Merge tag 'jfs-3.10' of git://github.com/kleikamp/linux-shaggy
[linux-3.10.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
52 #include "sunrpc.h"
53
54 /*
55  * Local variables
56  */
57
58 #ifdef RPC_DEBUG
59 # define RPCDBG_FACILITY        RPCDBG_XPRT
60 #endif
61
62 /*
63  * Local functions
64  */
65 static void      xprt_init(struct rpc_xprt *xprt, struct net *net);
66 static void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
67 static void     xprt_connect_status(struct rpc_task *task);
68 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
69 static void      xprt_destroy(struct rpc_xprt *xprt);
70
71 static DEFINE_SPINLOCK(xprt_list_lock);
72 static LIST_HEAD(xprt_list);
73
74 /*
75  * The transport code maintains an estimate on the maximum number of out-
76  * standing RPC requests, using a smoothed version of the congestion
77  * avoidance implemented in 44BSD. This is basically the Van Jacobson
78  * congestion algorithm: If a retransmit occurs, the congestion window is
79  * halved; otherwise, it is incremented by 1/cwnd when
80  *
81  *      -       a reply is received and
82  *      -       a full number of requests are outstanding and
83  *      -       the congestion window hasn't been updated recently.
84  */
85 #define RPC_CWNDSHIFT           (8U)
86 #define RPC_CWNDSCALE           (1U << RPC_CWNDSHIFT)
87 #define RPC_INITCWND            RPC_CWNDSCALE
88 #define RPC_MAXCWND(xprt)       ((xprt)->max_reqs << RPC_CWNDSHIFT)
89
90 #define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
91
92 /**
93  * xprt_register_transport - register a transport implementation
94  * @transport: transport to register
95  *
96  * If a transport implementation is loaded as a kernel module, it can
97  * call this interface to make itself known to the RPC client.
98  *
99  * Returns:
100  * 0:           transport successfully registered
101  * -EEXIST:     transport already registered
102  * -EINVAL:     transport module being unloaded
103  */
104 int xprt_register_transport(struct xprt_class *transport)
105 {
106         struct xprt_class *t;
107         int result;
108
109         result = -EEXIST;
110         spin_lock(&xprt_list_lock);
111         list_for_each_entry(t, &xprt_list, list) {
112                 /* don't register the same transport class twice */
113                 if (t->ident == transport->ident)
114                         goto out;
115         }
116
117         list_add_tail(&transport->list, &xprt_list);
118         printk(KERN_INFO "RPC: Registered %s transport module.\n",
119                transport->name);
120         result = 0;
121
122 out:
123         spin_unlock(&xprt_list_lock);
124         return result;
125 }
126 EXPORT_SYMBOL_GPL(xprt_register_transport);
127
128 /**
129  * xprt_unregister_transport - unregister a transport implementation
130  * @transport: transport to unregister
131  *
132  * Returns:
133  * 0:           transport successfully unregistered
134  * -ENOENT:     transport never registered
135  */
136 int xprt_unregister_transport(struct xprt_class *transport)
137 {
138         struct xprt_class *t;
139         int result;
140
141         result = 0;
142         spin_lock(&xprt_list_lock);
143         list_for_each_entry(t, &xprt_list, list) {
144                 if (t == transport) {
145                         printk(KERN_INFO
146                                 "RPC: Unregistered %s transport module.\n",
147                                 transport->name);
148                         list_del_init(&transport->list);
149                         goto out;
150                 }
151         }
152         result = -ENOENT;
153
154 out:
155         spin_unlock(&xprt_list_lock);
156         return result;
157 }
158 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
159
160 /**
161  * xprt_load_transport - load a transport implementation
162  * @transport_name: transport to load
163  *
164  * Returns:
165  * 0:           transport successfully loaded
166  * -ENOENT:     transport module not available
167  */
168 int xprt_load_transport(const char *transport_name)
169 {
170         struct xprt_class *t;
171         int result;
172
173         result = 0;
174         spin_lock(&xprt_list_lock);
175         list_for_each_entry(t, &xprt_list, list) {
176                 if (strcmp(t->name, transport_name) == 0) {
177                         spin_unlock(&xprt_list_lock);
178                         goto out;
179                 }
180         }
181         spin_unlock(&xprt_list_lock);
182         result = request_module("xprt%s", transport_name);
183 out:
184         return result;
185 }
186 EXPORT_SYMBOL_GPL(xprt_load_transport);
187
188 /**
189  * xprt_reserve_xprt - serialize write access to transports
190  * @task: task that is requesting access to the transport
191  * @xprt: pointer to the target transport
192  *
193  * This prevents mixing the payload of separate requests, and prevents
194  * transport connects from colliding with writes.  No congestion control
195  * is provided.
