Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6
[linux-2.6] / 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 static int                      rpc_task_id;
29 #endif
30
31 /*
32  * RPC slabs and memory pools
33  */
34 #define RPC_BUFFER_MAXSIZE      (2048)
35 #define RPC_BUFFER_POOLSIZE     (8)
36 #define RPC_TASK_POOLSIZE       (8)
37 static struct kmem_cache        *rpc_task_slabp __read_mostly;
38 static struct kmem_cache        *rpc_buffer_slabp __read_mostly;
39 static mempool_t        *rpc_task_mempool __read_mostly;
40 static mempool_t        *rpc_buffer_mempool __read_mostly;
41
42 static void                     __rpc_default_timer(struct rpc_task *task);
43 static void                     rpciod_killall(void);
44 static void                     rpc_async_schedule(struct work_struct *);
45 static void                      rpc_release_task(struct rpc_task *task);
46
47 /*
48  * RPC tasks sit here while waiting for conditions to improve.
49  */
50 static RPC_WAITQ(delay_queue, "delayq");
51
52 /*
53  * All RPC tasks are linked into this list
54  */
55 static LIST_HEAD(all_tasks);
56
57 /*
58  * rpciod-related stuff
59  */
60 static DEFINE_MUTEX(rpciod_mutex);
61 static unsigned int             rpciod_users;
62 struct workqueue_struct *rpciod_workqueue;
63
64 /*
65  * Spinlock for other critical sections of code.
66  */
67 static DEFINE_SPINLOCK(rpc_sched_lock);
68
69 /*
70  * Disable the timer for a given RPC task. Should be called with
71  * queue->lock and bh_disabled in order to avoid races within
72  * rpc_run_timer().
73  */
74 static inline void
75 __rpc_disable_timer(struct rpc_task *task)
76 {
77         dprintk("RPC: %5u disabling timer\n", task->tk_pid);
78         task->tk_timeout_fn = NULL;
79         task->tk_timeout = 0;
80 }
81
82 /*
83  * Run a timeout function.
84  * We use the callback in order to allow __rpc_wake_up_task()
85  * and friends to disable the timer synchronously on SMP systems
86  * without calling del_timer_sync(). The latter could cause a
87  * deadlock if called while we're holding spinlocks...
88  */
89 static void rpc_run_timer(struct rpc_task *task)
90 {
91         void (*callback)(struct rpc_task *);
92
93         callback = task->tk_timeout_fn;
94         task->tk_timeout_fn = NULL;
95         if (callback && RPC_IS_QUEUED(task)) {
96                 dprintk("RPC: %5u running timer\n", task->tk_pid);
97                 callback(task);
98         }
99         smp_mb__before_clear_bit();
100         clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
101         smp_mb__after_clear_bit();
102 }
103
104 /*
105  * Set up a timer for the current task.
106  */
107 static inline void
108 __rpc_add_timer(struct rpc_task *task, rpc_action timer)
109 {
110         if (!task->tk_timeout)
111                 return;
112
113         dprintk("RPC: %5u setting alarm for %lu ms\n",
114                         task->tk_pid, task->tk_timeout * 1000 / HZ);
115
116         if (timer)
117                 task->tk_timeout_fn = timer;
118         else
119                 task->tk_timeout_fn = __rpc_default_timer;
120         set_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate);
121         mod_timer(&task->tk_timer, jiffies + task->tk_timeout);
122 }
123
124 /*
125  * Delete any timer for the current task. Because we use del_timer_sync(),
126  * this function should never be called while holding queue->lock.
127  */
128 static void
129 rpc_delete_timer(struct rpc_task *task)
130 {
131         if (RPC_IS_QUEUED(task))
132                 return;
133         if (test_and_clear_bit(RPC_TASK_HAS_TIMER, &task->tk_runstate)) {
134                 del_singleshot_timer_sync(&task->tk_timer);
135                 dprintk("RPC: %5u deleting timer\n", task->tk_pid);
136         }
137 }
138
139 /*
140  * Add new request to a priority queue.
141  */
142 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
143 {
144         struct list_head *q;
145         struct rpc_task *t;
146
147         INIT_LIST_HEAD(&task->u.tk_wait.links);
148         q = &queue->tasks[task->tk_priority];
149         if (unlikely(task->tk_priority > queue->maxpriority))
150                 q = &queue->tasks[queue->maxpriority];
151         list_for_each_entry(t, q, u.tk_wait.list) {
152                 if (t->tk_cookie == task->tk_cookie) {
153                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
154                         return;
155                 }
156         }
157         list_add_tail(&task->u.tk_wait.list, q);
158 }
159
160 /*
161  * Add new request to wait queue.
162  *
163  * Swapper tasks always get inserted at the head of the queue.
164  * This should avoid many nasty memory deadlocks and hopefully
165  * improve overall performance.
166  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
167  */
168 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
169 {
170         BUG_ON (RPC_IS_QUEUED(task));
171
172         if (RPC_IS_PRIORITY(queue))
173                 __rpc_add_wait_queue_priority(queue, task);
174         else if (RPC_IS_SWAPPER(task))
175                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
176         else
177                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
178         task->u.tk_wait.rpc_waitq = queue;
179         queue->qlen++;
180         rpc_set_queued(task);
181
182         dprintk("RPC: %5u added to queue %p \"%s\"\n",
183                         task->tk_pid, queue, rpc_qname(queue));
184 }
185
186 /*
187  * Remove request from a priority queue.
188  */
189 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
190 {
191         struct rpc_task *t;
192
193         if (!list_empty(&task->u.tk_wait.links)) {
194                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
195                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
196                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
197         }
198         list_del(&task->u.tk_wait.list);
199 }
200
201 /*
202  * Remove request from queue.
203  * Note: must be called with spin lock held.
204  */
205 static void __rpc_remove_wait_queue(struct rpc_task *task)
206 {
207         struct rpc_wait_queue *queue;
208         queue = task->u.tk_wait.rpc_waitq;
209
210         if (RPC_IS_PRIORITY(queue))
211                 __rpc_remove_wait_queue_priority(task);
212         else
213                 list_del(&task->u.tk_wait.list);
214         queue->qlen--;
215         dprintk("RPC: %5u removed from queue %p \"%s\"\n",
216                         task->tk_pid, queue, rpc_qname(queue));
217 }
218
219 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
220 {
221         queue->priority = priority;
222         queue->count = 1 << (priority * 2);
223 }
224
225 static inline void rpc_set_waitqueue_cookie(struct rpc_wait_queue *queue, unsigned long cookie)
226 {
227         queue->cookie = cookie;
228         queue->nr = RPC_BATCH_COUNT;
229 }
230
231 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
232 {
233         rpc_set_waitqueue_priority(queue, queue->maxpriority);
234         rpc_set_waitqueue_cookie(queue, 0);
235 }
236
237 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, int maxprio)
238 {
239         int i;
240
241         spin_lock_init(&queue->lock);
242         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
243                 INIT_LIST_HEAD(&queue->tasks[i]);
244         queue->maxpriority = maxprio;
245         rpc_reset_waitqueue_priority(queue);
246 #ifdef RPC_DEBUG
247         queue->name = qname;
248 #endif
249 }
250
251 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
252 {
253         __rpc_init_priority_wait_queue(queue, qname, RPC_PRIORITY_HIGH);
254 }
255
256 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
257 {
258         __rpc_init_priority_wait_queue(queue, qname, 0);
259 }
260 EXPORT_SYMBOL(rpc_init_wait_queue);
261
262 static int rpc_wait_bit_interruptible(void *word)
263 {
264         if (signal_pending(current))
265                 return -ERESTARTSYS;
266         schedule();
267         return 0;
268 }
269
270 static void rpc_set_active(struct rpc_task *task)
271 {
272         if (test_and_set_bit(RPC_TASK_ACTIVE, &task->tk_runstate) != 0)
273                 return;
274         spin_lock(&rpc_sched_lock);
275 #ifdef RPC_DEBUG
276         task->tk_magic = RPC_TASK_MAGIC_ID;
277         task->tk_pid = rpc_task_id++;
278 #endif
279         /* Add to global list of all tasks */
280         list_add_tail(&task->tk_task, &all_tasks);
281         spin_unlock(&rpc_sched_lock);
282 }
283
284 /*
285  * Mark an RPC call as having completed by clearing the 'active' bit
286  */
287 static void rpc_mark_complete_task(struct rpc_task *task)
288 {
289         smp_mb__before_clear_bit();
290         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
291         smp_mb__after_clear_bit();
292         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
293 }
294
295 /*
296  * Allow callers to wait for completion of an RPC call
297  */
298 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
299 {
300         if (action == NULL)
301                 action = rpc_wait_bit_interruptible;
302         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
303                         action, TASK_INTERRUPTIBLE);
304 }
305 EXPORT_SYMBOL(__rpc_wait_for_completion_task);
306
307 /*
308  * Make an RPC task runnable.
309  *
310  * Note: If the task is ASYNC, this must be called with
311  * the spinlock held to protect the wait queue operation.
312  */
313 static void rpc_make_runnable(struct rpc_task *task)
314 {
315         BUG_ON(task->tk_timeout_fn);
316         rpc_clear_queued(task);
317         if (rpc_test_and_set_running(task))
318                 return;
319         /* We might have raced */
320         if (RPC_IS_QUEUED(task)) {
321                 rpc_clear_running(task);
322                 return;
323         }
324         if (RPC_IS_ASYNC(task)) {
325                 int status;
326
327                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
328                 status = queue_work(task->tk_workqueue, &task->u.tk_work);
329                 if (status < 0) {
330                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
331                         task->tk_status = status;
332                         return;
333                 }
334         } else
335                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
336 }
337
338 /*
339  * Prepare for sleeping on a wait queue.
340  * By always appending tasks to the list we ensure FIFO behavior.
341  * NB: An RPC task will only receive interrupt-driven events as long
342  * as it's on a wait queue.
343  */
344 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
345                         rpc_action action, rpc_action timer)
346 {
347         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
348                         task->tk_pid, rpc_qname(q), jiffies);
349
350         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
351                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
352                 return;
353         }
354
355         __rpc_add_wait_queue(q, task);
356
357         BUG_ON(task->tk_callback != NULL);
358         task->tk_callback = action;
359         __rpc_add_timer(task, timer);
360 }
361
362 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
363                                 rpc_action action, rpc_action timer)
364 {
365         /* Mark the task as being activated if so needed */
366         rpc_set_active(task);
367
368         /*
369          * Protect the queue operations.
370          */
371         spin_lock_bh(&q->lock);
372         __rpc_sleep_on(q, task, action, timer);
373         spin_unlock_bh(&q->lock);
374 }
375
376 /**
377  * __rpc_do_wake_up_task - wake up a single rpc_task
378  * @task: task to be woken up
379  *
380  * Caller must hold queue->lock, and have cleared the task queued flag.
381  */
382 static void __rpc_do_wake_up_task(struct rpc_task *task)
383 {
384         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
385                         task->tk_pid, jiffies);
386
387 #ifdef RPC_DEBUG
388         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
389 #endif
390         /* Has the task been executed yet? If not, we cannot wake it up! */
391         if (!RPC_IS_ACTIVATED(task)) {
392                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
393                 return;
394         }
395
396         __rpc_disable_timer(task);
397         __rpc_remove_wait_queue(task);
398
399         rpc_make_runnable(task);
400
401         dprintk("RPC:       __rpc_wake_up_task done\n");
402 }
403
404 /*
405  * Wake up the specified task
406  */
407 static void __rpc_wake_up_task(struct rpc_task *task)
408 {
409         if (rpc_start_wakeup(task)) {
410                 if (RPC_IS_QUEUED(task))
411                         __rpc_do_wake_up_task(task);
412                 rpc_finish_wakeup(task);
413         }
414 }
415
416 /*
417  * Default timeout handler if none specified by user
418  */
419 static void
420 __rpc_default_timer(struct rpc_task *task)
421 {
422         dprintk("RPC: %5u timeout (default timer)\n", task->tk_pid);
423         task->tk_status = -ETIMEDOUT;
424         rpc_wake_up_task(task);
425 }
426
427 /*
428  * Wake up the specified task
429  */
430 void rpc_wake_up_task(struct rpc_task *task)
431 {
432         rcu_read_lock_bh();
433         if (rpc_start_wakeup(task)) {
434                 if (RPC_IS_QUEUED(task)) {
435                         struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
436
437                         /* Note: we're already in a bh-safe context */
438                         spin_lock(&queue->lock);
439                         __rpc_do_wake_up_task(task);
440                         spin_unlock(&queue->lock);
441                 }
442                 rpc_finish_wakeup(task);
443         }
444         rcu_read_unlock_bh();
445 }
446
447 /*
448  * Wake up the next task on a priority queue.
449  */
450 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
451 {
452         struct list_head *q;
453         struct rpc_task *task;
454
455         /*
456          * Service a batch of tasks from a single cookie.
