afs: Probe multiple fileservers simultaneously
[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 __be32   xprt_alloc_xid(struct rpc_xprt *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_on_wq(xprtiod_workqueue,
521                                 &xprt->pending, xprt->snd_task);
522         }
523         spin_unlock_bh(&xprt->transport_lock);
524 }
525 EXPORT_SYMBOL_GPL(xprt_write_space);
526
527 /**
528  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
529  * @task: task whose timeout is to be set
530  *
531  * Set a request's retransmit timeout based on the transport's
532  * default timeout parameters.  Used by transports that don't adjust
533  * the retransmit timeout based on round-trip time estimation.
534  */
535 void xprt_set_retrans_timeout_def(struct rpc_task *task)
536 {
537         task->tk_timeout = task->tk_rqstp->rq_timeout;
538 }
539 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
540
541 /**
542  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
543  * @task: task whose timeout is to be set
544  *
545  * Set a request's retransmit timeout using the RTT estimator.
546  */
547 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
548 {
549         int timer = task->tk_msg.rpc_proc->p_timer;
550         struct rpc_clnt *clnt = task->tk_client;
551         struct rpc_rtt *rtt = clnt->cl_rtt;
552         struct rpc_rqst *req = task->tk_rqstp;
553         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
554
555         task->tk_timeout = rpc_calc_rto(rtt, timer);
556         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
557         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
558                 task->tk_timeout = max_timeout;
559 }
560 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
561
562 static void xprt_reset_majortimeo(struct rpc_rqst *req)
563 {
564         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
565
566         req->rq_majortimeo = req->rq_timeout;
567         if (to->to_exponential)
568                 req->rq_majortimeo <<= to->to_retries;
569         else
570                 req->rq_majortimeo += to->to_increment * to->to_retries;
571         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
572                 req->rq_majortimeo = to->to_maxval;
573         req->rq_majortimeo += jiffies;
574 }
575
576 /**
577  * xprt_adjust_timeout - adjust timeout values for next retransmit
578  * @req: RPC request containing parameters to use for the adjustment
579  *
580  */
581 int xprt_adjust_timeout(struct rpc_rqst *req)
582 {
583         struct rpc_xprt *xprt = req->rq_xprt;
584         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
585         int status = 0;
586
587         if (time_before(jiffies, req->rq_majortimeo)) {
588                 if (to->to_exponential)
589                         req->rq_timeout <<= 1;
590                 else
591                         req->rq_timeout += to->to_increment;
592                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
593                         req->rq_timeout = to->to_maxval;
594                 req->rq_retries++;
595         } else {
596                 req->rq_timeout = to->to_initval;
597                 req->rq_retries = 0;
598                 xprt_reset_majortimeo(req);
599                 /* Reset the RTT counters == "slow start" */
600                 spin_lock_bh(&xprt->transport_lock);
601                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
602                 spin_unlock_bh(&xprt->transport_lock);
603                 status = -ETIMEDOUT;
604         }
605
606         if (req->rq_timeout == 0) {
607                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
608                 req->rq_timeout = 5 * HZ;
609         }
610         return status;
611 }
612
613 static void xprt_autoclose(struct work_struct *work)
614 {
615         struct rpc_xprt *xprt =
616                 container_of(work, struct rpc_xprt, task_cleanup);
617
618         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
619         xprt->ops->close(xprt);
620         xprt_release_write(xprt, NULL);
621         wake_up_bit(&xprt->state, XPRT_LOCKED);
622 }
623
624 /**
625  * xprt_disconnect_done - mark a transport as disconnected
626  * @xprt: transport to flag for disconnect
627  *
628  */
629 void xprt_disconnect_done(struct rpc_xprt *xprt)
630 {
631         dprintk("RPC:       disconnected transport %p\n", xprt);
632         spin_lock_bh(&xprt->transport_lock);
633         xprt_clear_connected(xprt);
634         xprt_wake_pending_tasks(xprt, -EAGAIN);
635         spin_unlock_bh(&xprt->transport_lock);
636 }
637 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
638
639 /**
640  * xprt_force_disconnect - force a transport to disconnect
641  * @xprt: transport to disconnect
642  *
643  */
644 void xprt_force_disconnect(struct rpc_xprt *xprt)
645 {
646         /* Don't race with the test_bit() in xprt_clear_locked() */
647         spin_lock_bh(&xprt->transport_lock);
648         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
649         /* Try to schedule an autoclose RPC call */
650         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
651                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
652         xprt_wake_pending_tasks(xprt, -EAGAIN);
653         spin_unlock_bh(&xprt->transport_lock);
654 }
655 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
656
657 /**
658  * xprt_conditional_disconnect - force a transport to disconnect
659  * @xprt: transport to disconnect
660  * @cookie: 'connection cookie'
661  *
662  * This attempts to break the connection if and only if 'cookie' matches
663  * the current transport 'connection cookie'. It ensures that we don't
664  * try to break the connection more than once when we need to retransmit
665  * a batch of RPC requests.
