Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched
[linux-3.10.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/smp_lock.h>
20 #include <linux/spinlock.h>
21 #include <linux/mutex.h>
22
23 #include <linux/sunrpc/clnt.h>
24
25 #ifdef RPC_DEBUG
26 #define RPCDBG_FACILITY         RPCDBG_SCHED
27 #define RPC_TASK_MAGIC_ID       0xf00baa
28 #endif
29
30 /*
31  * RPC slabs and memory pools
32  */
33 #define RPC_BUFFER_MAXSIZE      (2048)
34 #define RPC_BUFFER_POOLSIZE     (8)
35 #define RPC_TASK_POOLSIZE       (8)
36 static struct kmem_cache        *rpc_task_slabp __read_mostly;
37 static struct kmem_cache        *rpc_buffer_slabp __read_mostly;
38 static mempool_t        *rpc_task_mempool __read_mostly;
39 static mempool_t        *rpc_buffer_mempool __read_mostly;
40
41 static void                     __rpc_default_timer(struct rpc_task *task);
42 static void                     rpc_async_schedule(struct work_struct *);
43 static void                      rpc_release_task(struct rpc_task *task);
44
45 /*
46  * RPC tasks sit here while waiting for conditions to improve.
47  */
48 static struct rpc_wait_queue delay_queue;
49
50 /*
51  * rpciod-related stuff
52  */
53 struct workqueue_struct *rpciod_workqueue;
54
55 /*
56  * Disable the timer for a given RPC task. Should be called with
57  * queue->lock and bh_disabled in order to avoid races within
58  * rpc_run_timer().
59  */
60 static inline void
61 __rpc_disable_timer(struct rpc_task *task)
62 {
63         dprintk("RPC: %5u disabling timer\n", task->tk_pid);
64         task->tk_timeout_fn = NULL;
65         task->tk_timeout = 0;
66 }
67
68 /*
69  * Run a timeout function.
70  * We use the callback in order to allow __rpc_wake_up_task()
71  * and friends to disable the timer synchronously on SMP systems
72  * without calling del_timer_sync(). The latter could cause a
73  * deadlock if called while we're holding spinlocks...
74  */
75 static void rpc_run_timer(struct rpc_task *task)
76 {
77         void (*callback)(struct rpc_task *);
78
79         callback = task->tk_timeout_fn;
80         task->tk_timeout_fn = NULL;
81         if (callback && RPC_IS_QUEUED(task)) {
82                 dprintk("RPC: %5u running timer\n", task->tk_pid);
83                 callback(task);
84         }
85         smp_mb__before_clear_bit();
86         clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
87         smp_mb__after_clear_bit();
88 }
89
90 /*
91  * Set up a timer for the current task.
92  */
93 static inline void
94 __rpc_add_timer(struct rpc_task *task, rpc_action timer)
95 {
96         if (!task->tk_timeout)
97                 return;
98
99         dprintk("RPC: %5u setting alarm for %lu ms\n",
100                         task->tk_pid, task->tk_timeout * 1000 / HZ);
101
102         if (timer)
103                 task->tk_timeout_fn = timer;
104         else
105                 task->tk_timeout_fn = __rpc_default_timer;
106         set_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
107         mod_timer(&task->tk_timer, jiffies + task->tk_timeout);
108 }
109
110 /*
111  * Delete any timer for the current task. Because we use del_timer_sync(),
112  * this function should never be called while holding queue->lock.
113  */
114 static void
115 rpc_delete_timer(struct rpc_task *task)
116 {
117         if (RPC_IS_QUEUED(task))
118                 return;
119         if (test_and_clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate)) {
120                 del_singleshot_timer_sync(&task->tk_timer);
121                 dprintk("RPC: %5u deleting timer\n", task->tk_pid);
122         }
123 }
124
125 /*
126  * Add new request to a priority queue.