457          */
458         q = &queue->tasks[queue->priority];
459         if (!list_empty(q)) {
460                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
461                 if (queue->cookie == task->tk_cookie) {
462                         if (--queue->nr)
463                                 goto out;
464                         list_move_tail(&task->u.tk_wait.list, q);
465                 }
466                 /*
467                  * Check if we need to switch queues.
468                  */
469                 if (--queue->count)
470                         goto new_cookie;
471         }
472
473         /*
474          * Service the next queue.
475          */
476         do {
477                 if (q == &queue->tasks[0])
478                         q = &queue->tasks[queue->maxpriority];
479                 else
480                         q = q - 1;
481                 if (!list_empty(q)) {
482                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
483                         goto new_queue;
484                 }
485         } while (q != &queue->tasks[queue->priority]);
486
487         rpc_reset_waitqueue_priority(queue);
488         return NULL;
489
490 new_queue:
491         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
492 new_cookie:
493         rpc_set_waitqueue_cookie(queue, task->tk_cookie);
494 out:
495         __rpc_wake_up_task(task);
496         return task;
497 }
498
499 /*
500  * Wake up the next task on the wait queue.
501  */
502 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
503 {
504         struct rpc_task *task = NULL;
505
506         dprintk("RPC:       wake_up_next(%p \"%s\")\n",
507                         queue, rpc_qname(queue));
508         rcu_read_lock_bh();
509         spin_lock(&queue->lock);
510         if (RPC_IS_PRIORITY(queue))
511                 task = __rpc_wake_up_next_priority(queue);
512         else {
513                 task_for_first(task, &queue->tasks[0])
514                         __rpc_wake_up_task(task);
515         }
516         spin_unlock(&queue->lock);
517         rcu_read_unlock_bh();
518
519         return task;
520 }
521
522 /**
523  * rpc_wake_up - wake up all rpc_tasks
524  * @queue: rpc_wait_queue on which the tasks are sleeping
525  *
526  * Grabs queue->lock
527  */
528 void rpc_wake_up(struct rpc_wait_queue *queue)
529 {
530         struct rpc_task *task, *next;
531         struct list_head *head;
532
533         rcu_read_lock_bh();
534         spin_lock(&queue->lock);
535         head = &queue->tasks[queue->maxpriority];
536         for (;;) {
537                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
538                         __rpc_wake_up_task(task);
539                 if (head == &queue->tasks[0])
540                         break;
541                 head--;
542         }
543         spin_unlock(&queue->lock);
544         rcu_read_unlock_bh();
545 }
546
547 /**
548  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
549  * @queue: rpc_wait_queue on which the tasks are sleeping
550  * @status: status value to set
551  *
552  * Grabs queue->lock
553  */
554 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
555 {
556         struct rpc_task *task, *next;
557         struct list_head *head;
558
559         rcu_read_lock_bh();
560         spin_lock(&queue->lock);
561         head = &queue->tasks[queue->maxpriority];
562         for (;;) {
563                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
564                         task->tk_status = status;
565                         __rpc_wake_up_task(task);
566                 }
567                 if (head == &queue->tasks[0])
568                         break;
569                 head--;
570         }
571         spin_unlock(&queue->lock);
572         rcu_read_unlock_bh();
573 }
574
575 static void __rpc_atrun(struct rpc_task *task)
576 {
577         rpc_wake_up_task(task);
578 }
579
580 /*
581  * Run a task at a later time
582  */
583 void rpc_delay(struct rpc_task *task, unsigned long delay)
584 {
585         task->tk_timeout = delay;
586         rpc_sleep_on(&delay_queue, task, NULL, __rpc_atrun);
587 }
588
589 /*
590  * Helper to call task->tk_ops->rpc_call_prepare
591  */
592 static void rpc_prepare_task(struct rpc_task *task)
593 {
594         lock_kernel();
595         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
596         unlock_kernel();
597 }
598
599 /*
600  * Helper that calls task->tk_ops->rpc_call_done if it exists
601  */
602 void rpc_exit_task(struct rpc_task *task)
603 {
604         task->tk_action = NULL;
605         if (task->tk_ops->rpc_call_done != NULL) {
606                 lock_kernel();
607                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
608                 unlock_kernel();
609                 if (task->tk_action != NULL) {
610                         WARN_ON(RPC_ASSASSINATED(task));
611                         /* Always release the RPC slot and buffer memory */
612                         xprt_release(task);
613                 }
614         }
615 }
616 EXPORT_SYMBOL(rpc_exit_task);
617
618 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
619 {
620         if (ops->rpc_release != NULL) {
621                 lock_kernel();
622                 ops->rpc_release(calldata);
623                 unlock_kernel();
624         }
625 }
626
627 /*
628  * This is the RPC `scheduler' (or rather, the finite state machine).
