Merge tag 'nfs-for-4.15-3' of git://git.linux-nfs.org/projects/anna/linux-nfs
[sfrench/cifs-2.6.git] / net / sunrpc / xprt.c
1 /*
2  *  linux/net/sunrpc/xprt.c
3  *
4  *  This is a generic RPC call interface supporting congestion avoidance,
5  *  and asynchronous calls.
6  *
7  *  The interface works like this:
8  *
9  *  -   When a process places a call, it allocates a request slot if
10  *      one is available. Otherwise, it sleeps on the backlog queue
11  *      (xprt_reserve).
12  *  -   Next, the caller puts together the RPC message, stuffs it into
13  *      the request struct, and calls xprt_transmit().
14  *  -   xprt_transmit sends the message and installs the caller on the
15  *      transport's wait list. At the same time, if a reply is expected,
16  *      it installs a timer that is run after the packet's timeout has
17  *      expired.
18  *  -   When a packet arrives, the data_ready handler walks the list of
19  *      pending requests for that transport. If a matching XID is found, the
20  *      caller is woken up, and the timer removed.
21  *  -   When no reply arrives within the timeout interval, the timer is
22  *      fired by the kernel and runs xprt_timer(). It either adjusts the
23  *      timeout values (minor timeout) or wakes up the caller with a status
24  *      of -ETIMEDOUT.
25  *  -   When the caller receives a notification from RPC that a reply arrived,
26  *      it should release the RPC slot, and process the reply.
27  *      If the call timed out, it may choose to retry the operation by
28  *      adjusting the initial timeout value, and simply calling rpc_call
29  *      again.
30  *
31  *  Support for async RPC is done through a set of RPC-specific scheduling
32  *  primitives that `transparently' work for processes as well as async
33  *  tasks that rely on callbacks.
34  *
35  *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
36  *
37  *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
38  */
39
40 #include <linux/module.h>
41
42 #include <linux/types.h>
43 #include <linux/interrupt.h>
44 #include <linux/workqueue.h>
45 #include <linux/net.h>
46 #include <linux/ktime.h>
47
48 #include <linux/sunrpc/clnt.h>
49 #include <linux/sunrpc/metrics.h>
50 #include <linux/sunrpc/bc_xprt.h>
51 #include <linux/rcupdate.h>
52
53 #include <trace/events/sunrpc.h>
54
55 #include "sunrpc.h"
56
57 /*
58  * Local variables
59  */
60
61 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
62 # define RPCDBG_FACILITY        RPCDBG_XPRT
63 #endif
64
65 /*
66  * Local functions
67  */
68 static void      xprt_init(struct rpc_xprt *xprt, struct net *net);
69 static void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
70 static void     xprt_connect_status(struct rpc_task *task);
71 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
72 static void     __xprt_put_cong(struct rpc_xprt *, struct rpc_rqst *);
73 static void      xprt_destroy(struct rpc_xprt *xprt);
74
75 static DEFINE_SPINLOCK(xprt_list_lock);
76 static LIST_HEAD(xprt_list);
77
78 /**
79  * xprt_register_transport - register a transport implementation
80  * @transport: transport to register
81  *
82  * If a transport implementation is loaded as a kernel module, it can
83  * call this interface to make itself known to the RPC client.
84  *
85  * Returns:
86  * 0:           transport successfully registered
87  * -EEXIST:     transport already registered
88  * -EINVAL:     transport module being unloaded
89  */
90 int xprt_register_transport(struct xprt_class *transport)
91 {
92         struct xprt_class *t;
93         int result;
94
95         result = -EEXIST;
96         spin_lock(&xprt_list_lock);
97         list_for_each_entry(t, &xprt_list, list) {
98                 /* don't register the same transport class twice */
99                 if (t->ident == transport->ident)
100                         goto out;
101         }
102
103         list_add_tail(&transport->list, &xprt_list);
104         printk(KERN_INFO "RPC: Registered %s transport module.\n",
105                transport->name);
106         result = 0;
107
108 out:
109         spin_unlock(&xprt_list_lock);
110         return result;
111 }
112 EXPORT_SYMBOL_GPL(xprt_register_transport);
113
114 /**
115  * xprt_unregister_transport - unregister a transport implementation
116  * @transport: transport to unregister
117  *
118  * Returns:
119  * 0:           transport successfully unregistered
120  * -ENOENT:     transport never registered
121  */
122 int xprt_unregister_transport(struct xprt_class *transport)
123 {
124         struct xprt_class *t;
125         int result;
126
127         result = 0;
128         spin_lock(&xprt_list_lock);
129         list_for_each_entry(t, &xprt_list, list) {
130                 if (t == transport) {
131                         printk(KERN_INFO
132                                 "RPC: Unregistered %s transport module.\n",
133                                 transport->name);
134                         list_del_init(&transport->list);
135                         goto out;
136                 }
137         }
138         result = -ENOENT;
139
140 out:
141         spin_unlock(&xprt_list_lock);
142         return result;
143 }
144 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
145
146 /**
147  * xprt_load_transport - load a transport implementation
148  * @transport_name: transport to load
149  *
150  * Returns:
151  * 0:           transport successfully loaded
152  * -ENOENT:     transport module not available
153  */
154 int xprt_load_transport(const char *transport_name)
155 {
156         struct xprt_class *t;
157         int result;
158
159         result = 0;
160         spin_lock(&xprt_list_lock);
161         list_for_each_entry(t, &xprt_list, list) {
162                 if (strcmp(t->name, transport_name) == 0) {
163                         spin_unlock(&xprt_list_lock);
164                         goto out;
165                 }
166         }
167         spin_unlock(&xprt_list_lock);
168         result = request_module("xprt%s", transport_name);
169 out:
170         return result;
171 }
172 EXPORT_SYMBOL_GPL(xprt_load_transport);
173
174 /**
175  * xprt_reserve_xprt - serialize write access to transports
176  * @task: task that is requesting access to the transport
177  * @xprt: pointer to the target transport
178  *
179  * This prevents mixing the payload of separate requests, and prevents
180  * transport connects from colliding with writes.  No congestion control
181  * is provided.
