congestion window is
556  * halved; otherwise, it is incremented by 1/cwnd when
557  *
558  *	-	a reply is received and
559  *	-	a full number of requests are outstanding and
560  *	-	the congestion window hasn't been updated recently.
561  */
562 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
563 {
564 	struct rpc_rqst *req = task->tk_rqstp;
565 	unsigned long cwnd = xprt->cwnd;
566 
567 	if (result >= 0 && cwnd <= xprt->cong) {
568 		/* The (cwnd >> 1) term makes sure
569 		 * the result gets rounded properly. */
570 		cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
571 		if (cwnd > RPC_MAXCWND(xprt))
572 			cwnd = RPC_MAXCWND(xprt);
573 		__xprt_lock_write_next_cong(xprt);
574 	} else if (result == -ETIMEDOUT) {
575 		cwnd >>= 1;
576 		if (cwnd < RPC_CWNDSCALE)
577 			cwnd = RPC_CWNDSCALE;
578 	}
579 	dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
580 			xprt->cong, xprt->cwnd, cwnd);
581 	xprt->cwnd = cwnd;
582 	__xprt_put_cong(xprt, req);
583 }
584 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
585 
586 /**
587  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
588  * @xprt: transport with waiting tasks
589  * @status: result code to plant in each task before waking it
590  *
591  */
592 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
593 {
594 	if (status < 0)
595 		rpc_wake_up_status(&xprt->pending, status);
596 	else
597 		rpc_wake_up(&xprt->pending);
598 }
599 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
600 
601 /**
602  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
603  * @xprt: transport
604  *
605  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
606  * we don't in general want to force a socket disconnection due to
607  * an incomplete RPC call transmission.
608  */
609 void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
610 {
611 	set_bit(XPRT_WRITE_SPACE, &xprt->state);
612 }
613 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
614 
615 static bool
616 xprt_clear_write_space_locked(struct rpc_xprt *xprt)
617 {
618 	if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
619 		__xprt_lock_write_next(xprt);
620 		dprintk("RPC:       write space: waking waiting task on "
621 				"xprt %p\n", xprt);
622 		return true;
623 	}
624 	return false;
625 }
626 
627 /**
628  * xprt_write_space - wake the task waiting for transport output buffer space
629  * @xprt: transport with waiting tasks
630  *
631  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
632  */
633 bool xprt_write_space(struct rpc_xprt *xprt)
634 {
635 	bool ret;
636 
637 	if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
638 		return false;
639 	spin_lock(&xprt->transport_lock);
640 	ret = xprt_clear_write_space_locked(xprt);
641 	spin_unlock(&xprt->transport_lock);
642 	return ret;
643 }
644 EXPORT_SYMBOL_GPL(xprt_write_space);
645 
646 static unsigned long xprt_abs_ktime_to_jiffies(ktime_t abstime)
647 {
648 	s64 delta = ktime_to_ns(ktime_get() - abstime);
649 	return likely(delta >= 0) ?
650 		jiffies - nsecs_to_jiffies(delta) :
651 		jiffies + nsecs_to_jiffies(-delta);
652 }
653 
654 static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req)
655 {
656 	const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
657 	unsigned long majortimeo = req->rq_timeout;
658 
659 	if (to->to_exponential)
660 		majortimeo <<= to->to_retries;
661 	else
662 		majortimeo += to->to_increment * to->to_retries;
663 	if (majortimeo > to->to_maxval || majortimeo == 0)
664 		majortimeo = to->to_maxval;
665 	return majortimeo;
666 }
667 
668 static void xprt_reset_majortimeo(struct rpc_rqst *req)
669 {
670 	req->rq_majortimeo += xprt_calc_majortimeo(req);
671 }
672 
673 static void xprt_reset_minortimeo(struct rpc_rqst *req)
674 {
675 	req->rq_minortimeo += req->rq_timeout;
676 }
677 
678 static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
679 {
680 	unsigned long time_init;
681 	struct rpc_xprt *xprt = req->rq_xprt;
682 
683 	if (likely(xprt && xprt_connected(xprt)))
684 		time_init = jiffies;
685 	else
686 		time_init = xprt_abs_ktime_to_jiffies(task->tk_start);
687 	req->rq_timeout = task->tk_client->cl_timeout->to_initval;
688 	req->rq_majortimeo = time_init + xprt_calc_majortimeo(req);
689 	req->rq_minortimeo = time_init + req->rq_timeout;
690 }
691 
692 /**
693  * xprt_adjust_timeout - adjust timeout values for next retransmit
694  * @req: RPC request containing parameters to use for the adjustment
695  *
696  */
697 int xprt_adjust_timeout(struct rpc_rqst *req)
698 {
699 	struct rpc_xprt *xprt = req->rq_xprt;
700 	const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
701 	int status = 0;
702 
703 	if (time_before(jiffies, req->rq_majortimeo)) {
704 		if (time_before(jiffies, req->rq_minortimeo))
705 			return status;
706 		if (to->to_exponential)
707 			req->rq_timeout <<= 1;
708 		else
709 			req->rq_timeout += to->to_increment;
710 		if (to->to_maxval && req->rq_timeout >= to->to_maxval)
711 			req->rq_timeout = to->to_maxval;
712 		req->rq_retries++;
713 	} else {
714 		req->rq_timeout = to->to_initval;
715 		req->rq_retries = 0;
716 		xprt_reset_majortimeo(req);
717 		/* Reset the RTT counters == "slow start" */
718 		spin_lock(&xprt->transport_lock);
719 		rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
720 		spin_unlock(&xprt->transport_lock);
721 		status = -ETIMEDOUT;
722 	}
723 	xprt_reset_minortimeo(req);
724 
725 	if (req->rq_timeout == 0) {
726 		printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
727 		req->rq_timeout = 5 * HZ;
728 	}
729 	return status;
730 }
731 
732 static void xprt_autoclose(struct work_struct *work)
733 {
734 	struct rpc_xprt *xprt =
735 		container_of(work, struct rpc_xprt, task_cleanup);
736 	unsigned int pflags = memalloc_nofs_save();
737 
738 	trace_xprt_disconnect_auto(xprt);
739 	xprt->connect_cookie++;
740 	smp_mb__before_atomic();
741 	clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
742 	xprt->ops->close(xprt);
743 	xprt_release_write(xprt, NULL);
744 	wake_up_bit(&xprt->state, XPRT_LOCKED);
745 	memalloc_nofs_restore(pflags);
746 }
747 
748 /**
749  * xprt_disconnect_done - mark a transport as disconnected
750  * @xprt: transport to flag for disconnect
751  *
752  */
753 void xprt_disconnect_done(struct rpc_xprt *xprt)
754 {
755 	trace_xprt_disconnect_done(xprt);
756 	spin_lock(&xprt->transport_lock);
757 	xprt_clear_connected(xprt);
758 	xprt_clear_write_space_locked(xprt);
759 	xprt_clear_congestion_window_wait_locked(xprt);
760 	xprt_wake_pending_tasks(xprt, -ENOTCONN);
761 	spin_unlock(&xprt->transport_lock);
762 }
763 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
764 
765 /**
766  * xprt_schedule_autoclose_locked - Try to schedule an autoclose RPC call
767  * @xprt: transport to disconnect
768  */
769 static void xprt_schedule_autoclose_locked(struct rpc_xprt *xprt)
770 {
771 	if (test_and_set_bit(XPRT_CLOSE_WAIT, &xprt->state))
772 		return;
773 	if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
774 		queue_work(xprtiod_workqueue, &xprt->task_cleanup);
775 	else if (xprt->snd_task && !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
776 		rpc_wake_up_queued_task_set_status(&xprt->pending,
777 						   xprt->snd_task, -ENOTCONN);
778 }
779 
780 /**
781  * xprt_force_disconnect - force a transport to disconnect
782  * @xprt: transport to disconnect
783  *
784  */
785 void xprt_force_disconnect(struct rpc_xprt *xprt)
786 {
787 	trace_xprt_disconnect_force(xprt);
788 
789 	/* Don't race with the test_bit() in xprt_clear_locked() */
790 	spin_lock(&xprt->transport_lock);
791 	xprt_schedule_autoclose_locked(xprt);
792 	spin_unlock(&xprt->transport_lock);
793 }
794 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
795 
796 static unsigned int
797 xprt_connect_cookie(struct rpc_xprt *xprt)
798 {
799 	return READ_ONCE(xprt->connect_cookie);
800 }
801 
802 static bool
803 xprt_request_retransmit_after_disconnect(struct rpc_task *task)
804 {
805 	struct rpc_rqst *req = task->tk_rqstp;
806 	struct rpc_xprt *xprt = req->rq_xprt;
807 
808 	return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
809 		!xprt_connected(xprt);
810 }
811 
812 /**
813  * xprt_conditional_disconnect - force a transport to disconnect
814  * @xprt: transport to disconnect
815  * @cookie: 'connection cookie'
816  *
817  * This attempts to break the connection if and only if 'cookie' matches
818  * the current transport 'connection cookie'. It ensures that we don't
819  * try to break the connection more than once when we need to retransmit
820  * a batch of RPC requests.
821  *
822  */
823 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
824 {
825 	/* Don't race with the test_bit() in xprt_clear_locked() */
826 	spin_lock(&xprt->transport_lock);
827 	if (cookie != xprt->connect_cookie)
828 		goto out;
829 	if (test_bit(XPRT_CLOSING, &xprt->state))
830 		goto out;
831 	xprt_schedule_autoclose_locked(xprt);
832 out:
833 	spin_unlock(&xprt->transport_lock);
834 }
835 
836 static bool
837 xprt_has_timer(const struct rpc_xprt *xprt)
838 {
839 	return xprt->idle_timeout != 0;
840 }
841 
842 static void
843 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
844 	__must_hold(&xprt->transport_lock)
845 {
846 	xprt->last_used = jiffies;
847 	if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))
848 		mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
849 }
850 
851 static void
852 xprt_init_autodisconnect(struct timer_list *t)
853 {
854 	struct rpc_xprt *xprt = from_timer(xprt, t, timer);
855 
856 	if (!RB_EMPTY_ROOT(&xprt->recv_queue))
857 		return;
858 	/* Reset xprt->last_used to avoid connect/autodisconnect cycling */
859 	xprt->last_used = jiffies;
860 	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
861 		return;
862 	queue_work(xprtiod_workqueue, &xprt->task_cleanup);
863 }
864 
865 #if IS_ENABLED(CONFIG_FAIL_SUNRPC)
866 static void xprt_inject_disconnect(struct rpc_xprt *xprt)
867 {
868 	if (!fail_sunrpc.ignore_client_disconnect &&
869 	    should_fail(&fail_sunrpc.attr, 1))
870 		xprt->ops->inject_disconnect(xprt);
871 }
872 #else
873 static inline void xprt_inject_disconnect(struct rpc_xprt *xprt)
874 {
875 }
876 #endif
877 
878 bool xprt_lock_connect(struct rpc_xprt *xprt,
879 		struct rpc_task *task,
880 		void *cookie)
881 {
882 	bool ret = false;
883 
884 	spin_lock(&xprt->transport_lock);
885 	if (!test_bit(XPRT_LOCKED, &xprt->state))
886 		goto out;
887 	if (xprt->snd_task != task)
888 		goto out;
889 	set_bit(XPRT_SND_IS_COOKIE, &xprt->state);
890 	xprt->snd_task = cookie;
891 	ret = true;
892 out:
893 	spin_unlock(&xprt->transport_lock);
894 	return ret;
895 }
896 EXPORT_SYMBOL_GPL(xprt_lock_connect);
897 
898 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
899 {
900 	spin_lock(&xprt->transport_lock);
901 	if (xprt->snd_task != cookie)
902 		goto out;
903 	if (!test_bit(XPRT_LOCKED, &xprt->state))
904 		goto out;
905 	xprt->snd_task =NULL;
906 	clear_bit(XPRT_SND_IS_COOKIE, &xprt->state);
907 	xprt->ops->release_xprt(xprt, NULL);
908 	xprt_schedule_autodisconnect(xprt);
909 out:
910 	spin_unlock(&xprt->transport_lock);
911 	wake_up_bit(&xprt->state, XPRT_LOCKED);
912 }
913 EXPORT_SYMBOL_GPL(xprt_unlock_connect);
914 
915 /**
916  * xprt_connect - schedule a transport connect operation
917  * @task: RPC task that is requesting the connect
918  *
919  */
920 void xprt_connect(struct rpc_task *task)
921 {
922 	struct rpc_xprt	*xprt = task->tk_rqstp->rq_xprt;
923 
924 	trace_xprt_connect(xprt);
925 
926 	if (!xprt_bound(xprt)) {
927 		task->tk_status = -EAGAIN;
928 		return;
929 	}
930 	if (!xprt_lock_write(xprt, task))
931 		return;
932 
933 	if (!xprt_connected(xprt) && !test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
934 		task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
935 		rpc_sleep_on_timeout(&xprt->pending, task, NULL,
936 				xprt_request_timeout(task->tk_rqstp));
937 
938 		if (test_bit(XPRT_CLOSING, &xprt->state))
939 			return;
940 		if (xprt_test_and_set_connecting(xprt))
941 			return;
942 		/* Race breaker */
943 		if (!xprt_connected(xprt)) {
944 			xprt->stat.connect_start = jiffies;
945 			xprt->ops->connect(xprt, task);
946 		} else {
947 			xprt_clear_connecting(xprt);
948 			task->tk_status = 0;
949 			rpc_wake_up_queued_task(&xprt->pending, task);
950 		}
951 	}
952 	xprt_release_write(xprt, task);
953 }
954 
955 /**
956  * xprt_reconnect_delay - compute the wait before scheduling a connect
957  * @xprt: transport instance
958  *
959  */
960 unsigned long xprt_reconnect_delay(const struct rpc_xprt *xprt)
961 {
962 	unsigned long start, now = jiffies;
963 
964 	start = xprt->stat.connect_start + xprt->reestablish_timeout;
965 	if (time_after(start, now))
966 		return start - now;
967 	return 0;
968 }
969 EXPORT_SYMBOL_GPL(xprt_reconnect_delay);
970 
971 /**
972  * xprt_reconnect_backoff - compute the new re-establish timeout
973  * @xprt: transport instance
974  * @init_to: initial reestablish timeout
975  *
976  */
977 void xprt_reconnect_backoff(struct rpc_xprt *xprt, unsigned long init_to)
978 {
979 	xprt->reestablish_timeout <<= 1;
980 	if (xprt->reestablish_timeout > xprt->max_reconnect_timeout)
981 		xprt->reestablish_timeout = xprt->max_reconnect_timeout;
982 	if (xprt->reestablish_timeout < init_to)
983 		xprt->reestablish_timeout = init_to;
984 }
985 EXPORT_SYMBOL_GPL(xprt_reconnect_backoff);
986 
987 enum xprt_xid_rb_cmp {
988 	XID_RB_EQUAL,
989 	XID_RB_LEFT,
990 	XID_RB_RIGHT,
991 };
992 static enum xprt_xid_rb_cmp
993 xprt_xid_cmp(__be32 xid1, __be32 xid2)
994 {
995 	if (xid1 == xid2)
996 		return XID_RB_EQUAL;
997 	if ((__force u32)xid1 < (__force u32)xid2)
998 		return XID_RB_LEFT;
999 	return XID_RB_RIGHT;
1000 }
1001 
1002 static struct rpc_rqst *
1003 xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
1004 {
1005 	struct rb_node *n = xprt->recv_queue.rb_node;
1006 	struct rpc_rqst *req;
1007 
1008 	while (n != NULL) {
1009 		req = rb_entry(n, struct rpc_rqst, rq_recv);
1010 		switch (xprt_xid_cmp(xid, req->rq_xid)) {
1011 		case XID_RB_LEFT:
1012 			n = n->rb_left;
1013 			break;
1014 		case XID_RB_RIGHT:
1015 			n = n->rb_right;
1016 			break;
1017 		case XID_RB_EQUAL:
1018 			return req;
1019 		}
1020 	}
1021 	return NULL;
1022 }
1023 
1024 static void
1025 xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
1026 {
1027 	struct rb_node **p = &xprt->recv_queue.rb_node;
1028 	struct rb_node *n = NULL;
1029 	struct rpc_rqst *req;
1030 
1031 	while (*p != NULL) {
1032 		n = *p;
1033 		req = rb_entry(n, struct rpc_rqst, rq_recv);
1034 		switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
1035 		case XID_RB_LEFT:
1036 			p = &n->rb_left;
1037 			break;
1038 		case XID_RB_RIGHT:
1039 			p = &n->rb_right;
1040 			break;
1041 		case XID_RB_EQUAL:
1042 			WARN_ON_ONCE(new != req);
1043 			return;
1044 		}
1045 	}
1046 	rb_link_node(&new->rq_recv, n, p);
1047 	rb_insert_color(&new->rq_recv, &xprt->recv_queue);
1048 }
1049 
1050 static void
1051 xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
1052 {
1053 	rb_erase(&req->rq_recv, &xprt->recv_queue);
1054 }
1055 
1056 /**
1057  * xprt_lookup_rqst - find an RPC request corresponding to an XID
1058  * @xprt: transport on which the original request was transmitted
1059  * @xid: RPC XID of incoming reply
1060  *
1061  * Caller holds xprt->queue_lock.
1062  */
1063 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
1064 {
1065 	struct rpc_rqst *entry;
1066 
1067 	entry = xprt_request_rb_find(xprt, xid);
1068 	if (entry != NULL) {
1069 		trace_xprt_lookup_rqst(xprt, xid, 0);
1070 		entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
1071 		return entry;
1072 	}
1073 
1074 	dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
1075 			ntohl(xid));
1076 	trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
1077 	xprt->stat.bad_xids++;
1078 	return NULL;
1079 }
1080 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
1081 
1082 static bool
1083 xprt_is_pinned_rqst(struct rpc_rqst *req)
1084 {
1085 	return atomic_read(&req->rq_pin) != 0;
1086 }
1087 
1088 /**
1089  * xprt_pin_rqst - Pin a request on the transport receive list
1090  * @req: Request to pin
1091  *
1092  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
1093  * so should be holding xprt->queue_lock.
1094  */
1095 void xprt_pin_rqst(struct rpc_rqst *req)
1096 {
1097 	atomic_inc(&req->rq_pin);
1098 }
1099 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
1100 
1101 /**
1102  * xprt_unpin_rqst - Unpin a request on the transport receive list
1103  * @req: Request to pin
1104  *
1105  * Caller should be holding xprt->queue_lock.
1106  */
1107 void xprt_unpin_rqst(struct rpc_rqst *req)
1108 {
1109 	if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
1110 		atomic_dec(&req->rq_pin);
1111 		return;
1112 	}
1113 	if (atomic_dec_and_test(&req->rq_pin))
1114 		wake_up_var(&req->rq_pin);
1115 }
1116 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
1117 
1118 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
1119 {
1120 	wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
1121 }
1122 
1123 static bool
1124 xprt_request_data_received(struct rpc_task *task)
1125 {
1126 	return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1127 		READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
1128 }
1129 
1130 static bool
1131 xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
1132 {
1133 	return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1134 		READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
1135 }
1136 
1137 /**
1138  * xprt_request_enqueue_receive - Add an request to the receive queue
1139  * @task: RPC task
1140  *
1141  */
1142 int
1143 xprt_request_enqueue_receive(struct rpc_task *task)
1144 {
1145 	struct rpc_rqst *req = task->tk_rqstp;
1146 	struct rpc_xprt *xprt = req->rq_xprt;
1147 	int ret;
1148 
1149 	if (!xprt_request_need_enqueue_receive(task, req))
1150 		return 0;
1151 
1152 	ret = xprt_request_prepare(task->tk_rqstp);
1153 	if (ret)
1154 		return ret;
1155 	spin_lock(&xprt->queue_lock);
1156 
1157 	/* Update the softirq receive buffer */
1158 	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1159 			sizeof(req->rq_private_buf));
1160 
1161 	/* Add request to the receive list */
1162 	xprt_request_rb_insert(xprt, req);
1163 	set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
1164 	spin_unlock(&xprt->queue_lock);
1165 
1166 	/* Turn off autodisconnect */
1167 	del_singleshot_timer_sync(&xprt->timer);
1168 	return 0;
1169 }
1170 
1171 /**
1172  * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
1173  * @task: RPC task
1174  *
1175  * Caller must hold xprt->queue_lock.