127  */
128 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
129 {
130         struct list_head *q;
131         struct rpc_task *t;
132
133         INIT_LIST_HEAD(&task->u.tk_wait.links);
134         q = &queue->tasks[task->tk_priority];
135         if (unlikely(task->tk_priority > queue->maxpriority))
136                 q = &queue->tasks[queue->maxpriority];
137         list_for_each_entry(t, q, u.tk_wait.list) {
138                 if (t->tk_owner == task->tk_owner) {
139                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
140                         return;
141                 }
142         }
143         list_add_tail(&task->u.tk_wait.list, q);
144 }
145
146 /*
147  * Add new request to wait queue.
148  *
149  * Swapper tasks always get inserted at the head of the queue.
150  * This should avoid many nasty memory deadlocks and hopefully
151  * improve overall performance.
152  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
153  */
154 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
155 {
156         BUG_ON (RPC_IS_QUEUED(task));
157
158         if (RPC_IS_PRIORITY(queue))
159                 __rpc_add_wait_queue_priority(queue, task);
160         else if (RPC_IS_SWAPPER(task))
161                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
162         else
163                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
164         task->u.tk_wait.rpc_waitq = queue;
165         queue->qlen++;
166         rpc_set_queued(task);
167
168         dprintk("RPC: %5u added to queue %p \"%s\"\n",
169                         task->tk_pid, queue, rpc_qname(queue));
170 }
171
172 /*
173  * Remove request from a priority queue.
174  */
175 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
176 {
177         struct rpc_task *t;
178
179         if (!list_empty(&task->u.tk_wait.links)) {
180                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
181                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
182                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
183         }
184         list_del(&task->u.tk_wait.list);
185 }
186
187 /*
188  * Remove request from queue.
189  * Note: must be called with spin lock held.
190  */
191 static void __rpc_remove_wait_queue(struct rpc_task *task)
192 {
193         struct rpc_wait_queue *queue;
194         queue = task->u.tk_wait.rpc_waitq;
195
196         if (RPC_IS_PRIORITY(queue))
197                 __rpc_remove_wait_queue_priority(task);
198         else
199                 list_del(&task->u.tk_wait.list);
200         queue->qlen--;
201         dprintk("RPC: %5u removed from queue %p \"%s\"\n",
202                         task->tk_pid, queue, rpc_qname(queue));
203 }
204
205 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
206 {
207         queue->priority = priority;
208         queue->count = 1 << (priority * 2);
209 }
210
211 static inline void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
212 {
213         queue->owner = pid;
214         queue->nr = RPC_BATCH_COUNT;
215 }
216
217 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
218 {
219         rpc_set_waitqueue_priority(queue, queue->maxpriority);
220         rpc_set_waitqueue_owner(queue, 0);
221 }
222
223 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
224 {
225         int i;
226
227         spin_lock_init(&queue->lock);
228         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
229                 INIT_LIST_HEAD(&queue->tasks[i]);
230         queue->maxpriority = nr_queues - 1;
231         rpc_reset_waitqueue_priority(queue);
232 #ifdef RPC_DEBUG
233         queue->name = qname;
234 #endif
235 }
236
237 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
238 {
239         __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
240 }
241
242 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
243 {
244         __rpc_init_priority_wait_queue(queue, qname, 1);
245 }
246 EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
247
248 static int rpc_wait_bit_interruptible(void *word)
249 {
250         if (signal_pending(current))
251                 return -ERESTARTSYS;
252         schedule();
253         return 0;
254 }
255
256 #ifdef RPC_DEBUG
257 static void rpc_task_set_debuginfo(struct rpc_task *task)
258 {
259         static atomic_t rpc_pid;
260
261         task->tk_magic = RPC_TASK_MAGIC_ID;
262         task->tk_pid = atomic_inc_return(&rpc_pid);
263 }
264 #else
265 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
266 {
267 }
268 #endif
269
270 static void rpc_set_active(struct rpc_task *task)
271 {
272         struct rpc_clnt *clnt;
273         if (test_and_set_bit(RPC_TASK_ACTIVE, &task->tk_runstate) != 0)
274                 return;
275         rpc_task_set_debuginfo(task);
276         /* Add to global list of all tasks */
277         clnt = task->tk_client;
278         if (clnt != NULL) {
279                 spin_lock(&clnt->cl_lock);
280                 list_add_tail(&task->tk_task, &clnt->cl_tasks);
281                 spin_unlock(&clnt->cl_lock);
282         }
283 }
284
285 /*
286  * Mark an RPC call as having completed by clearing the 'active' bit
287  */
288 static void rpc_mark_complete_task(struct rpc_task *task)
289 {
290         smp_mb__before_clear_bit();
291         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
292         smp_mb__after_clear_bit();
293         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
294 }
295
296 /*
297  * Allow callers to wait for completion of an RPC call
298  */
299 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
300 {
301         if (action == NULL)
302                 action = rpc_wait_bit_interruptible;
303         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
304                         action, TASK_INTERRUPTIBLE);
305 }
306 EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
307
308 /*
309  * Make an RPC task runnable.