182  */
183 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
184 {
185         struct rpc_rqst *req = task->tk_rqstp;
186         int priority;
187
188         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
189                 if (task == xprt->snd_task)
190                         return 1;
191                 goto out_sleep;
192         }
193         xprt->snd_task = task;
194         if (req != NULL)
195                 req->rq_ntrans++;
196
197         return 1;
198
199 out_sleep:
200         dprintk("RPC: %5u failed to lock transport %p\n",
201                         task->tk_pid, xprt);
202         task->tk_timeout = 0;
203         task->tk_status = -EAGAIN;
204         if (req == NULL)
205                 priority = RPC_PRIORITY_LOW;
206         else if (!req->rq_ntrans)
207                 priority = RPC_PRIORITY_NORMAL;
208         else
209                 priority = RPC_PRIORITY_HIGH;
210         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
211         return 0;
212 }
213 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
214
215 static void xprt_clear_locked(struct rpc_xprt *xprt)
216 {
217         xprt->snd_task = NULL;
218         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
219                 smp_mb__before_atomic();
220                 clear_bit(XPRT_LOCKED, &xprt->state);
221                 smp_mb__after_atomic();
222         } else
223                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
224 }
225
226 /*
227  * xprt_reserve_xprt_cong - serialize write access to transports
228  * @task: task that is requesting access to the transport
229  *
230  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
231  * integrated into the decision of whether a request is allowed to be
232  * woken up and given access to the transport.
233  */
234 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
235 {
236         struct rpc_rqst *req = task->tk_rqstp;
237         int priority;
238
239         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
240                 if (task == xprt->snd_task)
241                         return 1;
242                 goto out_sleep;
243         }
244         if (req == NULL) {
245                 xprt->snd_task = task;
246                 return 1;
247         }
248         if (__xprt_get_cong(xprt, task)) {
249                 xprt->snd_task = task;
250                 req->rq_ntrans++;
251                 return 1;
252         }
253         xprt_clear_locked(xprt);
254 out_sleep:
255         if (req)
256                 __xprt_put_cong(xprt, req);
257         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
258         task->tk_timeout = 0;
259         task->tk_status = -EAGAIN;
260         if (req == NULL)
261                 priority = RPC_PRIORITY_LOW;
262         else if (!req->rq_ntrans)
263                 priority = RPC_PRIORITY_NORMAL;
264         else
265                 priority = RPC_PRIORITY_HIGH;
266         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
267         return 0;
268 }
269 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
270
271 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
272 {
273         int retval;
274
275         spin_lock_bh(&xprt->transport_lock);
276         retval = xprt->ops->reserve_xprt(xprt, task);
277         spin_unlock_bh(&xprt->transport_lock);
278         return retval;
279 }
280
281 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
282 {
283         struct rpc_xprt *xprt = data;
284         struct rpc_rqst *req;
285
286         req = task->tk_rqstp;
287         xprt->snd_task = task;
288         if (req)
289                 req->rq_ntrans++;
290         return true;
291 }
292
293 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
294 {
295         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
296                 return;
297
298         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
299                                 __xprt_lock_write_func, xprt))
300                 return;
301         xprt_clear_locked(xprt);
302 }
303
304 static bool __xprt_lock_write_cong_func(struct rpc_task *task, void *data)
305 {
306         struct rpc_xprt *xprt = data;
307         struct rpc_rqst *req;
308
309         req = task->tk_rqstp;
310         if (req == NULL) {
311                 xprt->snd_task = task;
312                 return true;
313         }
314         if (__xprt_get_cong(xprt, task)) {
315                 xprt->snd_task = task;
316                 req->rq_ntrans++;
317                 return true;
318         }
319         return false;
320 }
321
322 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
323 {
324         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
325                 return;
326         if (RPCXPRT_CONGESTED(xprt))
327                 goto out_unlock;
328         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
329                                 __xprt_lock_write_cong_func, xprt))
330                 return;
331 out_unlock:
332         xprt_clear_locked(xprt);
333 }
334
335 static void xprt_task_clear_bytes_sent(struct rpc_task *task)
336 {
337         if (task != NULL) {
338                 struct rpc_rqst *req = task->tk_rqstp;
339                 if (req != NULL)
340                         req->rq_bytes_sent = 0;
341         }
342 }
343
344 /**
345  * xprt_release_xprt - allow other requests to use a transport
346  * @xprt: transport with other tasks potentially waiting
347  * @task: task that is releasing access to the transport
348  *
349  * Note that "task" can be NULL.  No congestion control is provided.
350  */
351 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
352 {
353         if (xprt->snd_task == task) {
354                 xprt_task_clear_bytes_sent(task);
355                 xprt_clear_locked(xprt);
356                 __xprt_lock_write_next(xprt);
357         }
358 }
359 EXPORT_SYMBOL_GPL(xprt_release_xprt);
360
361 /**
362  * xprt_release_xprt_cong - allow other requests to use a transport
363  * @xprt: transport with other tasks potentially waiting
364  * @task: task that is releasing access to the transport
365  *
366  * Note that "task" can be NULL.  Another task is awoken to use the
367  * transport if the transport's congestion window allows it.
368  */
369 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
370 {
371         if (xprt->snd_task == task) {
372                 xprt_task_clear_bytes_sent(task);
373                 xprt_clear_locked(xprt);
374                 __xprt_lock_write_next_cong(xprt);
375         }
376 }
377 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
378
379 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
380 {
381         spin_lock_bh(&xprt->transport_lock);
382         xprt->ops->release_xprt(xprt, task);
383         spin_unlock_bh(&xprt->transport_lock);
384 }
385
386 /*
387  * Van Jacobson congestion avoidance. Check if the congestion window
388  * overflowed. Put the task to sleep if this is the case.
