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

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  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 <trace/events/sunrpc.h>
 53 
 54 #include "sunrpc.h"
 55 
 56 /*
 57  * Local variables
 58  */
 59 
 60 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 61 # define RPCDBG_FACILITY        RPCDBG_XPRT
 62 #endif
 63 
 64 /*
 65  * Local functions
 66  */
 67 static void      xprt_init(struct rpc_xprt *xprt, struct net *net);
 68 static void     xprt_request_init(struct rpc_task *, struct rpc_xprt *);
 69 static void     xprt_connect_status(struct rpc_task *task);
 70 static int      __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
 71 static void     __xprt_put_cong(struct rpc_xprt *, struct rpc_rqst *);
 72 static void      xprt_destroy(struct rpc_xprt *xprt);
 73 
 74 static DEFINE_SPINLOCK(xprt_list_lock);
 75 static LIST_HEAD(xprt_list);
 76 
 77 /**
 78  * xprt_register_transport - register a transport implementation
 79  * @transport: transport to register
 80  *
 81  * If a transport implementation is loaded as a kernel module, it can
 82  * call this interface to make itself known to the RPC client.
 83  *
 84  * Returns:
 85  * 0:           transport successfully registered
 86  * -EEXIST:     transport already registered
 87  * -EINVAL:     transport module being unloaded
 88  */
 89 int xprt_register_transport(struct xprt_class *transport)
 90 {
 91         struct xprt_class *t;
 92         int result;
 93 
 94         result = -EEXIST;
 95         spin_lock(&xprt_list_lock);
 96         list_for_each_entry(t, &xprt_list, list) {
 97                 /* don't register the same transport class twice */
 98                 if (t->ident == transport->ident)
 99                         goto out;
100         }
101 
102         list_add_tail(&transport->list, &xprt_list);
103         printk(KERN_INFO "RPC: Registered %s transport module.\n",
104                transport->name);
105         result = 0;
106 
107 out:
108         spin_unlock(&xprt_list_lock);
109         return result;
110 }
111 EXPORT_SYMBOL_GPL(xprt_register_transport);
112 
113 /**
114  * xprt_unregister_transport - unregister a transport implementation
115  * @transport: transport to unregister
116  *
117  * Returns:
118  * 0:           transport successfully unregistered
119  * -ENOENT:     transport never registered
120  */
121 int xprt_unregister_transport(struct xprt_class *transport)
122 {
123         struct xprt_class *t;
124         int result;
125 
126         result = 0;
127         spin_lock(&xprt_list_lock);
128         list_for_each_entry(t, &xprt_list, list) {
129                 if (t == transport) {
130                         printk(KERN_INFO
131                                 "RPC: Unregistered %s transport module.\n",
132                                 transport->name);
133                         list_del_init(&transport->list);
134                         goto out;
135                 }
136         }
137         result = -ENOENT;
138 
139 out:
140         spin_unlock(&xprt_list_lock);
141         return result;
142 }
143 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
144 
145 /**
146  * xprt_load_transport - load a transport implementation
147  * @transport_name: transport to load
148  *
149  * Returns:
150  * 0:           transport successfully loaded
151  * -ENOENT:     transport module not available
152  */
153 int xprt_load_transport(const char *transport_name)
154 {
155         struct xprt_class *t;
156         int result;
157 
158         result = 0;
159         spin_lock(&xprt_list_lock);
160         list_for_each_entry(t, &xprt_list, list) {
161                 if (strcmp(t->name, transport_name) == 0) {
162                         spin_unlock(&xprt_list_lock);
163                         goto out;
164                 }
165         }
166         spin_unlock(&xprt_list_lock);
167         result = request_module("xprt%s", transport_name);
168 out:
169         return result;
170 }
171 EXPORT_SYMBOL_GPL(xprt_load_transport);
172 
173 /**
174  * xprt_reserve_xprt - serialize write access to transports
175  * @task: task that is requesting access to the transport
176  * @xprt: pointer to the target transport
177  *
178  * This prevents mixing the payload of separate requests, and prevents
179  * transport connects from colliding with writes.  No congestion control
180  * is provided.
181  */
182 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
183 {
184         struct rpc_rqst *req = task->tk_rqstp;
185         int priority;
186 
187         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
188                 if (task == xprt->snd_task)
189                         return 1;
190                 goto out_sleep;
191         }
192         xprt->snd_task = task;
193         if (req != NULL)
194                 req->rq_ntrans++;
195 
196         return 1;
197 
198 out_sleep:
199         dprintk("RPC: %5u failed to lock transport %p\n",
200                         task->tk_pid, xprt);
201         task->tk_timeout = 0;
202         task->tk_status = -EAGAIN;
203         if (req == NULL)
204                 priority = RPC_PRIORITY_LOW;
205         else if (!req->rq_ntrans)
206                 priority = RPC_PRIORITY_NORMAL;
207         else
208                 priority = RPC_PRIORITY_HIGH;
209         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
210         return 0;
211 }
212 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
213 
214 static void xprt_clear_locked(struct rpc_xprt *xprt)
215 {
216         xprt->snd_task = NULL;
217         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
218                 smp_mb__before_atomic();
219                 clear_bit(XPRT_LOCKED, &xprt->state);
220                 smp_mb__after_atomic();
221         } else
222                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
223 }
224 
225 /*
226  * xprt_reserve_xprt_cong - serialize write access to transports
227  * @task: task that is requesting access to the transport
228  *
229  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
230  * integrated into the decision of whether a request is allowed to be
231  * woken up and given access to the transport.
