Merge tag 'nfs-for-4.20-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
[sfrench/cifs-2.6.git] / net / sunrpc / xprt.c
1 /*
2  *  linux/net/sunrpc/xprt.c
3  *
4  *  This is a generic RPC call interface supporting congestion avoidance,
5  *  and asynchronous calls.
6  *
7  *  The interface works like this:
8  *
9  *  -   When a process places a call, it allocates a request slot if
10  *      one is available. Otherwise, it sleeps on the backlog queue
11  *      (xprt_reserve).
12  *  -   Next, the caller puts together the RPC message, stuffs it into
13  *      the request struct, and calls xprt_transmit().
14  *  -   xprt_transmit sends the message and installs the caller on the
15  *      transport's wait list. At the same time, if a reply is expected,
16  *      it installs a timer that is run after the packet's timeout has
17  *      expired.
18  *  -   When a packet arrives, the data_ready handler walks the list of
19  *      pending requests for that transport. If a matching XID is found, the
20  *      caller is woken up, and the timer removed.
21  *  -   When no reply arrives within the timeout interval, the timer is
22  *      fired by the kernel and runs xprt_timer(). It either adjusts the
23  *      timeout values (minor timeout) or wakes up the caller with a status
24  *      of -ETIMEDOUT.
25  *  -   When the caller receives a notification from RPC that a reply arrived,
26  *      it should release the RPC slot, and process the reply.
27  *      If the call timed out, it may choose to retry the operation by
28  *      adjusting the initial timeout value, and simply calling rpc_call
29  *      again.
30  *
31  *  Support for async RPC is done through a set of RPC-specific scheduling
32  *  primitives that `transparently' work for processes as well as async
33  *  tasks that rely on callbacks.
34  *
35  *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
36  *
37  *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
38  */
39
40 #include <linux/module.h>
41
42 #include <linux/types.h>
43 #include <linux/interrupt.h>
44 #include <linux/workqueue.h>
45 #include <linux/net.h>
46 #include <linux/ktime.h>
47
48 #include <linux/sunrpc/clnt.h>
49 #include <linux/sunrpc/metrics.h>
50 #include <linux/sunrpc/bc_xprt.h>
51 #include <linux/rcupdate.h>
52
53 #include <trace/events/sunrpc.h>
54
55 #include "sunrpc.h"
56
57 /*
58  * Local variables
59  */
60
61 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
62 # define RPCDBG_FACILITY        RPCDBG_XPRT
63 #endif
64
65 /*
66  * Local functions
67  */
68 static void      xprt_init(struct rpc_xprt *xprt, struct net *net);
69 static __be32   xprt_alloc_xid(struct rpc_xprt *xprt);
70 static void     xprt_connect_status(struct rpc_task *task);
71 static void      xprt_destroy(struct rpc_xprt *xprt);
72
73 static DEFINE_SPINLOCK(xprt_list_lock);
74 static LIST_HEAD(xprt_list);
75
76 /**
77  * xprt_register_transport - register a transport implementation
78  * @transport: transport to register
79  *
80  * If a transport implementation is loaded as a kernel module, it can
81  * call this interface to make itself known to the RPC client.
82  *
83  * Returns:
84  * 0:           transport successfully registered
85  * -EEXIST:     transport already registered
86  * -EINVAL:     transport module being unloaded
87  */
88 int xprt_register_transport(struct xprt_class *transport)
89 {
90         struct xprt_class *t;
91         int result;
92
93         result = -EEXIST;
94         spin_lock(&xprt_list_lock);
95         list_for_each_entry(t, &xprt_list, list) {
96                 /* don't register the same transport class twice */
97                 if (t->ident == transport->ident)
98                         goto out;
99         }
100
101         list_add_tail(&transport->list, &xprt_list);
102         printk(KERN_INFO "RPC: Registered %s transport module.\n",
103                transport->name);
104         result = 0;
105
106 out:
107         spin_unlock(&xprt_list_lock);
108         return result;
109 }
110 EXPORT_SYMBOL_GPL(xprt_register_transport);
111
112 /**
113  * xprt_unregister_transport - unregister a transport implementation
114  * @transport: transport to unregister
115  *
116  * Returns:
117  * 0:           transport successfully unregistered
118  * -ENOENT:     transport never registered
119  */
120 int xprt_unregister_transport(struct xprt_class *transport)
121 {
122         struct xprt_class *t;
123         int result;
124
125         result = 0;
126         spin_lock(&xprt_list_lock);
127         list_for_each_entry(t, &xprt_list, list) {
128                 if (t == transport) {
129                         printk(KERN_INFO
130                                 "RPC: Unregistered %s transport module.\n",
131                                 transport->name);
132                         list_del_init(&transport->list);
133                         goto out;
134                 }
135         }
136         result = -ENOENT;
137
138 out:
139         spin_unlock(&xprt_list_lock);
140         return result;
141 }
142 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
143
144 /**
145  * xprt_load_transport - load a transport implementation
146  * @transport_name: transport to load
147  *
148  * Returns:
149  * 0:           transport successfully loaded
150  * -ENOENT:     transport module not available
151  */
152 int xprt_load_transport(const char *transport_name)
153 {
154         struct xprt_class *t;
155         int result;
156
157         result = 0;
158         spin_lock(&xprt_list_lock);
159         list_for_each_entry(t, &xprt_list, list) {
160                 if (strcmp(t->name, transport_name) == 0) {
161                         spin_unlock(&xprt_list_lock);
162                         goto out;
163                 }
164         }
165         spin_unlock(&xprt_list_lock);
166         result = request_module("xprt%s", transport_name);
167 out:
168         return result;
169 }
170 EXPORT_SYMBOL_GPL(xprt_load_transport);
171
172 static void xprt_clear_locked(struct rpc_xprt *xprt)
173 {
174         xprt->snd_task = NULL;
175         if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
176                 smp_mb__before_atomic();
177                 clear_bit(XPRT_LOCKED, &xprt->state);
178                 smp_mb__after_atomic();
179         } else
180                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
181 }
182
183 /**
184  * xprt_reserve_xprt - serialize write access to transports
185  * @task: task that is requesting access to the transport
186  * @xprt: pointer to the target transport
187  *
188  * This prevents mixing the payload of separate requests, and prevents
189  * transport connects from colliding with writes.  No congestion control
190  * is provided.
191  */
192 int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
193 {
194         struct rpc_rqst *req = task->tk_rqstp;
195
196         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
197                 if (task == xprt->snd_task)
198                         return 1;
199                 goto out_sleep;
200         }
201         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
202                 goto out_unlock;
203         xprt->snd_task = task;
204
205         return 1;
206
207 out_unlock:
208         xprt_clear_locked(xprt);
209 out_sleep:
210         dprintk("RPC: %5u failed to lock transport %p\n",
211                         task->tk_pid, xprt);
212         task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
213         task->tk_status = -EAGAIN;
214         rpc_sleep_on(&xprt->sending, task, NULL);
215         return 0;
216 }
217 EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
218
219 static bool
220 xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
221 {
222         return test_bit(XPRT_CWND_WAIT, &xprt->state);
223 }
224
225 static void
226 xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
227 {
228         if (!list_empty(&xprt->xmit_queue)) {
229                 /* Peek at head of queue to see if it can make progress */
230                 if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
231                                         rq_xmit)->rq_cong)
232                         return;
233         }
234         set_bit(XPRT_CWND_WAIT, &xprt->state);
235 }
236
237 static void
238 xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
239 {
240         if (!RPCXPRT_CONGESTED(xprt))
241                 clear_bit(XPRT_CWND_WAIT, &xprt->state);
242 }
243
244 /*
245  * xprt_reserve_xprt_cong - serialize write access to transports
246  * @task: task that is requesting access to the transport
247  *
248  * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
249  * integrated into the decision of whether a request is allowed to be
250  * woken up and given access to the transport.
251  * Note that the lock is only granted if we know there are free slots.