196  */
197 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
198 {
199         struct rpc_rqst *req = task->tk_rqstp;
200         int priority;
201
202         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
203                 if (task == xprt->snd_task)
204                         return 1;
205                 goto out_sleep;
206         }
207         xprt->snd_task = task;
208         if (req != NULL) {
209                 req->rq_bytes_sent = 0;
210                 req->rq_ntrans++;
211         }
212
213         return 1;
214
215 out_sleep:
216         dprintk("RPC: %5u failed to lock transport %p\n",
217                         task->tk_pid, xprt);
218         task->tk_timeout = 0;
219         task->tk_status = -EAGAIN;
220         if (req == NULL)
221                 priority = RPC_PRIORITY_LOW;
222         else if (!req->rq_ntrans)
223                 priority = RPC_PRIORITY_NORMAL;
224         else
225                 priority = RPC_PRIORITY_HIGH;
226         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
227         return 0;
228 }
229 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
230
231 static void xprt_clear_locked(struct rpc_xprt *xprt)
232 {
233         xprt->snd_task = NULL;
234         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
235                 smp_mb__before_clear_bit();
236                 clear_bit(XPRT_LOCKED, &xprt->state);
237                 smp_mb__after_clear_bit();
238         } else
239                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
240 }
241
242 /*
243  * xprt_reserve_xprt_cong - serialize write access to transports
244  * @task: task that is requesting access to the transport
245  *
246  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
247  * integrated into the decision of whether a request is allowed to be
248  * woken up and given access to the transport.
249  */
250 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
251 {
252         struct rpc_rqst *req = task->tk_rqstp;
253         int priority;
254
255         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
256                 if (task == xprt->snd_task)
257                         return 1;
258                 goto out_sleep;
259         }
260         if (req == NULL) {
261                 xprt->snd_task = task;
262                 return 1;
263         }
264         if (__xprt_get_cong(xprt, task)) {
265                 xprt->snd_task = task;
266                 req->rq_bytes_sent = 0;
267                 req->rq_ntrans++;
268                 return 1;
269         }
270         xprt_clear_locked(xprt);
271 out_sleep:
272         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
273         task->tk_timeout = 0;
274         task->tk_status = -EAGAIN;
275         if (req == NULL)
276                 priority = RPC_PRIORITY_LOW;
277         else if (!req->rq_ntrans)
278                 priority = RPC_PRIORITY_NORMAL;
279         else
280                 priority = RPC_PRIORITY_HIGH;
281         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
282         return 0;
283 }
284 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
285
286 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
287 {
288         int retval;
289
290         spin_lock_bh(&xprt->transport_lock);
291         retval = xprt->ops->reserve_xprt(xprt, task);
292         spin_unlock_bh(&xprt->transport_lock);
293         return retval;
294 }
295
296 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
297 {
298         struct rpc_xprt *xprt = data;
299         struct rpc_rqst *req;
300
301         req = task->tk_rqstp;
302         xprt->snd_task = task;
303         if (req) {
304                 req->rq_bytes_sent = 0;
305                 req->rq_ntrans++;
306         }
307         return true;
308 }
309
310 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
311 {
312         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
313                 return;
314
315         if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_func, xprt))
316                 return;
317         xprt_clear_locked(xprt);
318 }
319
320 static bool __xprt_lock_write_cong_func(struct rpc_task *task, void *data)
321 {
322         struct rpc_xprt *xprt = data;
323         struct rpc_rqst *req;
324
325         req = task->tk_rqstp;
326         if (req == NULL) {
327                 xprt->snd_task = task;
328                 return true;
329         }
330         if (__xprt_get_cong(xprt, task)) {
331                 xprt->snd_task = task;
332                 req->rq_bytes_sent = 0;
333                 req->rq_ntrans++;
334                 return true;
335         }
336         return false;
337 }
338
339 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
340 {
341         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
342                 return;
343         if (RPCXPRT_CONGESTED(xprt))
344                 goto out_unlock;
345         if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_cong_func, xprt))
346                 return;
347 out_unlock:
348         xprt_clear_locked(xprt);
349 }
350
351 /**
352  * xprt_release_xprt - allow other requests to use a transport
353  * @xprt: transport with other tasks potentially waiting
354  * @task: task that is releasing access to the transport
355  *
356  * Note that "task" can be NULL.  No congestion control is provided.
357  */
358 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
359 {
360         if (xprt->snd_task == task) {
361                 xprt_clear_locked(xprt);
362                 __xprt_lock_write_next(xprt);
363         }
364 }
365 EXPORT_SYMBOL_GPL(xprt_release_xprt);
366
367 /**
368  * xprt_release_xprt_cong - allow other requests to use a transport
369  * @xprt: transport with other tasks potentially waiting
370  * @task: task that is releasing access to the transport
371  *
372  * Note that "task" can be NULL.  Another task is awoken to use the
373  * transport if the transport's congestion window allows it.
374  */
375 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
376 {
377         if (xprt->snd_task == task) {
378                 xprt_clear_locked(xprt);
379                 __xprt_lock_write_next_cong(xprt);
380         }
381 }
382 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
383
384 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
385 {
386         spin_lock_bh(&xprt->transport_lock);
387         xprt->ops->release_xprt(xprt, task);
388         spin_unlock_bh(&xprt->transport_lock);
389 }
390
391 /*
392  * Van Jacobson congestion avoidance. Check if the congestion window
393  * overflowed. Put the task to sleep if this is the case.