389  */
390 static int
391 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
392 {
393         struct rpc_rqst *req = task->tk_rqstp;
394
395         if (req->rq_cong)
396                 return 1;
397         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
398                         task->tk_pid, xprt->cong, xprt->cwnd);
399         if (RPCXPRT_CONGESTED(xprt))
400                 return 0;
401         req->rq_cong = 1;
402         xprt->cong += RPC_CWNDSCALE;
403         return 1;
404 }
405
406 /*
407  * Adjust the congestion window, and wake up the next task
408  * that has been sleeping due to congestion
409  */
410 static void
411 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
412 {
413         if (!req->rq_cong)
414                 return;
415         req->rq_cong = 0;
416         xprt->cong -= RPC_CWNDSCALE;
417         __xprt_lock_write_next_cong(xprt);
418 }
419
420 /**
421  * xprt_release_rqst_cong - housekeeping when request is complete
422  * @task: RPC request that recently completed
423  *
424  * Useful for transports that require congestion control.
425  */
426 void xprt_release_rqst_cong(struct rpc_task *task)
427 {
428         struct rpc_rqst *req = task->tk_rqstp;
429
430         __xprt_put_cong(req->rq_xprt, req);
431 }
432 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
433
434 /**
435  * xprt_adjust_cwnd - adjust transport congestion window
436  * @xprt: pointer to xprt
437  * @task: recently completed RPC request used to adjust window
438  * @result: result code of completed RPC request
439  *
440  * The transport code maintains an estimate on the maximum number of out-
441  * standing RPC requests, using a smoothed version of the congestion
442  * avoidance implemented in 44BSD. This is basically the Van Jacobson
443  * congestion algorithm: If a retransmit occurs, the congestion window is
444  * halved; otherwise, it is incremented by 1/cwnd when
445  *
446  *      -       a reply is received and
447  *      -       a full number of requests are outstanding and
448  *      -       the congestion window hasn't been updated recently.
449  */
450 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
451 {
452         struct rpc_rqst *req = task->tk_rqstp;
453         unsigned long cwnd = xprt->cwnd;
454
455         if (result >= 0 && cwnd <= xprt->cong) {
456                 /* The (cwnd >> 1) term makes sure
457                  * the result gets rounded properly. */
458                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
459                 if (cwnd > RPC_MAXCWND(xprt))
460                         cwnd = RPC_MAXCWND(xprt);
461                 __xprt_lock_write_next_cong(xprt);
462         } else if (result == -ETIMEDOUT) {
463                 cwnd >>= 1;
464                 if (cwnd < RPC_CWNDSCALE)
465                         cwnd = RPC_CWNDSCALE;
466         }
467         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
468                         xprt->cong, xprt->cwnd, cwnd);
469         xprt->cwnd = cwnd;
470         __xprt_put_cong(xprt, req);
471 }
472 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
473
474 /**
475  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
476  * @xprt: transport with waiting tasks
477  * @status: result code to plant in each task before waking it
478  *
479  */
480 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
481 {
482         if (status < 0)
483                 rpc_wake_up_status(&xprt->pending, status);
484         else
485                 rpc_wake_up(&xprt->pending);
486 }
487 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
488
489 /**
490  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
491  * @task: task to be put to sleep
492  * @action: function pointer to be executed after wait
493  *
494  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
495  * we don't in general want to force a socket disconnection due to
496  * an incomplete RPC call transmission.
497  */
498 void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
499 {
500         struct rpc_rqst *req = task->tk_rqstp;
501         struct rpc_xprt *xprt = req->rq_xprt;
502
503         task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
504         rpc_sleep_on(&xprt->pending, task, action);
505 }
506 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
507
508 /**
509  * xprt_write_space - wake the task waiting for transport output buffer space
510  * @xprt: transport with waiting tasks
511  *
512  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
513  */
514 void xprt_write_space(struct rpc_xprt *xprt)
515 {
516         spin_lock_bh(&xprt->transport_lock);
517         if (xprt->snd_task) {
518                 dprintk("RPC:       write space: waking waiting task on "
519                                 "xprt %p\n", xprt);
520                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
521         }
522         spin_unlock_bh(&xprt->transport_lock);
523 }
524 EXPORT_SYMBOL_GPL(xprt_write_space);
525
526 /**
527  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
528  * @task: task whose timeout is to be set
529  *
530  * Set a request's retransmit timeout based on the transport's
531  * default timeout parameters.  Used by transports that don't adjust
532  * the retransmit timeout based on round-trip time estimation.
533  */
534 void xprt_set_retrans_timeout_def(struct rpc_task *task)
535 {
536         task->tk_timeout = task->tk_rqstp->rq_timeout;
537 }
538 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
539
540 /**
541  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
542  * @task: task whose timeout is to be set
543  *
544  * Set a request's retransmit timeout using the RTT estimator.