666  *
667  */
668 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
669 {
670         /* Don't race with the test_bit() in xprt_clear_locked() */
671         spin_lock_bh(&xprt->transport_lock);
672         if (cookie != xprt->connect_cookie)
673                 goto out;
674         if (test_bit(XPRT_CLOSING, &xprt->state))
675                 goto out;
676         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
677         /* Try to schedule an autoclose RPC call */
678         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
679                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
680         xprt_wake_pending_tasks(xprt, -EAGAIN);
681 out:
682         spin_unlock_bh(&xprt->transport_lock);
683 }
684
685 static bool
686 xprt_has_timer(const struct rpc_xprt *xprt)
687 {
688         return xprt->idle_timeout != 0;
689 }
690
691 static void
692 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
693         __must_hold(&xprt->transport_lock)
694 {
695         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
696                 mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
697 }
698
699 static void
700 xprt_init_autodisconnect(struct timer_list *t)
701 {
702         struct rpc_xprt *xprt = from_timer(xprt, t, timer);
703
704         spin_lock(&xprt->transport_lock);
705         if (!list_empty(&xprt->recv))
706                 goto out_abort;
707         /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
708         xprt->last_used = jiffies;
709         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
710                 goto out_abort;
711         spin_unlock(&xprt->transport_lock);
712         queue_work(xprtiod_workqueue, &xprt->task_cleanup);
713         return;
714 out_abort:
715         spin_unlock(&xprt->transport_lock);
716 }
717
718 bool xprt_lock_connect(struct rpc_xprt *xprt,
719                 struct rpc_task *task,
720                 void *cookie)
721 {
722         bool ret = false;
723
724         spin_lock_bh(&xprt->transport_lock);
725         if (!test_bit(XPRT_LOCKED, &xprt->state))
726                 goto out;
727         if (xprt->snd_task != task)
728                 goto out;
729         xprt_task_clear_bytes_sent(task);
730         xprt->snd_task = cookie;
731         ret = true;
732 out:
733         spin_unlock_bh(&xprt->transport_lock);
734         return ret;
735 }
736
737 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
738 {
739         spin_lock_bh(&xprt->transport_lock);
740         if (xprt->snd_task != cookie)
741                 goto out;
742         if (!test_bit(XPRT_LOCKED, &xprt->state))
743                 goto out;
744         xprt->snd_task =NULL;
745         xprt->ops->release_xprt(xprt, NULL);
746         xprt_schedule_autodisconnect(xprt);
747 out:
748         spin_unlock_bh(&xprt->transport_lock);
749         wake_up_bit(&xprt->state, XPRT_LOCKED);
750 }
751
752 /**
753  * xprt_connect - schedule a transport connect operation
754  * @task: RPC task that is requesting the connect
755  *
756  */
757 void xprt_connect(struct rpc_task *task)
758 {
759         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
760
761         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
762                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
763
764         if (!xprt_bound(xprt)) {
765                 task->tk_status = -EAGAIN;
766                 return;
767         }
768         if (!xprt_lock_write(xprt, task))
769                 return;
770
771         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
772                 xprt->ops->close(xprt);
773
774         if (!xprt_connected(xprt)) {
775                 task->tk_rqstp->rq_bytes_sent = 0;
776                 task->tk_timeout = task->tk_rqstp->rq_timeout;
777                 task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
778                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
779
780                 if (test_bit(XPRT_CLOSING, &xprt->state))
781                         return;
782                 if (xprt_test_and_set_connecting(xprt))
783                         return;
784                 xprt->stat.connect_start = jiffies;
785                 xprt->ops->connect(xprt, task);
786         }
787         xprt_release_write(xprt, task);
788 }
789
790 static void xprt_connect_status(struct rpc_task *task)
791 {
792         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
793
794         if (task->tk_status == 0) {
795                 xprt->stat.connect_count++;
796                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