252  */
253 int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
254 {
255         struct rpc_rqst *req = task->tk_rqstp;
256
257         if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
258                 if (task == xprt->snd_task)
259                         return 1;
260                 goto out_sleep;
261         }
262         if (req == NULL) {
263                 xprt->snd_task = task;
264                 return 1;
265         }
266         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
267                 goto out_unlock;
268         if (!xprt_need_congestion_window_wait(xprt)) {
269                 xprt->snd_task = task;
270                 return 1;
271         }
272 out_unlock:
273         xprt_clear_locked(xprt);
274 out_sleep:
275         dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
276         task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
277         task->tk_status = -EAGAIN;
278         rpc_sleep_on(&xprt->sending, task, NULL);
279         return 0;
280 }
281 EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
282
283 static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
284 {
285         int retval;
286
287         if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
288                 return 1;
289         spin_lock_bh(&xprt->transport_lock);
290         retval = xprt->ops->reserve_xprt(xprt, task);
291         spin_unlock_bh(&xprt->transport_lock);
292         return retval;
293 }
294
295 static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
296 {
297         struct rpc_xprt *xprt = data;
298
299         xprt->snd_task = task;
300         return true;
301 }
302
303 static void __xprt_lock_write_next(struct rpc_xprt *xprt)
304 {
305         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
306                 return;
307         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
308                 goto out_unlock;
309         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
310                                 __xprt_lock_write_func, xprt))
311                 return;
312 out_unlock:
313         xprt_clear_locked(xprt);
314 }
315
316 static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
317 {
318         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
319                 return;
320         if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
321                 goto out_unlock;
322         if (xprt_need_congestion_window_wait(xprt))
323                 goto out_unlock;
324         if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
325                                 __xprt_lock_write_func, xprt))
326                 return;
327 out_unlock:
328         xprt_clear_locked(xprt);
329 }
330
331 /**
332  * xprt_release_xprt - allow other requests to use a transport
333  * @xprt: transport with other tasks potentially waiting
334  * @task: task that is releasing access to the transport
335  *
336  * Note that "task" can be NULL.  No congestion control is provided.
337  */
338 void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
339 {
340         if (xprt->snd_task == task) {
341                 xprt_clear_locked(xprt);
342                 __xprt_lock_write_next(xprt);
343         }
344 }
345 EXPORT_SYMBOL_GPL(xprt_release_xprt);
346
347 /**
348  * xprt_release_xprt_cong - allow other requests to use a transport
349  * @xprt: transport with other tasks potentially waiting
350  * @task: task that is releasing access to the transport
351  *
352  * Note that "task" can be NULL.  Another task is awoken to use the
353  * transport if the transport's congestion window allows it.
354  */
355 void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
356 {
357         if (xprt->snd_task == task) {
358                 xprt_clear_locked(xprt);
359                 __xprt_lock_write_next_cong(xprt);
360         }
361 }
362 EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
363
364 static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
365 {
366         if (xprt->snd_task != task)
367                 return;
368         spin_lock_bh(&xprt->transport_lock);
369         xprt->ops->release_xprt(xprt, task);
370         spin_unlock_bh(&xprt->transport_lock);
371 }
372
373 /*
374  * Van Jacobson congestion avoidance. Check if the congestion window
375  * overflowed. Put the task to sleep if this is the case.
376  */
377 static int
378 __xprt_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
379 {
380         if (req->rq_cong)
381                 return 1;
382         dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
383                         req->rq_task->tk_pid, xprt->cong, xprt->cwnd);
384         if (RPCXPRT_CONGESTED(xprt)) {
385                 xprt_set_congestion_window_wait(xprt);
386                 return 0;
387         }
388         req->rq_cong = 1;
389         xprt->cong += RPC_CWNDSCALE;
390         return 1;
391 }
392
393 /*
394  * Adjust the congestion window, and wake up the next task
395  * that has been sleeping due to congestion
396  */
397 static void
398 __xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
399 {
400         if (!req->rq_cong)
401                 return;
402         req->rq_cong = 0;
403         xprt->cong -= RPC_CWNDSCALE;
404         xprt_test_and_clear_congestion_window_wait(xprt);
405         __xprt_lock_write_next_cong(xprt);
406 }
407
408 /**
409  * xprt_request_get_cong - Request congestion control credits
410  * @xprt: pointer to transport
411  * @req: pointer to RPC request
412  *
413  * Useful for transports that require congestion control.
414  */
415 bool
416 xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
417 {
418         bool ret = false;
419
420         if (req->rq_cong)
421                 return true;
422         spin_lock_bh(&xprt->transport_lock);
423         ret = __xprt_get_cong(xprt, req) != 0;
424         spin_unlock_bh(&xprt->transport_lock);
425         return ret;
426 }
427 EXPORT_SYMBOL_GPL(xprt_request_get_cong);
428
429 /**
430  * xprt_release_rqst_cong - housekeeping when request is complete
431  * @task: RPC request that recently completed
432  *
433  * Useful for transports that require congestion control.
434  */
435 void xprt_release_rqst_cong(struct rpc_task *task)
436 {
437         struct rpc_rqst *req = task->tk_rqstp;
438
439         __xprt_put_cong(req->rq_xprt, req);
440 }
441 EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
442
443 /*
444  * Clear the congestion window wait flag and wake up the next
445  * entry on xprt->sending
446  */
447 static void
448 xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
449 {
450         if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
451                 spin_lock_bh(&xprt->transport_lock);
452                 __xprt_lock_write_next_cong(xprt);
453                 spin_unlock_bh(&xprt->transport_lock);
454         }
455 }
456
457 /**
458  * xprt_adjust_cwnd - adjust transport congestion window
459  * @xprt: pointer to xprt
460  * @task: recently completed RPC request used to adjust window
461  * @result: result code of completed RPC request
462  *
463  * The transport code maintains an estimate on the maximum number of out-
464  * standing RPC requests, using a smoothed version of the congestion
465  * avoidance implemented in 44BSD. This is basically the Van Jacobson
466  * congestion algorithm: If a retransmit occurs, the congestion window is
467  * halved; otherwise, it is incremented by 1/cwnd when
468  *
469  *      -       a reply is received and
470  *      -       a full number of requests are outstanding and
471  *      -       the congestion window hasn't been updated recently.
472  */
473 void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
474 {
475         struct rpc_rqst *req = task->tk_rqstp;
476         unsigned long cwnd = xprt->cwnd;
477
478         if (result >= 0 && cwnd <= xprt->cong) {
479                 /* The (cwnd >> 1) term makes sure
480                  * the result gets rounded properly. */
481                 cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
482                 if (cwnd > RPC_MAXCWND(xprt))
483                         cwnd = RPC_MAXCWND(xprt);
484                 __xprt_lock_write_next_cong(xprt);
485         } else if (result == -ETIMEDOUT) {
486                 cwnd >>= 1;
487                 if (cwnd < RPC_CWNDSCALE)
488                         cwnd = RPC_CWNDSCALE;
489         }
490         dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
491                         xprt->cong, xprt->cwnd, cwnd);
492         xprt->cwnd = cwnd;
493         __xprt_put_cong(xprt, req);
494 }
495 EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
496
497 /**
498  * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
499  * @xprt: transport with waiting tasks
500  * @status: result code to plant in each task before waking it
501  *
502  */
503 void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
504 {
505         if (status < 0)
506                 rpc_wake_up_status(&xprt->pending, status);
507         else
508                 rpc_wake_up(&xprt->pending);
509 }
510 EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
511
512 /**
513  * xprt_wait_for_buffer_space - wait for transport output buffer to clear
514  * @xprt: transport
515  *
516  * Note that we only set the timer for the case of RPC_IS_SOFT(), since
517  * we don't in general want to force a socket disconnection due to
518  * an incomplete RPC call transmission.