310  *
311  * Note: If the task is ASYNC, this must be called with
312  * the spinlock held to protect the wait queue operation.
313  */
314 static void rpc_make_runnable(struct rpc_task *task)
315 {
316         BUG_ON(task->tk_timeout_fn);
317         rpc_clear_queued(task);
318         if (rpc_test_and_set_running(task))
319                 return;
320         /* We might have raced */
321         if (RPC_IS_QUEUED(task)) {
322                 rpc_clear_running(task);
323                 return;
324         }
325         if (RPC_IS_ASYNC(task)) {
326                 int status;
327
328                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
329                 status = queue_work(task->tk_workqueue, &task->u.tk_work);
330                 if (status < 0) {
331                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
332                         task->tk_status = status;
333                         return;
334                 }
335         } else
336                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
337 }
338
339 /*
340  * Prepare for sleeping on a wait queue.
341  * By always appending tasks to the list we ensure FIFO behavior.
342  * NB: An RPC task will only receive interrupt-driven events as long
343  * as it's on a wait queue.
344  */
345 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
346                         rpc_action action, rpc_action timer)
347 {
348         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
349                         task->tk_pid, rpc_qname(q), jiffies);
350
351         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
352                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
353                 return;
354         }
355
356         __rpc_add_wait_queue(q, task);
357
358         BUG_ON(task->tk_callback != NULL);
359         task->tk_callback = action;
360         __rpc_add_timer(task, timer);
361 }
362
363 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
364                                 rpc_action action, rpc_action timer)
365 {
366         /* Mark the task as being activated if so needed */
367         rpc_set_active(task);
368
369         /*
370          * Protect the queue operations.
371          */
372         spin_lock_bh(&q->lock);
373         __rpc_sleep_on(q, task, action, timer);
374         spin_unlock_bh(&q->lock);
375 }
376 EXPORT_SYMBOL_GPL(rpc_sleep_on);
377
378 /**
379  * __rpc_do_wake_up_task - wake up a single rpc_task
380  * @task: task to be woken up
381  *
382  * Caller must hold queue->lock, and have cleared the task queued flag.
383  */
384 static void __rpc_do_wake_up_task(struct rpc_task *task)
385 {
386         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
387                         task->tk_pid, jiffies);
388
389 #ifdef RPC_DEBUG
390         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
391 #endif
392         /* Has the task been executed yet? If not, we cannot wake it up! */
393         if (!RPC_IS_ACTIVATED(task)) {
394                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
395                 return;
396         }
397
398         __rpc_disable_timer(task);
399         __rpc_remove_wait_queue(task);
400
401         rpc_make_runnable(task);
402
403         dprintk("RPC:       __rpc_wake_up_task done\n");
404 }
405
406 /*
407  * Wake up the specified task
408  */
409 static void __rpc_wake_up_task(struct rpc_task *task)
410 {
411         if (rpc_start_wakeup(task)) {
412                 if (RPC_IS_QUEUED(task))
413                         __rpc_do_wake_up_task(task);
414                 rpc_finish_wakeup(task);
415         }
416 }
417
418 /*
419  * Default timeout handler if none specified by user
420  */
421 static void
422 __rpc_default_timer(struct rpc_task *task)
423 {
424         dprintk("RPC: %5u timeout (default timer)\n", task->tk_pid);
425         task->tk_status = -ETIMEDOUT;
426         rpc_wake_up_task(task);
427 }
428
429 /*
430  * Wake up the specified task
431  */
432 void rpc_wake_up_task(struct rpc_task *task)
433 {
434         rcu_read_lock_bh();
435         if (rpc_start_wakeup(task)) {
436                 if (RPC_IS_QUEUED(task)) {
437                         struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
438
439                         /* Note: we're already in a bh-safe context */
440                         spin_lock(&queue->lock);
441                         __rpc_do_wake_up_task(task);
442                         spin_unlock(&queue->lock);
443                 }
444                 rpc_finish_wakeup(task);
445         }
446         rcu_read_unlock_bh();
447 }
448 EXPORT_SYMBOL_GPL(rpc_wake_up_task);
449
450 /*
451  * Wake up the next task on a priority queue.
452  */
453 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
454 {
455         struct list_head *q;
456         struct rpc_task *task;
457
458         /*
459          * Service a batch of tasks from a single owner.
460          */
461         q = &queue->tasks[queue->priority];
462         if (!list_empty(q)) {
463                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
464                 if (queue->owner == task->tk_owner) {
465                         if (--queue->nr)
466                                 goto out;
467                         list_move_tail(&task->u.tk_wait.list, q);
468                 }
469                 /*
470                  * Check if we need to switch queues.
471                  */
472                 if (--queue->count)
473                         goto new_owner;
474         }
475
476         /*
477          * Service the next queue.
478          */
479         do {
480                 if (q == &queue->tasks[0])
481                         q = &queue->tasks[queue->maxpriority];
482                 else
483                         q = q - 1;
484                 if (!list_empty(q)) {
485                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
486                         goto new_queue;
487                 }
488         } while (q != &queue->tasks[queue->priority]);
489
490         rpc_reset_waitqueue_priority(queue);
491         return NULL;
492
493 new_queue:
494         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
495 new_owner:
496         rpc_set_waitqueue_owner(queue, task->tk_owner);
497 out:
498         __rpc_wake_up_task(task);
499         return task;
500 }
501
502 /*
503  * Wake up the next task on the wait queue.
504  */
505 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
506 {
507         struct rpc_task *task = NULL;
508
509         dprintk("RPC:       wake_up_next(%p \"%s\")\n",
510                         queue, rpc_qname(queue));
511         rcu_read_lock_bh();
512         spin_lock(&queue->lock);
513         if (RPC_IS_PRIORITY(queue))
514                 task = __rpc_wake_up_next_priority(queue);
515         else {
516                 task_for_first(task, &queue->tasks[0])
517                         __rpc_wake_up_task(task);
518         }
519         spin_unlock(&queue->lock);
520         rcu_read_unlock_bh();
521
522         return task;
523 }
524 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
525
526 /**
527  * rpc_wake_up - wake up all rpc_tasks
528  * @queue: rpc_wait_queue on which the tasks are sleeping
529  *
530  * Grabs queue->lock
531  */
532 void rpc_wake_up(struct rpc_wait_queue *queue)
533 {
534         struct rpc_task *task, *next;
535         struct list_head *head;
536
537         rcu_read_lock_bh();
538         spin_lock(&queue->lock);
539         head = &queue->tasks[queue->maxpriority];
540         for (;;) {
541                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
542                         __rpc_wake_up_task(task);
543                 if (head == &queue->tasks[0])
544                         break;
545                 head--;
546         }
547         spin_unlock(&queue->lock);
548         rcu_read_unlock_bh();
549 }
550 EXPORT_SYMBOL_GPL(rpc_wake_up);
551
552 /**
553  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
554  * @queue: rpc_wait_queue on which the tasks are sleeping
555  * @status: status value to set
556  *
557  * Grabs queue->lock
558  */
559 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
560 {
561         struct rpc_task *task, *next;
562         struct list_head *head;
563
564         rcu_read_lock_bh();
565         spin_lock(&queue->lock);
566         head = &queue->tasks[queue->maxpriority];
567         for (;;) {
568                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
569                         task->tk_status = status;
570                         __rpc_wake_up_task(task);
571                 }
572                 if (head == &queue->tasks[0])
573                         break;
574                 head--;
575         }
576         spin_unlock(&queue->lock);
577         rcu_read_unlock_bh();
578 }
579 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
580
581 static void __rpc_atrun(struct rpc_task *task)
582 {
583         rpc_wake_up_task(task);
584 }
585
586 /*
587  * Run a task at a later time
588  */
589 void rpc_delay(struct rpc_task *task, unsigned long delay)
590 {
591         task->tk_timeout = delay;
592         rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
593 }
594 EXPORT_SYMBOL_GPL(rpc_delay);
595
596 /*
597  * Helper to call task->tk_ops->rpc_call_prepare
598  */
599 static void rpc_prepare_task(struct rpc_task *task)
600 {
601         lock_kernel();
602         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
603         unlock_kernel();
604 }
605
606 /*
607  * Helper that calls task->tk_ops->rpc_call_done if it exists
608  */
609 void rpc_exit_task(struct rpc_task *task)
610 {
611         task->tk_action = NULL;
612         if (task->tk_ops->rpc_call_done != NULL) {
613                 lock_kernel();
614                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
615                 unlock_kernel();
616                 if (task->tk_action != NULL) {
617                         WARN_ON(RPC_ASSASSINATED(task));
618                         /* Always release the RPC slot and buffer memory */
619                         xprt_release(task);
620                 }
621         }
622 }
623 EXPORT_SYMBOL_GPL(rpc_exit_task);
624
625 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
626 {
627         if (ops->rpc_release != NULL) {
628                 lock_kernel();
629                 ops->rpc_release(calldata);
630                 unlock_kernel();
631         }
632 }
633
634 /*
635  * This is the RPC `scheduler' (or rather, the finite state machine).
636  */
637 static void __rpc_execute(struct rpc_task *task)
638 {
639         int             status = 0;
640
641         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
642                         task->tk_pid, task->tk_flags);
643
644         BUG_ON(RPC_IS_QUEUED(task));
645
646         for (;;) {
647                 /*
648                  * Garbage collection of pending timers...
649                  */
650                 rpc_delete_timer(task);
651
652                 /*
653                  * Execute any pending callback.
654                  */
655                 if (RPC_DO_CALLBACK(task)) {
656                         /* Define a callback save pointer */
657                         void (*save_callback)(struct rpc_task *);
658
659                         /*
660                          * If a callback exists, save it, reset it,
661                          * call it.
662                          * The save is needed to stop from resetting
663                          * another callback set within the callback handler
664                          * - Dave
665                          */
666                         save_callback=task->tk_callback;
667                         task->tk_callback=NULL;
668                         save_callback(task);
669                 }
670
671                 /*
672                  * Perform the next FSM step.
673                  * tk_action may be NULL when the task has been killed
674                  * by someone else.
675                  */
676                 if (!RPC_IS_QUEUED(task)) {
677                         if (task->tk_action == NULL)
678                                 break;
679                         task->tk_action(task);
680                 }
681
682                 /*
683                  * Lockless check for whether task is sleeping or not.
684                  */
685                 if (!RPC_IS_QUEUED(task))
686                         continue;
687                 rpc_clear_running(task);
688                 if (RPC_IS_ASYNC(task)) {
689                         /* Careful! we may have raced... */
690                         if (RPC_IS_QUEUED(task))
691                                 return;
692                         if (rpc_test_and_set_running(task))
693                                 return;
694                         continue;
695                 }
696
697                 /* sync task: sleep here */
698                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
699                 /* Note: Caller should be using rpc_clnt_sigmask() */
700                 status = out_of_line_wait_on_bit(&task->tk_runstate,
701                                 RPC_TASK_QUEUED, rpc_wait_bit_interruptible,
702                                 TASK_INTERRUPTIBLE);
703                 if (status == -ERESTARTSYS) {
704                         /*
705                          * When a sync task receives a signal, it exits with
706                          * -ERESTARTSYS. In order to catch any callbacks that
707                          * clean up after sleeping on some queue, we don't
708                          * break the loop here, but go around once more.