394  */
395 static int
396 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
397 {
398         struct rpc_rqst *req = task->tk_rqstp;
399
400         if (req->rq_cong)
401                 return 1;
402         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
403                         task->tk_pid, xprt->cong, xprt->cwnd);
404         if (RPCXPRT_CONGESTED(xprt))
405                 return 0;
406         req->rq_cong = 1;
407         xprt->cong += RPC_CWNDSCALE;
408         return 1;
409 }
410
411 /*
412  * Adjust the congestion window, and wake up the next task
413  * that has been sleeping due to congestion
414  */
415 static void
416 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
417 {
418         if (!req->rq_cong)
419                 return;
420         req->rq_cong = 0;
421         xprt->cong -= RPC_CWNDSCALE;
422         __xprt_lock_write_next_cong(xprt);
423 }
424
425 /**
426  * xprt_release_rqst_cong - housekeeping when request is complete
427  * @task: RPC request that recently completed
428  *
429  * Useful for transports that require congestion control.
430  */
431 void xprt_release_rqst_cong(struct rpc_task *task)
432 {
433         struct rpc_rqst *req = task->tk_rqstp;
434
435         __xprt_put_cong(req->rq_xprt, req);
436 }
437 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
438
439 /**
440  * xprt_adjust_cwnd - adjust transport congestion window
441  * @xprt: pointer to xprt
442  * @task: recently completed RPC request used to adjust window
443  * @result: result code of completed RPC request
444  *
445  * We use a time-smoothed congestion estimator to avoid heavy oscillation.
446  */
447 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
448 {
449         struct rpc_rqst *req = task->tk_rqstp;
450         unsigned long cwnd = xprt->cwnd;
451
452         if (result >= 0 && cwnd <= xprt->cong) {
453                 /* The (cwnd >> 1) term makes sure
454                  * the result gets rounded properly. */
455                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
456                 if (cwnd > RPC_MAXCWND(xprt))
457                         cwnd = RPC_MAXCWND(xprt);
458                 __xprt_lock_write_next_cong(xprt);
459         } else if (result == -ETIMEDOUT) {
460                 cwnd >>= 1;
461                 if (cwnd < RPC_CWNDSCALE)
462                         cwnd = RPC_CWNDSCALE;
463         }
464         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
465                         xprt->cong, xprt->cwnd, cwnd);
466         xprt->cwnd = cwnd;
467         __xprt_put_cong(xprt, req);
468 }
469 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
470
471 /**
472  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
473  * @xprt: transport with waiting tasks
474  * @status: result code to plant in each task before waking it
475  *
476  */
477 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
478 {
479         if (status < 0)
480                 rpc_wake_up_status(&xprt->pending, status);
481         else
482                 rpc_wake_up(&xprt->pending);
483 }
484 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
485
486 /**
487  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
488  * @task: task to be put to sleep
489  * @action: function pointer to be executed after wait
490  *
491  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
492  * we don't in general want to force a socket disconnection due to
493  * an incomplete RPC call transmission.
494  */
495 void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
496 {
497         struct rpc_rqst *req = task->tk_rqstp;
498         struct rpc_xprt *xprt = req->rq_xprt;
499
500         task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
501         rpc_sleep_on(&xprt->pending, task, action);
502 }
503 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
504
505 /**
506  * xprt_write_space - wake the task waiting for transport output buffer space
507  * @xprt: transport with waiting tasks
508  *
509  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
510  */
511 void xprt_write_space(struct rpc_xprt *xprt)
512 {
513         spin_lock_bh(&xprt->transport_lock);
514         if (xprt->snd_task) {
515                 dprintk("RPC:       write space: waking waiting task on "
516                                 "xprt %p\n", xprt);
517                 rpc_wake_up_queued_task(&xprt->pending, xprt->snd_task);
518         }
519         spin_unlock_bh(&xprt->transport_lock);
520 }
521 EXPORT_SYMBOL_GPL(xprt_write_space);
522
523 /**
524  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
525  * @task: task whose timeout is to be set
526  *
527  * Set a request's retransmit timeout based on the transport's
528  * default timeout parameters.  Used by transports that don't adjust
529  * the retransmit timeout based on round-trip time estimation.
530  */
531 void xprt_set_retrans_timeout_def(struct rpc_task *task)
532 {
533         task->tk_timeout = task->tk_rqstp->rq_timeout;
534 }
535 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
536
537 /**
538  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
539  * @task: task whose timeout is to be set
540  *
541  * Set a request's retransmit timeout using the RTT estimator.