545  */
546 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
547 {
548         int timer = task->tk_msg.rpc_proc->p_timer;
549         struct rpc_clnt *clnt = task->tk_client;
550         struct rpc_rtt *rtt = clnt->cl_rtt;
551         struct rpc_rqst *req = task->tk_rqstp;
552         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
553
554         task->tk_timeout = rpc_calc_rto(rtt, timer);
555         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
556         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
557                 task->tk_timeout = max_timeout;
558 }
559 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
560
561 static void xprt_reset_majortimeo(struct rpc_rqst *req)
562 {
563         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
564
565         req->rq_majortimeo = req->rq_timeout;
566         if (to->to_exponential)
567                 req->rq_majortimeo <<= to->to_retries;
568         else
569                 req->rq_majortimeo += to->to_increment * to->to_retries;
570         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
571                 req->rq_majortimeo = to->to_maxval;
572         req->rq_majortimeo += jiffies;
573 }
574
575 /**
576  * xprt_adjust_timeout - adjust timeout values for next retransmit
577  * @req: RPC request containing parameters to use for the adjustment
578  *
579  */
580 int xprt_adjust_timeout(struct rpc_rqst *req)
581 {
582         struct rpc_xprt *xprt = req->rq_xprt;
583         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
584         int status = 0;
585
586         if (time_before(jiffies, req->rq_majortimeo)) {
587                 if (to->to_exponential)
588                         req->rq_timeout <<= 1;
589                 else
590                         req->rq_timeout += to->to_increment;
591                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
592                         req->rq_timeout = to->to_maxval;
593                 req->rq_retries++;
594         } else {
595                 req->rq_timeout = to->to_initval;
596                 req->rq_retries = 0;
597                 xprt_reset_majortimeo(req);
598                 /* Reset the RTT counters == "slow start" */
599                 spin_lock_bh(&xprt->transport_lock);
600                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
601                 spin_unlock_bh(&xprt->transport_lock);
602                 status = -ETIMEDOUT;
603         }
604
605         if (req->rq_timeout == 0) {
606                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
607                 req->rq_timeout = 5 * HZ;
608         }
609         return status;
610 }
611
612 static void xprt_autoclose(struct work_struct *work)
613 {
614         struct rpc_xprt *xprt =
615                 container_of(work, struct rpc_xprt, task_cleanup);
616
617         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
618         xprt->ops->close(xprt);
619         xprt_release_write(xprt, NULL);
620         wake_up_bit(&xprt->state, XPRT_LOCKED);
621 }
622
623 /**
624  * xprt_disconnect_done - mark a transport as disconnected
625  * @xprt: transport to flag for disconnect
626  *
627  */
628 void xprt_disconnect_done(struct rpc_xprt *xprt)
629 {
630         dprintk("RPC:       disconnected transport %p\n", xprt);
631         spin_lock_bh(&xprt->transport_lock);
632         xprt_clear_connected(xprt);
633         xprt_wake_pending_tasks(xprt, -EAGAIN);
634         spin_unlock_bh(&xprt->transport_lock);
635 }
636 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
637
638 /**
639  * xprt_force_disconnect - force a transport to disconnect
640  * @xprt: transport to disconnect
641  *
642  */
643 void xprt_force_disconnect(struct rpc_xprt *xprt)
644 {
645         /* Don't race with the test_bit() in xprt_clear_locked() */
646         spin_lock_bh(&xprt->transport_lock);
647         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
648         /* Try to schedule an autoclose RPC call */
649         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
650                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
651         xprt_wake_pending_tasks(xprt, -EAGAIN);
652         spin_unlock_bh(&xprt->transport_lock);
653 }
654 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
655
656 /**
657  * xprt_conditional_disconnect - force a transport to disconnect
658  * @xprt: transport to disconnect
659  * @cookie: 'connection cookie'
660  *
661  * This attempts to break the connection if and only if 'cookie' matches
662  * the current transport 'connection cookie'. It ensures that we don't
663  * try to break the connection more than once when we need to retransmit
664  * a batch of RPC requests.
665  *
666  */
667 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
668 {
669         /* Don't race with the test_bit() in xprt_clear_locked() */
670         spin_lock_bh(&xprt->transport_lock);
671         if (cookie != xprt->connect_cookie)
672                 goto out;
673         if (test_bit(XPRT_CLOSING, &xprt->state))
674                 goto out;
675         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
676         /* Try to schedule an autoclose RPC call */
677         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
678                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
679         xprt_wake_pending_tasks(xprt, -EAGAIN);
680 out:
681         spin_unlock_bh(&xprt->transport_lock);
682 }
683
684 static bool
685 xprt_has_timer(const struct rpc_xprt *xprt)
686 {
687         return xprt->idle_timeout != 0;
688 }
689
690 static void
691 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
692         __must_hold(&xprt->transport_lock)
693 {
694         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
695                 mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
696 }
697
698 static void
699 xprt_init_autodisconnect(struct timer_list *t)
700 {
701         struct rpc_xprt *xprt = from_timer(xprt, t, timer);
702
703         spin_lock(&xprt->transport_lock);
704         if (!list_empty(&xprt->recv))
705                 goto out_abort;
706         /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
707         xprt->last_used = jiffies;
708         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
709                 goto out_abort;
710         spin_unlock(&xprt->transport_lock);
711         queue_work(xprtiod_workqueue, &xprt->task_cleanup);
712         return;
713 out_abort:
714         spin_unlock(&xprt->transport_lock);
715 }
716
717 bool xprt_lock_connect(struct rpc_xprt *xprt,
718                 struct rpc_task *task,
719                 void *cookie)
720 {
721         bool ret = false;
722
723         spin_lock_bh(&xprt->transport_lock);
724         if (!test_bit(XPRT_LOCKED, &xprt->state))
725                 goto out;
726         if (xprt->snd_task != task)
727                 goto out;
728         xprt_task_clear_bytes_sent(task);
729         xprt->snd_task = cookie;
730         ret = true;
731 out:
732         spin_unlock_bh(&xprt->transport_lock);
733         return ret;
734 }
735
736 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
737 {
738         spin_lock_bh(&xprt->transport_lock);
739         if (xprt->snd_task != cookie)
740                 goto out;
741         if (!test_bit(XPRT_LOCKED, &xprt->state))
742                 goto out;
743         xprt->snd_task =NULL;
744         xprt->ops->release_xprt(xprt, NULL);
745         xprt_schedule_autodisconnect(xprt);
746 out:
747         spin_unlock_bh(&xprt->transport_lock);
748         wake_up_bit(&xprt->state, XPRT_LOCKED);
749 }
750
751 /**
752  * xprt_connect - schedule a transport connect operation
753  * @task: RPC task that is requesting the connect
754  *
755  */
756 void xprt_connect(struct rpc_task *task)
757 {
758         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
759
760         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
761                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
762
763         if (!xprt_bound(xprt)) {
764                 task->tk_status = -EAGAIN;
765                 return;
766         }
767         if (!xprt_lock_write(xprt, task))
768                 return;
769
770         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
771                 xprt->ops->close(xprt);
772
773         if (!xprt_connected(xprt)) {