232  */
233 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
234 {
235         struct rpc_rqst *req = task->tk_rqstp;
236         int priority;
237 
238         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
239                 if (task == xprt->snd_task)
240                         return 1;
241                 goto out_sleep;
242         }
243         if (req == NULL) {
244                 xprt->snd_task = task;
245                 return 1;
246         }
247         if (__xprt_get_cong(xprt, task)) {
248                 xprt->snd_task = task;
249                 req->rq_ntrans++;
250                 return 1;
251         }
252         xprt_clear_locked(xprt);
253 out_sleep:
254         if (req)
255                 __xprt_put_cong(xprt, req);
256         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
257         task->tk_timeout = 0;
258         task->tk_status = -EAGAIN;
259         if (req == NULL)
260                 priority = RPC_PRIORITY_LOW;
261         else if (!req->rq_ntrans)
262                 priority = RPC_PRIORITY_NORMAL;
263         else
264                 priority = RPC_PRIORITY_HIGH;
265         rpc_sleep_on_priority(&xprt->sending, task, NULL, priority);
266         return 0;
267 }
268 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
269 
270 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
271 {
272         int retval;
273 
274         spin_lock_bh(&xprt->transport_lock);
275         retval = xprt->ops->reserve_xprt(xprt, task);
276         spin_unlock_bh(&xprt->transport_lock);
277         return retval;
278 }
279 
280 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
281 {
282         struct rpc_xprt *xprt = data;
283         struct rpc_rqst *req;
284 
285         req = task->tk_rqstp;
286         xprt->snd_task = task;
287         if (req)
288                 req->rq_ntrans++;
289         return true;
290 }
291 
292 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
293 {
294         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
295                 return;
296 
297         if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_func, xprt))
298                 return;
299         xprt_clear_locked(xprt);
300 }
301 
302 static bool __xprt_lock_write_cong_func(struct rpc_task *task, void *data)
303 {
304         struct rpc_xprt *xprt = data;
305         struct rpc_rqst *req;
306 
307         req = task->tk_rqstp;
308         if (req == NULL) {
309                 xprt->snd_task = task;
310                 return true;
311         }
312         if (__xprt_get_cong(xprt, task)) {
313                 xprt->snd_task = task;
314                 req->rq_ntrans++;
315                 return true;
316         }
317         return false;
318 }
319 
320 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
321 {
322         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
323                 return;
324         if (RPCXPRT_CONGESTED(xprt))
325                 goto out_unlock;
326         if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_cong_func, xprt))
327                 return;
328 out_unlock:
329         xprt_clear_locked(xprt);
330 }
331 
332 static void xprt_task_clear_bytes_sent(struct rpc_task *task)
333 {
334         if (task != NULL) {
335                 struct rpc_rqst *req = task->tk_rqstp;
336                 if (req != NULL)
337                         req->rq_bytes_sent = 0;
338         }
339 }
340 
341 /**
342  * xprt_release_xprt - allow other requests to use a transport
343  * @xprt: transport with other tasks potentially waiting
344  * @task: task that is releasing access to the transport
345  *
346  * Note that "task" can be NULL.  No congestion control is provided.
347  */
348 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
349 {
350         if (xprt->snd_task == task) {
351                 xprt_task_clear_bytes_sent(task);
352                 xprt_clear_locked(xprt);
353                 __xprt_lock_write_next(xprt);
354         }
355 }
356 EXPORT_SYMBOL_GPL(xprt_release_xprt);
357 
358 /**
359  * xprt_release_xprt_cong - allow other requests to use a transport
360  * @xprt: transport with other tasks potentially waiting
361  * @task: task that is releasing access to the transport
362  *
363  * Note that "task" can be NULL.  Another task is awoken to use the
364  * transport if the transport's congestion window allows it.
365  */
366 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
367 {
368         if (xprt->snd_task == task) {
369                 xprt_task_clear_bytes_sent(task);
370                 xprt_clear_locked(xprt);
371                 __xprt_lock_write_next_cong(xprt);
372         }
373 }
374 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
375 
376 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
377 {
378         spin_lock_bh(&xprt->transport_lock);
379         xprt->ops->release_xprt(xprt, task);
380         spin_unlock_bh(&xprt->transport_lock);
381 }
382 
383 /*
384  * Van Jacobson congestion avoidance. Check if the congestion window
385  * overflowed. Put the task to sleep if this is the case.
386  */
387 static int
388 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_task *task)
389 {
390         struct rpc_rqst *req = task->tk_rqstp;
391 
392         if (req->rq_cong)
393                 return 1;
394         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
395                         task->tk_pid, xprt->cong, xprt->cwnd);
396         if (RPCXPRT_CONGESTED(xprt))
397                 return 0;
398         req->rq_cong = 1;
399         xprt->cong += RPC_CWNDSCALE;
400         return 1;
401 }
402 
403 /*
404  * Adjust the congestion window, and wake up the next task
405  * that has been sleeping due to congestion
406  */
407 static void
408 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
409 {
410         if (!req->rq_cong)
411                 return;
412         req->rq_cong = 0;
413         xprt->cong -= RPC_CWNDSCALE;
414         __xprt_lock_write_next_cong(xprt);
415 }
416 
417 /**
418  * xprt_release_rqst_cong - housekeeping when request is complete
419  * @task: RPC request that recently completed
420  *
421  * Useful for transports that require congestion control.
422  */
423 void xprt_release_rqst_cong(struct rpc_task *task)
424 {
425         struct rpc_rqst *req = task->tk_rqstp;
426 
427         __xprt_put_cong(req->rq_xprt, req);
428 }
429 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
430 
431 /**
432  * xprt_adjust_cwnd - adjust transport congestion window
433  * @xprt: pointer to xprt
434  * @task: recently completed RPC request used to adjust window
435  * @result: result code of completed RPC request
436  *
437  * The transport code maintains an estimate on the maximum number of out-
438  * standing RPC requests, using a smoothed version of the congestion
439  * avoidance implemented in 44BSD. This is basically the Van Jacobson
440  * congestion algorithm: If a retransmit occurs, the congestion window is
441  * halved; otherwise, it is incremented by 1/cwnd when
442  *
443  *      -       a reply is received and
444  *      -       a full number of requests are outstanding and
445  *      -       the congestion window hasn't been updated recently.
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         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
615         xprt->ops->close(xprt);
616         xprt_release_write(xprt, NULL);
617         wake_up_bit(&xprt->state, XPRT_LOCKED);
618 }
619 
620 /**
621  * xprt_disconnect_done - mark a transport as disconnected
622  * @xprt: transport to flag for disconnect
623  *
624  */
625 void xprt_disconnect_done(struct rpc_xprt *xprt)
626 {
627         dprintk("RPC:       disconnected transport %p\n", xprt);
628         spin_lock_bh(&xprt->transport_lock);
629         xprt_clear_connected(xprt);
630         xprt_wake_pending_tasks(xprt, -EAGAIN);
631         spin_unlock_bh(&xprt->transport_lock);
632 }
633 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
634 
635 /**
636  * xprt_force_disconnect - force a transport to disconnect
637  * @xprt: transport to disconnect
638  *
639  */
640 void xprt_force_disconnect(struct rpc_xprt *xprt)
641 {
642         /* Don't race with the test_bit() in xprt_clear_locked() */
643         spin_lock_bh(&xprt->transport_lock);
644         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
645         /* Try to schedule an autoclose RPC call */
646         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
647                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
648         xprt_wake_pending_tasks(xprt, -EAGAIN);
649         spin_unlock_bh(&xprt->transport_lock);
650 }
651 
652 /**
653  * xprt_conditional_disconnect - force a transport to disconnect
654  * @xprt: transport to disconnect
655  * @cookie: 'connection cookie'
656  *
657  * This attempts to break the connection if and only if 'cookie' matches
658  * the current transport 'connection cookie'. It ensures that we don't
659  * try to break the connection more than once when we need to retransmit
660  * a batch of RPC requests.
