Staging: me4000: replace some C99 comments
[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 #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_async_schedule(struct work_struct *);
42 static void                      rpc_release_task(struct rpc_task *task);
43 static void __rpc_queue_timer_fn(unsigned long ptr);
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 void
61 __rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
62 {
63         if (task->tk_timeout == 0)
64                 return;
65         dprintk("RPC: %5u disabling timer\n", task->tk_pid);
66         task->tk_timeout = 0;
67         list_del(&task->u.tk_wait.timer_list);
68         if (list_empty(&queue->timer_list.list))
69                 del_timer(&queue->timer_list.timer);
70 }
71
72 static void
73 rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
74 {
75         queue->timer_list.expires = expires;
76         mod_timer(&queue->timer_list.timer, expires);
77 }
78
79 /*
80  * Set up a timer for the current task.
81  */
82 static void
83 __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
84 {
85         if (!task->tk_timeout)
86                 return;
87
88         dprintk("RPC: %5u setting alarm for %lu ms\n",
89                         task->tk_pid, task->tk_timeout * 1000 / HZ);
90
91         task->u.tk_wait.expires = jiffies + task->tk_timeout;
92         if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
93                 rpc_set_queue_timer(queue, task->u.tk_wait.expires);
94         list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
95 }
96
97 /*
98  * Add new request to a priority queue.
99  */
100 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
101 {
102         struct list_head *q;
103         struct rpc_task *t;
104
105         INIT_LIST_HEAD(&task->u.tk_wait.links);
106         q = &queue->tasks[task->tk_priority];
107         if (unlikely(task->tk_priority > queue->maxpriority))
108                 q = &queue->tasks[queue->maxpriority];
109         list_for_each_entry(t, q, u.tk_wait.list) {
110                 if (t->tk_owner == task->tk_owner) {
111                         list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
112                         return;
113                 }
114         }
115         list_add_tail(&task->u.tk_wait.list, q);
116 }
117
118 /*
119  * Add new request to wait queue.
120  *
121  * Swapper tasks always get inserted at the head of the queue.
122  * This should avoid many nasty memory deadlocks and hopefully
123  * improve overall performance.
124  * Everyone else gets appended to the queue to ensure proper FIFO behavior.
125  */
126 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
127 {
128         BUG_ON (RPC_IS_QUEUED(task));
129
130         if (RPC_IS_PRIORITY(queue))
131                 __rpc_add_wait_queue_priority(queue, task);
132         else if (RPC_IS_SWAPPER(task))
133                 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
134         else
135                 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
136         task->tk_waitqueue = queue;
137         queue->qlen++;
138         rpc_set_queued(task);
139
140         dprintk("RPC: %5u added to queue %p \"%s\"\n",
141                         task->tk_pid, queue, rpc_qname(queue));
142 }
143
144 /*
145  * Remove request from a priority queue.
146  */
147 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
148 {
149         struct rpc_task *t;
150
151         if (!list_empty(&task->u.tk_wait.links)) {
152                 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
153                 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
154                 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
155         }
156 }
157
158 /*
159  * Remove request from queue.
160  * Note: must be called with spin lock held.
161  */
162 static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
163 {
164         __rpc_disable_timer(queue, task);
165         if (RPC_IS_PRIORITY(queue))
166                 __rpc_remove_wait_queue_priority(task);
167         list_del(&task->u.tk_wait.list);
168         queue->qlen--;
169         dprintk("RPC: %5u removed from queue %p \"%s\"\n",
170                         task->tk_pid, queue, rpc_qname(queue));
171 }
172
173 static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
174 {
175         queue->priority = priority;
176         queue->count = 1 << (priority * 2);
177 }
178
179 static inline void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
180 {
181         queue->owner = pid;
182         queue->nr = RPC_BATCH_COUNT;
183 }
184
185 static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
186 {
187         rpc_set_waitqueue_priority(queue, queue->maxpriority);
188         rpc_set_waitqueue_owner(queue, 0);
189 }
190
191 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
192 {
193         int i;
194
195         spin_lock_init(&queue->lock);
196         for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
197                 INIT_LIST_HEAD(&queue->tasks[i]);
198         queue->maxpriority = nr_queues - 1;
199         rpc_reset_waitqueue_priority(queue);
200         queue->qlen = 0;
201         setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
202         INIT_LIST_HEAD(&queue->timer_list.list);
203 #ifdef RPC_DEBUG
204         queue->name = qname;
205 #endif
206 }
207
208 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
209 {
210         __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
211 }
212
213 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
214 {
215         __rpc_init_priority_wait_queue(queue, qname, 1);
216 }
217 EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
218
219 void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
220 {
221         del_timer_sync(&queue->timer_list.timer);
222 }
223 EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
224
225 static int rpc_wait_bit_killable(void *word)
226 {
227         if (fatal_signal_pending(current))
228                 return -ERESTARTSYS;
229         schedule();
230         return 0;
231 }
232
233 #ifdef RPC_DEBUG
234 static void rpc_task_set_debuginfo(struct rpc_task *task)
235 {
236         static atomic_t rpc_pid;
237
238         task->tk_magic = RPC_TASK_MAGIC_ID;
239         task->tk_pid = atomic_inc_return(&rpc_pid);
240 }
241 #else
242 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
243 {
244 }
245 #endif
246
247 static void rpc_set_active(struct rpc_task *task)
248 {
249         struct rpc_clnt *clnt;
250         if (test_and_set_bit(RPC_TASK_ACTIVE, &task->tk_runstate) != 0)
251                 return;
252         rpc_task_set_debuginfo(task);
253         /* Add to global list of all tasks */
254         clnt = task->tk_client;
255         if (clnt != NULL) {
256                 spin_lock(&clnt->cl_lock);
257                 list_add_tail(&task->tk_task, &clnt->cl_tasks);
258                 spin_unlock(&clnt->cl_lock);
259         }
260 }
261
262 /*
263  * Mark an RPC call as having completed by clearing the 'active' bit
264  */
265 static void rpc_mark_complete_task(struct rpc_task *task)
266 {
267         smp_mb__before_clear_bit();
268         clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
269         smp_mb__after_clear_bit();
270         wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
271 }
272
273 /*
274  * Allow callers to wait for completion of an RPC call
275  */
276 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
277 {
278         if (action == NULL)
279                 action = rpc_wait_bit_killable;
280         return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
281                         action, TASK_KILLABLE);
282 }
283 EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
284
285 /*
286  * Make an RPC task runnable.
287  *
288  * Note: If the task is ASYNC, this must be called with
289  * the spinlock held to protect the wait queue operation.
290  */
291 static void rpc_make_runnable(struct rpc_task *task)
292 {
293         rpc_clear_queued(task);
294         if (rpc_test_and_set_running(task))
295                 return;
296         if (RPC_IS_ASYNC(task)) {
297                 int status;
298
299                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
300                 status = queue_work(rpciod_workqueue, &task->u.tk_work);
301                 if (status < 0) {
302                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
303                         task->tk_status = status;
304                         return;
305                 }
306         } else
307                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
308 }
309
310 /*
311  * Prepare for sleeping on a wait queue.
312  * By always appending tasks to the list we ensure FIFO behavior.
313  * NB: An RPC task will only receive interrupt-driven events as long
314  * as it's on a wait queue.
315  */
316 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
317                         rpc_action action)
318 {
319         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
320                         task->tk_pid, rpc_qname(q), jiffies);
321
322         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
323                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
324                 return;
325         }
326
327         __rpc_add_wait_queue(q, task);
328
329         BUG_ON(task->tk_callback != NULL);
330         task->tk_callback = action;
331         __rpc_add_timer(q, task);
332 }
333
334 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
335                                 rpc_action action)
336 {
337         /* Mark the task as being activated if so needed */
338         rpc_set_active(task);
339
340         /*
341          * Protect the queue operations.
342          */
343         spin_lock_bh(&q->lock);
344         __rpc_sleep_on(q, task, action);
345         spin_unlock_bh(&q->lock);
346 }
347 EXPORT_SYMBOL_GPL(rpc_sleep_on);
348
349 /**
350  * __rpc_do_wake_up_task - wake up a single rpc_task
351  * @queue: wait queue
352  * @task: task to be woken up
353  *
354  * Caller must hold queue->lock, and have cleared the task queued flag.
355  */
356 static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
357 {
358         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
359                         task->tk_pid, jiffies);
360
361 #ifdef RPC_DEBUG
362         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
363 #endif
364         /* Has the task been executed yet? If not, we cannot wake it up! */
365         if (!RPC_IS_ACTIVATED(task)) {
366                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
367                 return;
368         }
369
370         __rpc_remove_wait_queue(queue, task);
371
372         rpc_make_runnable(task);
373
374         dprintk("RPC:       __rpc_wake_up_task done\n");
375 }
376
377 /*
378  * Wake up a queued task while the queue lock is being held
379  */
380 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
381 {
382         if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
383                 __rpc_do_wake_up_task(queue, task);
384 }
385
386 /*
387  * Wake up a task on a specific queue
388  */
389 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
390 {
391         spin_lock_bh(&queue->lock);
392         rpc_wake_up_task_queue_locked(queue, task);
393         spin_unlock_bh(&queue->lock);
394 }
395 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
396
397 /*
398  * Wake up the specified task
399  */
400 static void rpc_wake_up_task(struct rpc_task *task)
401 {
402         rpc_wake_up_queued_task(task->tk_waitqueue, task);
403 }
404
405 /*
406  * Wake up the next task on a priority queue.
407  */
408 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
409 {
410         struct list_head *q;
411         struct rpc_task *task;
412
413         /*
414          * Service a batch of tasks from a single owner.
415          */
416         q = &queue->tasks[queue->priority];
417         if (!list_empty(q)) {
418                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
419                 if (queue->owner == task->tk_owner) {
420                         if (--queue->nr)
421                                 goto out;
422                         list_move_tail(&task->u.tk_wait.list, q);
423                 }
424                 /*
425                  * Check if we need to switch queues.
426                  */
427                 if (--queue->count)
428                         goto new_owner;
429         }
430
431         /*
432          * Service the next queue.
433          */
434         do {
435                 if (q == &queue->tasks[0])
436                         q = &queue->tasks[queue->maxpriority];
437                 else
438                         q = q - 1;
439                 if (!list_empty(q)) {
440                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
441                         goto new_queue;
442                 }
443         } while (q != &queue->tasks[queue->priority]);
444
445         rpc_reset_waitqueue_priority(queue);
446         return NULL;
447
448 new_queue:
449         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
450 new_owner:
451         rpc_set_waitqueue_owner(queue, task->tk_owner);
452 out:
453         rpc_wake_up_task_queue_locked(queue, task);
454         return task;
455 }
456
457 /*
458  * Wake up the next task on the wait queue.
459  */
460 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
461 {
462         struct rpc_task *task = NULL;
463
464         dprintk("RPC:       wake_up_next(%p \"%s\")\n",
465                         queue, rpc_qname(queue));
466         spin_lock_bh(&queue->lock);
467         if (RPC_IS_PRIORITY(queue))
468                 task = __rpc_wake_up_next_priority(queue);
469         else {
470                 task_for_first(task, &queue->tasks[0])
471                         rpc_wake_up_task_queue_locked(queue, task);
472         }
473         spin_unlock_bh(&queue->lock);
474
475         return task;
476 }
477 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
478
479 /**
480  * rpc_wake_up - wake up all rpc_tasks
481  * @queue: rpc_wait_queue on which the tasks are sleeping
482  *
483  * Grabs queue->lock
484  */
485 void rpc_wake_up(struct rpc_wait_queue *queue)
486 {
487         struct rpc_task *task, *next;
488         struct list_head *head;
489
490         spin_lock_bh(&queue->lock);
491         head = &queue->tasks[queue->maxpriority];
492         for (;;) {
493                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
494                         rpc_wake_up_task_queue_locked(queue, task);
495                 if (head == &queue->tasks[0])
496                         break;
497                 head--;
498         }
499         spin_unlock_bh(&queue->lock);
500 }
501 EXPORT_SYMBOL_GPL(rpc_wake_up);
502
503 /**
504  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
505  * @queue: rpc_wait_queue on which the tasks are sleeping
506  * @status: status value to set
507  *
508  * Grabs queue->lock
509  */
510 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
511 {
512         struct rpc_task *task, *next;
513         struct list_head *head;
514
515         spin_lock_bh(&queue->lock);
516         head = &queue->tasks[queue->maxpriority];
517         for (;;) {
518                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
519                         task->tk_status = status;
520                         rpc_wake_up_task_queue_locked(queue, task);
521                 }
522                 if (head == &queue->tasks[0])
523                         break;
524                 head--;
525         }
526         spin_unlock_bh(&queue->lock);
527 }
528 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
529
530 static void __rpc_queue_timer_fn(unsigned long ptr)
531 {
532         struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
533         struct rpc_task *task, *n;
534         unsigned long expires, now, timeo;
535
536         spin_lock(&queue->lock);
537         expires = now = jiffies;
538         list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
539                 timeo = task->u.tk_wait.expires;
540                 if (time_after_eq(now, timeo)) {
541                         dprintk("RPC: %5u timeout\n", task->tk_pid);
542                         task->tk_status = -ETIMEDOUT;
543                         rpc_wake_up_task_queue_locked(queue, task);
544                         continue;
545                 }
546                 if (expires == now || time_after(expires, timeo))
547                         expires = timeo;
548         }
549         if (!list_empty(&queue->timer_list.list))
550                 rpc_set_queue_timer(queue, expires);
551         spin_unlock(&queue->lock);
552 }
553
554 static void __rpc_atrun(struct rpc_task *task)
555 {
556         task->tk_status = 0;
557 }
558
559 /*
560  * Run a task at a later time
561  */
562 void rpc_delay(struct rpc_task *task, unsigned long delay)
563 {
564         task->tk_timeout = delay;
565         rpc_sleep_on(&delay_queue, task, __rpc_atrun);
566 }
567 EXPORT_SYMBOL_GPL(rpc_delay);
568
569 /*
570  * Helper to call task->tk_ops->rpc_call_prepare
571  */
572 static void rpc_prepare_task(struct rpc_task *task)
573 {
574         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
575 }
576
577 /*
578  * Helper that calls task->tk_ops->rpc_call_done if it exists
579  */
580 void rpc_exit_task(struct rpc_task *task)
581 {
582         task->tk_action = NULL;
583         if (task->tk_ops->rpc_call_done != NULL) {
584                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
585                 if (task->tk_action != NULL) {
586                         WARN_ON(RPC_ASSASSINATED(task));
587                         /* Always release the RPC slot and buffer memory */
588                         xprt_release(task);
589                 }
590         }
591 }
592 EXPORT_SYMBOL_GPL(rpc_exit_task);
593
594 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
595 {
596         if (ops->rpc_release != NULL)
597                 ops->rpc_release(calldata);
598 }
599
600 /*
601  * This is the RPC `scheduler' (or rather, the finite state machine).
602  */
603 static void __rpc_execute(struct rpc_task *task)
604 {
605         struct rpc_wait_queue *queue;
606         int task_is_async = RPC_IS_ASYNC(task);
607         int status = 0;
608
609         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
610                         task->tk_pid, task->tk_flags);
611
612         BUG_ON(RPC_IS_QUEUED(task));
613
614         for (;;) {
615
616                 /*
617                  * Execute any pending callback.
618                  */
619                 if (task->tk_callback) {
620                         void (*save_callback)(struct rpc_task *);
621
622                         /*
623                          * We set tk_callback to NULL before calling it,
624                          * in case it sets the tk_callback field itself:
625                          */
626                         save_callback = task->tk_callback;
627                         task->tk_callback = NULL;
628                         save_callback(task);
629                 }
630
631                 /*
632                  * Perform the next FSM step.
633                  * tk_action may be NULL when the task has been killed
634                  * by someone else.
635                  */
636                 if (!RPC_IS_QUEUED(task)) {
637                         if (task->tk_action == NULL)
638                                 break;
639                         task->tk_action(task);
640                 }
641
642                 /*
643                  * Lockless check for whether task is sleeping or not.
644                  */
645                 if (!RPC_IS_QUEUED(task))
646                         continue;
647                 /*
648                  * The queue->lock protects against races with
649                  * rpc_make_runnable().
650                  *
651                  * Note that once we clear RPC_TASK_RUNNING on an asynchronous
652                  * rpc_task, rpc_make_runnable() can assign it to a
653                  * different workqueue. We therefore cannot assume that the
654                  * rpc_task pointer may still be dereferenced.
655                  */
656                 queue = task->tk_waitqueue;
657                 spin_lock_bh(&queue->lock);
658                 if (!RPC_IS_QUEUED(task)) {
659                         spin_unlock_bh(&queue->lock);
660                         continue;
661                 }
662                 rpc_clear_running(task);
663                 spin_unlock_bh(&queue->lock);
664                 if (task_is_async)
665                         return;
666
667                 /* sync task: sleep here */
668                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
669                 status = out_of_line_wait_on_bit(&task->tk_runstate,
670                                 RPC_TASK_QUEUED, rpc_wait_bit_killable,
671                                 TASK_KILLABLE);
672                 if (status == -ERESTARTSYS) {
673                         /*
674                          * When a sync task receives a signal, it exits with
675                          * -ERESTARTSYS. In order to catch any callbacks that
676                          * clean up after sleeping on some queue, we don't
677                          * break the loop here, but go around once more.