629  */
630 static void __rpc_execute(struct rpc_task *task)
631 {
632         int             status = 0;
633
634         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
635                         task->tk_pid, task->tk_flags);
636
637         BUG_ON(RPC_IS_QUEUED(task));
638
639         for (;;) {
640                 /*
641                  * Garbage collection of pending timers...
642                  */
643                 rpc_delete_timer(task);
644
645                 /*
646                  * Execute any pending callback.
647                  */
648                 if (RPC_DO_CALLBACK(task)) {
649                         /* Define a callback save pointer */
650                         void (*save_callback)(struct rpc_task *);
651
652                         /*
653                          * If a callback exists, save it, reset it,
654                          * call it.
655                          * The save is needed to stop from resetting
656                          * another callback set within the callback handler
657                          * - Dave
658                          */
659                         save_callback=task->tk_callback;
660                         task->tk_callback=NULL;
661                         save_callback(task);
662                 }
663
664                 /*
665                  * Perform the next FSM step.
666                  * tk_action may be NULL when the task has been killed
667                  * by someone else.
668                  */
669                 if (!RPC_IS_QUEUED(task)) {
670                         if (task->tk_action == NULL)
671                                 break;
672                         task->tk_action(task);
673                 }
674
675                 /*
676                  * Lockless check for whether task is sleeping or not.
677                  */
678                 if (!RPC_IS_QUEUED(task))
679                         continue;
680                 rpc_clear_running(task);
681                 if (RPC_IS_ASYNC(task)) {
682                         /* Careful! we may have raced... */
683                         if (RPC_IS_QUEUED(task))
684                                 return;
685                         if (rpc_test_and_set_running(task))
686                                 return;
687                         continue;
688                 }
689
690                 /* sync task: sleep here */
691                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
692                 /* Note: Caller should be using rpc_clnt_sigmask() */
693                 status = out_of_line_wait_on_bit(&task->tk_runstate,
694                                 RPC_TASK_QUEUED, rpc_wait_bit_interruptible,
695                                 TASK_INTERRUPTIBLE);
696                 if (status == -ERESTARTSYS) {
697                         /*
698                          * When a sync task receives a signal, it exits with
699                          * -ERESTARTSYS. In order to catch any callbacks that
700                          * clean up after sleeping on some queue, we don't
701                          * break the loop here, but go around once more.
702                          */
703                         dprintk("RPC: %5u got signal\n", task->tk_pid);
704                         task->tk_flags |= RPC_TASK_KILLED;
705                         rpc_exit(task, -ERESTARTSYS);
706                         rpc_wake_up_task(task);
707                 }
708                 rpc_set_running(task);
709                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
710         }
711
712         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
713                         task->tk_status);
714         /* Release all resources associated with the task */
715         rpc_release_task(task);
716 }
717
718 /*
719  * User-visible entry point to the scheduler.
720  *
721  * This may be called recursively if e.g. an async NFS task updates
722  * the attributes and finds that dirty pages must be flushed.
723  * NOTE: Upon exit of this function the task is guaranteed to be
724  *       released. In particular note that tk_release() will have
725  *       been called, so your task memory may have been freed.
726  */
727 void rpc_execute(struct rpc_task *task)
728 {
729         rpc_set_active(task);
730         rpc_set_running(task);
731         __rpc_execute(task);
732 }
733
734 static void rpc_async_schedule(struct work_struct *work)
735 {
736         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
737 }
738
739 /**
740  * rpc_malloc - allocate an RPC buffer
741  * @task: RPC task that will use this buffer
742  * @size: requested byte size
743  *
744  * To prevent rpciod from hanging, this allocator never sleeps,
745  * returning NULL if the request cannot be serviced immediately.
746  * The caller can arrange to sleep in a way that is safe for rpciod.
747  *
748  * Most requests are 'small' (under 2KiB) and can be serviced from a
749  * mempool, ensuring that NFS reads and writes can always proceed,
750  * and that there is good locality of reference for these buffers.
751  *
752  * In order to avoid memory starvation triggering more writebacks of
753  * NFS requests, we avoid using GFP_KERNEL.