797                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
798                                 task->tk_pid);
799                 return;
800         }
801
802         switch (task->tk_status) {
803         case -ECONNREFUSED:
804         case -ECONNRESET:
805         case -ECONNABORTED:
806         case -ENETUNREACH:
807         case -EHOSTUNREACH:
808         case -EPIPE:
809         case -EAGAIN:
810                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
811                 break;
812         case -ETIMEDOUT:
813                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
814                                 "out\n", task->tk_pid);
815                 break;
816         default:
817                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
818                                 "server %s\n", task->tk_pid, -task->tk_status,
819                                 xprt->servername);
820                 task->tk_status = -EIO;
821         }
822 }
823
824 /**
825  * xprt_lookup_rqst - find an RPC request corresponding to an XID
826  * @xprt: transport on which the original request was transmitted
827  * @xid: RPC XID of incoming reply
828  *
829  * Caller holds xprt->recv_lock.
830  */
831 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
832 {
833         struct rpc_rqst *entry;
834
835         list_for_each_entry(entry, &xprt->recv, rq_list)
836                 if (entry->rq_xid == xid) {
837                         trace_xprt_lookup_rqst(xprt, xid, 0);
838                         entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
839                         return entry;
840                 }
841
842         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
843                         ntohl(xid));
844         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
845         xprt->stat.bad_xids++;
846         return NULL;
847 }
848 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
849
850 /**
851  * xprt_pin_rqst - Pin a request on the transport receive list
852  * @req: Request to pin
853  *
854  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
855  * so should be holding the xprt transport lock.
856  */
857 void xprt_pin_rqst(struct rpc_rqst *req)
858 {
859         set_bit(RPC_TASK_MSG_RECV, &req->rq_task->tk_runstate);
860 }
861 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
862
863 /**
864  * xprt_unpin_rqst - Unpin a request on the transport receive list
865  * @req: Request to pin
866  *
867  * Caller should be holding the xprt transport lock.
868  */
869 void xprt_unpin_rqst(struct rpc_rqst *req)
870 {
871         struct rpc_task *task = req->rq_task;
872
873         clear_bit(RPC_TASK_MSG_RECV, &task->tk_runstate);
874         if (test_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate))
875                 wake_up_bit(&task->tk_runstate, RPC_TASK_MSG_RECV);
876 }
877 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
878
879 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
880 __must_hold(&req->rq_xprt->recv_lock)
881 {
882         struct rpc_task *task = req->rq_task;
883
884         if (task && test_bit(RPC_TASK_MSG_RECV, &task->tk_runstate)) {
885                 spin_unlock(&req->rq_xprt->recv_lock);
886                 set_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
887                 wait_on_bit(&task->tk_runstate, RPC_TASK_MSG_RECV,
888                                 TASK_UNINTERRUPTIBLE);
889                 clear_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
890                 spin_lock(&req->rq_xprt->recv_lock);
891         }
892 }
893
894 /**
895  * xprt_update_rtt - Update RPC RTT statistics
896  * @task: RPC request that recently completed
897  *
898  * Caller holds xprt->recv_lock.
899  */
900 void xprt_update_rtt(struct rpc_task *task)
901 {
902         struct rpc_rqst *req = task->tk_rqstp;
903         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
904         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
905         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
906
907         if (timer) {
908                 if (req->rq_ntrans == 1)
909                         rpc_update_rtt(rtt, timer, m);
910                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
911         }
912 }
913 EXPORT_SYMBOL_GPL(xprt_update_rtt);
914
915 /**
916  * xprt_complete_rqst - called when reply processing is complete
917  * @task: RPC request that recently completed
918  * @copied: actual number of bytes received from the transport
919  *
920  * Caller holds xprt->recv_lock.