678                          */
679                         dprintk("RPC: %5u got signal\n", task->tk_pid);
680                         task->tk_flags |= RPC_TASK_KILLED;
681                         rpc_exit(task, -ERESTARTSYS);
682                         rpc_wake_up_task(task);
683                 }
684                 rpc_set_running(task);
685                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
686         }
687
688         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
689                         task->tk_status);
690         /* Release all resources associated with the task */
691         rpc_release_task(task);
692 }
693
694 /*
695  * User-visible entry point to the scheduler.
696  *
697  * This may be called recursively if e.g. an async NFS task updates
698  * the attributes and finds that dirty pages must be flushed.
699  * NOTE: Upon exit of this function the task is guaranteed to be
700  *       released. In particular note that tk_release() will have
701  *       been called, so your task memory may have been freed.
702  */
703 void rpc_execute(struct rpc_task *task)
704 {
705         rpc_set_active(task);
706         rpc_set_running(task);
707         __rpc_execute(task);
708 }
709
710 static void rpc_async_schedule(struct work_struct *work)
711 {
712         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
713 }
714
715 struct rpc_buffer {
716         size_t  len;
717         char    data[];
718 };
719
720 /**
721  * rpc_malloc - allocate an RPC buffer
722  * @task: RPC task that will use this buffer
723  * @size: requested byte size
724  *
725  * To prevent rpciod from hanging, this allocator never sleeps,
726  * returning NULL if the request cannot be serviced immediately.
727  * The caller can arrange to sleep in a way that is safe for rpciod.
728  *
729  * Most requests are 'small' (under 2KiB) and can be serviced from a
730  * mempool, ensuring that NFS reads and writes can always proceed,
731  * and that there is good locality of reference for these buffers.
732  *
733  * In order to avoid memory starvation triggering more writebacks of
734  * NFS requests, we avoid using GFP_KERNEL.
735  */
736 void *rpc_malloc(struct rpc_task *task, size_t size)
737 {
738         struct rpc_buffer *buf;
739         gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
740
741         size += sizeof(struct rpc_buffer);
742         if (size <= RPC_BUFFER_MAXSIZE)
743                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
744         else
745                 buf = kmalloc(size, gfp);
746
747         if (!buf)
748                 return NULL;
749
750         buf->len = size;
751         dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
752                         task->tk_pid, size, buf);
753         return &buf->data;
754 }
755 EXPORT_SYMBOL_GPL(rpc_malloc);
756
757 /**
758  * rpc_free - free buffer allocated via rpc_malloc
759  * @buffer: buffer to free
760  *
761  */
762 void rpc_free(void *buffer)
763 {
764         size_t size;
765         struct rpc_buffer *buf;
766
767         if (!buffer)
768                 return;
769
770         buf = container_of(buffer, struct rpc_buffer, data);
771         size = buf->len;
772
773         dprintk("RPC:       freeing buffer of size %zu at %p\n",
774                         size, buf);
775
776         if (size <= RPC_BUFFER_MAXSIZE)
777                 mempool_free(buf, rpc_buffer_mempool);
778         else
779                 kfree(buf);
780 }
781 EXPORT_SYMBOL_GPL(rpc_free);
782
783 /*
784  * Creation and deletion of RPC task structures
785  */
786 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
787 {
788         memset(task, 0, sizeof(*task));
789         atomic_set(&task->tk_count, 1);
790         task->tk_flags  = task_setup_data->flags;
791         task->tk_ops = task_setup_data->callback_ops;
792         task->tk_calldata = task_setup_data->callback_data;
793         INIT_LIST_HEAD(&task->tk_task);
794
795         /* Initialize retry counters */
796         task->tk_garb_retry = 2;
797         task->tk_cred_retry = 2;
798
799         task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
800         task->tk_owner = current->tgid;
801
802         /* Initialize workqueue for async tasks */
803         task->tk_workqueue = task_setup_data->workqueue;
804
805         task->tk_client = task_setup_data->rpc_client;
806         if (task->tk_client != NULL) {
807                 kref_get(&task->tk_client->cl_kref);
808                 if (task->tk_client->cl_softrtry)
809                         task->tk_flags |= RPC_TASK_SOFT;
810         }
811
812         if (task->tk_ops->rpc_call_prepare != NULL)
813                 task->tk_action = rpc_prepare_task;
814
815         if (task_setup_data->rpc_message != NULL) {
816                 task->tk_msg.rpc_proc = task_setup_data->rpc_message->rpc_proc;
817                 task->tk_msg.rpc_argp = task_setup_data->rpc_message->rpc_argp;
818                 task->tk_msg.rpc_resp = task_setup_data->rpc_message->rpc_resp;
819                 /* Bind the user cred */
820                 rpcauth_bindcred(task, task_setup_data->rpc_message->rpc_cred, task_setup_data->flags);
821                 if (task->tk_action == NULL)
822                         rpc_call_start(task);
823         }
824
825         /* starting timestamp */
826         task->tk_start = jiffies;
827
828         dprintk("RPC:       new task initialized, procpid %u\n",
829                                 task_pid_nr(current));
830 }
831
832 static struct rpc_task *
833 rpc_alloc_task(void)
834 {
835         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
836 }
837
838 /*
839  * Create a new task for the specified client.