709                          */
710                         dprintk("RPC: %5u got signal\n", task->tk_pid);
711                         task->tk_flags |= RPC_TASK_KILLED;
712                         rpc_exit(task, -ERESTARTSYS);
713                         rpc_wake_up_task(task);
714                 }
715                 rpc_set_running(task);
716                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
717         }
718
719         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
720                         task->tk_status);
721         /* Release all resources associated with the task */
722         rpc_release_task(task);
723 }
724
725 /*
726  * User-visible entry point to the scheduler.
727  *
728  * This may be called recursively if e.g. an async NFS task updates
729  * the attributes and finds that dirty pages must be flushed.
730  * NOTE: Upon exit of this function the task is guaranteed to be
731  *       released. In particular note that tk_release() will have
732  *       been called, so your task memory may have been freed.
733  */
734 void rpc_execute(struct rpc_task *task)
735 {
736         rpc_set_active(task);
737         rpc_set_running(task);
738         __rpc_execute(task);
739 }
740
741 static void rpc_async_schedule(struct work_struct *work)
742 {
743         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
744 }
745
746 struct rpc_buffer {
747         size_t  len;
748         char    data[];
749 };
750
751 /**
752  * rpc_malloc - allocate an RPC buffer
753  * @task: RPC task that will use this buffer
754  * @size: requested byte size
755  *
756  * To prevent rpciod from hanging, this allocator never sleeps,
757  * returning NULL if the request cannot be serviced immediately.
758  * The caller can arrange to sleep in a way that is safe for rpciod.
759  *
760  * Most requests are 'small' (under 2KiB) and can be serviced from a
761  * mempool, ensuring that NFS reads and writes can always proceed,
762  * and that there is good locality of reference for these buffers.
763  *
764  * In order to avoid memory starvation triggering more writebacks of
765  * NFS requests, we avoid using GFP_KERNEL.
766  */
767 void *rpc_malloc(struct rpc_task *task, size_t size)
768 {
769         struct rpc_buffer *buf;
770         gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
771
772         size += sizeof(struct rpc_buffer);
773         if (size <= RPC_BUFFER_MAXSIZE)
774                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
775         else
776                 buf = kmalloc(size, gfp);
777
778         if (!buf)
779                 return NULL;
780
781         buf->len = size;
782         dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
783                         task->tk_pid, size, buf);
784         return &buf->data;
785 }
786 EXPORT_SYMBOL_GPL(rpc_malloc);
787
788 /**
789  * rpc_free - free buffer allocated via rpc_malloc
790  * @buffer: buffer to free
791  *
792  */
793 void rpc_free(void *buffer)
794 {
795         size_t size;
796         struct rpc_buffer *buf;
797
798         if (!buffer)
799                 return;
800
801         buf = container_of(buffer, struct rpc_buffer, data);
802         size = buf->len;
803
804         dprintk("RPC:       freeing buffer of size %zu at %p\n",
805                         size, buf);
806
807         if (size <= RPC_BUFFER_MAXSIZE)
808                 mempool_free(buf, rpc_buffer_mempool);
809         else
810                 kfree(buf);
811 }
812 EXPORT_SYMBOL_GPL(rpc_free);
813
814 /*
815  * Creation and deletion of RPC task structures
816  */
817 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
818 {
819         memset(task, 0, sizeof(*task));
820         setup_timer(&task->tk_timer, (void (*)(unsigned long))rpc_run_timer,
821                         (unsigned long)task);
822         atomic_set(&task->tk_count, 1);
823         task->tk_flags  = task_setup_data->flags;
824         task->tk_ops = task_setup_data->callback_ops;
825         task->tk_calldata = task_setup_data->callback_data;
826         INIT_LIST_HEAD(&task->tk_task);
827
828         /* Initialize retry counters */
829         task->tk_garb_retry = 2;
830         task->tk_cred_retry = 2;
831
832         task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
833         task->tk_owner = current->tgid;
834
835         /* Initialize workqueue for async tasks */
836         task->tk_workqueue = rpciod_workqueue;
837
838         task->tk_client = task_setup_data->rpc_client;
839         if (task->tk_client != NULL) {
840                 kref_get(&task->tk_client->cl_kref);
841                 if (task->tk_client->cl_softrtry)
842                         task->tk_flags |= RPC_TASK_SOFT;
843                 if (!task->tk_client->cl_intr)
844                         task->tk_flags |= RPC_TASK_NOINTR;
845         }
846
847         if (task->tk_ops->rpc_call_prepare != NULL)
848                 task->tk_action = rpc_prepare_task;
849
850         if (task_setup_data->rpc_message != NULL) {
851                 memcpy(&task->tk_msg, task_setup_data->rpc_message, sizeof(task->tk_msg));
852                 /* Bind the user cred */
853                 if (task->tk_msg.rpc_cred != NULL)
854                         rpcauth_holdcred(task);
855                 else
856                         rpcauth_bindcred(task);
857                 if (task->tk_action == NULL)
858                         rpc_call_start(task);
859         }
860
861         /* starting timestamp */
862         task->tk_start = jiffies;
863
864         dprintk("RPC:       new task initialized, procpid %u\n",
865                                 task_pid_nr(current));
866 }
867
868 static struct rpc_task *
869 rpc_alloc_task(void)
870 {
871         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
872 }
873
874 static void rpc_free_task(struct rcu_head *rcu)
875 {
876         struct rpc_task *task = container_of(rcu, struct rpc_task, u.tk_rcu);
877         dprintk("RPC: %5u freeing task\n", task->tk_pid);
878         mempool_free(task, rpc_task_mempool);
879 }
880
881 /*
882  * Create a new task for the specified client.
883  */
884 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
885 {
886         struct rpc_task *task = setup_data->task;
887         unsigned short flags = 0;
888
889         if (task == NULL) {
890                 task = rpc_alloc_task();
891                 if (task == NULL)
892                         goto out;
893                 flags = RPC_TASK_DYNAMIC;
894         }
895
896         rpc_init_task(task, setup_data);
897
898         task->tk_flags |= flags;
899         dprintk("RPC:       allocated task %p\n", task);
900 out:
901         return task;
902 }
903
904
905 void rpc_put_task(struct rpc_task *task)
906 {
907         const struct rpc_call_ops *tk_ops = task->tk_ops;
908         void *calldata = task->tk_calldata;
909
910         if (!atomic_dec_and_test(&task->tk_count))
911                 return;
912         /* Release resources */
913         if (task->tk_rqstp)
914                 xprt_release(task);
915         if (task->tk_msg.rpc_cred)
916                 rpcauth_unbindcred(task);
917         if (task->tk_client) {
918                 rpc_release_client(task->tk_client);
919                 task->tk_client = NULL;
920         }
921         if (task->tk_flags & RPC_TASK_DYNAMIC)
922                 call_rcu_bh(&task->u.tk_rcu, rpc_free_task);
923         rpc_release_calldata(tk_ops, calldata);
924 }
925 EXPORT_SYMBOL_GPL(rpc_put_task);
926
927 static void rpc_release_task(struct rpc_task *task)
928 {
929 #ifdef RPC_DEBUG
930         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
931 #endif
932         dprintk("RPC: %5u release task\n", task->tk_pid);
933
934         if (!list_empty(&task->tk_task)) {
935                 struct rpc_clnt *clnt = task->tk_client;
936                 /* Remove from client task list */
937                 spin_lock(&clnt->cl_lock);
938                 list_del(&task->tk_task);
939                 spin_unlock(&clnt->cl_lock);
940         }
941         BUG_ON (RPC_IS_QUEUED(task));
942
943         /* Synchronously delete any running timer */
944         rpc_delete_timer(task);
945
946 #ifdef RPC_DEBUG
947         task->tk_magic = 0;
948 #endif
949         /* Wake up anyone who is waiting for task completion */
950         rpc_mark_complete_task(task);
951
952         rpc_put_task(task);
953 }
954
955 /*
956  * Kill all tasks for the given client.
957  * XXX: kill their descendants as well?
958  */
959 void rpc_killall_tasks(struct rpc_clnt *clnt)
960 {
961         struct rpc_task *rovr;
962
963
964         if (list_empty(&clnt->cl_tasks))
965                 return;
966         dprintk("RPC:       killing all tasks for client %p\n", clnt);
967         /*
968          * Spin lock all_tasks to prevent changes...
969          */
970         spin_lock(&clnt->cl_lock);
971         list_for_each_entry(rovr, &clnt->cl_tasks, tk_task) {
972                 if (! RPC_IS_ACTIVATED(rovr))
973                         continue;
974                 if (!(rovr->tk_flags & RPC_TASK_KILLED)) {
975                         rovr->tk_flags |= RPC_TASK_KILLED;
976                         rpc_exit(rovr, -EIO);
977                         rpc_wake_up_task(rovr);
978                 }
979         }
980         spin_unlock(&clnt->cl_lock);
981 }
982 EXPORT_SYMBOL_GPL(rpc_killall_tasks);
983
984 int rpciod_up(void)
985 {
986         return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
987 }
988
989 void rpciod_down(void)
990 {
991         module_put(THIS_MODULE);
992 }
993
994 /*
995  * Start up the rpciod workqueue.
996  */
997 static int rpciod_start(void)
998 {
999         struct workqueue_struct *wq;
1000
1001         /*
1002          * Create the rpciod thread and wait for it to start.
1003          */
1004         dprintk("RPC:       creating workqueue rpciod\n");
1005         wq = create_workqueue("rpciod");
1006         rpciod_workqueue = wq;
1007         return rpciod_workqueue != NULL;
1008 }
1009
1010 static void rpciod_stop(void)
1011 {
1012         struct workqueue_struct *wq = NULL;
1013
1014         if (rpciod_workqueue == NULL)
1015                 return;
1016         dprintk("RPC:       destroying workqueue rpciod\n");
1017
1018         wq = rpciod_workqueue;
1019         rpciod_workqueue = NULL;
1020         destroy_workqueue(wq);
1021 }
1022
1023 void
1024 rpc_destroy_mempool(void)
1025 {
1026         rpciod_stop();
1027         if (rpc_buffer_mempool)
1028                 mempool_destroy(rpc_buffer_mempool);
1029         if (rpc_task_mempool)
1030                 mempool_destroy(rpc_task_mempool);
1031         if (rpc_task_slabp)
1032                 kmem_cache_destroy(rpc_task_slabp);
1033         if (rpc_buffer_slabp)
1034                 kmem_cache_destroy(rpc_buffer_slabp);
1035 }
1036
1037 int
1038 rpc_init_mempool(void)
1039 {
1040         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1041                                              sizeof(struct rpc_task),
1042                                              0, SLAB_HWCACHE_ALIGN,
1043                                              NULL);
1044         if (!rpc_task_slabp)
1045                 goto err_nomem;
1046         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1047                                              RPC_BUFFER_MAXSIZE,
1048                                              0, SLAB_HWCACHE_ALIGN,
1049                                              NULL);
1050         if (!rpc_buffer_slabp)
1051                 goto err_nomem;
1052         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1053                                                     rpc_task_slabp);
1054         if (!rpc_task_mempool)
1055                 goto err_nomem;
1056         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1057                                                       rpc_buffer_slabp);
1058         if (!rpc_buffer_mempool)
1059                 goto err_nomem;
1060         if (!rpciod_start())
1061                 goto err_nomem;
1062         /*
1063          * The following is not strictly a mempool initialisation,
1064          * but there is no harm in doing it here
1065          */
1066         rpc_init_wait_queue(&delay_queue, "delayq");
1067         return 0;
1068 err_nomem:
1069         rpc_destroy_mempool();
1070         return -ENOMEM;
1071 }