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Linux/net/sunrpc/xprt.c

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  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 '' 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 

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