519  */
520 void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
521 {
522         set_bit(XPRT_WRITE_SPACE, &xprt->state);
523 }
524 EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
525
526 static bool
527 xprt_clear_write_space_locked(struct rpc_xprt *xprt)
528 {
529         if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
530                 __xprt_lock_write_next(xprt);
531                 dprintk("RPC:       write space: waking waiting task on "
532                                 "xprt %p\n", xprt);
533                 return true;
534         }
535         return false;
536 }
537
538 /**
539  * xprt_write_space - wake the task waiting for transport output buffer space
540  * @xprt: transport with waiting tasks
541  *
542  * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
543  */
544 bool xprt_write_space(struct rpc_xprt *xprt)
545 {
546         bool ret;
547
548         if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
549                 return false;
550         spin_lock_bh(&xprt->transport_lock);
551         ret = xprt_clear_write_space_locked(xprt);
552         spin_unlock_bh(&xprt->transport_lock);
553         return ret;
554 }
555 EXPORT_SYMBOL_GPL(xprt_write_space);
556
557 /**
558  * xprt_set_retrans_timeout_def - set a request's retransmit timeout
559  * @task: task whose timeout is to be set
560  *
561  * Set a request's retransmit timeout based on the transport's
562  * default timeout parameters.  Used by transports that don't adjust
563  * the retransmit timeout based on round-trip time estimation.
564  */
565 void xprt_set_retrans_timeout_def(struct rpc_task *task)
566 {
567         task->tk_timeout = task->tk_rqstp->rq_timeout;
568 }
569 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_def);
570
571 /**
572  * xprt_set_retrans_timeout_rtt - set a request's retransmit timeout
573  * @task: task whose timeout is to be set
574  *
575  * Set a request's retransmit timeout using the RTT estimator.
576  */
577 void xprt_set_retrans_timeout_rtt(struct rpc_task *task)
578 {
579         int timer = task->tk_msg.rpc_proc->p_timer;
580         struct rpc_clnt *clnt = task->tk_client;
581         struct rpc_rtt *rtt = clnt->cl_rtt;
582         struct rpc_rqst *req = task->tk_rqstp;
583         unsigned long max_timeout = clnt->cl_timeout->to_maxval;
584
585         task->tk_timeout = rpc_calc_rto(rtt, timer);
586         task->tk_timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
587         if (task->tk_timeout > max_timeout || task->tk_timeout == 0)
588                 task->tk_timeout = max_timeout;
589 }
590 EXPORT_SYMBOL_GPL(xprt_set_retrans_timeout_rtt);
591
592 static void xprt_reset_majortimeo(struct rpc_rqst *req)
593 {
594         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
595
596         req->rq_majortimeo = req->rq_timeout;
597         if (to->to_exponential)
598                 req->rq_majortimeo <<= to->to_retries;
599         else
600                 req->rq_majortimeo += to->to_increment * to->to_retries;
601         if (req->rq_majortimeo > to->to_maxval || req->rq_majortimeo == 0)
602                 req->rq_majortimeo = to->to_maxval;
603         req->rq_majortimeo += jiffies;
604 }
605
606 /**
607  * xprt_adjust_timeout - adjust timeout values for next retransmit
608  * @req: RPC request containing parameters to use for the adjustment
609  *
610  */
611 int xprt_adjust_timeout(struct rpc_rqst *req)
612 {
613         struct rpc_xprt *xprt = req->rq_xprt;
614         const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
615         int status = 0;
616
617         if (time_before(jiffies, req->rq_majortimeo)) {
618                 if (to->to_exponential)
619                         req->rq_timeout <<= 1;
620                 else
621                         req->rq_timeout += to->to_increment;
622                 if (to->to_maxval && req->rq_timeout >= to->to_maxval)
623                         req->rq_timeout = to->to_maxval;
624                 req->rq_retries++;
625         } else {
626                 req->rq_timeout = to->to_initval;
627                 req->rq_retries = 0;
628                 xprt_reset_majortimeo(req);
629                 /* Reset the RTT counters == "slow start" */
630                 spin_lock_bh(&xprt->transport_lock);
631                 rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
632                 spin_unlock_bh(&xprt->transport_lock);
633                 status = -ETIMEDOUT;
634         }
635
636         if (req->rq_timeout == 0) {
637                 printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
638                 req->rq_timeout = 5 * HZ;
639         }
640         return status;
641 }
642
643 static void xprt_autoclose(struct work_struct *work)
644 {
645         struct rpc_xprt *xprt =
646                 container_of(work, struct rpc_xprt, task_cleanup);
647
648         clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
649         xprt->ops->close(xprt);
650         xprt_release_write(xprt, NULL);
651         wake_up_bit(&xprt->state, XPRT_LOCKED);
652 }
653
654 /**
655  * xprt_disconnect_done - mark a transport as disconnected
656  * @xprt: transport to flag for disconnect
657  *
658  */
659 void xprt_disconnect_done(struct rpc_xprt *xprt)
660 {
661         dprintk("RPC:       disconnected transport %p\n", xprt);
662         spin_lock_bh(&xprt->transport_lock);
663         xprt_clear_connected(xprt);
664         xprt_clear_write_space_locked(xprt);
665         xprt_wake_pending_tasks(xprt, -EAGAIN);
666         spin_unlock_bh(&xprt->transport_lock);
667 }
668 EXPORT_SYMBOL_GPL(xprt_disconnect_done);
669
670 /**
671  * xprt_force_disconnect - force a transport to disconnect
672  * @xprt: transport to disconnect
673  *
674  */
675 void xprt_force_disconnect(struct rpc_xprt *xprt)
676 {
677         /* Don't race with the test_bit() in xprt_clear_locked() */
678         spin_lock_bh(&xprt->transport_lock);
679         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
680         /* Try to schedule an autoclose RPC call */
681         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
682                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
683         xprt_wake_pending_tasks(xprt, -EAGAIN);
684         spin_unlock_bh(&xprt->transport_lock);
685 }
686 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
687
688 static unsigned int
689 xprt_connect_cookie(struct rpc_xprt *xprt)
690 {
691         return READ_ONCE(xprt->connect_cookie);
692 }
693
694 static bool
695 xprt_request_retransmit_after_disconnect(struct rpc_task *task)
696 {
697         struct rpc_rqst *req = task->tk_rqstp;
698         struct rpc_xprt *xprt = req->rq_xprt;
699
700         return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
701                 !xprt_connected(xprt);
702 }
703
704 /**
705  * xprt_conditional_disconnect - force a transport to disconnect
706  * @xprt: transport to disconnect
707  * @cookie: 'connection cookie'
708  *
709  * This attempts to break the connection if and only if 'cookie' matches
710  * the current transport 'connection cookie'. It ensures that we don't
711  * try to break the connection more than once when we need to retransmit
712  * a batch of RPC requests.
713  *
714  */
715 void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
716 {
717         /* Don't race with the test_bit() in xprt_clear_locked() */
718         spin_lock_bh(&xprt->transport_lock);
719         if (cookie != xprt->connect_cookie)
720                 goto out;
721         if (test_bit(XPRT_CLOSING, &xprt->state))
722                 goto out;
723         set_bit(XPRT_CLOSE_WAIT, &xprt->state);
724         /* Try to schedule an autoclose RPC call */
725         if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
726                 queue_work(xprtiod_workqueue, &xprt->task_cleanup);
727         xprt_wake_pending_tasks(xprt, -EAGAIN);
728 out:
729         spin_unlock_bh(&xprt->transport_lock);
730 }
731
732 static bool
733 xprt_has_timer(const struct rpc_xprt *xprt)
734 {
735         return xprt->idle_timeout != 0;
736 }
737
738 static void
739 xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
740         __must_hold(&xprt->transport_lock)
741 {
742         if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))
743                 mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
744 }
745
746 static void
747 xprt_init_autodisconnect(struct timer_list *t)
748 {
749         struct rpc_xprt *xprt = from_timer(xprt, t, timer);
750
751         spin_lock(&xprt->transport_lock);
752         if (!RB_EMPTY_ROOT(&xprt->recv_queue))
753                 goto out_abort;
754         /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
755         xprt->last_used = jiffies;
756         if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
757                 goto out_abort;
758         spin_unlock(&xprt->transport_lock);
759         queue_work(xprtiod_workqueue, &xprt->task_cleanup);
760         return;
761 out_abort:
762         spin_unlock(&xprt->transport_lock);
763 }
764
765 bool xprt_lock_connect(struct rpc_xprt *xprt,
766                 struct rpc_task *task,
767                 void *cookie)
768 {
769         bool ret = false;
770
771         spin_lock_bh(&xprt->transport_lock);
772         if (!test_bit(XPRT_LOCKED, &xprt->state))
773                 goto out;
774         if (xprt->snd_task != task)
775                 goto out;
776         xprt->snd_task = cookie;
777         ret = true;
778 out:
779         spin_unlock_bh(&xprt->transport_lock);
780         return ret;
781 }
782
783 void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
784 {
785         spin_lock_bh(&xprt->transport_lock);
786         if (xprt->snd_task != cookie)
787                 goto out;
788         if (!test_bit(XPRT_LOCKED, &xprt->state))
789                 goto out;
790         xprt->snd_task =NULL;
791         xprt->ops->release_xprt(xprt, NULL);
792         xprt_schedule_autodisconnect(xprt);
793 out:
794         spin_unlock_bh(&xprt->transport_lock);
795         wake_up_bit(&xprt->state, XPRT_LOCKED);
796 }
797
798 /**
799  * xprt_connect - schedule a transport connect operation
800  * @task: RPC task that is requesting the connect
801  *
802  */
803 void xprt_connect(struct rpc_task *task)
804 {
805         struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
806
807         dprintk("RPC: %5u xprt_connect xprt %p %s connected\n", task->tk_pid,
808                         xprt, (xprt_connected(xprt) ? "is" : "is not"));
809
810         if (!xprt_bound(xprt)) {
811                 task->tk_status = -EAGAIN;
812                 return;
813         }
814         if (!xprt_lock_write(xprt, task))
815                 return;
816
817         if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
818                 xprt->ops->close(xprt);
819
820         if (!xprt_connected(xprt)) {
821                 task->tk_timeout = task->tk_rqstp->rq_timeout;
822                 task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
823                 rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
824
825                 if (test_bit(XPRT_CLOSING, &xprt->state))
826                         return;
827                 if (xprt_test_and_set_connecting(xprt))
828                         return;
829                 xprt->stat.connect_start = jiffies;
830                 xprt->ops->connect(xprt, task);
831         }
832         xprt_release_write(xprt, task);
833 }
834
835 static void xprt_connect_status(struct rpc_task *task)
836 {
837         switch (task->tk_status) {
838         case 0:
839                 dprintk("RPC: %5u xprt_connect_status: connection established\n",
840                                 task->tk_pid);
841                 break;
842         case -ECONNREFUSED:
843         case -ECONNRESET:
844         case -ECONNABORTED:
845         case -ENETUNREACH:
846         case -EHOSTUNREACH:
847         case -EPIPE:
848         case -EAGAIN:
849                 dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
850                 break;
851         case -ETIMEDOUT:
852                 dprintk("RPC: %5u xprt_connect_status: connect attempt timed "
853                                 "out\n", task->tk_pid);
854                 break;
855         default:
856                 dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
857                                 "server %s\n", task->tk_pid, -task->tk_status,
858                                 task->tk_rqstp->rq_xprt->servername);
859                 task->tk_status = -EIO;
860         }
861 }
862
863 enum xprt_xid_rb_cmp {
864         XID_RB_EQUAL,
865         XID_RB_LEFT,
866         XID_RB_RIGHT,
867 };
868 static enum xprt_xid_rb_cmp
869 xprt_xid_cmp(__be32 xid1, __be32 xid2)
870 {
871         if (xid1 == xid2)
872                 return XID_RB_EQUAL;
873         if ((__force u32)xid1 < (__force u32)xid2)
874                 return XID_RB_LEFT;
875         return XID_RB_RIGHT;
876 }
877
878 static struct rpc_rqst *
879 xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
880 {
881         struct rb_node *n = xprt->recv_queue.rb_node;
882         struct rpc_rqst *req;
883
884         while (n != NULL) {
885                 req = rb_entry(n, struct rpc_rqst, rq_recv);
886                 switch (xprt_xid_cmp(xid, req->rq_xid)) {
887                 case XID_RB_LEFT:
888                         n = n->rb_left;
889                         break;
890                 case XID_RB_RIGHT:
891                         n = n->rb_right;
892                         break;
893                 case XID_RB_EQUAL:
894                         return req;
895                 }
896         }
897         return NULL;
898 }
899
900 static void
901 xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
902 {
903         struct rb_node **p = &xprt->recv_queue.rb_node;
904         struct rb_node *n = NULL;
905         struct rpc_rqst *req;
906
907         while (*p != NULL) {
908                 n = *p;
909                 req = rb_entry(n, struct rpc_rqst, rq_recv);
910                 switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
911                 case XID_RB_LEFT:
912                         p = &n->rb_left;
913                         break;
914                 case XID_RB_RIGHT:
915                         p = &n->rb_right;
916                         break;
917                 case XID_RB_EQUAL:
918                         WARN_ON_ONCE(new != req);
919                         return;
920                 }
921         }
922         rb_link_node(&new->rq_recv, n, p);
923         rb_insert_color(&new->rq_recv, &xprt->recv_queue);
924 }
925
926 static void
927 xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
928 {
929         rb_erase(&req->rq_recv, &xprt->recv_queue);
930 }
931
932 /**
933  * xprt_lookup_rqst - find an RPC request corresponding to an XID
934  * @xprt: transport on which the original request was transmitted
935  * @xid: RPC XID of incoming reply
936  *
937  * Caller holds xprt->queue_lock.
938  */
939 struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
940 {
941         struct rpc_rqst *entry;
942
943         entry = xprt_request_rb_find(xprt, xid);
944         if (entry != NULL) {
945                 trace_xprt_lookup_rqst(xprt, xid, 0);
946                 entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
947                 return entry;
948         }
949
950         dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
951                         ntohl(xid));
952         trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
953         xprt->stat.bad_xids++;
954         return NULL;
955 }
956 EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
957
958 static bool
959 xprt_is_pinned_rqst(struct rpc_rqst *req)
960 {
961         return atomic_read(&req->rq_pin) != 0;
962 }
963
964 /**
965  * xprt_pin_rqst - Pin a request on the transport receive list
966  * @req: Request to pin
967  *
968  * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
969  * so should be holding the xprt receive lock.
970  */
971 void xprt_pin_rqst(struct rpc_rqst *req)
972 {
973         atomic_inc(&req->rq_pin);
974 }
975 EXPORT_SYMBOL_GPL(xprt_pin_rqst);
976
977 /**
978  * xprt_unpin_rqst - Unpin a request on the transport receive list
979  * @req: Request to pin
980  *
981  * Caller should be holding the xprt receive lock.
982  */
983 void xprt_unpin_rqst(struct rpc_rqst *req)
984 {
985         if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
986                 atomic_dec(&req->rq_pin);
987                 return;
988         }
989         if (atomic_dec_and_test(&req->rq_pin))
990                 wake_up_var(&req->rq_pin);
991 }
992 EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
993
994 static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
995 {
996         wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
997 }
998
999 static bool
1000 xprt_request_data_received(struct rpc_task *task)
1001 {
1002         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1003                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
1004 }
1005
1006 static bool
1007 xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
1008 {
1009         return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
1010                 READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
1011 }
1012
1013 /**
1014  * xprt_request_enqueue_receive - Add an request to the receive queue
1015  * @task: RPC task
1016  *
1017  */
1018 void
1019 xprt_request_enqueue_receive(struct rpc_task *task)
1020 {
1021         struct rpc_rqst *req = task->tk_rqstp;
1022         struct rpc_xprt *xprt = req->rq_xprt;
1023
1024         if (!xprt_request_need_enqueue_receive(task, req))
1025                 return;
1026         spin_lock(&xprt->queue_lock);
1027
1028         /* Update the softirq receive buffer */
1029         memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
1030                         sizeof(req->rq_private_buf));
1031
1032         /* Add request to the receive list */
1033         xprt_request_rb_insert(xprt, req);
1034         set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
1035         spin_unlock(&xprt->queue_lock);
1036
1037         xprt_reset_majortimeo(req);
1038         /* Turn off autodisconnect */
1039         del_singleshot_timer_sync(&xprt->timer);
1040 }
1041
1042 /**
1043  * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
1044  * @task: RPC task
1045  *
1046  * Caller must hold xprt->queue_lock.
1047  */
1048 static void
1049 xprt_request_dequeue_receive_locked(struct rpc_task *task)
1050 {
1051         struct rpc_rqst *req = task->tk_rqstp;
1052
1053         if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1054                 xprt_request_rb_remove(req->rq_xprt, req);
1055 }
1056
1057 /**
1058  * xprt_update_rtt - Update RPC RTT statistics
1059  * @task: RPC request that recently completed
1060  *
1061  * Caller holds xprt->queue_lock.
1062  */
1063 void xprt_update_rtt(struct rpc_task *task)
1064 {
1065         struct rpc_rqst *req = task->tk_rqstp;
1066         struct rpc_rtt *rtt = task->tk_client->cl_rtt;
1067         unsigned int timer = task->tk_msg.rpc_proc->p_timer;
1068         long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
1069
1070         if (timer) {
1071                 if (req->rq_ntrans == 1)
1072                         rpc_update_rtt(rtt, timer, m);
1073                 rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
1074         }
1075 }
1076 EXPORT_SYMBOL_GPL(xprt_update_rtt);
1077
1078 /**
1079  * xprt_complete_rqst - called when reply processing is complete
1080  * @task: RPC request that recently completed
1081  * @copied: actual number of bytes received from the transport
1082  *
1083  * Caller holds xprt->queue_lock.
1084  */
1085 void xprt_complete_rqst(struct rpc_task *task, int copied)
1086 {
1087         struct rpc_rqst *req = task->tk_rqstp;
1088         struct rpc_xprt *xprt = req->rq_xprt;
1089
1090         dprintk("RPC: %5u xid %08x complete (%d bytes received)\n",
1091                         task->tk_pid, ntohl(req->rq_xid), copied);
1092         trace_xprt_complete_rqst(xprt, req->rq_xid, copied);
1093
1094         xprt->stat.recvs++;
1095
1096         req->rq_private_buf.len = copied;
1097         /* Ensure all writes are done before we update */
1098         /* req->rq_reply_bytes_recvd */
1099         smp_wmb();
1100         req->rq_reply_bytes_recvd = copied;
1101         xprt_request_dequeue_receive_locked(task);
1102         rpc_wake_up_queued_task(&xprt->pending, task);
1103 }
1104 EXPORT_SYMBOL_GPL(xprt_complete_rqst);
1105
1106 static void xprt_timer(struct rpc_task *task)
1107 {
1108         struct rpc_rqst *req = task->tk_rqstp;
1109         struct rpc_xprt *xprt = req->rq_xprt;
1110
1111         if (task->tk_status != -ETIMEDOUT)
1112                 return;
1113
1114         trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
1115         if (!req->rq_reply_bytes_recvd) {
1116                 if (xprt->ops->timer)
1117                         xprt->ops->timer(xprt, task);
1118         } else
1119                 task->tk_status = 0;
1120 }
1121
1122 /**
1123  * xprt_request_wait_receive - wait for the reply to an RPC request
1124  * @task: RPC task about to send a request
1125  *
1126  */
1127 void xprt_request_wait_receive(struct rpc_task *task)
1128 {
1129         struct rpc_rqst *req = task->tk_rqstp;
1130         struct rpc_xprt *xprt = req->rq_xprt;
1131
1132         if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
1133                 return;
1134         /*
1135          * Sleep on the pending queue if we're expecting a reply.
1136          * The spinlock ensures atomicity between the test of
1137          * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
1138          */
1139         spin_lock(&xprt->queue_lock);
1140         if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
1141                 xprt->ops->set_retrans_timeout(task);
1142                 rpc_sleep_on(&xprt->pending, task, xprt_timer);
1143                 /*
1144                  * Send an extra queue wakeup call if the
1145                  * connection was dropped in case the call to
1146                  * rpc_sleep_on() raced.
1147                  */
1148                 if (xprt_request_retransmit_after_disconnect(task))
1149                         rpc_wake_up_queued_task_set_status(&xprt->pending,
1150                                         task, -ENOTCONN);
1151         }
1152         spin_unlock(&xprt->queue_lock);
1153 }
1154
1155 static bool
1156 xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
1157 {
1158         return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1159 }
1160
1161 /**
1162  * xprt_request_enqueue_transmit - queue a task for transmission
1163  * @task: pointer to rpc_task
1164  *
1165  * Add a task to the transmission queue.
1166  */
1167 void
1168 xprt_request_enqueue_transmit(struct rpc_task *task)
1169 {
1170         struct rpc_rqst *pos, *req = task->tk_rqstp;
1171         struct rpc_xprt *xprt = req->rq_xprt;
1172
1173         if (xprt_request_need_enqueue_transmit(task, req)) {
1174                 spin_lock(&xprt->queue_lock);
1175                 /*
1176                  * Requests that carry congestion control credits are added
1177                  * to the head of the list to avoid starvation issues.
1178                  */
1179                 if (req->rq_cong) {
1180                         xprt_clear_congestion_window_wait(xprt);
1181                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1182                                 if (pos->rq_cong)
1183                                         continue;
1184                                 /* Note: req is added _before_ pos */
1185                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1186                                 INIT_LIST_HEAD(&req->rq_xmit2);
1187                                 goto out;
1188                         }
1189                 } else if (RPC_IS_SWAPPER(task)) {
1190                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1191                                 if (pos->rq_cong || pos->rq_bytes_sent)
1192                                         continue;
1193                                 if (RPC_IS_SWAPPER(pos->rq_task))
1194                                         continue;
1195                                 /* Note: req is added _before_ pos */
1196                                 list_add_tail(&req->rq_xmit, &pos->rq_xmit);
1197                                 INIT_LIST_HEAD(&req->rq_xmit2);
1198                                 goto out;
1199                         }
1200                 } else {
1201                         list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
1202                                 if (pos->rq_task->tk_owner != task->tk_owner)
1203                                         continue;
1204                                 list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
1205                                 INIT_LIST_HEAD(&req->rq_xmit);
1206                                 goto out;
1207                         }
1208                 }
1209                 list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
1210                 INIT_LIST_HEAD(&req->rq_xmit2);
1211 out:
1212                 set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
1213                 spin_unlock(&xprt->queue_lock);
1214         }
1215 }
1216
1217 /**
1218  * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
1219  * @task: pointer to rpc_task
1220  *
1221  * Remove a task from the transmission queue
1222  * Caller must hold xprt->queue_lock
1223  */
1224 static void
1225 xprt_request_dequeue_transmit_locked(struct rpc_task *task)
1226 {
1227         struct rpc_rqst *req = task->tk_rqstp;
1228
1229         if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1230                 return;
1231         if (!list_empty(&req->rq_xmit)) {
1232                 list_del(&req->rq_xmit);
1233                 if (!list_empty(&req->rq_xmit2)) {
1234                         struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
1235                                         struct rpc_rqst, rq_xmit2);
1236                         list_del(&req->rq_xmit2);
1237                         list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
1238                 }
1239         } else
1240                 list_del(&req->rq_xmit2);
1241 }
1242
1243 /**
1244  * xprt_request_dequeue_transmit - remove a task from the transmission queue
1245  * @task: pointer to rpc_task
1246  *
1247  * Remove a task from the transmission queue
1248  */
1249 static void
1250 xprt_request_dequeue_transmit(struct rpc_task *task)
1251 {
1252         struct rpc_rqst *req = task->tk_rqstp;
1253         struct rpc_xprt *xprt = req->rq_xprt;
1254
1255         spin_lock(&xprt->queue_lock);
1256         xprt_request_dequeue_transmit_locked(task);
1257         spin_unlock(&xprt->queue_lock);
1258 }
1259
1260 /**
1261  * xprt_request_prepare - prepare an encoded request for transport
1262  * @req: pointer to rpc_rqst
1263  *
1264  * Calls into the transport layer to do whatever is needed to prepare
1265  * the request for transmission or receive.
1266  */
1267 void
1268 xprt_request_prepare(struct rpc_rqst *req)
1269 {
1270         struct rpc_xprt *xprt = req->rq_xprt;
1271
1272         if (xprt->ops->prepare_request)
1273                 xprt->ops->prepare_request(req);
1274 }
1275
1276 /**
1277  * xprt_request_need_retransmit - Test if a task needs retransmission
1278  * @task: pointer to rpc_task
1279  *
1280  * Test for whether a connection breakage requires the task to retransmit
1281  */
1282 bool
1283 xprt_request_need_retransmit(struct rpc_task *task)
1284 {
1285         return xprt_request_retransmit_after_disconnect(task);
1286 }
1287
1288 /**
1289  * xprt_prepare_transmit - reserve the transport before sending a request
1290  * @task: RPC task about to send a request
1291  *
1292  */
1293 bool xprt_prepare_transmit(struct rpc_task *task)
1294 {
1295         struct rpc_rqst *req = task->tk_rqstp;
1296         struct rpc_xprt *xprt = req->rq_xprt;
1297
1298         dprintk("RPC: %5u xprt_prepare_transmit\n", task->tk_pid);
1299
1300         if (!xprt_lock_write(xprt, task)) {
1301                 /* Race breaker: someone may have transmitted us */
1302                 if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1303                         rpc_wake_up_queued_task_set_status(&xprt->sending,
1304                                         task, 0);
1305                 return false;
1306
1307         }
1308         return true;
1309 }
1310
1311 void xprt_end_transmit(struct rpc_task *task)
1312 {
1313         xprt_release_write(task->tk_rqstp->rq_xprt, task);
1314 }
1315
1316 /**
1317  * xprt_request_transmit - send an RPC request on a transport
1318  * @req: pointer to request to transmit
1319  * @snd_task: RPC task that owns the transport lock
1320  *
1321  * This performs the transmission of a single request.
1322  * Note that if the request is not the same as snd_task, then it
1323  * does need to be pinned.
1324  * Returns '0' on success.
1325  */
1326 static int
1327 xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
1328 {
1329         struct rpc_xprt *xprt = req->rq_xprt;
1330         struct rpc_task *task = req->rq_task;
1331         unsigned int connect_cookie;
1332         int is_retrans = RPC_WAS_SENT(task);
1333         int status;
1334
1335         dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
1336
1337         if (!req->rq_bytes_sent) {
1338                 if (xprt_request_data_received(task)) {
1339                         status = 0;
1340                         goto out_dequeue;
1341                 }
1342                 /* Verify that our message lies in the RPCSEC_GSS window */
1343                 if (rpcauth_xmit_need_reencode(task)) {
1344                         status = -EBADMSG;
1345                         goto out_dequeue;
1346                 }
1347         }
1348
1349         /*
1350          * Update req->rq_ntrans before transmitting to avoid races with
1351          * xprt_update_rtt(), which needs to know that it is recording a
1352          * reply to the first transmission.
1353          */
1354         req->rq_ntrans++;
1355
1356         connect_cookie = xprt->connect_cookie;
1357         status = xprt->ops->send_request(req);
1358         trace_xprt_transmit(xprt, req->rq_xid, status);
1359         if (status != 0) {
1360                 req->rq_ntrans--;
1361                 return status;
1362         }
1363
1364         if (is_retrans)
1365                 task->tk_client->cl_stats->rpcretrans++;
1366
1367         xprt_inject_disconnect(xprt);
1368
1369         dprintk("RPC: %5u xmit complete\n", task->tk_pid);
1370         task->tk_flags |= RPC_TASK_SENT;
1371         spin_lock_bh(&xprt->transport_lock);
1372
1373         xprt->stat.sends++;
1374         xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
1375         xprt->stat.bklog_u += xprt->backlog.qlen;
1376         xprt->stat.sending_u += xprt->sending.qlen;
1377         xprt->stat.pending_u += xprt->pending.qlen;
1378         spin_unlock_bh(&xprt->transport_lock);
1379
1380         req->rq_connect_cookie = connect_cookie;
1381 out_dequeue:
1382         xprt_request_dequeue_transmit(task);
1383         rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
1384         return status;
1385 }
1386
1387 /**
1388  * xprt_transmit - send an RPC request on a transport
1389  * @task: controlling RPC task
1390  *
1391  * Attempts to drain the transmit queue. On exit, either the transport
1392  * signalled an error that needs to be handled before transmission can
1393  * resume, or @task finished transmitting, and detected that it already
1394  * received a reply.
1395  */
1396 void
1397 xprt_transmit(struct rpc_task *task)
1398 {
1399         struct rpc_rqst *next, *req = task->tk_rqstp;
1400         struct rpc_xprt *xprt = req->rq_xprt;
1401         int status;
1402
1403         spin_lock(&xprt->queue_lock);
1404         while (!list_empty(&xprt->xmit_queue)) {
1405                 next = list_first_entry(&xprt->xmit_queue,
1406                                 struct rpc_rqst, rq_xmit);
1407                 xprt_pin_rqst(next);
1408                 spin_unlock(&xprt->queue_lock);
1409                 status = xprt_request_transmit(next, task);
1410                 if (status == -EBADMSG && next != req)
1411                         status = 0;
1412                 cond_resched();
1413                 spin_lock(&xprt->queue_lock);
1414                 xprt_unpin_rqst(next);
1415                 if (status == 0) {
1416                         if (!xprt_request_data_received(task) ||
1417                             test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1418                                 continue;
1419                 } else if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
1420                         task->tk_status = status;
1421                 break;
1422         }
1423         spin_unlock(&xprt->queue_lock);
1424 }
1425
1426 static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
1427 {
1428         set_bit(XPRT_CONGESTED, &xprt->state);
1429         rpc_sleep_on(&xprt->backlog, task, NULL);
1430 }
1431
1432 static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
1433 {
1434         if (rpc_wake_up_next(&xprt->backlog) == NULL)
1435                 clear_bit(XPRT_CONGESTED, &xprt->state);
1436 }
1437
1438 static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
1439 {
1440         bool ret = false;
1441
1442         if (!test_bit(XPRT_CONGESTED, &xprt->state))
1443                 goto out;
1444         spin_lock(&xprt->reserve_lock);
1445         if (test_bit(XPRT_CONGESTED, &xprt->state)) {
1446                 rpc_sleep_on(&xprt->backlog, task, NULL);
1447                 ret = true;
1448         }
1449         spin_unlock(&xprt->reserve_lock);
1450 out:
1451         return ret;
1452 }
1453
1454 static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
1455 {
1456         struct rpc_rqst *req = ERR_PTR(-EAGAIN);
1457