1176  */
1177 static void
1178 xprt_request_dequeue_receive_locked(struct rpc_task *task)
1179 {
1180 	struct rpc_rqst *req = task->tk_rqstp;
1181 
1182 	if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1183 		xprt_request_rb_remove(req->rq_xprt, req);
1184 }
1185 
1186 /**
1187  * xprt_update_rtt - Update RPC RTT statistics
1188  * @task: RPC request that recently completed
1189  *
1190  * Caller holds xprt->queue_lock.
1191  */
1192 void xprt_update_rtt(struct rpc_task *task)
1193 {
1194 	struct rpc_rqst *req = task->tk_rqstp;
1195 	struct rpc_rtt *rtt = task->tk_client->cl_rtt;
1196 	unsigned int timer = task->tk_msg.rpc_proc->p_timer;
1197 	long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
1198 
1199 	if (timer) {
1200 		if (req->rq_ntrans == 1)
1201 			rpc_update_rtt(rtt, timer, m);
1202 		rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
1203 	}
1204 }
1205 EXPORT_SYMBOL_GPL(xprt_update_rtt);
1206 
1207 /**
1208  * xprt_complete_rqst - called when reply processing is complete
1209  * @task: RPC request that recently completed
1210  * @copied: actual number of bytes received from the transport
1211  *
1212  * Caller holds xprt->queue_lock.
1213  */
1214 void xprt_complete_rqst(struct rpc_task *task, int copied)
1215 {
1216 	struct rpc_rqst *req = task->tk_rqstp;
1217 	struct rpc_xprt *xprt = req->rq_xprt;
1218 
1219 	xprt->stat.recvs++;
1220 
1221 	req->rq_private_buf.len = copied;
1222 	/* Ensure all writes are done before we update */
1223 	/* req->rq_reply_bytes_recvd */
1224 	smp_wmb();
1225 	req->rq_reply_bytes_recvd = copied;
1226 	xprt_request_dequeue_receive_locked(task);
1227 	rpc_wake_up_queued_task(&xprt->pending, task);
1228 }
1229 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
1230 
1231 static void xprt_timer(struct rpc_task *task)
1232 {
1233 	struct rpc_rqst *req = task->tk_rqstp;
1234 	struct rpc_xprt *xprt = req->rq_xprt;
1235 
1236 	if (task->tk_status != -ETIMEDOUT)
1237 		return;
1238 
1239 	trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
1240 	if (!req->rq_reply_bytes_recvd) {
1241 		if (xprt->ops->timer)
1242 			xprt->ops->timer(xprt, task);
1243 	} else
1244 		task->tk_status = 0;
1245 }
1246 
1247 /**
1248  * xprt_wait_for_reply_request_def - wait for reply
1249  * @task: pointer to rpc_task
1250  *
1251  * Set a request's retransmit timeout based on the transport's
1252  * default timeout parameters.  Used by transports that don't adjust
1253  * the retransmit timeout based on round-trip time estimation,
1254  * and put the task to sleep on the pending queue.
1255  */
1256 void xprt_wait_for_reply_request_def(struct rpc_task *task)
1257 {
1258 	struct rpc_rqst *req = task->tk_rqstp;
1259 
1260 	rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1261 			xprt_request_timeout(req));
1262 }
1263 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_def);
1264 
1265 /**
1266  * xprt_wait_for_reply_request_rtt - wait for reply using RTT estimator
1267  * @task: pointer to rpc_task
1268  *
1269  * Set a request's retransmit timeout using the RTT estimator,
1270  * and put the task to sleep on the pending queue.
1271  */
1272 void xprt_wait_for_reply_request_rtt(struct rpc_task *task)
1273 {
1274 	int timer = task->tk_msg.rpc_proc->p_timer;
1275 	struct rpc_clnt *clnt = task->tk_client;
1276 	struct rpc_rtt *rtt = clnt->cl_rtt;
1277 	struct rpc_rqst *req = task->tk_rqstp;
1278 	unsigned long max_timeout = clnt->cl_timeout->to_maxval;
1279 	unsigned long timeout;
1280 
1281 	timeout = rpc_calc_rto(rtt, timer);
1282 	timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
1283 	if (timeout > max_timeout || timeout == 0)
1284 		timeout = max_timeout;
1285 	rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
1286 			jiffies + timeout);
1287 }
1288 EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_rtt);
1289 
1290 /**
1291  * xprt_request_wait_receive - wait for the reply to an RPC request
1292  * @task: RPC task about to send a request
1293  *
1294  */
1295 void xprt_request_wait_receive(struct rpc_task *task)
1296 {
1297 	struct rpc_rqst *req = task->tk_rqstp;
1298 	struct rpc_xprt *xprt = req->rq_xprt;
1299 
1300 	if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1301 		return;
1302 	/*
1303 	 * Sleep on the pending queue if we're expecting a reply.
1304 	 * The spinlock ensures atomicity between the test of
1305 	 * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1306 	 */
1307 	spin_lock(&xprt->queue_lock);
1308 	if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
1309 		xprt->ops->wait_for_reply_request(task);
1310 		/*
1311 		 * Send an extra queue wakeup call if the
1312 		 * connection was dropped in case the call to
1313 		 * rpc_sleep_on() raced.
1314 		 */
1315 		if (xprt_request_retransmit_after_disconnect(task))
1316 			rpc_wake_up_queued_task_set_status(&xprt->pending,
1317 					task, -ENOTCONN);
1318 	}
1319 	spin_unlock(&xprt->queue_lock);
1320 }
1321 
1322 static bool
1323 xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
1324 {
1325 	return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1326 }
1327 
1328 /**
1329  * xprt_request_enqueue_transmit - queue a task for transmission
1330  * @task: pointer to rpc_task
1331  *
1332  * Add a task to the transmission queue.
1333  */
1334 void
1335 xprt_request_enqueue_transmit(struct rpc_task *task)
1336 {
1337 	struct rpc_rqst *pos, *req = task->tk_rqstp;
1338 	struct rpc_xprt *xprt = req->rq_xprt;
1339 
1340 	if (xprt_request_need_enqueue_transmit(task, req)) {
1341 		req->rq_bytes_sent = 0;
1342 		spin_lock(&xprt->queue_lock);
1343 		/*
1344 		 * Requests that carry congestion control credits are added
1345 		 * to the head of the list to avoid starvation issues.