542  */
543 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
544 {
545         int timer = task->tk_msg.rpc_proc->p_timer;
546         struct rpc_clnt *clnt = task->tk_client;
547         struct rpc_rtt *rtt = clnt->cl_rtt;
548         struct rpc_rqst *req = task->tk_rqstp;
549         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
550
551         task->tk_timeout = rpc_calc_rto(rtt, timer);
552         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
553         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
554                 task->tk_timeout = max_timeout;
555 }
556 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
557
558 static void xprt_reset_majortimeo(struct rpc_rqst *req)
559 {
560         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
561
562         req->rq_majortimeo = req->rq_timeout;
563         if (to->to_exponential)
564                 req->rq_majortimeo <<= to->to_retries;
565         else
566                 req->rq_majortimeo += to->to_increment * to->to_retries;
567         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
568                 req->rq_majortimeo = to->to_maxval;
569         req->rq_majortimeo += jiffies;
570 }
571
572 /**
573  * xprt_adjust_timeout - adjust timeout values for next retransmit
574  * @req: RPC request containing parameters to use for the adjustment
575  *
576  */
577 int xprt_adjust_timeout(struct rpc_rqst *req)
578 {
579         struct rpc_xprt *xprt = req->rq_xprt;
580         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
581         int status = 0;
582
583         if (time_before(jiffies, req->rq_majortimeo)) {
584                 if (to->to_exponential)
585                         req->rq_timeout <<= 1;
586                 else
587                         req->rq_timeout += to->to_increment;
588                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
589                         req->rq_timeout = to->to_maxval;
590                 req->rq_retries++;
591         } else {
592                 req->rq_timeout = to->to_initval;
593                 req->rq_retries = 0;
594                 xprt_reset_majortimeo(req);
595                 /* Reset the RTT counters == "slow start" */
596                 spin_lock_bh(&xprt->transport_lock);
597                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
598                 spin_unlock_bh(&xprt->transport_lock);
599                 status = -ETIMEDOUT;
600         }
601
602         if (req->rq_timeout == 0) {
603                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
604                 req->rq_timeout = 5 * HZ;
605         }
606         return status;
607 }
608
609 static void xprt_autoclose(struct work_struct *work)
610 {
611         struct rpc_xprt *xprt =
612                 container_of(work, struct rpc_xprt, task_cleanup);
613
614         xprt->ops->close(xprt);
615         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
616         xprt_release_write(xprt, NULL);
617 }
618
619 /**
620  * xprt_disconnect_done - mark a transport as disconnected
621  * @xprt: transport to flag for disconnect
622  *
623  */
624 void xprt_disconnect_done(struct rpc_xprt *xprt)
625 {
626         dprintk("RPC:       disconnected transport %p\n", xprt);
627         spin_lock_bh(&xprt->transport_lock);
628         xprt_clear_connected(xprt);
629         xprt_wake_pending_tasks(xprt, -EAGAIN);
630         spin_unlock_bh(&xprt->transport_lock);
631 }
632 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
633
634 /**
635  * xprt_force_disconnect - force a transport to disconnect
636  * @xprt: transport to disconnect
637  *
638  */
639 void xprt_force_disconnect(struct rpc_xprt *xprt)
640 {
641         /* Don't race with the test_bit() in xprt_clear_locked() */
642         spin_lock_bh(&xprt->transport_lock);
643         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
644         /* Try to schedule an autoclose RPC call */
645         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
646                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
647         xprt_wake_pending_tasks(xprt, -EAGAIN);
648         spin_unlock_bh(&xprt->transport_lock);
649 }
650
651 /**
652  * xprt_conditional_disconnect - force a transport to disconnect
653  * @xprt: transport to disconnect
654  * @cookie: 'connection cookie'
655  *
656  * This attempts to break the connection if and only if 'cookie' matches
657  * the current transport 'connection cookie'. It ensures that we don't
658  * try to break the connection more than once when we need to retransmit
659  * a batch of RPC requests.
660  *
661  */
662 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
663 {
664         /* Don't race with the test_bit() in xprt_clear_locked() */
665         spin_lock_bh(&xprt->transport_lock);
666         if (cookie != xprt->connect_cookie)
667                 goto out;
668         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
669                 goto out;
670         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
671         /* Try to schedule an autoclose RPC call */
672         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
673                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
674         xprt_wake_pending_tasks(xprt, -EAGAIN);
675 out:
676         spin_unlock_bh(&xprt->transport_lock);
677 }
678
679 static void
680 xprt_init_autodisconnect(unsigned long data)
681 {
682         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
683
684         spin_lock(&xprt->transport_lock);
685         if (!list_empty(&xprt->recv))
686                 goto out_abort;
687         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
688                 goto out_abort;
689         spin_unlock(&xprt->transport_lock);
690         set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
691         queue_work(rpciod_workqueue, &xprt->task_cleanup);
692         return;
693 out_abort:
694         spin_unlock(&xprt->transport_lock);
695 }
696
697 /**
698  * xprt_connect - schedule a transport connect operation
699  * @task: RPC task that is requesting the connect
700  *
701  */
702 void xprt_connect(struct rpc_task *task)
703 {
704         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
705
706         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
707                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