921  */
922 void xprt_complete_rqst(struct rpc_task *task, int copied)
923 {
924         struct rpc_rqst *req = task->tk_rqstp;
925         struct rpc_xprt *xprt = req->rq_xprt;
926
927         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
928                         task->tk_pid, ntohl(req->rq_xid), copied);
929         trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
930
931         xprt->stat.recvs++;
932
933         list_del_init(&req->rq_list);
934         req->rq_private_buf.len = copied;
935         /* Ensure all writes are done before we update */
936         /* req->rq_reply_bytes_recvd */
937         smp_wmb();
938         req->rq_reply_bytes_recvd = copied;
939         rpc_wake_up_queued_task(&xprt->pending, task);
940 }
941 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
942
943 static void xprt_timer(struct rpc_task *task)
944 {
945         struct rpc_rqst *req = task->tk_rqstp;
946         struct rpc_xprt *xprt = req->rq_xprt;
947
948         if (task->tk_status != -ETIMEDOUT)
949                 return;
950
951         trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
952         if (!req->rq_reply_bytes_recvd) {
953                 if (xprt->ops->timer)
954                         xprt->ops->timer(xprt, task);
955         } else
956                 task->tk_status = 0;
957 }
958
959 /**
960  * xprt_prepare_transmit - reserve the transport before sending a request
961  * @task: RPC task about to send a request
962  *
963  */
964 bool xprt_prepare_transmit(struct rpc_task *task)
965 {
966         struct rpc_rqst *req = task->tk_rqstp;
967         struct rpc_xprt *xprt = req->rq_xprt;
968         bool ret = false;
969
970         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
971
972         spin_lock_bh(&xprt->transport_lock);
973         if (!req->rq_bytes_sent) {
974                 if (req->rq_reply_bytes_recvd) {
975                         task->tk_status = req->rq_reply_bytes_recvd;
976                         goto out_unlock;
977                 }
978                 if ((task->tk_flags & RPC_TASK_NO_RETRANS_TIMEOUT)
979                     && xprt_connected(xprt)
980                     && req->rq_connect_cookie == xprt->connect_cookie) {
981                         xprt->ops->set_retrans_timeout(task);
982                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
983                         goto out_unlock;
984                 }
985         }
986         if (!xprt->ops->reserve_xprt(xprt, task)) {
987                 task->tk_status = -EAGAIN;
988                 goto out_unlock;
989         }
990         ret = true;
991 out_unlock:
992         spin_unlock_bh(&xprt->transport_lock);
993         return ret;
994 }
995
996 void xprt_end_transmit(struct rpc_task *task)
997 {
998         xprt_release_write(task->tk_rqstp->rq_xprt, task);
999 }
1000
1001 /**
1002  * xprt_transmit - send an RPC request on a transport
1003  * @task: controlling RPC task
1004  *
1005  * We have to copy the iovec because sendmsg fiddles with its contents.
1006  */
1007 void xprt_transmit(struct rpc_task *task)
1008 {
1009         struct rpc_rqst *req = task->tk_rqstp;
1010         struct rpc_xprt *xprt = req->rq_xprt;
1011         unsigned int connect_cookie;
1012         int status;
1013
1014         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
1015
1016         if (!req->rq_reply_bytes_recvd) {
1017                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
1018                         /*
1019                          * Add to the list only if we're expecting a reply
1020                          */
1021                         /* Update the softirq receive buffer */
1022                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1023                                         sizeof(req->rq_private_buf));
1024                         /* Add request to the receive list */
1025                         spin_lock(&xprt->recv_lock);
1026                         list_add_tail(&req->rq_list, &xprt->recv);
1027                         spin_unlock(&xprt->recv_lock);
1028                         xprt_reset_majortimeo(req);
1029                         /* Turn off autodisconnect */
1030                         del_singleshot_timer_sync(&xprt->timer);
1031                 }
1032         } else if (!req->rq_bytes_sent)
1033                 return;
1034
1035         connect_cookie = xprt->connect_cookie;
1036         status = xprt->ops->send_request(task);
1037         trace_xprt_transmit(xprt, req->rq_xid, status);
1038         if (status != 0) {
1039                 task->tk_status = status;
1040                 return;
1041         }
1042         xprt_inject_disconnect(xprt);
1043
1044         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
1045         task->tk_flags |= RPC_TASK_SENT;
1046         spin_lock_bh(&xprt->transport_lock);
1047
1048         xprt->ops->set_retrans_timeout(task);
1049
1050         xprt->stat.sends++;
1051         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1052         xprt->stat.bklog_u += xprt->backlog.qlen;
1053         xprt->stat.sending_u += xprt->sending.qlen;
1054         xprt->stat.pending_u += xprt->pending.qlen;
1055         spin_unlock_bh(&xprt->transport_lock);
1056
1057         req->rq_connect_cookie = connect_cookie;
1058         if (rpc_reply_expected(task) && !READ_ONCE(req->rq_reply_bytes_recvd)) {
1059                 /*
1060                  * Sleep on the pending queue if we're expecting a reply.