1458         if (xprt->num_reqs >= xprt->max_reqs)
1459                 goto out;
1460         ++xprt->num_reqs;
1461         spin_unlock(&xprt->reserve_lock);
1462         req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS);
1463         spin_lock(&xprt->reserve_lock);
1464         if (req != NULL)
1465                 goto out;
1466         --xprt->num_reqs;
1467         req = ERR_PTR(-ENOMEM);
1468 out:
1469         return req;
1470 }
1471
1472 static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1473 {
1474         if (xprt->num_reqs > xprt->min_reqs) {
1475                 --xprt->num_reqs;
1476                 kfree(req);
1477                 return true;
1478         }
1479         return false;
1480 }
1481
1482 void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
1483 {
1484         struct rpc_rqst *req;
1485
1486         spin_lock(&xprt->reserve_lock);
1487         if (!list_empty(&xprt->free)) {
1488                 req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
1489                 list_del(&req->rq_list);
1490                 goto out_init_req;
1491         }
1492         req = xprt_dynamic_alloc_slot(xprt);
1493         if (!IS_ERR(req))
1494                 goto out_init_req;
1495         switch (PTR_ERR(req)) {
1496         case -ENOMEM:
1497                 dprintk("RPC:       dynamic allocation of request slot "
1498                                 "failed! Retrying\n");
1499                 task->tk_status = -ENOMEM;
1500                 break;
1501         case -EAGAIN:
1502                 xprt_add_backlog(xprt, task);
1503                 dprintk("RPC:       waiting for request slot\n");
1504                 /* fall through */
1505         default:
1506                 task->tk_status = -EAGAIN;
1507         }
1508         spin_unlock(&xprt->reserve_lock);
1509         return;
1510 out_init_req:
1511         xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
1512                                      xprt->num_reqs);
1513         spin_unlock(&xprt->reserve_lock);
1514
1515         task->tk_status = 0;
1516         task->tk_rqstp = req;
1517 }
1518 EXPORT_SYMBOL_GPL(xprt_alloc_slot);
1519
1520 void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
1521 {
1522         spin_lock(&xprt->reserve_lock);
1523         if (!xprt_dynamic_free_slot(xprt, req)) {
1524                 memset(req, 0, sizeof(*req));   /* mark unused */
1525                 list_add(&req->rq_list, &xprt->free);
1526         }
1527         xprt_wake_up_backlog(xprt);
1528         spin_unlock(&xprt->reserve_lock);
1529 }
1530 EXPORT_SYMBOL_GPL(xprt_free_slot);
1531
1532 static void xprt_free_all_slots(struct rpc_xprt *xprt)
1533 {
1534         struct rpc_rqst *req;
1535         while (!list_empty(&xprt->free)) {
1536                 req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
1537                 list_del(&req->rq_list);
1538                 kfree(req);
1539         }
1540 }
1541
1542 struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
1543                 unsigned int num_prealloc,
1544                 unsigned int max_alloc)
1545 {
1546         struct rpc_xprt *xprt;
1547         struct rpc_rqst *req;
1548         int i;
1549
1550         xprt = kzalloc(size, GFP_KERNEL);
1551         if (xprt == NULL)
1552                 goto out;
1553
1554         xprt_init(xprt, net);
1555
1556         for (i = 0; i < num_prealloc; i++) {
1557                 req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
1558                 if (!req)
1559                         goto out_free;
1560                 list_add(&req->rq_list, &xprt->free);
1561         }
1562         if (max_alloc > num_prealloc)
1563                 xprt->max_reqs = max_alloc;
1564         else
1565                 xprt->max_reqs = num_prealloc;
1566         xprt->min_reqs = num_prealloc;
1567         xprt->num_reqs = num_prealloc;
1568
1569         return xprt;
1570
1571 out_free:
1572         xprt_free(xprt);
1573 out:
1574         return NULL;
1575 }
1576 EXPORT_SYMBOL_GPL(xprt_alloc);
1577
1578 void xprt_free(struct rpc_xprt *xprt)
1579 {
1580         put_net(xprt->xprt_net);
1581         xprt_free_all_slots(xprt);
1582         kfree_rcu(xprt, rcu);
1583 }
1584 EXPORT_SYMBOL_GPL(xprt_free);
1585
1586 static void
1587 xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
1588 {
1589         req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
1590 }
1591
1592 static __be32
1593 xprt_alloc_xid(struct rpc_xprt *xprt)
1594 {
1595         __be32 xid;
1596
1597         spin_lock(&xprt->reserve_lock);
1598         xid = (__force __be32)xprt->xid++;
1599         spin_unlock(&xprt->reserve_lock);
1600         return xid;
1601 }
1602
1603 static void
1604 xprt_init_xid(struct rpc_xprt *xprt)
1605 {
1606         xprt->xid = prandom_u32();
1607 }
1608
1609 static void
1610 xprt_request_init(struct rpc_task *task)
1611 {
1612         struct rpc_xprt *xprt = task->tk_xprt;
1613         struct rpc_rqst *req = task->tk_rqstp;
1614
1615         req->rq_timeout = task->tk_client->cl_timeout->to_initval;
1616         req->rq_task    = task;
1617         req->rq_xprt    = xprt;
1618         req->rq_buffer  = NULL;
1619         req->rq_xid     = xprt_alloc_xid(xprt);
1620         xprt_init_connect_cookie(req, xprt);
1621         req->rq_bytes_sent = 0;
1622         req->rq_snd_buf.len = 0;
1623         req->rq_snd_buf.buflen = 0;
1624         req->rq_rcv_buf.len = 0;
1625         req->rq_rcv_buf.buflen = 0;
1626         req->rq_release_snd_buf = NULL;
1627         xprt_reset_majortimeo(req);
1628         dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,
1629                         req, ntohl(req->rq_xid));
1630 }
1631
1632 static void
1633 xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
1634 {
1635         xprt->ops->alloc_slot(xprt, task);
1636         if (task->tk_rqstp != NULL)
1637                 xprt_request_init(task);
1638 }
1639
1640 /**
1641  * xprt_reserve - allocate an RPC request slot
1642  * @task: RPC task requesting a slot allocation
1643  *
1644  * If the transport is marked as being congested, or if no more
1645  * slots are available, place the task on the transport's
1646  * backlog queue.
1647  */
1648 void xprt_reserve(struct rpc_task *task)
1649 {
1650         struct rpc_xprt *xprt = task->tk_xprt;
1651
1652         task->tk_status = 0;
1653         if (task->tk_rqstp != NULL)
1654                 return;
1655
1656         task->tk_timeout = 0;
1657         task->tk_status = -EAGAIN;
1658         if (!xprt_throttle_congested(xprt, task))
1659                 xprt_do_reserve(xprt, task);
1660 }
1661
1662 /**
1663  * xprt_retry_reserve - allocate an RPC request slot
1664  * @task: RPC task requesting a slot allocation
1665  *
1666  * If no more slots are available, place the task on the transport's
1667  * backlog queue.
1668  * Note that the only difference with xprt_reserve is that we now
1669  * ignore the value of the XPRT_CONGESTED flag.
