~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/net/sunrpc/xprt.c

Version: ~ [ linux-5.12-rc7 ] ~ [ linux-5.11.13 ] ~ [ linux-5.10.29 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.111 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.186 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.230 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.266 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.266 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp