eda32ae7dec48856558a0a3d845f3f44671b6882
[linux-2.6.git] / net / sunrpc / sched.c
1 /*
2  * linux/net/sunrpc/sched.c
3  *
4  * Scheduling for synchronous and asynchronous RPC requests.
5  *
6  * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
7  *
8  * TCP NFS related read + write fixes
9  * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
10  */
11
12 #include <linux/module.h>
13
14 #include <linux/sched.h>
15 #include <linux/interrupt.h>
16 #include <linux/slab.h>
17 #include <linux/mempool.h>
18 #include <linux/smp.h>
19 #include <linux/spinlock.h>
20 #include <linux/mutex.h>
21 #include <linux/freezer.h>
22
23 #include <linux/sunrpc/clnt.h>
24
25 #include "sunrpc.h"
26
27 #ifdef RPC_DEBUG
28 #define RPCDBG_FACILITY         RPCDBG_SCHED
29 #endif
30
31 #define CREATE_TRACE_POINTS
32 #include <trace/events/sunrpc.h>
33
34 /*
35  * RPC slabs and memory pools
36  */
37 #define RPC_BUFFER_MAXSIZE      (2048)
38 #define RPC_BUFFER_POOLSIZE     (8)
39 #define RPC_TASK_POOLSIZE       (8)
40 static struct kmem_cache        *rpc_task_slabp __read_mostly;
41 static struct kmem_cache        *rpc_buffer_slabp __read_mostly;
42 static mempool_t        *rpc_task_mempool __read_mostly;
43 static mempool_t        *rpc_buffer_mempool __read_mostly;
44
45 static void                     rpc_async_schedule(struct work_struct *);
46 static void                      rpc_release_task(struct rpc_task *task);
47 static void __rpc_queue_timer_fn(unsigned long ptr);
48
49 /*
50  * RPC tasks sit here while waiting for conditions to improve.
51  */
52 static struct rpc_wait_queue delay_queue;
53
54 /*
55  * rpciod-related stuff
56  */
57 struct workqueue_struct *rpciod_workqueue;
58
59 /*
60  * Disable the timer for a given RPC task. Should be called with
61  * queue->lock and bh_disabled in order to avoid races within
62  * rpc_run_timer().
63  */
64 static void
65 __rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
66 {
67         if (task->tk_timeout == 0)
68                 return;
69         dprintk("RPC: %5u disabling timer\n", task->tk_pid);
70         task->tk_timeout = 0;
71         list_del(&task->u.tk_wait.timer_list);
72         if (list_empty(&queue->timer_list.list))
73                 del_timer(&queue->timer_list.timer);
74 }
75
76 static void
77 rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
78 {
79         queue->timer_list.expires = expires;
80         mod_timer(&queue->timer_list.timer, expires);
81 }
82
83 /*
84  * Set up a timer for the current task.
85  */
86 static void
87 __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
88 {
89         if (!task->tk_timeout)
90                 return;
91
92         dprintk("RPC: %5u setting alarm for %lu ms\n",
93                         task->tk_pid, task->tk_timeout * 1000 / HZ);
94
95         task->u.tk_wait.expires = jiffies + task->tk_timeout;
96         if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
97                 rpc_set_queue_timer(queue, task->u.tk_wait.expires);
98         list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
99 }
100
101 /*
102  * Add new request to a priority queue.
103  */
104 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
105                 struct rpc_task *task,
106                 unsigned char queue_priority)
107 {
108         struct list_head *q;
109         struct rpc_task *t;
110
111         INIT_LIST_HEAD(&task->u.tk_wait.links);
112         q = &queue->tasks[queue_priority];
113         if (unlikely(queue_priority > queue->maxpriority))
114                 q = &queue->tasks[queue->maxpriority];
115         list_for_each_entry(t, q, u.tk_wait.list) {
116                 if (t->tk_owner == task->tk_owner) {
117                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
118                         return;
119                 }
120         }
121         list_add_tail(&task->u.tk_wait.list, q);
122 }
123
124 /*
125  * Add new request to wait queue.
126  *
127  * Swapper tasks always get inserted at the head of the queue.
128  * This should avoid many nasty memory deadlocks and hopefully
129  * improve overall performance.
130  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
131  */
132 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
133                 struct rpc_task *task,
134                 unsigned char queue_priority)
135 {
136         BUG_ON (RPC_IS_QUEUED(task));
137
138         if (RPC_IS_PRIORITY(queue))
139                 __rpc_add_wait_queue_priority(queue, task, queue_priority);
140         else if (RPC_IS_SWAPPER(task))
141                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
142         else
143                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
144         task->tk_waitqueue = queue;
145         queue->qlen++;
146         rpc_set_queued(task);
147
148         dprintk("RPC: %5u added to queue %p \"%s\"\n",
149                         task->tk_pid, queue, rpc_qname(queue));
150 }
151
152 /*
153  * Remove request from a priority queue.
154  */
155 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
156 {
157         struct rpc_task *t;
158
159         if (!list_empty(&task->u.tk_wait.links)) {
160                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
161                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
162                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
163         }
164 }
165
166 /*
167  * Remove request from queue.
168  * Note: must be called with spin lock held.
169  */
170 static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
171 {
172         __rpc_disable_timer(queue, task);
173         if (RPC_IS_PRIORITY(queue))
174                 __rpc_remove_wait_queue_priority(task);
175         list_del(&task->u.tk_wait.list);
176         queue->qlen--;
177         dprintk("RPC: %5u removed from queue %p \"%s\"\n",
178                         task->tk_pid, queue, rpc_qname(queue));
179 }
180
181 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
182 {
183         queue->priority = priority;
184         queue->count = 1 << (priority * 2);
185 }
186
187 static inline void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
188 {
189         queue->owner = pid;
190         queue->nr = RPC_BATCH_COUNT;
191 }
192
193 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
194 {
195         rpc_set_waitqueue_priority(queue, queue->maxpriority);
196         rpc_set_waitqueue_owner(queue, 0);
197 }
198
199 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
200 {
201         int i;
202
203         spin_lock_init(&queue->lock);
204         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
205                 INIT_LIST_HEAD(&queue->tasks[i]);
206         queue->maxpriority = nr_queues - 1;
207         rpc_reset_waitqueue_priority(queue);
208         queue->qlen = 0;
209         setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
210         INIT_LIST_HEAD(&queue->timer_list.list);
211         rpc_assign_waitqueue_name(queue, qname);
212 }
213
214 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
215 {
216         __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
217 }
218 EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
219
220 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
221 {
222         __rpc_init_priority_wait_queue(queue, qname, 1);
223 }
224 EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
225
226 void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
227 {
228         del_timer_sync(&queue->timer_list.timer);
229 }
230 EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
231
232 static int rpc_wait_bit_killable(void *word)
233 {
234         if (fatal_signal_pending(current))
235                 return -ERESTARTSYS;
236         freezable_schedule();
237         return 0;
238 }
239
240 #ifdef RPC_DEBUG
241 static void rpc_task_set_debuginfo(struct rpc_task *task)
242 {
243         static atomic_t rpc_pid;
244
245         task->tk_pid = atomic_inc_return(&rpc_pid);
246 }
247 #else
248 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
249 {
250 }
251 #endif
252
253 static void rpc_set_active(struct rpc_task *task)
254 {
255         trace_rpc_task_begin(task->tk_client, task, NULL);
256
257         rpc_task_set_debuginfo(task);
258         set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
259 }
260
261 /*
262  * Mark an RPC call as having completed by clearing the 'active' bit
263  * and then waking up all tasks that were sleeping.
264  */
265 static int rpc_complete_task(struct rpc_task *task)
266 {
267         void *m = &task->tk_runstate;
268         wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
269         struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
270         unsigned long flags;
271         int ret;
272
273         trace_rpc_task_complete(task->tk_client, task, NULL);
274
275         spin_lock_irqsave(&wq->lock, flags);
276         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
277         ret = atomic_dec_and_test(&task->tk_count);
278         if (waitqueue_active(wq))
279                 __wake_up_locked_key(wq, TASK_NORMAL, &k);
280         spin_unlock_irqrestore(&wq->lock, flags);
281         return ret;
282 }
283
284 /*
285  * Allow callers to wait for completion of an RPC call
286  *
287  * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
288  * to enforce taking of the wq->lock and hence avoid races with
289  * rpc_complete_task().
290  */
291 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
292 {
293         if (action == NULL)
294                 action = rpc_wait_bit_killable;
295         return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
296                         action, TASK_KILLABLE);
297 }
298 EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
299
300 /*
301  * Make an RPC task runnable.
302  *
303  * Note: If the task is ASYNC, this must be called with
304  * the spinlock held to protect the wait queue operation.
305  */
306 static void rpc_make_runnable(struct rpc_task *task)
307 {
308         rpc_clear_queued(task);
309         if (rpc_test_and_set_running(task))
310                 return;
311         if (RPC_IS_ASYNC(task)) {
312                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
313                 queue_work(rpciod_workqueue, &task->u.tk_work);
314         } else
315                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
316 }
317
318 /*
319  * Prepare for sleeping on a wait queue.
320  * By always appending tasks to the list we ensure FIFO behavior.
321  * NB: An RPC task will only receive interrupt-driven events as long
322  * as it's on a wait queue.
323  */
324 static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
325                 struct rpc_task *task,
326                 rpc_action action,
327                 unsigned char queue_priority)
328 {
329         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
330                         task->tk_pid, rpc_qname(q), jiffies);
331
332         trace_rpc_task_sleep(task->tk_client, task, q);
333
334         __rpc_add_wait_queue(q, task, queue_priority);
335
336         BUG_ON(task->tk_callback != NULL);
337         task->tk_callback = action;
338         __rpc_add_timer(q, task);
339 }
340
341 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
342                                 rpc_action action)
343 {
344         /* We shouldn't ever put an inactive task to sleep */
345         BUG_ON(!RPC_IS_ACTIVATED(task));
346
347         /*
348          * Protect the queue operations.
349          */
350         spin_lock_bh(&q->lock);
351         __rpc_sleep_on_priority(q, task, action, task->tk_priority);
352         spin_unlock_bh(&q->lock);
353 }
354 EXPORT_SYMBOL_GPL(rpc_sleep_on);
355
356 void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
357                 rpc_action action, int priority)
358 {
359         /* We shouldn't ever put an inactive task to sleep */
360         BUG_ON(!RPC_IS_ACTIVATED(task));
361
362         /*
363          * Protect the queue operations.
364          */
365         spin_lock_bh(&q->lock);
366         __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
367         spin_unlock_bh(&q->lock);
368 }
369
370 /**
371  * __rpc_do_wake_up_task - wake up a single rpc_task
372  * @queue: wait queue
373  * @task: task to be woken up
374  *
375  * Caller must hold queue->lock, and have cleared the task queued flag.
376  */
377 static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
378 {
379         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
380                         task->tk_pid, jiffies);
381
382         /* Has the task been executed yet? If not, we cannot wake it up! */
383         if (!RPC_IS_ACTIVATED(task)) {
384                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
385                 return;
386         }
387
388         trace_rpc_task_wakeup(task->tk_client, task, queue);
389
390         __rpc_remove_wait_queue(queue, task);
391
392         rpc_make_runnable(task);
393
394         dprintk("RPC:       __rpc_wake_up_task done\n");
395 }
396
397 /*
398  * Wake up a queued task while the queue lock is being held
399  */
400 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
401 {
402         if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
403                 __rpc_do_wake_up_task(queue, task);
404 }
405
406 /*
407  * Tests whether rpc queue is empty
408  */
409 int rpc_queue_empty(struct rpc_wait_queue *queue)
410 {
411         int res;
412
413         spin_lock_bh(&queue->lock);
414         res = queue->qlen;
415         spin_unlock_bh(&queue->lock);
416         return res == 0;
417 }
418 EXPORT_SYMBOL_GPL(rpc_queue_empty);
419
420 /*
421  * Wake up a task on a specific queue
422  */
423 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
424 {
425         spin_lock_bh(&queue->lock);
426         rpc_wake_up_task_queue_locked(queue, task);
427         spin_unlock_bh(&queue->lock);
428 }
429 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
430
431 /*
432  * Wake up the next task on a priority queue.
433  */
434 static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
435 {
436         struct list_head *q;
437         struct rpc_task *task;
438
439         /*
440          * Service a batch of tasks from a single owner.
441          */
442         q = &queue->tasks[queue->priority];
443         if (!list_empty(q)) {
444                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
445                 if (queue->owner == task->tk_owner) {
446                         if (--queue->nr)
447                                 goto out;
448                         list_move_tail(&task->u.tk_wait.list, q);
449                 }
450                 /*
451                  * Check if we need to switch queues.
452                  */
453                 if (--queue->count)
454                         goto new_owner;
455         }
456
457         /*
458          * Service the next queue.
459          */
460         do {
461                 if (q == &queue->tasks[0])
462                         q = &queue->tasks[queue->maxpriority];
463                 else
464                         q = q - 1;
465                 if (!list_empty(q)) {
466                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
467                         goto new_queue;
468                 }
469         } while (q != &queue->tasks[queue->priority]);
470
471         rpc_reset_waitqueue_priority(queue);
472         return NULL;
473
474 new_queue:
475         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
476 new_owner:
477         rpc_set_waitqueue_owner(queue, task->tk_owner);
478 out:
479         return task;
480 }
481
482 static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
483 {
484         if (RPC_IS_PRIORITY(queue))
485                 return __rpc_find_next_queued_priority(queue);
486         if (!list_empty(&queue->tasks[0]))
487                 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
488         return NULL;
489 }
490
491 /*
492  * Wake up the first task on the wait queue.
493  */
494 struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
495                 bool (*func)(struct rpc_task *, void *), void *data)
496 {
497         struct rpc_task *task = NULL;
498
499         dprintk("RPC:       wake_up_first(%p \"%s\")\n",
500                         queue, rpc_qname(queue));
501         spin_lock_bh(&queue->lock);
502         task = __rpc_find_next_queued(queue);
503         if (task != NULL) {
504                 if (func(task, data))
505                         rpc_wake_up_task_queue_locked(queue, task);
506                 else
507                         task = NULL;
508         }
509         spin_unlock_bh(&queue->lock);
510
511         return task;
512 }
513 EXPORT_SYMBOL_GPL(rpc_wake_up_first);
514
515 static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
516 {
517         return true;
518 }
519
520 /*
521  * Wake up the next task on the wait queue.
522 */
523 struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
524 {
525         return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
526 }
527 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
528
529 /**
530  * rpc_wake_up - wake up all rpc_tasks
531  * @queue: rpc_wait_queue on which the tasks are sleeping
532  *
533  * Grabs queue->lock
534  */
535 void rpc_wake_up(struct rpc_wait_queue *queue)
536 {
537         struct list_head *head;
538
539         spin_lock_bh(&queue->lock);
540         head = &queue->tasks[queue->maxpriority];
541         for (;;) {
542                 while (!list_empty(head)) {
543                         struct rpc_task *task;
544                         task = list_first_entry(head,
545                                         struct rpc_task,
546                                         u.tk_wait.list);
547                         rpc_wake_up_task_queue_locked(queue, task);
548                 }
549                 if (head == &queue->tasks[0])
550                         break;
551                 head--;
552         }
553         spin_unlock_bh(&queue->lock);
554 }
555 EXPORT_SYMBOL_GPL(rpc_wake_up);
556
557 /**
558  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
559  * @queue: rpc_wait_queue on which the tasks are sleeping
560  * @status: status value to set
561  *
562  * Grabs queue->lock
563  */
564 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
565 {
566         struct list_head *head;
567
568         spin_lock_bh(&queue->lock);
569         head = &queue->tasks[queue->maxpriority];
570         for (;;) {
571                 while (!list_empty(head)) {
572                         struct rpc_task *task;
573                         task = list_first_entry(head,
574                                         struct rpc_task,
575                                         u.tk_wait.list);
576                         task->tk_status = status;
577                         rpc_wake_up_task_queue_locked(queue, task);
578                 }
579                 if (head == &queue->tasks[0])
580                         break;
581                 head--;
582         }
583         spin_unlock_bh(&queue->lock);
584 }
585 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
586
587 static void __rpc_queue_timer_fn(unsigned long ptr)
588 {
589         struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
590         struct rpc_task *task, *n;
591         unsigned long expires, now, timeo;
592
593         spin_lock(&queue->lock);
594         expires = now = jiffies;
595         list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
596                 timeo = task->u.tk_wait.expires;
597                 if (time_after_eq(now, timeo)) {
598                         dprintk("RPC: %5u timeout\n", task->tk_pid);
599                         task->tk_status = -ETIMEDOUT;
600                         rpc_wake_up_task_queue_locked(queue, task);
601                         continue;
602                 }
603                 if (expires == now || time_after(expires, timeo))
604                         expires = timeo;
605         }
606         if (!list_empty(&queue->timer_list.list))
607                 rpc_set_queue_timer(queue, expires);
608         spin_unlock(&queue->lock);
609 }
610
611 static void __rpc_atrun(struct rpc_task *task)
612 {
613         task->tk_status = 0;
614 }
615
616 /*
617  * Run a task at a later time
618  */
619 void rpc_delay(struct rpc_task *task, unsigned long delay)
620 {
621         task->tk_timeout = delay;
622         rpc_sleep_on(&delay_queue, task, __rpc_atrun);
623 }
624 EXPORT_SYMBOL_GPL(rpc_delay);
625
626 /*
627  * Helper to call task->tk_ops->rpc_call_prepare
628  */
629 void rpc_prepare_task(struct rpc_task *task)
630 {
631         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
632 }
633
634 static void
635 rpc_init_task_statistics(struct rpc_task *task)
636 {
637         /* Initialize retry counters */
638         task->tk_garb_retry = 2;
639         task->tk_cred_retry = 2;
640         task->tk_rebind_retry = 2;
641
642         /* starting timestamp */
643         task->tk_start = ktime_get();
644 }
645
646 static void
647 rpc_reset_task_statistics(struct rpc_task *task)
648 {
649         task->tk_timeouts = 0;
650         task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
651
652         rpc_init_task_statistics(task);
653 }
654
655 /*
656  * Helper that calls task->tk_ops->rpc_call_done if it exists
657  */
658 void rpc_exit_task(struct rpc_task *task)
659 {
660         task->tk_action = NULL;
661         if (task->tk_ops->rpc_call_done != NULL) {
662                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
663                 if (task->tk_action != NULL) {
664                         WARN_ON(RPC_ASSASSINATED(task));
665                         /* Always release the RPC slot and buffer memory */
666                         xprt_release(task);
667                         rpc_reset_task_statistics(task);
668                 }
669         }
670 }
671
672 void rpc_exit(struct rpc_task *task, int status)
673 {
674         task->tk_status = status;
675         task->tk_action = rpc_exit_task;
676         if (RPC_IS_QUEUED(task))
677                 rpc_wake_up_queued_task(task->tk_waitqueue, task);
678 }
679 EXPORT_SYMBOL_GPL(rpc_exit);
680
681 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
682 {
683         if (ops->rpc_release != NULL)
684                 ops->rpc_release(calldata);
685 }
686
687 /*
688  * This is the RPC `scheduler' (or rather, the finite state machine).
689  */
690 static void __rpc_execute(struct rpc_task *task)
691 {
692         struct rpc_wait_queue *queue;
693         int task_is_async = RPC_IS_ASYNC(task);
694         int status = 0;
695
696         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
697                         task->tk_pid, task->tk_flags);
698
699         BUG_ON(RPC_IS_QUEUED(task));
700
701         for (;;) {
702                 void (*do_action)(struct rpc_task *);
703
704                 /*
705                  * Execute any pending callback first.
706                  */
707                 do_action = task->tk_callback;
708                 task->tk_callback = NULL;
709                 if (do_action == NULL) {
710                         /*
711                          * Perform the next FSM step.
712                          * tk_action may be NULL if the task has been killed.
713                          * In particular, note that rpc_killall_tasks may
714                          * do this at any time, so beware when dereferencing.
715                          */
716                         do_action = task->tk_action;
717                         if (do_action == NULL)
718                                 break;
719                 }
720                 trace_rpc_task_run_action(task->tk_client, task, task->tk_action);
721                 do_action(task);
722
723                 /*
724                  * Lockless check for whether task is sleeping or not.
725                  */
726                 if (!RPC_IS_QUEUED(task))
727                         continue;
728                 /*
729                  * The queue->lock protects against races with
730                  * rpc_make_runnable().
731                  *
732                  * Note that once we clear RPC_TASK_RUNNING on an asynchronous
733                  * rpc_task, rpc_make_runnable() can assign it to a
734                  * different workqueue. We therefore cannot assume that the
735                  * rpc_task pointer may still be dereferenced.
736                  */
737                 queue = task->tk_waitqueue;
738                 spin_lock_bh(&queue->lock);
739                 if (!RPC_IS_QUEUED(task)) {
740                         spin_unlock_bh(&queue->lock);
741                         continue;
742                 }
743                 rpc_clear_running(task);
744                 spin_unlock_bh(&queue->lock);
745                 if (task_is_async)
746                         return;
747
748                 /* sync task: sleep here */
749                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
750                 status = out_of_line_wait_on_bit(&task->tk_runstate,
751                                 RPC_TASK_QUEUED, rpc_wait_bit_killable,
752                                 TASK_KILLABLE);
753                 if (status == -ERESTARTSYS) {
754                         /*
755                          * When a sync task receives a signal, it exits with
756                          * -ERESTARTSYS. In order to catch any callbacks that
757                          * clean up after sleeping on some queue, we don't
758                          * break the loop here, but go around once more.
759                          */
760                         dprintk("RPC: %5u got signal\n", task->tk_pid);
761                         task->tk_flags |= RPC_TASK_KILLED;
762                         rpc_exit(task, -ERESTARTSYS);
763                 }
764                 rpc_set_running(task);
765                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
766         }
767
768         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
769                         task->tk_status);
770         /* Release all resources associated with the task */
771         rpc_release_task(task);
772 }
773
774 /*
775  * User-visible entry point to the scheduler.
776  *
777  * This may be called recursively if e.g. an async NFS task updates
778  * the attributes and finds that dirty pages must be flushed.
779  * NOTE: Upon exit of this function the task is guaranteed to be
780  *       released. In particular note that tk_release() will have
781  *       been called, so your task memory may have been freed.
782  */
783 void rpc_execute(struct rpc_task *task)
784 {
785         rpc_set_active(task);
786         rpc_make_runnable(task);
787         if (!RPC_IS_ASYNC(task))
788                 __rpc_execute(task);
789 }
790
791 static void rpc_async_schedule(struct work_struct *work)
792 {
793         current->flags |= PF_FSTRANS;
794         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
795         current->flags &= ~PF_FSTRANS;
796 }
797
798 /**
799  * rpc_malloc - allocate an RPC buffer
800  * @task: RPC task that will use this buffer
801  * @size: requested byte size
802  *
803  * To prevent rpciod from hanging, this allocator never sleeps,
804  * returning NULL if the request cannot be serviced immediately.
805  * The caller can arrange to sleep in a way that is safe for rpciod.
806  *
807  * Most requests are 'small' (under 2KiB) and can be serviced from a
808  * mempool, ensuring that NFS reads and writes can always proceed,
809  * and that there is good locality of reference for these buffers.
810  *
811  * In order to avoid memory starvation triggering more writebacks of
812  * NFS requests, we avoid using GFP_KERNEL.
813  */
814 void *rpc_malloc(struct rpc_task *task, size_t size)
815 {
816         struct rpc_buffer *buf;
817         gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
818
819         size += sizeof(struct rpc_buffer);
820         if (size <= RPC_BUFFER_MAXSIZE)
821                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
822         else
823                 buf = kmalloc(size, gfp);
824
825         if (!buf)
826                 return NULL;
827
828         buf->len = size;
829         dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
830                         task->tk_pid, size, buf);
831         return &buf->data;
832 }
833 EXPORT_SYMBOL_GPL(rpc_malloc);
834
835 /**
836  * rpc_free - free buffer allocated via rpc_malloc
837  * @buffer: buffer to free
838  *
839  */
840 void rpc_free(void *buffer)
841 {
842         size_t size;
843         struct rpc_buffer *buf;
844
845         if (!buffer)
846                 return;
847
848         buf = container_of(buffer, struct rpc_buffer, data);
849         size = buf->len;
850
851         dprintk("RPC:       freeing buffer of size %zu at %p\n",
852                         size, buf);
853
854         if (size <= RPC_BUFFER_MAXSIZE)
855                 mempool_free(buf, rpc_buffer_mempool);
856         else
857                 kfree(buf);
858 }
859 EXPORT_SYMBOL_GPL(rpc_free);
860
861 /*
862  * Creation and deletion of RPC task structures
863  */
864 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
865 {
866         memset(task, 0, sizeof(*task));
867         atomic_set(&task->tk_count, 1);
868         task->tk_flags  = task_setup_data->flags;
869         task->tk_ops = task_setup_data->callback_ops;
870         task->tk_calldata = task_setup_data->callback_data;
871         INIT_LIST_HEAD(&task->tk_task);
872
873         task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
874         task->tk_owner = current->tgid;
875
876         /* Initialize workqueue for async tasks */
877         task->tk_workqueue = task_setup_data->workqueue;
878
879         if (task->tk_ops->rpc_call_prepare != NULL)
880                 task->tk_action = rpc_prepare_task;
881
882         rpc_init_task_statistics(task);
883
884         dprintk("RPC:       new task initialized, procpid %u\n",
885                                 task_pid_nr(current));
886 }
887
888 static struct rpc_task *
889 rpc_alloc_task(void)
890 {
891         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
892 }
893
894 /*
895  * Create a new task for the specified client.
896  */
897 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
898 {
899         struct rpc_task *task = setup_data->task;
900         unsigned short flags = 0;
901
902         if (task == NULL) {
903                 task = rpc_alloc_task();
904                 if (task == NULL) {
905                         rpc_release_calldata(setup_data->callback_ops,
906                                         setup_data->callback_data);
907                         return ERR_PTR(-ENOMEM);
908                 }
909                 flags = RPC_TASK_DYNAMIC;
910         }
911
912         rpc_init_task(task, setup_data);
913         task->tk_flags |= flags;
914         dprintk("RPC:       allocated task %p\n", task);
915         return task;
916 }
917
918 static void rpc_free_task(struct rpc_task *task)
919 {
920         const struct rpc_call_ops *tk_ops = task->tk_ops;
921         void *calldata = task->tk_calldata;
922
923         if (task->tk_flags & RPC_TASK_DYNAMIC) {
924                 dprintk("RPC: %5u freeing task\n", task->tk_pid);
925                 mempool_free(task, rpc_task_mempool);
926         }
927         rpc_release_calldata(tk_ops, calldata);
928 }
929
930 static void rpc_async_release(struct work_struct *work)
931 {
932         rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
933 }
934
935 static void rpc_release_resources_task(struct rpc_task *task)
936 {
937         if (task->tk_rqstp)
938                 xprt_release(task);
939         if (task->tk_msg.rpc_cred) {
940                 put_rpccred(task->tk_msg.rpc_cred);
941                 task->tk_msg.rpc_cred = NULL;
942         }
943         rpc_task_release_client(task);
944 }
945
946 static void rpc_final_put_task(struct rpc_task *task,
947                 struct workqueue_struct *q)
948 {
949         if (q != NULL) {
950                 INIT_WORK(&task->u.tk_work, rpc_async_release);
951                 queue_work(q, &task->u.tk_work);
952         } else
953                 rpc_free_task(task);
954 }
955
956 static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
957 {
958         if (atomic_dec_and_test(&task->tk_count)) {
959                 rpc_release_resources_task(task);
960                 rpc_final_put_task(task, q);
961         }
962 }
963
964 void rpc_put_task(struct rpc_task *task)
965 {
966         rpc_do_put_task(task, NULL);
967 }
968 EXPORT_SYMBOL_GPL(rpc_put_task);
969
970 void rpc_put_task_async(struct rpc_task *task)
971 {
972         rpc_do_put_task(task, task->tk_workqueue);
973 }
974 EXPORT_SYMBOL_GPL(rpc_put_task_async);
975
976 static void rpc_release_task(struct rpc_task *task)
977 {
978         dprintk("RPC: %5u release task\n", task->tk_pid);
979
980         BUG_ON (RPC_IS_QUEUED(task));
981
982         rpc_release_resources_task(task);
983
984         /*
985          * Note: at this point we have been removed from rpc_clnt->cl_tasks,
986          * so it should be safe to use task->tk_count as a test for whether
987          * or not any other processes still hold references to our rpc_task.
988          */
989         if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
990                 /* Wake up anyone who may be waiting for task completion */
991                 if (!rpc_complete_task(task))
992                         return;
993         } else {
994                 if (!atomic_dec_and_test(&task->tk_count))
995                         return;
996         }
997         rpc_final_put_task(task, task->tk_workqueue);
998 }
999
1000 int rpciod_up(void)
1001 {
1002         return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1003 }
1004
1005 void rpciod_down(void)
1006 {
1007         module_put(THIS_MODULE);
1008 }
1009
1010 /*
1011  * Start up the rpciod workqueue.
1012  */
1013 static int rpciod_start(void)
1014 {
1015         struct workqueue_struct *wq;
1016
1017         /*
1018          * Create the rpciod thread and wait for it to start.
1019          */
1020         dprintk("RPC:       creating workqueue rpciod\n");
1021         wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 0);
1022         rpciod_workqueue = wq;
1023         return rpciod_workqueue != NULL;
1024 }
1025
1026 static void rpciod_stop(void)
1027 {
1028         struct workqueue_struct *wq = NULL;
1029
1030         if (rpciod_workqueue == NULL)
1031                 return;
1032         dprintk("RPC:       destroying workqueue rpciod\n");
1033
1034         wq = rpciod_workqueue;
1035         rpciod_workqueue = NULL;
1036         destroy_workqueue(wq);
1037 }
1038
1039 void
1040 rpc_destroy_mempool(void)
1041 {
1042         rpciod_stop();
1043         if (rpc_buffer_mempool)
1044                 mempool_destroy(rpc_buffer_mempool);
1045         if (rpc_task_mempool)
1046                 mempool_destroy(rpc_task_mempool);
1047         if (rpc_task_slabp)
1048                 kmem_cache_destroy(rpc_task_slabp);
1049         if (rpc_buffer_slabp)
1050                 kmem_cache_destroy(rpc_buffer_slabp);
1051         rpc_destroy_wait_queue(&delay_queue);
1052 }
1053
1054 int
1055 rpc_init_mempool(void)
1056 {
1057         /*
1058          * The following is not strictly a mempool initialisation,
1059          * but there is no harm in doing it here
1060          */
1061         rpc_init_wait_queue(&delay_queue, "delayq");
1062         if (!rpciod_start())
1063                 goto err_nomem;
1064
1065         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1066                                              sizeof(struct rpc_task),
1067                                              0, SLAB_HWCACHE_ALIGN,
1068                                              NULL);
1069         if (!rpc_task_slabp)
1070                 goto err_nomem;
1071         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1072                                              RPC_BUFFER_MAXSIZE,
1073                                              0, SLAB_HWCACHE_ALIGN,
1074                                              NULL);
1075         if (!rpc_buffer_slabp)
1076                 goto err_nomem;
1077         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1078                                                     rpc_task_slabp);
1079         if (!rpc_task_mempool)
1080                 goto err_nomem;
1081         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1082                                                       rpc_buffer_slabp);
1083         if (!rpc_buffer_mempool)
1084                 goto err_nomem;
1085         return 0;
1086 err_nomem:
1087         rpc_destroy_mempool();
1088         return -ENOMEM;
1089 }