1346 		 */
1347 		if (req->rq_cong) {
1348 			xprt_clear_congestion_window_wait(xprt);
1349 			list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1350 				if (pos->rq_cong)
1351 					continue;
1352 				/* Note: req is added _before_ pos */
1353 				list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1354 				INIT_LIST_HEAD(&req->rq_xmit2);
1355 				goto out;
1356 			}
1357 		} else if (!req->rq_seqno) {
1358 			list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1359 				if (pos->rq_task->tk_owner != task->tk_owner)
1360 					continue;
1361 				list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
1362 				INIT_LIST_HEAD(&req->rq_xmit);
1363 				goto out;
1364 			}
1365 		}
1366 		list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
1367 		INIT_LIST_HEAD(&req->rq_xmit2);
1368 out:
1369 		atomic_long_inc(&xprt->xmit_queuelen);
1370 		set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1371 		spin_unlock(&xprt->queue_lock);
1372 	}
1373 }
1374 
1375 /**
1376  * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
1377  * @task: pointer to rpc_task
1378  *
1379  * Remove a task from the transmission queue
1380  * Caller must hold xprt->queue_lock
1381  */
1382 static void
1383 xprt_request_dequeue_transmit_locked(struct rpc_task *task)
1384 {
1385 	struct rpc_rqst *req = task->tk_rqstp;
1386 
1387 	if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1388 		return;
1389 	if (!list_empty(&req->rq_xmit)) {
1390 		list_del(&req->rq_xmit);
1391 		if (!list_empty(&req->rq_xmit2)) {
1392 			struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
1393 					struct rpc_rqst, rq_xmit2);
1394 			list_del(&req->rq_xmit2);
1395 			list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
1396 		}
1397 	} else
1398 		list_del(&req->rq_xmit2);
1399 	atomic_long_dec(&req->rq_xprt->xmit_queuelen);
1400 }
1401 
1402 /**
1403  * xprt_request_dequeue_transmit - remove a task from the transmission queue
1404  * @task: pointer to rpc_task
1405  *
1406  * Remove a task from the transmission queue
1407  */
1408 static void
1409 xprt_request_dequeue_transmit(struct rpc_task *task)
1410 {
1411 	struct rpc_rqst *req = task->tk_rqstp;
1412 	struct rpc_xprt *xprt = req->rq_xprt;
1413 
1414 	spin_lock(&xprt->queue_lock);
1415 	xprt_request_dequeue_transmit_locked(task);
1416 	spin_unlock(&xprt->queue_lock);
1417 }
1418 
1419 /**
1420  * xprt_request_dequeue_xprt - remove a task from the transmit+receive queue
1421  * @task: pointer to rpc_task
1422  *
1423  * Remove a task from the transmit and receive queues, and ensure that
1424  * it is not pinned by the receive work item.
1425  */
1426 void
1427 xprt_request_dequeue_xprt(struct rpc_task *task)
1428 {
1429 	struct rpc_rqst	*req = task->tk_rqstp;
1430 	struct rpc_xprt *xprt = req->rq_xprt;
1431 
1432 	if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
1433 	    test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
1434 	    xprt_is_pinned_rqst(req)) {
1435 		spin_lock(&xprt->queue_lock);
1436 		xprt_request_dequeue_transmit_locked(task);
1437 		xprt_request_dequeue_receive_locked(task);
1438 		while (xprt_is_pinned_rqst(req)) {
1439 			set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1440 			spin_unlock(&xprt->queue_lock);
1441 			xprt_wait_on_pinned_rqst(req);
1442 			spin_lock(&xprt->queue_lock);
1443 			clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1444 		}
1445 		spin_unlock(&xprt->queue_lock);
1446 	}
1447 }
1448 
1449 /**
1450  * xprt_request_prepare - prepare an encoded request for transport
1451  * @req: pointer to rpc_rqst
1452  *
1453  * Calls into the transport layer to do whatever is needed to prepare
1454  * the request for transmission or receive.
1455  * Returns error, or zero.
1456  */
1457 static int
1458 xprt_request_prepare(struct rpc_rqst *req)
1459 {
1460 	struct rpc_xprt *xprt = req->rq_xprt;
1461 
1462 	if (xprt->ops->prepare_request)
1463 		return xprt->ops->prepare_request(req);
1464 	return 0;
1465 }
1466 
1467 /**
1468  * xprt_request_need_retransmit - Test if a task needs retransmission
1469  * @task: pointer to rpc_task
1470  *
1471  * Test for whether a connection breakage requires the task to retransmit
1472  */
1473 bool
1474 xprt_request_need_retransmit(struct rpc_task *task)
1475 {
1476 	return xprt_request_retransmit_after_disconnect(task);
1477 }
1478 
1479 /**
1480  * xprt_prepare_transmit - reserve the transport before sending a request
1481  * @task: RPC task about to send a request
1482  *
1483  */
1484 bool xprt_prepare_transmit(struct rpc_task *task)
1485 {
1486 	struct rpc_rqst	*req = task->tk_rqstp;
1487 	struct rpc_xprt	*xprt = req->rq_xprt;
1488 
1489 	if (!xprt_lock_write(xprt, task)) {
1490 		/* Race breaker: someone may have transmitted us */
1491 		if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1492 			rpc_wake_up_queued_task_set_status(&xprt->sending,
1493 					task, 0);
1494 		return false;
1495 
1496 	}
1497 	if (atomic_read(&xprt->swapper))
1498 		/* This will be clear in __rpc_execute */
1499 		current->flags |= PF_MEMALLOC;
1500 	return true;
1501 }
1502 
1503 void xprt_end_transmit(struct rpc_task *task)
1504 {
1505 	struct rpc_xprt	*xprt = task->tk_rqstp->rq_xprt;
1506 
1507 	xprt_inject_disconnect(xprt);
1508 	xprt_release_write(xprt, task);
1509 }
1510 
1511 /**
1512  * xprt_request_transmit - send an RPC request on a transport
1513  * @req: pointer to request to transmit
1514  * @snd_task: RPC task that owns the transport lock
1515  *
1516  * This performs the transmission of a single request.
1517  * Note that if the request is not the same as snd_task, then it
1518  * does need to be pinned.
1519  * Returns '0' on success.
1520  */
1521 static int
1522 xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
1523 {
1524 	struct rpc_xprt *xprt = req->rq_xprt;
1525 	struct rpc_task *task = req->rq_task;
1526 	unsigned int connect_cookie;
1527 	int is_retrans = RPC_WAS_SENT(task);
1528 	int status;
1529 
1530 	if (!req->rq_bytes_sent) {
1531 		if (xprt_request_data_received(task)) {
1532 			status = 0;
1533 			goto out_dequeue;
1534 		}
1535 		/* Verify that our message lies in the RPCSEC_GSS window */
1536 		if (rpcauth_xmit_need_reencode(task)) {
1537 			status = -EBADMSG;
1538 			goto out_dequeue;
1539 		}
1540 		if (RPC_SIGNALLED(task)) {
1541 			status = -ERESTARTSYS;
1542 			goto out_dequeue;
1543 		}
1544 	}
1545 
1546 	/*
1547 	 * Update req->rq_ntrans before transmitting to avoid races with
1548 	 * xprt_update_rtt(), which needs to know that it is recording a
1549 	 * reply to the first transmission.