661  *
662  */
663 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
664 {
665         /* Don't race with the test_bit() in xprt_clear_locked() */
666         spin_lock_bh(&xprt->transport_lock);
667         if (cookie != xprt->connect_cookie)
668                 goto out;
669         if (test_bit(XPRT_CLOSING, &xprt->state) || !xprt_connected(xprt))
670                 goto out;
671         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
672         /* Try to schedule an autoclose RPC call */
673         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
674                 queue_work(rpciod_workqueue, &xprt->task_cleanup);
675         xprt_wake_pending_tasks(xprt, -EAGAIN);
676 out:
677         spin_unlock_bh(&xprt->transport_lock);
678 }
679 
680 static void
681 xprt_init_autodisconnect(unsigned long data)
682 {
683         struct rpc_xprt *xprt = (struct rpc_xprt *)data;
684 
685         spin_lock(&xprt->transport_lock);
686         if (!list_empty(&xprt->recv))
687                 goto out_abort;
688         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
689                 goto out_abort;
690         spin_unlock(&xprt->transport_lock);
691         queue_work(rpciod_workqueue, &xprt->task_cleanup);
692         return;
693 out_abort:
694         spin_unlock(&xprt->transport_lock);
695 }
696 
697 bool xprt_lock_connect(struct rpc_xprt *xprt,
698                 struct rpc_task *task,
699                 void *cookie)
700 {
701         bool ret = false;
702 
703         spin_lock_bh(&xprt->transport_lock);
704         if (!test_bit(XPRT_LOCKED, &xprt->state))
705                 goto out;
706         if (xprt->snd_task != task)
707                 goto out;
708         xprt_task_clear_bytes_sent(task);
709         xprt->snd_task = cookie;
710         ret = true;
711 out:
712         spin_unlock_bh(&xprt->transport_lock);
713         return ret;
714 }
715 
716 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
717 {
718         spin_lock_bh(&xprt->transport_lock);
719         if (xprt->snd_task != cookie)
720                 goto out;
721         if (!test_bit(XPRT_LOCKED, &xprt->state))
722                 goto out;
723         xprt->snd_task =NULL;
724         xprt->ops->release_xprt(xprt, NULL);
725 out:
726         spin_unlock_bh(&xprt->transport_lock);
727         wake_up_bit(&xprt->state, XPRT_LOCKED);
728 }
729 
730 /**
731  * xprt_connect - schedule a transport connect operation
732  * @task: RPC task that is requesting the connect
733  *
734  */
735 void xprt_connect(struct rpc_task *task)
736 {
737         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
738 
739         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
740                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
741 
742         if (!xprt_bound(xprt)) {
743                 task->tk_status = -EAGAIN;
744                 return;
745         }
746         if (!xprt_lock_write(xprt, task))
747                 return;
748 
749         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
750                 xprt->ops->close(xprt);
751 
752         if (!xprt_connected(xprt)) {
753                 task->tk_rqstp->rq_bytes_sent = 0;
754                 task->tk_timeout = task->tk_rqstp->rq_timeout;
755                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
756 
757                 if (test_bit(XPRT_CLOSING, &xprt->state))
758                         return;
759                 if (xprt_test_and_set_connecting(xprt))
760                         return;
761                 xprt->stat.connect_start = jiffies;
762                 xprt->ops->connect(xprt, task);
763         }
764         xprt_release_write(xprt, task);
765 }
766 
767 static void xprt_connect_status(struct rpc_task *task)
768 {
769         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
770 
771         if (task->tk_status == 0) {
772                 xprt->stat.connect_count++;
773                 xprt->stat.connect_time += (long)jiffies - xprt->stat.connect_start;
774                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
775                                 task->tk_pid);
776                 return;
777         }
778 
779         switch (task->tk_status) {
780         case -ECONNREFUSED:
781         case -ECONNRESET:
782         case -ECONNABORTED:
783         case -ENETUNREACH:
784         case -EHOSTUNREACH:
785         case -EPIPE:
786         case -EAGAIN:
787                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
788                 break;
789         case -ETIMEDOUT:
790                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
791                                 "out\n", task->tk_pid);
792                 break;
793         default:
794                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
795                                 "server %s\n", task->tk_pid, -task->tk_status,
796                                 xprt->servername);
797                 task->tk_status = -EIO;
798         }
799 }
800 
801 /**
802  * xprt_lookup_rqst - find an RPC request corresponding to an XID
803  * @xprt: transport on which the original request was transmitted
804  * @xid: RPC XID of incoming reply
805  *
806  */
807 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
808 {
809         struct rpc_rqst *entry;
810 
811         list_for_each_entry(entry, &xprt->recv, rq_list)
812                 if (entry->rq_xid == xid) {
813                         trace_xprt_lookup_rqst(xprt, xid, 0);
814                         return entry;
815                 }
816 
817         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
818                         ntohl(xid));
819         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
820         xprt->stat.bad_xids++;
821         return NULL;
822 }
823 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
824 
825 static void xprt_update_rtt(struct rpc_task *task)
826 {
827         struct rpc_rqst *req = task->tk_rqstp;
828         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
829         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
830         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
831 
832         if (timer) {
833                 if (req->rq_ntrans == 1)
834                         rpc_update_rtt(rtt, timer, m);
835                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
836         }
837 }
838 
839 /**
840  * xprt_complete_rqst - called when reply processing is complete
841  * @task: RPC request that recently completed
842  * @copied: actual number of bytes received from the transport
843  *
844  * Caller holds transport lock.