1670  */
1671 void xprt_retry_reserve(struct rpc_task *task)
1672 {
1673         struct rpc_xprt *xprt = task->tk_xprt;
1674
1675         task->tk_status = 0;
1676         if (task->tk_rqstp != NULL)
1677                 return;
1678
1679         task->tk_timeout = 0;
1680         task->tk_status = -EAGAIN;
1681         xprt_do_reserve(xprt, task);
1682 }
1683
1684 static void
1685 xprt_request_dequeue_all(struct rpc_task *task, struct rpc_rqst *req)
1686 {
1687         struct rpc_xprt *xprt = req->rq_xprt;
1688
1689         if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
1690             test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
1691             xprt_is_pinned_rqst(req)) {
1692                 spin_lock(&xprt->queue_lock);
1693                 xprt_request_dequeue_transmit_locked(task);
1694                 xprt_request_dequeue_receive_locked(task);
1695                 while (xprt_is_pinned_rqst(req)) {
1696                         set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1697                         spin_unlock(&xprt->queue_lock);
1698                         xprt_wait_on_pinned_rqst(req);
1699                         spin_lock(&xprt->queue_lock);
1700                         clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
1701                 }
1702                 spin_unlock(&xprt->queue_lock);
1703         }
1704 }
1705
1706 /**
1707  * xprt_release - release an RPC request slot
1708  * @task: task which is finished with the slot
1709  *
1710  */
1711 void xprt_release(struct rpc_task *task)
1712 {
1713         struct rpc_xprt *xprt;
1714         struct rpc_rqst *req = task->tk_rqstp;
1715
1716         if (req == NULL) {
1717                 if (task->tk_client) {
1718                         xprt = task->tk_xprt;
1719                         xprt_release_write(xprt, task);
1720                 }
1721                 return;
1722         }
1723
1724         xprt = req->rq_xprt;
1725         if (task->tk_ops->rpc_count_stats != NULL)
1726                 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
1727         else if (task->tk_client)
1728                 rpc_count_iostats(task, task->tk_client->cl_metrics);
1729         xprt_request_dequeue_all(task, req);
1730         spin_lock_bh(&xprt->transport_lock);
1731         xprt->ops->release_xprt(xprt, task);
1732         if (xprt->ops->release_request)
1733                 xprt->ops->release_request(task);
1734         xprt->last_used = jiffies;
1735         xprt_schedule_autodisconnect(xprt);
1736         spin_unlock_bh(&xprt->transport_lock);
1737         if (req->rq_buffer)
1738                 xprt->ops->buf_free(task);
1739         xprt_inject_disconnect(xprt);
1740         xdr_free_bvec(&req->rq_rcv_buf);
1741         if (req->rq_cred != NULL)
1742                 put_rpccred(req->rq_cred);
1743         task->tk_rqstp = NULL;
1744         if (req->rq_release_snd_buf)
1745                 req->rq_release_snd_buf(req);
1746
1747         dprintk("RPC: %5u release request %p\n", task->tk_pid, req);
1748         if (likely(!bc_prealloc(req)))
1749                 xprt->ops->free_slot(xprt, req);
1750         else
1751                 xprt_free_bc_request(req);
1752 }
1753
1754 #ifdef CONFIG_SUNRPC_BACKCHANNEL
1755 void
1756 xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
1757 {
1758         struct xdr_buf *xbufp = &req->rq_snd_buf;
1759
1760         task->tk_rqstp = req;
1761         req->rq_task = task;
1762         xprt_init_connect_cookie(req, req->rq_xprt);
1763         /*
1764          * Set up the xdr_buf length.
1765          * This also indicates that the buffer is XDR encoded already.
1766          */
1767         xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
1768                 xbufp->tail[0].iov_len;
1769         req->rq_bytes_sent = 0;
1770 }
1771 #endif
1772
1773 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
1774 {
1775         kref_init(&xprt->kref);
1776
1777         spin_lock_init(&xprt->transport_lock);
1778         spin_lock_init(&xprt->reserve_lock);
1779         spin_lock_init(&xprt->queue_lock);
1780
1781         INIT_LIST_HEAD(&xprt->free);
1782         xprt->recv_queue = RB_ROOT;
1783         INIT_LIST_HEAD(&xprt->xmit_queue);
1784 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1785         spin_lock_init(&xprt->bc_pa_lock);
1786         INIT_LIST_HEAD(&xprt->bc_pa_list);
1787 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1788         INIT_LIST_HEAD(&xprt->xprt_switch);
1789
1790         xprt->last_used = jiffies;
1791         xprt->cwnd = RPC_INITCWND;
1792         xprt->bind_index = 0;
1793
1794         rpc_init_wait_queue(&xprt->binding, "xprt_binding");
1795         rpc_init_wait_queue(&xprt->pending, "xprt_pending");
1796         rpc_init_wait_queue(&xprt->sending, "xprt_sending");
1797         rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
1798
1799         xprt_init_xid(xprt);
1800
1801         xprt->xprt_net = get_net(net);
1802 }
1803
1804 /**
1805  * xprt_create_transport - create an RPC transport
1806  * @args: rpc transport creation arguments
1807  *
1808  */
1809 struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
1810 {
1811         struct rpc_xprt *xprt;
1812         struct xprt_class *t;
1813
1814         spin_lock(&xprt_list_lock);
1815         list_for_each_entry(t, &xprt_list, list) {
1816                 if (t->ident == args->ident) {
1817                         spin_unlock(&xprt_list_lock);
1818                         goto found;
1819                 }
1820         }
1821         spin_unlock(&xprt_list_lock);
1822         dprintk("RPC: transport (%d) not supported\n", args->ident);
1823         return ERR_PTR(-EIO);
1824
1825 found:
1826         xprt = t->setup(args);
1827         if (IS_ERR(xprt)) {
1828                 dprintk("RPC:       xprt_create_transport: failed, %ld\n",
1829                                 -PTR_ERR(xprt));
1830                 goto out;
1831         }
1832         if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
1833                 xprt->idle_timeout = 0;
1834         INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
1835         if (xprt_has_timer(xprt))
1836                 timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
1837         else
1838                 timer_setup(&xprt->timer, NULL, 0);
1839
1840         if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
1841                 xprt_destroy(xprt);
1842                 return ERR_PTR(-EINVAL);
1843         }
1844         xprt->servername = kstrdup(args->servername, GFP_KERNEL);
1845         if (xprt->servername == NULL) {
1846                 xprt_destroy(xprt);
1847                 return ERR_PTR(-ENOMEM);
1848         }
1849
1850         rpc_xprt_debugfs_register(xprt);
1851
1852         dprintk("RPC:       created transport %p with %u slots\n", xprt,
1853                         xprt->max_reqs);
1854 out:
1855         return xprt;
1856 }
1857
1858 static void xprt_destroy_cb(struct work_struct *work)
1859 {
1860         struct rpc_xprt *xprt =
1861                 container_of(work, struct rpc_xprt, task_cleanup);
1862
1863         rpc_xprt_debugfs_unregister(xprt);
1864         rpc_destroy_wait_queue(&xprt->binding);
1865         rpc_destroy_wait_queue(&xprt->pending);
1866         rpc_destroy_wait_queue(&xprt->sending);
1867         rpc_destroy_wait_queue(&xprt->backlog);
1868         kfree(xprt->servername);
1869         /*
1870          * Tear down transport state and free the rpc_xprt
1871          */
1872         xprt->ops->destroy(xprt);
1873 }
1874
1875 /**
1876  * xprt_destroy - destroy an RPC transport, killing off all requests.
1877  * @xprt: transport to destroy
1878  *
1879  */
1880 static void xprt_destroy(struct rpc_xprt *xprt)
1881 {
1882         dprintk("RPC:       destroying transport %p\n", xprt);
1883
1884         /*
1885          * Exclude transport connect/disconnect handlers and autoclose
1886          */
1887         wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
1888
1889         del_timer_sync(&xprt->timer);
1890
1891         /*
1892          * Destroy sockets etc from the system workqueue so they can
1893          * safely flush receive work running on rpciod.
1894          */
1895         INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
1896         schedule_work(&xprt->task_cleanup);
1897 }
1898
1899 static void xprt_destroy_kref(struct kref *kref)
1900 {
1901         xprt_destroy(container_of(kref, struct rpc_xprt, kref));
1902 }
1903
1904 /**
1905  * xprt_get - return a reference to an RPC transport.
1906  * @xprt: pointer to the transport
1907  *
1908  */
1909 struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
1910 {
1911         if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
1912                 return xprt;
1913         return NULL;
1914 }
1915 EXPORT_SYMBOL_GPL(xprt_get);
1916
1917 /**
1918  * xprt_put - release a reference to an RPC transport.
1919  * @xprt: pointer to the transport
1920  *
1921  */
1922 void xprt_put(struct rpc_xprt *xprt)
1923 {
1924         if (xprt != NULL)
1925                 kref_put(&xprt->kref, xprt_destroy_kref);
1926 }
1927 EXPORT_SYMBOL_GPL(xprt_put);