708
709         if (!xprt_bound(xprt)) {
710                 task->tk_status = -EAGAIN;
711                 return;
712         }
713         if (!xprt_lock_write(xprt, task))
714                 return;
715
716         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
717                 xprt->ops->close(xprt);
718
719         if (xprt_connected(xprt))
720                 xprt_release_write(xprt, task);
721         else {
722                 task->tk_rqstp->rq_bytes_sent = 0;
723                 task->tk_timeout = task->tk_rqstp->rq_timeout;
724                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
725
726                 if (test_bit(XPRT_CLOSING, &xprt->state))
727                         return;
728                 if (xprt_test_and_set_connecting(xprt))
729                         return;
730                 xprt->stat.connect_start = jiffies;
731                 xprt->ops->connect(xprt, task);
732         }
733 }
734
735 static void xprt_connect_status(struct rpc_task *task)
736 {
737         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
738
739         if (task->tk_status == 0) {
740                 xprt->stat.connect_count++;
741                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
742                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
743                                 task->tk_pid);
744                 return;
745         }
746
747         switch (task->tk_status) {
748         case -EAGAIN:
749                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
750                 break;
751         case -ETIMEDOUT:
752                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
753                                 "out\n", task->tk_pid);
754                 break;
755         default:
756                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
757                                 "server %s\n", task->tk_pid, -task->tk_status,
758                                 xprt->servername);
759                 xprt_release_write(xprt, task);
760                 task->tk_status = -EIO;
761         }
762 }
763
764 /**
765  * xprt_lookup_rqst - find an RPC request corresponding to an XID
766  * @xprt: transport on which the original request was transmitted
767  * @xid: RPC XID of incoming reply
768  *
769  */
770 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
771 {
772         struct rpc_rqst *entry;
773
774         list_for_each_entry(entry, &xprt->recv, rq_list)
775                 if (entry->rq_xid == xid)
776                         return entry;
777
778         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
779                         ntohl(xid));
780         xprt->stat.bad_xids++;
781         return NULL;
782 }
783 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
784
785 static void xprt_update_rtt(struct rpc_task *task)
786 {
787         struct rpc_rqst *req = task->tk_rqstp;
788         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
789         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
790         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
791
792         if (timer) {
793                 if (req->rq_ntrans == 1)
794                         rpc_update_rtt(rtt, timer, m);
795                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
796         }
797 }
798
799 /**
800  * xprt_complete_rqst - called when reply processing is complete
801  * @task: RPC request that recently completed
802  * @copied: actual number of bytes received from the transport
803  *
804  * Caller holds transport lock.
805  */
806 void xprt_complete_rqst(struct rpc_task *task, int copied)
807 {
808         struct rpc_rqst *req = task->tk_rqstp;
809         struct rpc_xprt *xprt = req->rq_xprt;
810
811         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
812                         task->tk_pid, ntohl(req->rq_xid), copied);
813
814         xprt->stat.recvs++;
815         req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
816         if (xprt->ops->timer != NULL)
817                 xprt_update_rtt(task);
818
819         list_del_init(&req->rq_list);
820         req->rq_private_buf.len = copied;
821         /* Ensure all writes are done before we update */
822         /* req->rq_reply_bytes_recvd */
823         smp_wmb();
824         req->rq_reply_bytes_recvd = copied;
825         rpc_wake_up_queued_task(&xprt->pending, task);
826 }
827 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
828
829 static void xprt_timer(struct rpc_task *task)
830 {
831         struct rpc_rqst *req = task->tk_rqstp;
832         struct rpc_xprt *xprt = req->rq_xprt;
833
834         if (task->tk_status != -ETIMEDOUT)
835                 return;
836         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
837
838         spin_lock_bh(&xprt->transport_lock);
839         if (!req->rq_reply_bytes_recvd) {
840                 if (xprt->ops->timer)
841                         xprt->ops->timer(xprt, task);
842         } else
843                 task->tk_status = 0;
844         spin_unlock_bh(&xprt->transport_lock);
845 }
846
847 static inline int xprt_has_timer(struct rpc_xprt *xprt)
848 {
849         return xprt->idle_timeout != 0;
850 }
851
852 /**
853  * xprt_prepare_transmit - reserve the transport before sending a request
854  * @task: RPC task about to send a request
855  *
856  */
857 int xprt_prepare_transmit(struct rpc_task *task)
858 {
859         struct rpc_rqst *req = task->tk_rqstp;
860         struct rpc_xprt *xprt = req->rq_xprt;
861         int err = 0;
862
863         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
864
865         spin_lock_bh(&xprt->transport_lock);
866         if (req->rq_reply_bytes_recvd && !req->rq_bytes_sent) {
867                 err = req->rq_reply_bytes_recvd;
868                 goto out_unlock;
869         }
870         if (!xprt->ops->reserve_xprt(xprt, task))
871                 err = -EAGAIN;
872 out_unlock:
873         spin_unlock_bh(&xprt->transport_lock);
874         return err;
875 }
876
877 void xprt_end_transmit(struct rpc_task *task)
878 {
879         xprt_release_write(task->tk_rqstp->rq_xprt, task);
880 }
881
882 /**
883  * xprt_transmit - send an RPC request on a transport
884  * @task: controlling RPC task
885  *
886  * We have to copy the iovec because sendmsg fiddles with its contents.