845  */
846 void xprt_complete_rqst(struct rpc_task *task, int copied)
847 {
848         struct rpc_rqst *req = task->tk_rqstp;
849         struct rpc_xprt *xprt = req->rq_xprt;
850 
851         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
852                         task->tk_pid, ntohl(req->rq_xid), copied);
853         trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
854 
855         xprt->stat.recvs++;
856         req->rq_rtt = ktime_sub(ktime_get(), req->rq_xtime);
857         if (xprt->ops->timer != NULL)
858                 xprt_update_rtt(task);
859 
860         list_del_init(&req->rq_list);
861         req->rq_private_buf.len = copied;
862         /* Ensure all writes are done before we update */
863         /* req->rq_reply_bytes_recvd */
864         smp_wmb();
865         req->rq_reply_bytes_recvd = copied;
866         rpc_wake_up_queued_task(&xprt->pending, task);
867 }
868 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
869 
870 static void xprt_timer(struct rpc_task *task)
871 {
872         struct rpc_rqst *req = task->tk_rqstp;
873         struct rpc_xprt *xprt = req->rq_xprt;
874 
875         if (task->tk_status != -ETIMEDOUT)
876                 return;
877         dprintk("RPC: %5u xprt_timer\n", task->tk_pid);
878 
879         spin_lock_bh(&xprt->transport_lock);
880         if (!req->rq_reply_bytes_recvd) {
881                 if (xprt->ops->timer)
882                         xprt->ops->timer(xprt, task);
883         } else
884                 task->tk_status = 0;
885         spin_unlock_bh(&xprt->transport_lock);
886 }
887 
888 static inline int xprt_has_timer(struct rpc_xprt *xprt)
889 {
890         return xprt->idle_timeout != 0;
891 }
892 
893 /**
894  * xprt_prepare_transmit - reserve the transport before sending a request
895  * @task: RPC task about to send a request
896  *
897  */
898 bool xprt_prepare_transmit(struct rpc_task *task)
899 {
900         struct rpc_rqst *req = task->tk_rqstp;
901         struct rpc_xprt *xprt = req->rq_xprt;
902         bool ret = false;
903 
904         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
905 
906         spin_lock_bh(&xprt->transport_lock);
907         if (!req->rq_bytes_sent) {
908                 if (req->rq_reply_bytes_recvd) {
909                         task->tk_status = req->rq_reply_bytes_recvd;
910                         goto out_unlock;
911                 }
912                 if ((task->tk_flags & RPC_TASK_NO_RETRANS_TIMEOUT)
913                     && xprt_connected(xprt)
914                     && req->rq_connect_cookie == xprt->connect_cookie) {
915                         xprt->ops->set_retrans_timeout(task);
916                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
917                         goto out_unlock;
918                 }
919         }
920         if (!xprt->ops->reserve_xprt(xprt, task)) {
921                 task->tk_status = -EAGAIN;
922                 goto out_unlock;
923         }
924         ret = true;
925 out_unlock:
926         spin_unlock_bh(&xprt->transport_lock);
927         return ret;
928 }
929 
930 void xprt_end_transmit(struct rpc_task *task)
931 {
932         xprt_release_write(task->tk_rqstp->rq_xprt, task);
933 }
934 
935 /**
936  * xprt_transmit - send an RPC request on a transport
937  * @task: controlling RPC task
938  *
939  * We have to copy the iovec because sendmsg fiddles with its contents.
940  */
941 void xprt_transmit(struct rpc_task *task)
942 {
943         struct rpc_rqst *req = task->tk_rqstp;
944         struct rpc_xprt *xprt = req->rq_xprt;
945         int status, numreqs;
946 
947         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
948 
949         if (!req->rq_reply_bytes_recvd) {
950                 if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
951                         /*
952                          * Add to the list only if we're expecting a reply
953                          */
954                         spin_lock_bh(&xprt->transport_lock);
955                         /* Update the softirq receive buffer */
956                         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
957                                         sizeof(req->rq_private_buf));
958                         /* Add request to the receive list */
959                         list_add_tail(&req->rq_list, &xprt->recv);
960                         spin_unlock_bh(&xprt->transport_lock);
961                         xprt_reset_majortimeo(req);
962                         /* Turn off autodisconnect */
963                         del_singleshot_timer_sync(&xprt->timer);
964                 }
965         } else if (!req->rq_bytes_sent)
966                 return;
967 
968         req->rq_xtime = ktime_get();
969         status = xprt->ops->send_request(task);
970         trace_xprt_transmit(xprt, req->rq_xid, status);
971         if (status != 0) {
972                 task->tk_status = status;
973                 return;
974         }
975         xprt_inject_disconnect(xprt);
976 
977         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
978         task->tk_flags |= RPC_TASK_SENT;
979         spin_lock_bh(&xprt->transport_lock);
980 
981         xprt->ops->set_retrans_timeout(task);
982 
983         numreqs = atomic_read(&xprt->num_reqs);
984         if (numreqs > xprt->stat.max_slots)
985                 xprt->stat.max_slots = numreqs;
986         xprt->stat.sends++;
987         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
988         xprt->stat.bklog_u += xprt->backlog.qlen;
989         xprt->stat.sending_u += xprt->sending.qlen;
990         xprt->stat.pending_u += xprt->pending.qlen;
991 
992         /* Don't race with disconnect */
993         if (!xprt_connected(xprt))
994                 task->tk_status = -ENOTCONN;
995         else {
996                 /*
997                  * Sleep on the pending queue since
998                  * we're expecting a reply.