1061                  * The spinlock ensures atomicity between the test of
1062                  * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1063                  */
1064                 spin_lock(&xprt->recv_lock);
1065                 if (!req->rq_reply_bytes_recvd) {
1066                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
1067                         /*
1068                          * Send an extra queue wakeup call if the
1069                          * connection was dropped in case the call to
1070                          * rpc_sleep_on() raced.
1071                          */
1072                         if (!xprt_connected(xprt))
1073                                 xprt_wake_pending_tasks(xprt, -ENOTCONN);
1074                 }
1075                 spin_unlock(&xprt->recv_lock);
1076         }
1077 }
1078
1079 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1080 {
1081         set_bit(XPRT_CONGESTED, &xprt->state);
1082         rpc_sleep_on(&xprt->backlog, task, NULL);
1083 }
1084
1085 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
1086 {
1087         if (rpc_wake_up_next(&xprt->backlog) == NULL)
1088                 clear_bit(XPRT_CONGESTED, &xprt->state);
1089 }
1090
1091 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1092 {
1093         bool ret = false;
1094
1095         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1096                 goto out;
1097         spin_lock(&xprt->reserve_lock);
1098         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1099                 rpc_sleep_on(&xprt->backlog, task, NULL);
1100                 ret = true;
1101         }
1102         spin_unlock(&xprt->reserve_lock);
1103 out:
1104         return ret;
1105 }
1106
1107 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1108 {
1109         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1110
1111         if (xprt->num_reqs >= xprt->max_reqs)
1112                 goto out;
1113         ++xprt->num_reqs;
1114         spin_unlock(&xprt->reserve_lock);
1115         req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
1116         spin_lock(&xprt->reserve_lock);
1117         if (req != NULL)
1118                 goto out;
1119         --xprt->num_reqs;
1120         req = ERR_PTR(-ENOMEM);
1121 out:
1122         return req;
1123 }
1124
1125 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1126 {
1127         if (xprt->num_reqs > xprt->min_reqs) {
1128                 --xprt->num_reqs;
1129                 kfree(req);
1130                 return true;
1131         }
1132         return false;
1133 }
1134
1135 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1136 {
1137         struct rpc_rqst *req;
1138
1139         spin_lock(&xprt->reserve_lock);
1140         if (!list_empty(&xprt->free)) {
1141                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1142                 list_del(&req->rq_list);
1143                 goto out_init_req;
1144         }
1145         req = xprt_dynamic_alloc_slot(xprt);
1146         if (!IS_ERR(req))
1147                 goto out_init_req;
1148         switch (PTR_ERR(req)) {
1149         case -ENOMEM:
1150                 dprintk("RPC:       dynamic allocation of request slot "
1151                                 "failed! Retrying\n");
1152                 task->tk_status = -ENOMEM;
1153                 break;
1154         case -EAGAIN:
1155                 xprt_add_backlog(xprt, task);
1156                 dprintk("RPC:       waiting for request slot\n");
1157                 /* fall through */
1158         default:
1159                 task->tk_status = -EAGAIN;
1160         }
1161         spin_unlock(&xprt->reserve_lock);
1162         return;
1163 out_init_req:
1164         xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
1165                                      xprt->num_reqs);
1166         spin_unlock(&xprt->reserve_lock);
1167
1168         task->tk_status = 0;
1169         task->tk_rqstp = req;
1170 }
1171 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1172
1173 void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1174 {
1175         /* Note: grabbing the xprt_lock_write() ensures that we throttle
1176          * new slot allocation if the transport is congested (i.e. when
1177          * reconnecting a stream transport or when out of socket write
1178          * buffer space).