1550 	 */
1551 	req->rq_ntrans++;
1552 
1553 	trace_rpc_xdr_sendto(task, &req->rq_snd_buf);
1554 	connect_cookie = xprt->connect_cookie;
1555 	status = xprt->ops->send_request(req);
1556 	if (status != 0) {
1557 		req->rq_ntrans--;
1558 		trace_xprt_transmit(req, status);
1559 		return status;
1560 	}
1561 
1562 	if (is_retrans) {
1563 		task->tk_client->cl_stats->rpcretrans++;
1564 		trace_xprt_retransmit(req);
1565 	}
1566 
1567 	xprt_inject_disconnect(xprt);
1568 
1569 	task->tk_flags |= RPC_TASK_SENT;
1570 	spin_lock(&xprt->transport_lock);
1571 
1572 	xprt->stat.sends++;
1573 	xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1574 	xprt->stat.bklog_u += xprt->backlog.qlen;
1575 	xprt->stat.sending_u += xprt->sending.qlen;
1576 	xprt->stat.pending_u += xprt->pending.qlen;
1577 	spin_unlock(&xprt->transport_lock);
1578 
1579 	req->rq_connect_cookie = connect_cookie;
1580 out_dequeue:
1581 	trace_xprt_transmit(req, status);
1582 	xprt_request_dequeue_transmit(task);
1583 	rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
1584 	return status;
1585 }
1586 
1587 /**
1588  * xprt_transmit - send an RPC request on a transport
1589  * @task: controlling RPC task
1590  *
1591  * Attempts to drain the transmit queue. On exit, either the transport
1592  * signalled an error that needs to be handled before transmission can
1593  * resume, or @task finished transmitting, and detected that it already
1594  * received a reply.
1595  */
1596 void
1597 xprt_transmit(struct rpc_task *task)
1598 {
1599 	struct rpc_rqst *next, *req = task->tk_rqstp;
1600 	struct rpc_xprt	*xprt = req->rq_xprt;
1601 	int status;
1602 
1603 	spin_lock(&xprt->queue_lock);
1604 	for (;;) {
1605 		next = list_first_entry_or_null(&xprt->xmit_queue,
1606 						struct rpc_rqst, rq_xmit);
1607 		if (!next)
1608 			break;
1609 		xprt_pin_rqst(next);
1610 		spin_unlock(&xprt->queue_lock);
1611 		status = xprt_request_transmit(next, task);
1612 		if (status == -EBADMSG && next != req)
1613 			status = 0;
1614 		spin_lock(&xprt->queue_lock);
1615 		xprt_unpin_rqst(next);
1616 		if (status < 0) {
1617 			if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1618 				task->tk_status = status;
1619 			break;
1620 		}
1621 		/* Was @task transmitted, and has it received a reply? */
1622 		if (xprt_request_data_received(task) &&
1623 		    !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1624 			break;
1625 		cond_resched_lock(&xprt->queue_lock);
1626 	}
1627 	spin_unlock(&xprt->queue_lock);
1628 }
1629 
1630 static void xprt_complete_request_init(struct rpc_task *task)
1631 {
1632 	if (task->tk_rqstp)
1633 		xprt_request_init(task);
1634 }
1635 
1636 void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1637 {
1638 	set_bit(XPRT_CONGESTED, &xprt->state);
1639 	rpc_sleep_on(&xprt->backlog, task, xprt_complete_request_init);
1640 }
1641 EXPORT_SYMBOL_GPL(xprt_add_backlog);
1642 
1643 static bool __xprt_set_rq(struct rpc_task *task, void *data)
1644 {
1645 	struct rpc_rqst *req = data;
1646 
1647 	if (task->tk_rqstp == NULL) {
1648 		memset(req, 0, sizeof(*req));	/* mark unused */
1649 		task->tk_rqstp = req;
1650 		return true;
1651 	}
1652 	return false;
1653 }
1654 
1655 bool xprt_wake_up_backlog(struct rpc_xprt *xprt, struct rpc_rqst *req)
1656 {
1657 	if (rpc_wake_up_first(&xprt->backlog, __xprt_set_rq, req) == NULL) {
1658 		clear_bit(XPRT_CONGESTED, &xprt->state);
1659 		return false;
1660 	}
1661 	return true;
1662 }
1663 EXPORT_SYMBOL_GPL(xprt_wake_up_backlog);
1664 
1665 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1666 {
1667 	bool ret = false;
1668 
1669 	if (!test_bit(XPRT_CONGESTED, &xprt->state))
1670 		goto out;
1671 	spin_lock(&xprt->reserve_lock);
1672 	if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1673 		xprt_add_backlog(xprt, task);
1674 		ret = true;
1675 	}
1676 	spin_unlock(&xprt->reserve_lock);
1677 out:
1678 	return ret;
1679 }
1680 
1681 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1682 {
1683 	struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1684 
1685 	if (xprt->num_reqs >= xprt->max_reqs)
1686 		goto out;
1687 	++xprt->num_reqs;
1688 	spin_unlock(&xprt->reserve_lock);
1689 	req = kzalloc(sizeof(*req), rpc_task_gfp_mask());
1690 	spin_lock(&xprt->reserve_lock);
1691 	if (req != NULL)
1692 		goto out;
1693 	--xprt->num_reqs;
1694 	req = ERR_PTR(-ENOMEM);
1695 out:
1696 	return req;
1697 }
1698 
1699 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1700 {
1701 	if (xprt->num_reqs > xprt->min_reqs) {
1702 		--xprt->num_reqs;
1703 		kfree(req);
1704 		return true;
1705 	}
1706 	return false;
1707 }
1708 
1709 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1710 {
1711 	struct rpc_rqst *req;
1712 
1713 	spin_lock(&xprt->reserve_lock);
1714 	if (!list_empty(&xprt->free)) {
1715 		req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1716 		list_del(&req->rq_list);
1717 		goto out_init_req;
1718 	}
1719 	req = xprt_dynamic_alloc_slot(xprt);
1720 	if (!IS_ERR(req))
1721 		goto out_init_req;
1722 	switch (PTR_ERR(req)) {
1723 	case -ENOMEM:
1724 		dprintk("RPC:       dynamic allocation of request slot "
1725 				"failed! Retrying\n");
1726 		task->tk_status = -ENOMEM;
1727 		break;
1728 	case -EAGAIN:
1729 		xprt_add_backlog(xprt, task);
1730 		dprintk("RPC:       waiting for request slot\n");
1731 		fallthrough;
1732 	default:
1733 		task->tk_status = -EAGAIN;
1734 	}
1735 	spin_unlock(&xprt->reserve_lock);
1736 	return;
1737 out_init_req:
1738 	xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
1739 				     xprt->num_reqs);
1740 	spin_unlock(&xprt->reserve_lock);
1741 
1742 	task->tk_status = 0;
1743 	task->tk_rqstp = req;
1744 }
1745 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1746 
1747 void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1748 {
1749 	spin_lock(&xprt->reserve_lock);
1750 	if (!xprt_wake_up_backlog(xprt, req) &&
1751 	    !xprt_dynamic_free_slot(xprt, req)) {
1752 		memset(req, 0, sizeof(*req));	/* mark unused */
1753 		list_add(&req->rq_list, &xprt->free);
1754 	}
1755 	spin_unlock(&xprt->reserve_lock);
1756 }