999                  */
1000                 if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task))
1001                         rpc_sleep_on(&xprt->pending, task, xprt_timer);
1002                 req->rq_connect_cookie = xprt->connect_cookie;
1003         }
1004         spin_unlock_bh(&xprt->transport_lock);
1005 }
1006 
1007 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1008 {
1009         set_bit(XPRT_CONGESTED, &xprt->state);
1010         rpc_sleep_on(&xprt->backlog, task, NULL);
1011 }
1012 
1013 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
1014 {
1015         if (rpc_wake_up_next(&xprt->backlog) == NULL)
1016                 clear_bit(XPRT_CONGESTED, &xprt->state);
1017 }
1018 
1019 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1020 {
1021         bool ret = false;
1022 
1023         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1024                 goto out;
1025         spin_lock(&xprt->reserve_lock);
1026         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1027                 rpc_sleep_on(&xprt->backlog, task, NULL);
1028                 ret = true;
1029         }
1030         spin_unlock(&xprt->reserve_lock);
1031 out:
1032         return ret;
1033 }
1034 
1035 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
1036 {
1037         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1038 
1039         if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
1040                 goto out;
1041         req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
1042         if (req != NULL)
1043                 goto out;
1044         atomic_dec(&xprt->num_reqs);
1045         req = ERR_PTR(-ENOMEM);
1046 out:
1047         return req;
1048 }
1049 
1050 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1051 {
1052         if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
1053                 kfree(req);
1054                 return true;
1055         }
1056         return false;
1057 }
1058 
1059 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1060 {
1061         struct rpc_rqst *req;
1062 
1063         spin_lock(&xprt->reserve_lock);
1064         if (!list_empty(&xprt->free)) {
1065                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1066                 list_del(&req->rq_list);
1067                 goto out_init_req;
1068         }
1069         req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT|__GFP_NOWARN);
1070         if (!IS_ERR(req))
1071                 goto out_init_req;
1072         switch (PTR_ERR(req)) {
1073         case -ENOMEM:
1074                 dprintk("RPC:       dynamic allocation of request slot "
1075                                 "failed! Retrying\n");
1076                 task->tk_status = -ENOMEM;
1077                 break;
1078         case -EAGAIN:
1079                 xprt_add_backlog(xprt, task);
1080                 dprintk("RPC:       waiting for request slot\n");
1081         default:
1082                 task->tk_status = -EAGAIN;
1083         }
1084         spin_unlock(&xprt->reserve_lock);
1085         return;
1086 out_init_req:
1087         task->tk_status = 0;
1088         task->tk_rqstp = req;
1089         xprt_request_init(task, xprt);
1090         spin_unlock(&xprt->reserve_lock);
1091 }
1092 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1093 
1094 void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1095 {
1096         /* Note: grabbing the xprt_lock_write() ensures that we throttle
1097          * new slot allocation if the transport is congested (i.e. when
1098          * reconnecting a stream transport or when out of socket write
1099          * buffer space).
1100          */
1101         if (xprt_lock_write(xprt, task)) {
1102                 xprt_alloc_slot(xprt, task);
1103                 xprt_release_write(xprt, task);
1104         }
1105 }
1106 EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
1107 
1108 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1109 {
1110         spin_lock(&xprt->reserve_lock);
1111         if (!xprt_dynamic_free_slot(xprt, req)) {
1112                 memset(req, 0, sizeof(*req));   /* mark unused */
1113                 list_add(&req->rq_list, &xprt->free);
1114         }
1115         xprt_wake_up_backlog(xprt);
1116         spin_unlock(&xprt->reserve_lock);
1117 }
1118 
1119 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1120 {
1121         struct rpc_rqst *req;
1122         while (!list_empty(&xprt->free)) {
1123                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1124                 list_del(&req->rq_list);
1125                 kfree(req);
1126         }
1127 }
1128 
1129 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1130                 unsigned int num_prealloc,
1131                 unsigned int max_alloc)
1132 {
1133         struct rpc_xprt *xprt;
1134         struct rpc_rqst *req;
1135         int i;
1136 
1137         xprt = kzalloc(size, GFP_KERNEL);
1138         if (xprt == NULL)
1139                 goto out;
1140 
1141         xprt_init(xprt, net);
1142 
1143         for (i = 0; i < num_prealloc; i++) {
1144                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1145                 if (!req)
1146                         goto out_free;
1147                 list_add(&req->rq_list, &xprt->free);
1148         }
1149         if (max_alloc > num_prealloc)
1150                 xprt->max_reqs = max_alloc;
1151         else
1152                 xprt->max_reqs = num_prealloc;
1153         xprt->min_reqs = num_prealloc;
1154         atomic_set(&xprt->num_reqs, num_prealloc);
1155 
1156         return xprt;
1157 
1158 out_free:
1159         xprt_free(xprt);
1160 out:
1161         return NULL;
1162 }
1163 EXPORT_SYMBOL_GPL(xprt_alloc);
1164 
1165 void xprt_free(struct rpc_xprt *xprt)
1166 {
1167         put_net(xprt->xprt_net);
1168         xprt_free_all_slots(xprt);
1169         kfree(xprt);
1170 }
1171 EXPORT_SYMBOL_GPL(xprt_free);
1172 
1173 /**
1174  * xprt_reserve - allocate an RPC request slot
1175  * @task: RPC task requesting a slot allocation
1176  *
1177  * If the transport is marked as being congested, or if no more
1178  * slots are available, place the task on the transport's
1179  * backlog queue.