1179          */
1180         if (xprt_lock_write(xprt, task)) {
1181                 xprt_alloc_slot(xprt, task);
1182                 xprt_release_write(xprt, task);
1183         }
1184 }
1185 EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1186
1187 void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1188 {
1189         spin_lock(&xprt->reserve_lock);
1190         if (!xprt_dynamic_free_slot(xprt, req)) {
1191                 memset(req, 0, sizeof(*req));   /* mark unused */
1192                 list_add(&req->rq_list, &xprt->free);
1193         }
1194         xprt_wake_up_backlog(xprt);
1195         spin_unlock(&xprt->reserve_lock);
1196 }
1197 EXPORT_SYMBOL_GPL(xprt_free_slot);
1198
1199 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1200 {
1201         struct rpc_rqst *req;
1202         while (!list_empty(&xprt->free)) {
1203                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1204                 list_del(&req->rq_list);
1205                 kfree(req);
1206         }
1207 }
1208
1209 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1210                 unsigned int num_prealloc,
1211                 unsigned int max_alloc)
1212 {
1213         struct rpc_xprt *xprt;
1214         struct rpc_rqst *req;
1215         int i;
1216
1217         xprt = kzalloc(size, GFP_KERNEL);
1218         if (xprt == NULL)
1219                 goto out;
1220
1221         xprt_init(xprt, net);
1222
1223         for (i = 0; i < num_prealloc; i++) {
1224                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1225                 if (!req)
1226                         goto out_free;
1227                 list_add(&req->rq_list, &xprt->free);
1228         }
1229         if (max_alloc > num_prealloc)
1230                 xprt->max_reqs = max_alloc;
1231         else
1232                 xprt->max_reqs = num_prealloc;
1233         xprt->min_reqs = num_prealloc;
1234         xprt->num_reqs = num_prealloc;
1235
1236         return xprt;
1237
1238 out_free:
1239         xprt_free(xprt);
1240 out:
1241         return NULL;
1242 }
1243 EXPORT_SYMBOL_GPL(xprt_alloc);
1244
1245 void xprt_free(struct rpc_xprt *xprt)
1246 {
1247         put_net(xprt->xprt_net);
1248         xprt_free_all_slots(xprt);
1249         kfree_rcu(xprt, rcu);
1250 }
1251 EXPORT_SYMBOL_GPL(xprt_free);
1252
1253 /**
1254  * xprt_reserve - allocate an RPC request slot
1255  * @task: RPC task requesting a slot allocation
1256  *
1257  * If the transport is marked as being congested, or if no more
1258  * slots are available, place the task on the transport's
1259  * backlog queue.
1260  */
1261 void xprt_reserve(struct rpc_task *task)
1262 {
1263         struct rpc_xprt *xprt = task->tk_xprt;
1264
1265         task->tk_status = 0;
1266         if (task->tk_rqstp != NULL)
1267                 return;
1268
1269         task->tk_timeout = 0;
1270         task->tk_status = -EAGAIN;
1271         if (!xprt_throttle_congested(xprt, task))
1272                 xprt->ops->alloc_slot(xprt, task);
1273 }
1274
1275 /**
1276  * xprt_retry_reserve - allocate an RPC request slot
1277  * @task: RPC task requesting a slot allocation
1278  *
1279  * If no more slots are available, place the task on the transport's
1280  * backlog queue.
1281  * Note that the only difference with xprt_reserve is that we now
1282  * ignore the value of the XPRT_CONGESTED flag.