887  */
888 void xprt_transmit(struct rpc_task *task)
889 {
890         struct rpc_rqst *req = task->tk_rqstp;
891         struct rpc_xprt *xprt = req->rq_xprt;
892         int status, numreqs;
893
894         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
895
896         if (!req->rq_reply_bytes_recvd) {
897                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
898                         /*
899                          * Add to the list only if we're expecting a reply
900                          */
901                         spin_lock_bh(&xprt->transport_lock);
902                         /* Update the softirq receive buffer */
903                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
904                                         sizeof(req->rq_private_buf));
905                         /* Add request to the receive list */
906                         list_add_tail(&req->rq_list, &xprt->recv);
907                         spin_unlock_bh(&xprt->transport_lock);
908                         xprt_reset_majortimeo(req);
909                         /* Turn off autodisconnect */
910                         del_singleshot_timer_sync(&xprt->timer);
911                 }
912         } else if (!req->rq_bytes_sent)
913                 return;
914
915         req->rq_connect_cookie = xprt->connect_cookie;
916         req->rq_xtime = ktime_get();
917         status = xprt->ops->send_request(task);
918         if (status != 0) {
919                 task->tk_status = status;
920                 return;
921         }
922
923         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
924         task->tk_flags |= RPC_TASK_SENT;
925         spin_lock_bh(&xprt->transport_lock);
926
927         xprt->ops->set_retrans_timeout(task);
928
929         numreqs = atomic_read(&xprt->num_reqs);
930         if (numreqs > xprt->stat.max_slots)
931                 xprt->stat.max_slots = numreqs;
932         xprt->stat.sends++;
933         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
934         xprt->stat.bklog_u += xprt->backlog.qlen;
935         xprt->stat.sending_u += xprt->sending.qlen;
936         xprt->stat.pending_u += xprt->pending.qlen;
937
938         /* Don't race with disconnect */
939         if (!xprt_connected(xprt))
940                 task->tk_status = -ENOTCONN;
941         else if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task)) {
942                 /*
943                  * Sleep on the pending queue since
944                  * we're expecting a reply.
945                  */
946                 rpc_sleep_on(&xprt->pending, task, xprt_timer);
947         }
948         spin_unlock_bh(&xprt->transport_lock);
949 }
950
951 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
952 {
953         set_bit(XPRT_CONGESTED, &xprt->state);
954         rpc_sleep_on(&xprt->backlog, task, NULL);
955 }
956
957 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
958 {
959         if (rpc_wake_up_next(&xprt->backlog) == NULL)
960                 clear_bit(XPRT_CONGESTED, &xprt->state);
961 }
962
963 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
964 {
965         bool ret = false;
966
967         if (!test_bit(XPRT_CONGESTED, &xprt->state))
968                 goto out;
969         spin_lock(&xprt->reserve_lock);
970         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
971                 rpc_sleep_on(&xprt->backlog, task, NULL);
972                 ret = true;
973         }
974         spin_unlock(&xprt->reserve_lock);
975 out:
976         return ret;
977 }
978
979 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
980 {
981         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
982
983         if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
984                 goto out;
985         req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
986         if (req != NULL)
987                 goto out;
988         atomic_dec(&xprt->num_reqs);
989         req = ERR_PTR(-ENOMEM);
990 out:
991         return req;
992 }
993
994 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
995 {
996         if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
997                 kfree(req);
998                 return true;
999         }
1000         return false;
1001 }
1002
1003 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1004 {
1005         struct rpc_rqst *req;
1006
1007         spin_lock(&xprt->reserve_lock);
1008         if (!list_empty(&xprt->free)) {
1009                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1010                 list_del(&req->rq_list);
1011                 goto out_init_req;
1012         }
1013         req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
1014         if (!IS_ERR(req))
1015                 goto out_init_req;
1016         switch (PTR_ERR(req)) {
1017         case -ENOMEM:
1018                 dprintk("RPC:       dynamic allocation of request slot "
1019                                 "failed! Retrying\n");
1020                 task->tk_status = -ENOMEM;
1021                 break;
1022         case -EAGAIN:
1023                 xprt_add_backlog(xprt, task);
1024                 dprintk("RPC:       waiting for request slot\n");
1025         default:
1026                 task->tk_status = -EAGAIN;
1027         }
1028         spin_unlock(&xprt->reserve_lock);
1029         return;
1030 out_init_req:
1031         task->tk_status = 0;
1032         task->tk_rqstp = req;
1033         xprt_request_init(task, xprt);
1034         spin_unlock(&xprt->reserve_lock);
1035 }
1036 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1037
1038 void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1039 {
1040         /* Note: grabbing the xprt_lock_write() ensures that we throttle
1041          * new slot allocation if the transport is congested (i.e. when
1042          * reconnecting a stream transport or when out of socket write
1043          * buffer space).