754  */
755 void *rpc_malloc(struct rpc_task *task, size_t size)
756 {
757         size_t *buf;
758         gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
759
760         size += sizeof(size_t);
761         if (size <= RPC_BUFFER_MAXSIZE)
762                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
763         else
764                 buf = kmalloc(size, gfp);
765         *buf = size;
766         dprintk("RPC: %5u allocated buffer of size %u at %p\n",
767                         task->tk_pid, size, buf);
768         return (void *) ++buf;
769 }
770
771 /**
772  * rpc_free - free buffer allocated via rpc_malloc
773  * @buffer: buffer to free
774  *
775  */
776 void rpc_free(void *buffer)
777 {
778         size_t size, *buf = (size_t *) buffer;
779
780         if (!buffer)
781                 return;
782         size = *buf;
783         buf--;
784
785         dprintk("RPC:       freeing buffer of size %u at %p\n",
786                         size, buf);
787         if (size <= RPC_BUFFER_MAXSIZE)
788                 mempool_free(buf, rpc_buffer_mempool);
789         else
790                 kfree(buf);
791 }
792
793 /*
794  * Creation and deletion of RPC task structures
795  */
796 void rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
797 {
798         memset(task, 0, sizeof(*task));
799         init_timer(&task->tk_timer);
800         task->tk_timer.data     = (unsigned long) task;
801         task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
802         atomic_set(&task->tk_count, 1);
803         task->tk_client = clnt;
804         task->tk_flags  = flags;
805         task->tk_ops = tk_ops;
806         if (tk_ops->rpc_call_prepare != NULL)
807                 task->tk_action = rpc_prepare_task;
808         task->tk_calldata = calldata;
809
810         /* Initialize retry counters */
811         task->tk_garb_retry = 2;
812         task->tk_cred_retry = 2;
813
814         task->tk_priority = RPC_PRIORITY_NORMAL;
815         task->tk_cookie = (unsigned long)current;
816
817         /* Initialize workqueue for async tasks */
818         task->tk_workqueue = rpciod_workqueue;
819
820         if (clnt) {
821                 atomic_inc(&clnt->cl_users);
822                 if (clnt->cl_softrtry)
823                         task->tk_flags |= RPC_TASK_SOFT;
824                 if (!clnt->cl_intr)
825                         task->tk_flags |= RPC_TASK_NOINTR;
826         }
827
828         BUG_ON(task->tk_ops == NULL);
829
830         /* starting timestamp */
831         task->tk_start = jiffies;
832
833         dprintk("RPC:       new task initialized, procpid %u\n",
834                                 current->pid);
835 }
836
837 static struct rpc_task *
838 rpc_alloc_task(void)
839 {
840         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
841 }
842
843 static void rpc_free_task(struct rcu_head *rcu)
844 {
845         struct rpc_task *task = container_of(rcu, struct rpc_task, u.tk_rcu);
846         dprintk("RPC: %5u freeing task\n", task->tk_pid);
847         mempool_free(task, rpc_task_mempool);
848 }
849
850 /*
851  * Create a new task for the specified client.  We have to
852  * clean up after an allocation failure, as the client may
853  * have specified "oneshot".