1283  */
1284 void xprt_retry_reserve(struct rpc_task *task)
1285 {
1286         struct rpc_xprt *xprt = task->tk_xprt;
1287
1288         task->tk_status = 0;
1289         if (task->tk_rqstp != NULL)
1290                 return;
1291
1292         task->tk_timeout = 0;
1293         task->tk_status = -EAGAIN;
1294         xprt->ops->alloc_slot(xprt, task);
1295 }
1296
1297 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1298 {
1299         __be32 xid;
1300
1301         spin_lock(&xprt->reserve_lock);
1302         xid = (__force __be32)xprt->xid++;
1303         spin_unlock(&xprt->reserve_lock);
1304         return xid;
1305 }
1306
1307 static inline void xprt_init_xid(struct rpc_xprt *xprt)
1308 {
1309         xprt->xid = prandom_u32();
1310 }
1311
1312 void xprt_request_init(struct rpc_task *task)
1313 {
1314         struct rpc_xprt *xprt = task->tk_xprt;
1315         struct rpc_rqst *req = task->tk_rqstp;
1316
1317         INIT_LIST_HEAD(&req->rq_list);
1318         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1319         req->rq_task    = task;
1320         req->rq_xprt    = xprt;
1321         req->rq_buffer  = NULL;
1322         req->rq_xid     = xprt_alloc_xid(xprt);
1323         req->rq_connect_cookie = xprt->connect_cookie - 1;
1324         req->rq_bytes_sent = 0;
1325         req->rq_snd_buf.len = 0;
1326         req->rq_snd_buf.buflen = 0;
1327         req->rq_rcv_buf.len = 0;
1328         req->rq_rcv_buf.buflen = 0;
1329         req->rq_release_snd_buf = NULL;
1330         xprt_reset_majortimeo(req);
1331         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1332                         req, ntohl(req->rq_xid));
1333 }
1334
1335 /**
1336  * xprt_release - release an RPC request slot
1337  * @task: task which is finished with the slot
1338  *
1339  */
1340 void xprt_release(struct rpc_task *task)
1341 {
1342         struct rpc_xprt *xprt;
1343         struct rpc_rqst *req = task->tk_rqstp;
1344
1345         if (req == NULL) {
1346                 if (task->tk_client) {
1347                         xprt = task->tk_xprt;
1348                         if (xprt->snd_task == task)
1349                                 xprt_release_write(xprt, task);
1350                 }
1351                 return;
1352         }
1353
1354         xprt = req->rq_xprt;
1355         if (task->tk_ops->rpc_count_stats != NULL)
1356                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1357         else if (task->tk_client)
1358                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1359         spin_lock(&xprt->recv_lock);
1360         if (!list_empty(&req->rq_list)) {
1361                 list_del_init(&req->rq_list);
1362                 xprt_wait_on_pinned_rqst(req);
1363         }
1364         spin_unlock(&xprt->recv_lock);
1365         spin_lock_bh(&xprt->transport_lock);
1366         xprt->ops->release_xprt(xprt, task);
1367         if (xprt->ops->release_request)
1368                 xprt->ops->release_request(task);
1369         xprt->last_used = jiffies;
1370         xprt_schedule_autodisconnect(xprt);
1371         spin_unlock_bh(&xprt->transport_lock);
1372         if (req->rq_buffer)
1373                 xprt->ops->buf_free(task);
1374         xprt_inject_disconnect(xprt);
1375         if (req->rq_cred != NULL)
1376                 put_rpccred(req->rq_cred);
1377         task->tk_rqstp = NULL;
1378         if (req->rq_release_snd_buf)
1379                 req->rq_release_snd_buf(req);
1380
1381         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1382         if (likely(!bc_prealloc(req)))
1383                 xprt->ops->free_slot(xprt, req);
1384         else
1385                 xprt_free_bc_request(req);
1386 }
1387
1388 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1389 {
1390         kref_init(&xprt->kref);
1391
1392         spin_lock_init(&xprt->transport_lock);
1393         spin_lock_init(&xprt->reserve_lock);
1394         spin_lock_init(&xprt->recv_lock);
1395
1396         INIT_LIST_HEAD(&xprt->free);
1397         INIT_LIST_HEAD(&xprt->recv);
1398 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1399         spin_lock_init(&xprt->bc_pa_lock);
1400         INIT_LIST_HEAD(&xprt->bc_pa_list);
1401 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1402         INIT_LIST_HEAD(&xprt->xprt_switch);
1403
1404         xprt->last_used = jiffies;
1405         xprt->cwnd = RPC_INITCWND;
1406         xprt->bind_index = 0;
1407