1044          */
1045         if (xprt_lock_write(xprt, task)) {
1046                 xprt_alloc_slot(xprt, task);
1047                 xprt_release_write(xprt, task);
1048         }
1049 }
1050 EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1051
1052 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1053 {
1054         spin_lock(&xprt->reserve_lock);
1055         if (!xprt_dynamic_free_slot(xprt, req)) {
1056                 memset(req, 0, sizeof(*req));   /* mark unused */
1057                 list_add(&req->rq_list, &xprt->free);
1058         }
1059         xprt_wake_up_backlog(xprt);
1060         spin_unlock(&xprt->reserve_lock);
1061 }
1062
1063 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1064 {
1065         struct rpc_rqst *req;
1066         while (!list_empty(&xprt->free)) {
1067                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1068                 list_del(&req->rq_list);
1069                 kfree(req);
1070         }
1071 }
1072
1073 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1074                 unsigned int num_prealloc,
1075                 unsigned int max_alloc)
1076 {
1077         struct rpc_xprt *xprt;
1078         struct rpc_rqst *req;
1079         int i;
1080
1081         xprt = kzalloc(size, GFP_KERNEL);
1082         if (xprt == NULL)
1083                 goto out;
1084
1085         xprt_init(xprt, net);
1086
1087         for (i = 0; i < num_prealloc; i++) {
1088                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1089                 if (!req)
1090                         break;
1091                 list_add(&req->rq_list, &xprt->free);
1092         }
1093         if (i < num_prealloc)
1094                 goto out_free;
1095         if (max_alloc > num_prealloc)
1096                 xprt->max_reqs = max_alloc;
1097         else
1098                 xprt->max_reqs = num_prealloc;
1099         xprt->min_reqs = num_prealloc;
1100         atomic_set(&xprt->num_reqs, num_prealloc);
1101
1102         return xprt;
1103
1104 out_free:
1105         xprt_free(xprt);
1106 out:
1107         return NULL;
1108 }
1109 EXPORT_SYMBOL_GPL(xprt_alloc);
1110
1111 void xprt_free(struct rpc_xprt *xprt)
1112 {
1113         put_net(xprt->xprt_net);
1114         xprt_free_all_slots(xprt);
1115         kfree(xprt);
1116 }
1117 EXPORT_SYMBOL_GPL(xprt_free);
1118
1119 /**
1120  * xprt_reserve - allocate an RPC request slot
1121  * @task: RPC task requesting a slot allocation
1122  *
1123  * If the transport is marked as being congested, or if no more
1124  * slots are available, place the task on the transport's
1125  * backlog queue.
1126  */
1127 void xprt_reserve(struct rpc_task *task)
1128 {
1129         struct rpc_xprt *xprt;
1130
1131         task->tk_status = 0;
1132         if (task->tk_rqstp != NULL)
1133                 return;
1134
1135         task->tk_timeout = 0;
1136         task->tk_status = -EAGAIN;
1137         rcu_read_lock();
1138         xprt = rcu_dereference(task->tk_client->cl_xprt);
1139         if (!xprt_throttle_congested(xprt, task))
1140                 xprt->ops->alloc_slot(xprt, task);
1141         rcu_read_unlock();
1142 }
1143
1144 /**
1145  * xprt_retry_reserve - allocate an RPC request slot
1146  * @task: RPC task requesting a slot allocation
1147  *
1148  * If no more slots are available, place the task on the transport's
1149  * backlog queue.
1150  * Note that the only difference with xprt_reserve is that we now
1151  * ignore the value of the XPRT_CONGESTED flag.
1152  */
1153 void xprt_retry_reserve(struct rpc_task *task)
1154 {
1155         struct rpc_xprt *xprt;
1156
1157         task->tk_status = 0;
1158         if (task->tk_rqstp != NULL)
1159                 return;
1160
1161         task->tk_timeout = 0;
1162         task->tk_status = -EAGAIN;
1163         rcu_read_lock();
1164         xprt = rcu_dereference(task->tk_client->cl_xprt);
1165         xprt->ops->alloc_slot(xprt, task);
1166         rcu_read_unlock();
1167 }
1168
1169 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1170 {
1171         return (__force __be32)xprt->xid++;
1172 }
1173
1174 static inline void xprt_init_xid(struct rpc_xprt *xprt)
1175 {
1176         xprt->xid = net_random();
1177 }
1178
1179 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1180 {
1181         struct rpc_rqst *req = task->tk_rqstp;
1182
1183         INIT_LIST_HEAD(&req->rq_list);
1184         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1185         req->rq_task    = task;
1186         req->rq_xprt    = xprt;
1187         req->rq_buffer  = NULL;
1188         req->rq_xid     = xprt_alloc_xid(xprt);
1189         req->rq_release_snd_buf = NULL;
1190         xprt_reset_majortimeo(req);
1191         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1192                         req, ntohl(req->rq_xid));
1193 }
1194
1195 /**
1196  * xprt_release - release an RPC request slot
1197  * @task: task which is finished with the slot
1198  *
1199  */
1200 void xprt_release(struct rpc_task *task)
1201 {
1202         struct rpc_xprt *xprt;
1203         struct rpc_rqst *req = task->tk_rqstp;
1204
1205         if (req == NULL) {
1206                 if (task->tk_client) {
1207                         rcu_read_lock();
1208                         xprt = rcu_dereference(task->tk_client->cl_xprt);
1209                         if (xprt->snd_task == task)
1210                                 xprt_release_write(xprt, task);
1211                         rcu_read_unlock();
1212                 }
1213                 return;
1214         }