854  */
855 struct rpc_task *rpc_new_task(struct rpc_clnt *clnt, int flags, const struct rpc_call_ops *tk_ops, void *calldata)
856 {
857         struct rpc_task *task;
858
859         task = rpc_alloc_task();
860         if (!task)
861                 goto cleanup;
862
863         rpc_init_task(task, clnt, flags, tk_ops, calldata);
864
865         dprintk("RPC:       allocated task %p\n", task);
866         task->tk_flags |= RPC_TASK_DYNAMIC;
867 out:
868         return task;
869
870 cleanup:
871         /* Check whether to release the client */
872         if (clnt) {
873                 printk("rpc_new_task: failed, users=%d, oneshot=%d\n",
874                         atomic_read(&clnt->cl_users), clnt->cl_oneshot);
875                 atomic_inc(&clnt->cl_users); /* pretend we were used ... */
876                 rpc_release_client(clnt);
877         }
878         goto out;
879 }
880
881
882 void rpc_put_task(struct rpc_task *task)
883 {
884         const struct rpc_call_ops *tk_ops = task->tk_ops;
885         void *calldata = task->tk_calldata;
886
887         if (!atomic_dec_and_test(&task->tk_count))
888                 return;
889         /* Release resources */
890         if (task->tk_rqstp)
891                 xprt_release(task);
892         if (task->tk_msg.rpc_cred)
893                 rpcauth_unbindcred(task);
894         if (task->tk_client) {
895                 rpc_release_client(task->tk_client);
896                 task->tk_client = NULL;
897         }
898         if (task->tk_flags & RPC_TASK_DYNAMIC)
899                 call_rcu_bh(&task->u.tk_rcu, rpc_free_task);
900         rpc_release_calldata(tk_ops, calldata);
901 }
902 EXPORT_SYMBOL(rpc_put_task);
903
904 static void rpc_release_task(struct rpc_task *task)
905 {
906 #ifdef RPC_DEBUG
907         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
908 #endif
909         dprintk("RPC: %5u release task\n", task->tk_pid);
910
911         /* Remove from global task list */
912         spin_lock(&rpc_sched_lock);
913         list_del(&task->tk_task);
914         spin_unlock(&rpc_sched_lock);
915
916         BUG_ON (RPC_IS_QUEUED(task));
917
918         /* Synchronously delete any running timer */
919         rpc_delete_timer(task);
920
921 #ifdef RPC_DEBUG
922         task->tk_magic = 0;
923 #endif
924         /* Wake up anyone who is waiting for task completion */
925         rpc_mark_complete_task(task);
926
927         rpc_put_task(task);
928 }
929
930 /**
931  * rpc_run_task - Allocate a new RPC task, then run rpc_execute against it
932  * @clnt: pointer to RPC client
933  * @flags: RPC flags
934  * @ops: RPC call ops
935  * @data: user call data
936  */
937 struct rpc_task *rpc_run_task(struct rpc_clnt *clnt, int flags,
938                                         const struct rpc_call_ops *ops,
939                                         void *data)
940 {
941         struct rpc_task *task;
942         task = rpc_new_task(clnt, flags, ops, data);
943         if (task == NULL) {
944                 rpc_release_calldata(ops, data);
945                 return ERR_PTR(-ENOMEM);
946         }
947         atomic_inc(&task->tk_count);
948         rpc_execute(task);
949         return task;
950 }
951 EXPORT_SYMBOL(rpc_run_task);
952
953 /*
954  * Kill all tasks for the given client.
955  * XXX: kill their descendants as well?
956  */
957 void rpc_killall_tasks(struct rpc_clnt *clnt)
958 {
959         struct rpc_task *rovr;
960         struct list_head *le;
961
962         dprintk("RPC:       killing all tasks for client %p\n", clnt);
963
964         /*
965          * Spin lock all_tasks to prevent changes...
966          */
967         spin_lock(&rpc_sched_lock);
968         alltask_for_each(rovr, le, &all_tasks) {
969                 if (! RPC_IS_ACTIVATED(rovr))
970                         continue;
971                 if (!clnt || rovr->tk_client == clnt) {
972                         rovr->tk_flags |= RPC_TASK_KILLED;
973                         rpc_exit(rovr, -EIO);
974                         rpc_wake_up_task(rovr);
975                 }
976         }
977         spin_unlock(&rpc_sched_lock);
978 }
979
980 static DECLARE_MUTEX_LOCKED(rpciod_running);
981
982 static void rpciod_killall(void)
983 {
984         unsigned long flags;
985
986         while (!list_empty(&all_tasks)) {
987                 clear_thread_flag(TIF_SIGPENDING);
988                 rpc_killall_tasks(NULL);
989                 flush_workqueue(rpciod_workqueue);
990                 if (!list_empty(&all_tasks)) {
991                         dprintk("RPC:       rpciod_killall: waiting for tasks "
992                                         "to exit\n");
993                         yield();
994                 }
995         }
996
997         spin_lock_irqsave(&current->sighand->siglock, flags);
998         recalc_sigpending();
999         spin_unlock_irqrestore(&current->sighand->siglock, flags);
1000 }
1001
1002 /*
1003  * Start up the rpciod process if it's not already running.
1004  */
1005 int
1006 rpciod_up(void)
1007 {
1008         struct workqueue_struct *wq;
1009         int error = 0;
1010
1011         mutex_lock(&rpciod_mutex);
1012         dprintk("RPC:       rpciod_up: users %u\n", rpciod_users);
1013         rpciod_users++;
1014         if (rpciod_workqueue)
1015                 goto out;
1016         /*
1017          * If there's no pid, we should be the first user.