1757 EXPORT_SYMBOL_GPL(xprt_free_slot);
1758 
1759 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1760 {
1761 	struct rpc_rqst *req;
1762 	while (!list_empty(&xprt->free)) {
1763 		req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1764 		list_del(&req->rq_list);
1765 		kfree(req);
1766 	}
1767 }
1768 
1769 static DEFINE_IDA(rpc_xprt_ids);
1770 
1771 void xprt_cleanup_ids(void)
1772 {
1773 	ida_destroy(&rpc_xprt_ids);
1774 }
1775 
1776 static int xprt_alloc_id(struct rpc_xprt *xprt)
1777 {
1778 	int id;
1779 
1780 	id = ida_simple_get(&rpc_xprt_ids, 0, 0, GFP_KERNEL);
1781 	if (id < 0)
1782 		return id;
1783 
1784 	xprt->id = id;
1785 	return 0;
1786 }
1787 
1788 static void xprt_free_id(struct rpc_xprt *xprt)
1789 {
1790 	ida_simple_remove(&rpc_xprt_ids, xprt->id);
1791 }
1792 
1793 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1794 		unsigned int num_prealloc,
1795 		unsigned int max_alloc)
1796 {
1797 	struct rpc_xprt *xprt;
1798 	struct rpc_rqst *req;
1799 	int i;
1800 
1801 	xprt = kzalloc(size, GFP_KERNEL);
1802 	if (xprt == NULL)
1803 		goto out;
1804 
1805 	xprt_alloc_id(xprt);
1806 	xprt_init(xprt, net);
1807 
1808 	for (i = 0; i < num_prealloc; i++) {
1809 		req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1810 		if (!req)
1811 			goto out_free;
1812 		list_add(&req->rq_list, &xprt->free);
1813 	}
1814 	if (max_alloc > num_prealloc)
1815 		xprt->max_reqs = max_alloc;
1816 	else
1817 		xprt->max_reqs = num_prealloc;
1818 	xprt->min_reqs = num_prealloc;
1819 	xprt->num_reqs = num_prealloc;
1820 
1821 	return xprt;
1822 
1823 out_free:
1824 	xprt_free(xprt);
1825 out:
1826 	return NULL;
1827 }
1828 EXPORT_SYMBOL_GPL(xprt_alloc);
1829 
1830 void xprt_free(struct rpc_xprt *xprt)
1831 {
1832 	put_net_track(xprt->xprt_net, &xprt->ns_tracker);
1833 	xprt_free_all_slots(xprt);
1834 	xprt_free_id(xprt);
1835 	rpc_sysfs_xprt_destroy(xprt);
1836 	kfree_rcu(xprt, rcu);
1837 }
1838 EXPORT_SYMBOL_GPL(xprt_free);
1839 
1840 static void
1841 xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
1842 {
1843 	req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
1844 }
1845 
1846 static __be32
1847 xprt_alloc_xid(struct rpc_xprt *xprt)
1848 {
1849 	__be32 xid;
1850 
1851 	spin_lock(&xprt->reserve_lock);
1852 	xid = (__force __be32)xprt->xid++;
1853 	spin_unlock(&xprt->reserve_lock);
1854 	return xid;
1855 }
1856 
1857 static void
1858 xprt_init_xid(struct rpc_xprt *xprt)
1859 {
1860 	xprt->xid = prandom_u32();
1861 }
1862 
1863 static void
1864 xprt_request_init(struct rpc_task *task)
1865 {
1866 	struct rpc_xprt *xprt = task->tk_xprt;
1867 	struct rpc_rqst	*req = task->tk_rqstp;
1868 
1869 	req->rq_task	= task;
1870 	req->rq_xprt    = xprt;
1871 	req->rq_buffer  = NULL;
1872 	req->rq_xid	= xprt_alloc_xid(xprt);
1873 	xprt_init_connect_cookie(req, xprt);
1874 	req->rq_snd_buf.len = 0;
1875 	req->rq_snd_buf.buflen = 0;
1876 	req->rq_rcv_buf.len = 0;
1877 	req->rq_rcv_buf.buflen = 0;
1878 	req->rq_snd_buf.bvec = NULL;
1879 	req->rq_rcv_buf.bvec = NULL;
1880 	req->rq_release_snd_buf = NULL;
1881 	xprt_init_majortimeo(task, req);
1882 
1883 	trace_xprt_reserve(req);
1884 }
1885 
1886 static void
1887 xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
1888 {
1889 	xprt->ops->alloc_slot(xprt, task);
1890 	if (task->tk_rqstp != NULL)
1891 		xprt_request_init(task);
1892 }
1893 
1894 /**
1895  * xprt_reserve - allocate an RPC request slot
1896  * @task: RPC task requesting a slot allocation
1897  *
1898  * If the transport is marked as being congested, or if no more
1899  * slots are available, place the task on the transport's
1900  * backlog queue.
1901  */
1902 void xprt_reserve(struct rpc_task *task)
1903 {
1904 	struct rpc_xprt *xprt = task->tk_xprt;
1905 
1906 	task->tk_status = 0;
1907 	if (task->tk_rqstp != NULL)
1908 		return;
1909 
1910 	task->tk_status = -EAGAIN;
1911 	if (!xprt_throttle_congested(xprt, task))
1912 		xprt_do_reserve(xprt, task);
1913 }
1914 
1915 /**
1916  * xprt_retry_reserve - allocate an RPC request slot
1917  * @task: RPC task requesting a slot allocation
1918  *
1919  * If no more slots are available, place the task on the transport's
1920  * backlog queue.
1921  * Note that the only difference with xprt_reserve is that we now
1922  * ignore the value of the XPRT_CONGESTED flag.
1923  */
1924 void xprt_retry_reserve(struct rpc_task *task)
1925 {
1926 	struct rpc_xprt *xprt = task->tk_xprt;
1927 
1928 	task->tk_status = 0;
1929 	if (task->tk_rqstp != NULL)
1930 		return;
1931 
1932 	task->tk_status = -EAGAIN;
1933 	xprt_do_reserve(xprt, task);
1934 }
1935 
1936 /**
1937  * xprt_release - release an RPC request slot
1938  * @task: task which is finished with the slot
1939  *
1940  */
1941 void xprt_release(struct rpc_task *task)
1942 {
1943 	struct rpc_xprt	*xprt;
1944 	struct rpc_rqst	*req = task->tk_rqstp;
1945 
1946 	if (req == NULL) {
1947 		if (task->tk_client) {
1948 			xprt = task->tk_xprt;
1949 			xprt_release_write(xprt, task);
1950 		}
1951 		return;
1952 	}
1953 
1954 	xprt = req->rq_xprt;
1955 	xprt_request_dequeue_xprt(task);
1956 	spin_lock(&xprt->transport_lock);
1957 	xprt->ops->release_xprt(xprt, task);
1958 	if (xprt->ops->release_request)
1959 		xprt->ops->release_request(task);
1960 	xprt_schedule_autodisconnect(xprt);
1961 	spin_unlock(&xprt->transport_lock);
1962 	if (req->rq_buffer)
1963 		xprt->ops->buf_free(task);
1964 	xdr_free_bvec(&req->rq_rcv_buf);
1965 	xdr_free_bvec(&req->rq_snd_buf);
1966 	if (req->rq_cred != NULL)
1967 		put_rpccred(req->rq_cred);
1968 	if (req->rq_release_snd_buf)
1969 		req->rq_release_snd_buf(req);
1970 
1971 	task->tk_rqstp = NULL;
1972 	if (likely(!bc_prealloc(req)))
1973 		xprt->ops->free_slot(xprt, req);
1974 	else
1975 		xprt_free_bc_request(req);
1976 }
1977 
1978 #ifdef CONFIG_SUNRPC_BACKCHANNEL
1979 void
1980 xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
1981 {
1982 	struct xdr_buf *xbufp = &req->rq_snd_buf;
1983 
1984 	task->tk_rqstp = req;
1985 	req->rq_task = task;
1986 	xprt_init_connect_cookie(req, req->rq_xprt);
1987 	/*
1988 	 * Set up the xdr_buf length.