1180  */
1181 void xprt_reserve(struct rpc_task *task)
1182 {
1183         struct rpc_xprt *xprt;
1184 
1185         task->tk_status = 0;
1186         if (task->tk_rqstp != NULL)
1187                 return;
1188 
1189         task->tk_timeout = 0;
1190         task->tk_status = -EAGAIN;
1191         rcu_read_lock();
1192         xprt = rcu_dereference(task->tk_client->cl_xprt);
1193         if (!xprt_throttle_congested(xprt, task))
1194                 xprt->ops->alloc_slot(xprt, task);
1195         rcu_read_unlock();
1196 }
1197 
1198 /**
1199  * xprt_retry_reserve - allocate an RPC request slot
1200  * @task: RPC task requesting a slot allocation
1201  *
1202  * If no more slots are available, place the task on the transport's
1203  * backlog queue.
1204  * Note that the only difference with xprt_reserve is that we now
1205  * ignore the value of the XPRT_CONGESTED flag.
1206  */
1207 void xprt_retry_reserve(struct rpc_task *task)
1208 {
1209         struct rpc_xprt *xprt;
1210 
1211         task->tk_status = 0;
1212         if (task->tk_rqstp != NULL)
1213                 return;
1214 
1215         task->tk_timeout = 0;
1216         task->tk_status = -EAGAIN;
1217         rcu_read_lock();
1218         xprt = rcu_dereference(task->tk_client->cl_xprt);
1219         xprt->ops->alloc_slot(xprt, task);
1220         rcu_read_unlock();
1221 }
1222 
1223 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1224 {
1225         return (__force __be32)xprt->xid++;
1226 }
1227 
1228 static inline void xprt_init_xid(struct rpc_xprt *xprt)
1229 {
1230         xprt->xid = prandom_u32();
1231 }
1232 
1233 static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
1234 {
1235         struct rpc_rqst *req = task->tk_rqstp;
1236 
1237         INIT_LIST_HEAD(&req->rq_list);
1238         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1239         req->rq_task    = task;
1240         req->rq_xprt    = xprt;
1241         req->rq_buffer  = NULL;
1242         req->rq_xid     = xprt_alloc_xid(xprt);
1243         req->rq_connect_cookie = xprt->connect_cookie - 1;
1244         req->rq_bytes_sent = 0;
1245         req->rq_snd_buf.len = 0;
1246         req->rq_snd_buf.buflen = 0;
1247         req->rq_rcv_buf.len = 0;
1248         req->rq_rcv_buf.buflen = 0;
1249         req->rq_release_snd_buf = NULL;
1250         xprt_reset_majortimeo(req);
1251         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1252                         req, ntohl(req->rq_xid));
1253 }
1254 
1255 /**
1256  * xprt_release - release an RPC request slot
1257  * @task: task which is finished with the slot
1258  *
1259  */
1260 void xprt_release(struct rpc_task *task)
1261 {
1262         struct rpc_xprt *xprt;
1263         struct rpc_rqst *req = task->tk_rqstp;
1264 
1265         if (req == NULL) {
1266                 if (task->tk_client) {
1267                         rcu_read_lock();
1268                         xprt = rcu_dereference(task->tk_client->cl_xprt);
1269                         if (xprt->snd_task == task)
1270                                 xprt_release_write(xprt, task);
1271                         rcu_read_unlock();
1272                 }
1273                 return;
1274         }
1275 
1276         xprt = req->rq_xprt;
1277         if (task->tk_ops->rpc_count_stats != NULL)
1278                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1279         else if (task->tk_client)
1280                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1281         spin_lock_bh(&xprt->transport_lock);
1282         xprt->ops->release_xprt(xprt, task);
1283         if (xprt->ops->release_request)
1284                 xprt->ops->release_request(task);
1285         if (!list_empty(&req->rq_list))
1286                 list_del(&req->rq_list);
1287         xprt->last_used = jiffies;
1288         if (list_empty(&xprt->recv) && xprt_has_timer(xprt))
1289                 mod_timer(&xprt->timer,
1290                                 xprt->last_used + xprt->idle_timeout);
1291         spin_unlock_bh(&xprt->transport_lock);
1292         if (req->rq_buffer)
1293                 xprt->ops->buf_free(req->rq_buffer);
1294         xprt_inject_disconnect(xprt);
1295         if (req->rq_cred != NULL)
1296                 put_rpccred(req->rq_cred);
1297         task->tk_rqstp = NULL;
1298         if (req->rq_release_snd_buf)
1299                 req->rq_release_snd_buf(req);
1300 
1301         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1302         if (likely(!bc_prealloc(req)))