1215
1216         xprt = req->rq_xprt;
1217         if (task->tk_ops->rpc_count_stats != NULL)
1218                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1219         else if (task->tk_client)
1220                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1221         spin_lock_bh(&xprt->transport_lock);
1222         xprt->ops->release_xprt(xprt, task);
1223         if (xprt->ops->release_request)
1224                 xprt->ops->release_request(task);
1225         if (!list_empty(&req->rq_list))
1226                 list_del(&req->rq_list);
1227         xprt->last_used = jiffies;
1228         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1229                 mod_timer(&xprt->timer,
1230                                 xprt->last_used + xprt->idle_timeout);
1231         spin_unlock_bh(&xprt->transport_lock);
1232         if (req->rq_buffer)
1233                 xprt->ops->buf_free(req->rq_buffer);
1234         if (req->rq_cred != NULL)
1235                 put_rpccred(req->rq_cred);
1236         task->tk_rqstp = NULL;
1237         if (req->rq_release_snd_buf)
1238                 req->rq_release_snd_buf(req);
1239
1240         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1241         if (likely(!bc_prealloc(req)))
1242                 xprt_free_slot(xprt, req);
1243         else
1244                 xprt_free_bc_request(req);
1245 }
1246
1247 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1248 {
1249         atomic_set(&xprt->count, 1);
1250
1251         spin_lock_init(&xprt->transport_lock);
1252         spin_lock_init(&xprt->reserve_lock);
1253
1254         INIT_LIST_HEAD(&xprt->free);
1255         INIT_LIST_HEAD(&xprt->recv);
1256 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1257         spin_lock_init(&xprt->bc_pa_lock);
1258         INIT_LIST_HEAD(&xprt->bc_pa_list);
1259 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1260
1261         xprt->last_used = jiffies;
1262         xprt->cwnd = RPC_INITCWND;
1263         xprt->bind_index = 0;
1264
1265         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1266         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1267         rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1268         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1269
1270         xprt_init_xid(xprt);
1271
1272         xprt->xprt_net = get_net(net);
1273 }
1274
1275 /**
1276  * xprt_create_transport - create an RPC transport
1277  * @args: rpc transport creation arguments
1278  *
1279  */
1280 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1281 {
1282         struct rpc_xprt *xprt;
1283         struct xprt_class *t;
1284
1285         spin_lock(&xprt_list_lock);
1286         list_for_each_entry(t, &xprt_list, list) {
1287                 if (t->ident == args->ident) {
1288                         spin_unlock(&xprt_list_lock);
1289                         goto found;
1290                 }
1291         }
1292         spin_unlock(&xprt_list_lock);
1293         printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident);
1294         return ERR_PTR(-EIO);
1295
1296 found:
1297         xprt = t->setup(args);
1298         if (IS_ERR(xprt)) {
1299                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1300                                 -PTR_ERR(xprt));
1301                 goto out;
1302         }
1303         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1304         if (xprt_has_timer(xprt))
1305                 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1306                             (unsigned long)xprt);
1307         else
1308                 init_timer(&xprt->timer);
1309
1310         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1311                 xprt_destroy(xprt);
1312                 return ERR_PTR(-EINVAL);
1313         }
1314         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1315         if (xprt->servername == NULL) {
1316                 xprt_destroy(xprt);
1317                 return ERR_PTR(-ENOMEM);
1318         }
1319
1320         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1321                         xprt->max_reqs);
1322 out:
1323         return xprt;
1324 }
1325
1326 /**
1327  * xprt_destroy - destroy an RPC transport, killing off all requests.
1328  * @xprt: transport to destroy
1329  *
1330  */
1331 static void xprt_destroy(struct rpc_xprt *xprt)
1332 {
1333         dprintk("RPC:       destroying transport %p\n", xprt);
1334         del_timer_sync(&xprt->timer);
1335
1336         rpc_destroy_wait_queue(&xprt->binding);
1337         rpc_destroy_wait_queue(&xprt->pending);
1338         rpc_destroy_wait_queue(&xprt->sending);
1339         rpc_destroy_wait_queue(&xprt->backlog);
1340         cancel_work_sync(&xprt->task_cleanup);
1341         kfree(xprt->servername);
1342         /*
1343          * Tear down transport state and free the rpc_xprt
1344          */
1345         xprt->ops->destroy(xprt);
1346 }
1347
1348 /**
1349  * xprt_put - release a reference to an RPC transport.
1350  * @xprt: pointer to the transport
1351  *
1352  */
1353 void xprt_put(struct rpc_xprt *xprt)
1354 {
1355         if (atomic_dec_and_test(&xprt->count))
1356                 xprt_destroy(xprt);
1357 }
1358
1359 /**
1360  * xprt_get - return a reference to an RPC transport.
1361  * @xprt: pointer to the transport
1362  *
1363  */
1364 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1365 {
1366         if (atomic_inc_not_zero(&xprt->count))
1367                 return xprt;
1368         return NULL;
1369 }