1989 	 * This also indicates that the buffer is XDR encoded already.
1990 	 */
1991 	xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
1992 		xbufp->tail[0].iov_len;
1993 }
1994 #endif
1995 
1996 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1997 {
1998 	kref_init(&xprt->kref);
1999 
2000 	spin_lock_init(&xprt->transport_lock);
2001 	spin_lock_init(&xprt->reserve_lock);
2002 	spin_lock_init(&xprt->queue_lock);
2003 
2004 	INIT_LIST_HEAD(&xprt->free);
2005 	xprt->recv_queue = RB_ROOT;
2006 	INIT_LIST_HEAD(&xprt->xmit_queue);
2007 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
2008 	spin_lock_init(&xprt->bc_pa_lock);
2009 	INIT_LIST_HEAD(&xprt->bc_pa_list);
2010 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
2011 	INIT_LIST_HEAD(&xprt->xprt_switch);
2012 
2013 	xprt->last_used = jiffies;
2014 	xprt->cwnd = RPC_INITCWND;
2015 	xprt->bind_index = 0;
2016 
2017 	rpc_init_wait_queue(&xprt->binding, "xprt_binding");
2018 	rpc_init_wait_queue(&xprt->pending, "xprt_pending");
2019 	rpc_init_wait_queue(&xprt->sending, "xprt_sending");
2020 	rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
2021 
2022 	xprt_init_xid(xprt);
2023 
2024 	xprt->xprt_net = get_net_track(net, &xprt->ns_tracker, GFP_KERNEL);
2025 }
2026 
2027 /**
2028  * xprt_create_transport - create an RPC transport
2029  * @args: rpc transport creation arguments
2030  *
2031  */
2032 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
2033 {
2034 	struct rpc_xprt	*xprt;
2035 	const struct xprt_class *t;
2036 
2037 	t = xprt_class_find_by_ident(args->ident);
2038 	if (!t) {
2039 		dprintk("RPC: transport (%d) not supported\n", args->ident);
2040 		return ERR_PTR(-EIO);
2041 	}
2042 
2043 	xprt = t->setup(args);
2044 	xprt_class_release(t);
2045 
2046 	if (IS_ERR(xprt))
2047 		goto out;
2048 	if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
2049 		xprt->idle_timeout = 0;
2050 	INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
2051 	if (xprt_has_timer(xprt))
2052 		timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
2053 	else
2054 		timer_setup(&xprt->timer, NULL, 0);
2055 
2056 	if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
2057 		xprt_destroy(xprt);
2058 		return ERR_PTR(-EINVAL);
2059 	}
2060 	xprt->servername = kstrdup(args->servername, GFP_KERNEL);
2061 	if (xprt->servername == NULL) {
2062 		xprt_destroy(xprt);
2063 		return ERR_PTR(-ENOMEM);
2064 	}
2065 
2066 	rpc_xprt_debugfs_register(xprt);
2067 
2068 	trace_xprt_create(xprt);
2069 out:
2070 	return xprt;
2071 }
2072 
2073 static void xprt_destroy_cb(struct work_struct *work)
2074 {
2075 	struct rpc_xprt *xprt =
2076 		container_of(work, struct rpc_xprt, task_cleanup);
2077 
2078 	trace_xprt_destroy(xprt);
2079 
2080 	rpc_xprt_debugfs_unregister(xprt);
2081 	rpc_destroy_wait_queue(&xprt->binding);
2082 	rpc_destroy_wait_queue(&xprt->pending);
2083 	rpc_destroy_wait_queue(&xprt->sending);
2084 	rpc_destroy_wait_queue(&xprt->backlog);
2085 	kfree(xprt->servername);
2086 	/*
2087 	 * Destroy any existing back channel
2088 	 */
2089 	xprt_destroy_backchannel(xprt, UINT_MAX);
2090 
2091 	/*
2092 	 * Tear down transport state and free the rpc_xprt
2093 	 */
2094 	xprt->ops->destroy(xprt);
2095 }
2096 
2097 /**
2098  * xprt_destroy - destroy an RPC transport, killing off all requests.
2099  * @xprt: transport to destroy
2100  *
2101  */
2102 static void xprt_destroy(struct rpc_xprt *xprt)
2103 {
2104 	/*
2105 	 * Exclude transport connect/disconnect handlers and autoclose
2106 	 */
2107 	wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
2108 
2109 	/*
2110 	 * xprt_schedule_autodisconnect() can run after XPRT_LOCKED
2111 	 * is cleared.  We use ->transport_lock to ensure the mod_timer()
2112 	 * can only run *before* del_time_sync(), never after.
2113 	 */
2114 	spin_lock(&xprt->transport_lock);
2115 	del_timer_sync(&xprt->timer);
2116 	spin_unlock(&xprt->transport_lock);
2117 
2118 	/*
2119 	 * Destroy sockets etc from the system workqueue so they can
2120 	 * safely flush receive work running on rpciod.
2121 	 */
2122 	INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
2123 	schedule_work(&xprt->task_cleanup);
2124 }
2125 
2126 static void xprt_destroy_kref(struct kref *kref)
2127 {
2128 	xprt_destroy(container_of(kref, struct rpc_xprt, kref));
2129 }
2130 
2131 /**
2132  * xprt_get - return a reference to an RPC transport.
2133  * @xprt: pointer to the transport
2134  *
2135  */
2136 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
2137 {
2138 	if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
2139 		return xprt;
2140 	return NULL;
2141 }
2142 EXPORT_SYMBOL_GPL(xprt_get);
2143 
2144 /**
2145  * xprt_put - release a reference to an RPC transport.
2146  * @xprt: pointer to the transport
2147  *
2148  */
2149 void xprt_put(struct rpc_xprt *xprt)
2150 {
2151 	if (xprt != NULL)
2152 		kref_put(&xprt->kref, xprt_destroy_kref);
2153 }
2154 EXPORT_SYMBOL_GPL(xprt_put);
2155