1303                 xprt_free_slot(xprt, req);
1304         else
1305                 xprt_free_bc_request(req);
1306 }
1307 
1308 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1309 {
1310         atomic_set(&xprt->count, 1);
1311 
1312         spin_lock_init(&xprt->transport_lock);
1313         spin_lock_init(&xprt->reserve_lock);
1314 
1315         INIT_LIST_HEAD(&xprt->free);
1316         INIT_LIST_HEAD(&xprt->recv);
1317 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1318         spin_lock_init(&xprt->bc_pa_lock);
1319         INIT_LIST_HEAD(&xprt->bc_pa_list);
1320 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1321 
1322         xprt->last_used = jiffies;
1323         xprt->cwnd = RPC_INITCWND;
1324         xprt->bind_index = 0;
1325 
1326         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1327         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1328         rpc_init_priority_wait_queue(&xprt->sending, "xprt_sending");
1329         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1330 
1331         xprt_init_xid(xprt);
1332 
1333         xprt->xprt_net = get_net(net);
1334 }
1335 
1336 /**
1337  * xprt_create_transport - create an RPC transport
1338  * @args: rpc transport creation arguments
1339  *
1340  */
1341 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1342 {
1343         struct rpc_xprt *xprt;
1344         struct xprt_class *t;
1345 
1346         spin_lock(&xprt_list_lock);
1347         list_for_each_entry(t, &xprt_list, list) {
1348                 if (t->ident == args->ident) {
1349                         spin_unlock(&xprt_list_lock);
1350                         goto found;
1351                 }
1352         }
1353         spin_unlock(&xprt_list_lock);
1354         dprintk("RPC: transport (%d) not supported\n", args->ident);
1355         return ERR_PTR(-EIO);
1356 
1357 found:
1358         xprt = t->setup(args);
1359         if (IS_ERR(xprt)) {
1360                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1361                                 -PTR_ERR(xprt));
1362                 goto out;
1363         }
1364         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1365                 xprt->idle_timeout = 0;
1366         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1367         if (xprt_has_timer(xprt))
1368                 setup_timer(&xprt->timer, xprt_init_autodisconnect,
1369                             (unsigned long)xprt);
1370         else
1371                 init_timer(&xprt->timer);
1372 
1373         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1374                 xprt_destroy(xprt);
1375                 return ERR_PTR(-EINVAL);
1376         }
1377         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1378         if (xprt->servername == NULL) {
1379                 xprt_destroy(xprt);
1380                 return ERR_PTR(-ENOMEM);
1381         }
1382 
1383         rpc_xprt_debugfs_register(xprt);
1384 
1385         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1386                         xprt->max_reqs);
1387 out:
1388         return xprt;
1389 }
1390 
1391 /**
1392  * xprt_destroy - destroy an RPC transport, killing off all requests.
1393  * @xprt: transport to destroy
1394  *
1395  */
1396 static void xprt_destroy(struct rpc_xprt *xprt)
1397 {
1398         dprintk("RPC:       destroying transport %p\n", xprt);
1399 
1400         /* Exclude transport connect/disconnect handlers */
1401         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
1402 
1403         del_timer_sync(&xprt->timer);
1404 
1405         rpc_xprt_debugfs_unregister(xprt);
1406         rpc_destroy_wait_queue(&xprt->binding);
1407         rpc_destroy_wait_queue(&xprt->pending);
1408         rpc_destroy_wait_queue(&xprt->sending);
1409         rpc_destroy_wait_queue(&xprt->backlog);
1410         cancel_work_sync(&xprt->task_cleanup);
1411         kfree(xprt->servername);
1412         /*
1413          * Tear down transport state and free the rpc_xprt
1414          */
1415         xprt->ops->destroy(xprt);
1416 }
1417 
1418 /**
1419  * xprt_put - release a reference to an RPC transport.
1420  * @xprt: pointer to the transport
1421  *
1422  */
1423 void xprt_put(struct rpc_xprt *xprt)
1424 {
1425         if (atomic_dec_and_test(&xprt->count))
1426                 xprt_destroy(xprt);
1427 }
1428 

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