1408         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1409         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1410         rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1411         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1412
1413         xprt_init_xid(xprt);
1414
1415         xprt->xprt_net = get_net(net);
1416 }
1417
1418 /**
1419  * xprt_create_transport - create an RPC transport
1420  * @args: rpc transport creation arguments
1421  *
1422  */
1423 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1424 {
1425         struct rpc_xprt *xprt;
1426         struct xprt_class *t;
1427
1428         spin_lock(&xprt_list_lock);
1429         list_for_each_entry(t, &xprt_list, list) {
1430                 if (t->ident == args->ident) {
1431                         spin_unlock(&xprt_list_lock);
1432                         goto found;
1433                 }
1434         }
1435         spin_unlock(&xprt_list_lock);
1436         dprintk("RPC: transport (%d) not supported\n", args->ident);
1437         return ERR_PTR(-EIO);
1438
1439 found:
1440         xprt = t->setup(args);
1441         if (IS_ERR(xprt)) {
1442                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1443                                 -PTR_ERR(xprt));
1444                 goto out;
1445         }
1446         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1447                 xprt->idle_timeout = 0;
1448         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1449         if (xprt_has_timer(xprt))
1450                 timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
1451         else
1452                 timer_setup(&xprt->timer, NULL, 0);
1453
1454         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1455                 xprt_destroy(xprt);
1456                 return ERR_PTR(-EINVAL);
1457         }
1458         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1459         if (xprt->servername == NULL) {
1460                 xprt_destroy(xprt);
1461                 return ERR_PTR(-ENOMEM);
1462         }
1463
1464         rpc_xprt_debugfs_register(xprt);
1465
1466         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1467                         xprt->max_reqs);
1468 out:
1469         return xprt;
1470 }
1471
1472 static void xprt_destroy_cb(struct work_struct *work)
1473 {
1474         struct rpc_xprt *xprt =
1475                 container_of(work, struct rpc_xprt, task_cleanup);
1476
1477         rpc_xprt_debugfs_unregister(xprt);
1478         rpc_destroy_wait_queue(&xprt->binding);
1479         rpc_destroy_wait_queue(&xprt->pending);
1480         rpc_destroy_wait_queue(&xprt->sending);
1481         rpc_destroy_wait_queue(&xprt->backlog);
1482         kfree(xprt->servername);
1483         /*
1484          * Tear down transport state and free the rpc_xprt
1485          */
1486         xprt->ops->destroy(xprt);
1487 }
1488
1489 /**
1490  * xprt_destroy - destroy an RPC transport, killing off all requests.
1491  * @xprt: transport to destroy
1492  *
1493  */
1494 static void xprt_destroy(struct rpc_xprt *xprt)
1495 {
1496         dprintk("RPC:       destroying transport %p\n", xprt);
1497
1498         /*
1499          * Exclude transport connect/disconnect handlers and autoclose
1500          */
1501         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
1502
1503         del_timer_sync(&xprt->timer);
1504
1505         /*
1506          * Destroy sockets etc from the system workqueue so they can
1507          * safely flush receive work running on rpciod.
1508          */
1509         INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
1510         schedule_work(&xprt->task_cleanup);
1511 }
1512
1513 static void xprt_destroy_kref(struct kref *kref)
1514 {
1515         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
1516 }
1517
1518 /**
1519  * xprt_get - return a reference to an RPC transport.
1520  * @xprt: pointer to the transport
1521  *
1522  */
1523 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1524 {
1525         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
1526                 return xprt;
1527         return NULL;
1528 }
1529 EXPORT_SYMBOL_GPL(xprt_get);
1530
1531 /**
1532  * xprt_put - release a reference to an RPC transport.
1533  * @xprt: pointer to the transport
1534  *
1535  */
1536 void xprt_put(struct rpc_xprt *xprt)
1537 {
1538         if (xprt != NULL)
1539                 kref_put(&xprt->kref, xprt_destroy_kref);
1540 }
1541 EXPORT_SYMBOL_GPL(xprt_put);