1018          */
1019         if (rpciod_users > 1)
1020                 printk(KERN_WARNING "rpciod_up: no workqueue, %u users??\n", rpciod_users);
1021         /*
1022          * Create the rpciod thread and wait for it to start.
1023          */
1024         error = -ENOMEM;
1025         wq = create_workqueue("rpciod");
1026         if (wq == NULL) {
1027                 printk(KERN_WARNING "rpciod_up: create workqueue failed, error=%d\n", error);
1028                 rpciod_users--;
1029                 goto out;
1030         }
1031         rpciod_workqueue = wq;
1032         error = 0;
1033 out:
1034         mutex_unlock(&rpciod_mutex);
1035         return error;
1036 }
1037
1038 void
1039 rpciod_down(void)
1040 {
1041         mutex_lock(&rpciod_mutex);
1042         dprintk("RPC:       rpciod_down sema %u\n", rpciod_users);
1043         if (rpciod_users) {
1044                 if (--rpciod_users)
1045                         goto out;
1046         } else
1047                 printk(KERN_WARNING "rpciod_down: no users??\n");
1048
1049         if (!rpciod_workqueue) {
1050                 dprintk("RPC:       rpciod_down: Nothing to do!\n");
1051                 goto out;
1052         }
1053         rpciod_killall();
1054
1055         destroy_workqueue(rpciod_workqueue);
1056         rpciod_workqueue = NULL;
1057  out:
1058         mutex_unlock(&rpciod_mutex);
1059 }
1060
1061 #ifdef RPC_DEBUG
1062 void rpc_show_tasks(void)
1063 {
1064         struct list_head *le;
1065         struct rpc_task *t;
1066
1067         spin_lock(&rpc_sched_lock);
1068         if (list_empty(&all_tasks)) {
1069                 spin_unlock(&rpc_sched_lock);
1070                 return;
1071         }
1072         printk("-pid- proc flgs status -client- -prog- --rqstp- -timeout "
1073                 "-rpcwait -action- ---ops--\n");
1074         alltask_for_each(t, le, &all_tasks) {
1075                 const char *rpc_waitq = "none";
1076
1077                 if (RPC_IS_QUEUED(t))
1078                         rpc_waitq = rpc_qname(t->u.tk_wait.rpc_waitq);
1079
1080                 printk("%5u %04d %04x %6d %8p %6d %8p %8ld %8s %8p %8p\n",
1081                         t->tk_pid,
1082                         (t->tk_msg.rpc_proc ? t->tk_msg.rpc_proc->p_proc : -1),
1083                         t->tk_flags, t->tk_status,
1084                         t->tk_client,
1085                         (t->tk_client ? t->tk_client->cl_prog : 0),
1086                         t->tk_rqstp, t->tk_timeout,
1087                         rpc_waitq,
1088                         t->tk_action, t->tk_ops);
1089         }
1090         spin_unlock(&rpc_sched_lock);
1091 }
1092 #endif
1093
1094 void
1095 rpc_destroy_mempool(void)
1096 {
1097         if (rpc_buffer_mempool)
1098                 mempool_destroy(rpc_buffer_mempool);
1099         if (rpc_task_mempool)
1100                 mempool_destroy(rpc_task_mempool);
1101         if (rpc_task_slabp)
1102                 kmem_cache_destroy(rpc_task_slabp);
1103         if (rpc_buffer_slabp)
1104                 kmem_cache_destroy(rpc_buffer_slabp);
1105 }
1106
1107 int
1108 rpc_init_mempool(void)
1109 {
1110         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1111                                              sizeof(struct rpc_task),
1112                                              0, SLAB_HWCACHE_ALIGN,
1113                                              NULL, NULL);
1114         if (!rpc_task_slabp)
1115                 goto err_nomem;
1116         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1117                                              RPC_BUFFER_MAXSIZE,
1118                                              0, SLAB_HWCACHE_ALIGN,
1119                                              NULL, NULL);
1120         if (!rpc_buffer_slabp)
1121                 goto err_nomem;
1122         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1123                                                     rpc_task_slabp);
1124         if (!rpc_task_mempool)
1125                 goto err_nomem;
1126         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1127                                                       rpc_buffer_slabp);
1128         if (!rpc_buffer_mempool)
1129                 goto err_nomem;
1130         return 0;
1131 err_nomem:
1132         rpc_destroy_mempool();
1133         return -ENOMEM;
1134 }