774                 task->tk_rqstp->rq_bytes_sent = 0;
775                 task->tk_timeout = task->tk_rqstp->rq_timeout;
776                 task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
777                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
778
779                 if (test_bit(XPRT_CLOSING, &xprt->state))
780                         return;
781                 if (xprt_test_and_set_connecting(xprt))
782                         return;
783                 xprt->stat.connect_start = jiffies;
784                 xprt->ops->connect(xprt, task);
785         }
786         xprt_release_write(xprt, task);
787 }
788
789 static void xprt_connect_status(struct rpc_task *task)
790 {
791         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
792
793         if (task->tk_status == 0) {
794                 xprt->stat.connect_count++;
795                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
796                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
797                                 task->tk_pid);
798                 return;
799         }
800
801         switch (task->tk_status) {
802         case -ECONNREFUSED:
803         case -ECONNRESET:
804         case -ECONNABORTED:
805         case -ENETUNREACH:
806         case -EHOSTUNREACH:
807         case -EPIPE:
808         case -EAGAIN:
809                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
810                 break;
811         case -ETIMEDOUT:
812                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
813                                 "out\n", task->tk_pid);
814                 break;
815         default:
816                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
817                                 "server %s\n", task->tk_pid, -task->tk_status,
818                                 xprt->servername);
819                 task->tk_status = -EIO;
820         }
821 }
822
823 /**
824  * xprt_lookup_rqst - find an RPC request corresponding to an XID
825  * @xprt: transport on which the original request was transmitted
826  * @xid: RPC XID of incoming reply
827  *
828  */
829 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
830 {
831         struct rpc_rqst *entry;
832
833         list_for_each_entry(entry, &xprt->recv, rq_list)
834                 if (entry->rq_xid == xid) {
835                         trace_xprt_lookup_rqst(xprt, xid, 0);
836                         return entry;
837                 }
838
839         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
840                         ntohl(xid));
841         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
842         xprt->stat.bad_xids++;
843         return NULL;
844 }
845 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
846
847 /**
848  * xprt_pin_rqst - Pin a request on the transport receive list
849  * @req: Request to pin
850  *
851  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
852  * so should be holding the xprt transport lock.
853  */
854 void xprt_pin_rqst(struct rpc_rqst *req)
855 {
856         set_bit(RPC_TASK_MSG_RECV, &req->rq_task->tk_runstate);
857 }
858 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
859
860 /**
861  * xprt_unpin_rqst - Unpin a request on the transport receive list
862  * @req: Request to pin
863  *
864  * Caller should be holding the xprt transport lock.
865  */
866 void xprt_unpin_rqst(struct rpc_rqst *req)
867 {
868         struct rpc_task *task = req->rq_task;
869
870         clear_bit(RPC_TASK_MSG_RECV, &task->tk_runstate);
871         if (test_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate))
872                 wake_up_bit(&task->tk_runstate, RPC_TASK_MSG_RECV);
873 }
874 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
875
876 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
877 __must_hold(&req->rq_xprt->recv_lock)
878 {
879         struct rpc_task *task = req->rq_task;
880         
881         if (task && test_bit(RPC_TASK_MSG_RECV, &task->tk_runstate)) {
882                 spin_unlock(&req->rq_xprt->recv_lock);
883                 set_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
884                 wait_on_bit(&task->tk_runstate, RPC_TASK_MSG_RECV,
885                                 TASK_UNINTERRUPTIBLE);
886                 clear_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
887                 spin_lock(&req->rq_xprt->recv_lock);
888         }
889 }
890
891 static void xprt_update_rtt(struct rpc_task *task)
892 {
893         struct rpc_rqst *req = task->tk_rqstp;
894         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
895         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
896         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
897
898         if (timer) {
899                 if (req->rq_ntrans == 1)
900                         rpc_update_rtt(rtt, timer, m);
901                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
902         }
903 }
904
905 /**
906  * xprt_complete_rqst - called when reply processing is complete
907  * @task: RPC request that recently completed
908  * @copied: actual number of bytes received from the transport
909  *
910  * Caller holds transport lock.
911  */
912 void xprt_complete_rqst(struct rpc_task *task, int copied)
913 {
914         struct rpc_rqst *req = task->tk_rqstp;
915         struct rpc_xprt *xprt = req->rq_xprt;
916
917         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
918                         task->tk_pid, ntohl(req->rq_xid), copied);
919         trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
920
921         xprt->stat.recvs++;
922         req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
923         if (xprt->ops->timer != NULL)
924                 xprt_update_rtt(task);
925
926         list_del_init(&req->rq_list);
927         req->rq_private_buf.len = copied;
928         /* Ensure all writes are done before we update */
929         /* req->rq_reply_bytes_recvd */
930         smp_wmb();
931         req->rq_reply_bytes_recvd = copied;
932         rpc_wake_up_queued_task(&xprt->pending, task);
933 }
934 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
935
936 static void xprt_timer(struct rpc_task *task)
937 {
938         struct rpc_rqst *req = task->tk_rqstp;
939         struct rpc_xprt *xprt = req->rq_xprt;
940
941         if (task->tk_status != -ETIMEDOUT)
942                 return;
943         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
944
945         if (!req->rq_reply_bytes_recvd) {
946                 if (xprt->ops->timer)
947                         xprt->ops->timer(xprt, task);
948         } else
949                 task->tk_status = 0;
950 }
951
952 /**
953  * xprt_prepare_transmit - reserve the transport before sending a request
954  * @task: RPC task about to send a request
955  *
956  */
957 bool xprt_prepare_transmit(struct rpc_task *task)
958 {
959         struct rpc_rqst *req = task->tk_rqstp;
960         struct rpc_xprt *xprt = req->rq_xprt;
961         bool ret = false;
962
963         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
964
965         spin_lock_bh(&xprt->transport_lock);
966         if (!req->rq_bytes_sent) {
967                 if (req->rq_reply_bytes_recvd) {
968                         task->tk_status = req->rq_reply_bytes_recvd;
969                         goto out_unlock;
970                 }
971                 if ((task->tk_flags & RPC_TASK_NO_RETRANS_TIMEOUT)
972                     && xprt_connected(xprt)
973                     && req->rq_connect_cookie == xprt->connect_cookie) {
974                         xprt->ops->set_retrans_timeout(task);
975                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
976                         goto out_unlock;
977                 }
978         }
979         if (!xprt->ops->reserve_xprt(xprt, task)) {
980                 task->tk_status = -EAGAIN;
981                 goto out_unlock;
982         }
983         ret = true;
984 out_unlock:
985         spin_unlock_bh(&xprt->transport_lock);
986         return ret;
987 }
988
989 void xprt_end_transmit(struct rpc_task *task)
990 {
991         xprt_release_write(task->tk_rqstp->rq_xprt, task);
992 }
993
994 /**
995  * xprt_transmit - send an RPC request on a transport
996  * @task: controlling RPC task
997  *
998  * We have to copy the iovec because sendmsg fiddles with its contents.
999  */
1000 void xprt_transmit(struct rpc_task *task)
1001 {
1002         struct rpc_rqst *req = task->tk_rqstp;
1003         struct rpc_xprt *xprt = req->rq_xprt;
1004         unsigned int connect_cookie;
1005         int status, numreqs;
1006
1007         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
1008
1009         if (!req->rq_reply_bytes_recvd) {
1010                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
1011                         /*
1012                          * Add to the list only if we're expecting a reply
1013                          */
1014                         /* Update the softirq receive buffer */
1015                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1016                                         sizeof(req->rq_private_buf));
1017                         /* Add request to the receive list */
1018                         spin_lock(&xprt->recv_lock);
1019                         list_add_tail(&req->rq_list, &xprt->recv);
1020                         spin_unlock(&xprt->recv_lock);
1021                         xprt_reset_majortimeo(req);
1022                         /* Turn off autodisconnect */
1023                         del_singleshot_timer_sync(&xprt->timer);
1024                 }
1025         } else if (!req->rq_bytes_sent)
1026                 return;
1027
1028         connect_cookie = xprt->connect_cookie;
1029         req->rq_xtime = ktime_get();
1030         status = xprt->ops->send_request(task);
1031         trace_xprt_transmit(xprt, req->rq_xid, status);
1032         if (status != 0) {
1033                 task->tk_status = status;
1034                 return;
1035         }
1036         xprt_inject_disconnect(xprt);
1037
1038         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
1039         task->tk_flags |= RPC_TASK_SENT;
1040         spin_lock_bh(&xprt->transport_lock);
1041
1042         xprt->ops->set_retrans_timeout(task);
1043
1044         numreqs = atomic_read(&xprt->num_reqs);
1045         if (numreqs > xprt->stat.max_slots)
1046                 xprt->stat.max_slots = numreqs;
1047         xprt->stat.sends++;
1048         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1049         xprt->stat.bklog_u += xprt->backlog.qlen;
1050         xprt->stat.sending_u += xprt->sending.qlen;
1051         xprt->stat.pending_u += xprt->pending.qlen;
1052         spin_unlock_bh(&xprt->transport_lock);
1053
1054         req->rq_connect_cookie = connect_cookie;
1055         if (rpc_reply_expected(task) && !READ_ONCE(req->rq_reply_bytes_recvd)) {
1056                 /*
1057                  * Sleep on the pending queue if we're expecting a reply.
1058                  * The spinlock ensures atomicity between the test of
1059                  * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1060                  */
1061                 spin_lock(&xprt->recv_lock);
1062                 if (!req->rq_reply_bytes_recvd) {
1063                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
1064                         /*
1065                          * Send an extra queue wakeup call if the
1066                          * connection was dropped in case the call to
1067                          * rpc_sleep_on() raced.
1068                          */
1069                         if (!xprt_connected(xprt))
1070                                 xprt_wake_pending_tasks(xprt, -ENOTCONN);
1071                 }
1072                 spin_unlock(&xprt->recv_lock);
1073         }
1074 }
1075
1076 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1077 {
1078         set_bit(XPRT_CONGESTED, &xprt->state);
1079         rpc_sleep_on(&xprt->backlog, task, NULL);
1080 }
1081
1082 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
1083 {
1084         if (rpc_wake_up_next(&xprt->backlog) == NULL)
1085                 clear_bit(XPRT_CONGESTED, &xprt->state);
1086 }
1087
1088 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1089 {
1090         bool ret = false;
1091
1092         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1093                 goto out;
1094         spin_lock(&xprt->reserve_lock);
1095         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1096                 rpc_sleep_on(&xprt->backlog, task, NULL);
1097                 ret = true;
1098         }
1099         spin_unlock(&xprt->reserve_lock);
1100 out:
1101         return ret;
1102 }
1103
1104 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1105 {
1106         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1107
1108         if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
1109                 goto out;
1110         spin_unlock(&xprt->reserve_lock);
1111         req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
1112         spin_lock(&xprt->reserve_lock);
1113         if (req != NULL)
1114                 goto out;
1115         atomic_dec(&xprt->num_reqs);
1116         req = ERR_PTR(-ENOMEM);
1117 out:
1118         return req;
1119 }
1120
1121 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1122 {
1123         if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
1124                 kfree(req);
1125                 return true;
1126         }
1127         return false;
1128 }
1129
1130 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1131 {
1132         struct rpc_rqst *req;
1133
1134         spin_lock(&xprt->reserve_lock);
1135         if (!list_empty(&xprt->free)) {
1136                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1137                 list_del(&req->rq_list);
1138                 goto out_init_req;
1139         }
1140         req = xprt_dynamic_alloc_slot(xprt);
1141         if (!IS_ERR(req))
1142                 goto out_init_req;
1143         switch (PTR_ERR(req)) {
1144         case -ENOMEM:
1145                 dprintk("RPC:       dynamic allocation of request slot "
1146                                 "failed! Retrying\n");
1147                 task->tk_status = -ENOMEM;
1148                 break;
1149         case -EAGAIN:
1150                 xprt_add_backlog(xprt, task);
1151                 dprintk("RPC:       waiting for request slot\n");
1152                 /* fall through */
1153         default:
1154                 task->tk_status = -EAGAIN;
1155         }
1156         spin_unlock(&xprt->reserve_lock);
1157         return;
1158 out_init_req:
1159         task->tk_status = 0;
1160         task->tk_rqstp = req;
1161         xprt_request_init(task, xprt);
1162         spin_unlock(&xprt->reserve_lock);
1163 }
1164 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1165
1166 void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1167 {
1168         /* Note: grabbing the xprt_lock_write() ensures that we throttle
1169          * new slot allocation if the transport is congested (i.e. when
1170          * reconnecting a stream transport or when out of socket write
1171          * buffer space).
1172          */
1173         if (xprt_lock_write(xprt, task)) {
1174                 xprt_alloc_slot(xprt, task);
1175                 xprt_release_write(xprt, task);
1176         }
1177 }
1178 EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1179
1180 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1181 {
1182         spin_lock(&xprt->reserve_lock);
1183         if (!xprt_dynamic_free_slot(xprt, req)) {
1184                 memset(req, 0, sizeof(*req));   /* mark unused */
1185                 list_add(&req->rq_list, &xprt->free);
1186         }
1187         xprt_wake_up_backlog(xprt);
1188         spin_unlock(&xprt->reserve_lock);
1189 }
1190
1191 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1192 {
1193         struct rpc_rqst *req;
1194         while (!list_empty(&xprt->free)) {
1195                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1196                 list_del(&req->rq_list);
1197                 kfree(req);
1198         }
1199 }
1200
1201 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1202                 unsigned int num_prealloc,
1203                 unsigned int max_alloc)
1204 {
1205         struct rpc_xprt *xprt;
1206         struct rpc_rqst *req;
1207         int i;
1208
1209         xprt = kzalloc(size, GFP_KERNEL);
1210         if (xprt == NULL)
1211                 goto out;
1212
1213         xprt_init(xprt, net);
1214
1215         for (i = 0; i < num_prealloc; i++) {
1216                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1217                 if (!req)
1218                         goto out_free;
1219                 list_add(&req->rq_list, &xprt->free);
1220         }
1221         if (max_alloc > num_prealloc)
1222                 xprt->max_reqs = max_alloc;
1223         else
1224                 xprt->max_reqs = num_prealloc;
1225         xprt->min_reqs = num_prealloc;
1226         atomic_set(&xprt->num_reqs, num_prealloc);
1227
1228         return xprt;
1229
1230 out_free:
1231         xprt_free(xprt);
1232 out:
1233         return NULL;
1234 }
1235 EXPORT_SYMBOL_GPL(xprt_alloc);
1236
1237 void xprt_free(struct rpc_xprt *xprt)
1238 {
1239         put_net(xprt->xprt_net);
1240         xprt_free_all_slots(xprt);
1241         kfree_rcu(xprt, rcu);
1242 }
1243 EXPORT_SYMBOL_GPL(xprt_free);
1244
1245 /**
1246  * xprt_reserve - allocate an RPC request slot
1247  * @task: RPC task requesting a slot allocation
1248  *
1249  * If the transport is marked as being congested, or if no more
1250  * slots are available, place the task on the transport's
1251  * backlog queue.
1252  */
1253 void xprt_reserve(struct rpc_task *task)
1254 {
1255         struct rpc_xprt *xprt = task->tk_xprt;
1256
1257         task->tk_status = 0;
1258         if (task->tk_rqstp != NULL)
1259                 return;
1260
1261         task->tk_timeout = 0;
1262         task->tk_status = -EAGAIN;
1263         if (!xprt_throttle_congested(xprt, task))
1264                 xprt->ops->alloc_slot(xprt, task);
1265 }
1266
1267 /**
1268  * xprt_retry_reserve - allocate an RPC request slot
1269  * @task: RPC task requesting a slot allocation
1270  *
1271  * If no more slots are available, place the task on the transport's
1272  * backlog queue.
1273  * Note that the only difference with xprt_reserve is that we now
1274  * ignore the value of the XPRT_CONGESTED flag.
1275  */
1276 void xprt_retry_reserve(struct rpc_task *task)
1277 {
1278         struct rpc_xprt *xprt = task->tk_xprt;
1279
1280         task->tk_status = 0;
1281         if (task->tk_rqstp != NULL)
1282                 return;
1283
1284         task->tk_timeout = 0;
1285         task->tk_status = -EAGAIN;
1286         xprt->ops->alloc_slot(xprt, task);
1287 }
1288
1289 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1290 {
1291         return (__force __be32)xprt->xid++;
1292 }
1293
1294 static inline void xprt_init_xid(struct rpc_xprt *xprt)
1295 {
1296         xprt->xid = prandom_u32();
1297 }
1298
1299 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1300 {
1301         struct rpc_rqst *req = task->tk_rqstp;
1302
1303         INIT_LIST_HEAD(&req->rq_list);
1304         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1305         req->rq_task    = task;
1306         req->rq_xprt    = xprt;
1307         req->rq_buffer  = NULL;
1308         req->rq_xid     = xprt_alloc_xid(xprt);
1309         req->rq_connect_cookie = xprt->connect_cookie - 1;
1310         req->rq_bytes_sent = 0;
1311         req->rq_snd_buf.len = 0;
1312         req->rq_snd_buf.buflen = 0;
1313         req->rq_rcv_buf.len = 0;
1314         req->rq_rcv_buf.buflen = 0;
1315         req->rq_release_snd_buf = NULL;
1316         xprt_reset_majortimeo(req);
1317         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1318                         req, ntohl(req->rq_xid));
1319 }
1320
1321 /**
1322  * xprt_release - release an RPC request slot
1323  * @task: task which is finished with the slot
1324  *
1325  */
1326 void xprt_release(struct rpc_task *task)
1327 {
1328         struct rpc_xprt *xprt;
1329         struct rpc_rqst *req = task->tk_rqstp;
1330
1331         if (req == NULL) {
1332                 if (task->tk_client) {
1333                         xprt = task->tk_xprt;
1334                         if (xprt->snd_task == task)
1335                                 xprt_release_write(xprt, task);
1336                 }
1337                 return;
1338         }
1339
1340         xprt = req->rq_xprt;
1341         if (task->tk_ops->rpc_count_stats != NULL)
1342                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1343         else if (task->tk_client)
1344                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1345         spin_lock(&xprt->recv_lock);
1346         if (!list_empty(&req->rq_list)) {
1347                 list_del_init(&req->rq_list);
1348                 xprt_wait_on_pinned_rqst(req);
1349         }
1350         spin_unlock(&xprt->recv_lock);
1351         spin_lock_bh(&xprt->transport_lock);
1352         xprt->ops->release_xprt(xprt, task);
1353         if (xprt->ops->release_request)
1354                 xprt->ops->release_request(task);
1355         xprt->last_used = jiffies;
1356         xprt_schedule_autodisconnect(xprt);
1357         spin_unlock_bh(&xprt->transport_lock);
1358         if (req->rq_buffer)
1359                 xprt->ops->buf_free(task);
1360         xprt_inject_disconnect(xprt);
1361         if (req->rq_cred != NULL)
1362                 put_rpccred(req->rq_cred);
1363         task->tk_rqstp = NULL;
1364         if (req->rq_release_snd_buf)
1365                 req->rq_release_snd_buf(req);
1366
1367         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1368         if (likely(!bc_prealloc(req)))
1369                 xprt_free_slot(xprt, req);
1370         else
1371                 xprt_free_bc_request(req);
1372 }
1373
1374 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1375 {
1376         kref_init(&xprt->kref);
1377
1378         spin_lock_init(&xprt->transport_lock);
1379         spin_lock_init(&xprt->reserve_lock);
1380         spin_lock_init(&xprt->recv_lock);
1381
1382         INIT_LIST_HEAD(&xprt->free);
1383         INIT_LIST_HEAD(&xprt->recv);
1384 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1385         spin_lock_init(&xprt->bc_pa_lock);
1386         INIT_LIST_HEAD(&xprt->bc_pa_list);
1387 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1388         INIT_LIST_HEAD(&xprt->xprt_switch);
1389
1390         xprt->last_used = jiffies;
1391         xprt->cwnd = RPC_INITCWND;
1392         xprt->bind_index = 0;
1393
1394         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1395         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1396         rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1397         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1398
1399         xprt_init_xid(xprt);
1400
1401         xprt->xprt_net = get_net(net);
1402 }
1403
1404 /**
1405  * xprt_create_transport - create an RPC transport
1406  * @args: rpc transport creation arguments
1407  *
1408  */
1409 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1410 {
1411         struct rpc_xprt *xprt;
1412         struct xprt_class *t;
1413
1414         spin_lock(&xprt_list_lock);
1415         list_for_each_entry(t, &xprt_list, list) {
1416                 if (t->ident == args->ident) {
1417                         spin_unlock(&xprt_list_lock);
1418                         goto found;
1419                 }
1420         }
1421         spin_unlock(&xprt_list_lock);
1422         dprintk("RPC: transport (%d) not supported\n", args->ident);
1423         return ERR_PTR(-EIO);
1424
1425 found:
1426         xprt = t->setup(args);
1427         if (IS_ERR(xprt)) {
1428                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1429                                 -PTR_ERR(xprt));
1430                 goto out;
1431         }
1432         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1433                 xprt->idle_timeout = 0;
1434         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1435         if (xprt_has_timer(xprt))
1436                 timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
1437         else
1438                 timer_setup(&xprt->timer, NULL, 0);
1439
1440         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1441                 xprt_destroy(xprt);
1442                 return ERR_PTR(-EINVAL);
1443         }
1444         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1445         if (xprt->servername == NULL) {
1446                 xprt_destroy(xprt);
1447                 return ERR_PTR(-ENOMEM);
1448         }
1449
1450         rpc_xprt_debugfs_register(xprt);
1451
1452         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1453                         xprt->max_reqs);
1454 out:
1455         return xprt;
1456 }
1457
1458 static void xprt_destroy_cb(struct work_struct *work)
1459 {
1460         struct rpc_xprt *xprt =
1461                 container_of(work, struct rpc_xprt, task_cleanup);
1462
1463         rpc_xprt_debugfs_unregister(xprt);
1464         rpc_destroy_wait_queue(&xprt->binding);
1465         rpc_destroy_wait_queue(&xprt->pending);
1466         rpc_destroy_wait_queue(&xprt->sending);
1467         rpc_destroy_wait_queue(&xprt->backlog);
1468         kfree(xprt->servername);
1469         /*
1470          * Tear down transport state and free the rpc_xprt
1471          */
1472         xprt->ops->destroy(xprt);
1473 }
1474
1475 /**
1476  * xprt_destroy - destroy an RPC transport, killing off all requests.
1477  * @xprt: transport to destroy
1478  *
1479  */
1480 static void xprt_destroy(struct rpc_xprt *xprt)
1481 {
1482         dprintk("RPC:       destroying transport %p\n", xprt);
1483
1484         /*
1485          * Exclude transport connect/disconnect handlers and autoclose
1486          */
1487         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
1488
1489         del_timer_sync(&xprt->timer);
1490
1491         /*
1492          * Destroy sockets etc from the system workqueue so they can
1493          * safely flush receive work running on rpciod.
1494          */
1495         INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
1496         schedule_work(&xprt->task_cleanup);
1497 }
1498
1499 static void xprt_destroy_kref(struct kref *kref)
1500 {
1501         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
1502 }
1503
1504 /**
1505  * xprt_get - return a reference to an RPC transport.
1506  * @xprt: pointer to the transport
1507  *
1508  */
1509 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1510 {
1511         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
1512                 return xprt;
1513         return NULL;
1514 }
1515 EXPORT_SYMBOL_GPL(xprt_get);
1516
1517 /**
1518  * xprt_put - release a reference to an RPC transport.
1519  * @xprt: pointer to the transport
1520  *
1521  */
1522 void xprt_put(struct rpc_xprt *xprt)
1523 {
1524         if (xprt != NULL)
1525                 kref_put(&xprt->kref, xprt_destroy_kref);
1526 }
1527 EXPORT_SYMBOL_GPL(xprt_put);