840  */
841 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
842 {
843         struct rpc_task *task = setup_data->task;
844         unsigned short flags = 0;
845
846         if (task == NULL) {
847                 task = rpc_alloc_task();
848                 if (task == NULL)
849                         goto out;
850                 flags = RPC_TASK_DYNAMIC;
851         }
852
853         rpc_init_task(task, setup_data);
854
855         task->tk_flags |= flags;
856         dprintk("RPC:       allocated task %p\n", task);
857 out:
858         return task;
859 }
860
861 static void rpc_free_task(struct rpc_task *task)
862 {
863         const struct rpc_call_ops *tk_ops = task->tk_ops;
864         void *calldata = task->tk_calldata;
865
866         if (task->tk_flags & RPC_TASK_DYNAMIC) {
867                 dprintk("RPC: %5u freeing task\n", task->tk_pid);
868                 mempool_free(task, rpc_task_mempool);
869         }
870         rpc_release_calldata(tk_ops, calldata);
871 }
872
873 static void rpc_async_release(struct work_struct *work)
874 {
875         rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
876 }
877
878 void rpc_put_task(struct rpc_task *task)
879 {
880         if (!atomic_dec_and_test(&task->tk_count))
881                 return;
882         /* Release resources */
883         if (task->tk_rqstp)
884                 xprt_release(task);
885         if (task->tk_msg.rpc_cred)
886                 rpcauth_unbindcred(task);
887         if (task->tk_client) {
888                 rpc_release_client(task->tk_client);
889                 task->tk_client = NULL;
890         }
891         if (task->tk_workqueue != NULL) {
892                 INIT_WORK(&task->u.tk_work, rpc_async_release);
893                 queue_work(task->tk_workqueue, &task->u.tk_work);
894         } else
895                 rpc_free_task(task);
896 }
897 EXPORT_SYMBOL_GPL(rpc_put_task);
898
899 static void rpc_release_task(struct rpc_task *task)
900 {
901 #ifdef RPC_DEBUG
902         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
903 #endif
904         dprintk("RPC: %5u release task\n", task->tk_pid);
905
906         if (!list_empty(&task->tk_task)) {
907                 struct rpc_clnt *clnt = task->tk_client;
908                 /* Remove from client task list */
909                 spin_lock(&clnt->cl_lock);
910                 list_del(&task->tk_task);
911                 spin_unlock(&clnt->cl_lock);
912         }
913         BUG_ON (RPC_IS_QUEUED(task));
914
915 #ifdef RPC_DEBUG
916         task->tk_magic = 0;
917 #endif
918         /* Wake up anyone who is waiting for task completion */
919         rpc_mark_complete_task(task);
920
921         rpc_put_task(task);
922 }
923
924 /*
925  * Kill all tasks for the given client.
926  * XXX: kill their descendants as well?
927  */
928 void rpc_killall_tasks(struct rpc_clnt *clnt)
929 {
930         struct rpc_task *rovr;
931
932
933         if (list_empty(&clnt->cl_tasks))
934                 return;
935         dprintk("RPC:       killing all tasks for client %p\n", clnt);
936         /*
937          * Spin lock all_tasks to prevent changes...
938          */
939         spin_lock(&clnt->cl_lock);
940         list_for_each_entry(rovr, &clnt->cl_tasks, tk_task) {
941                 if (! RPC_IS_ACTIVATED(rovr))
942                         continue;
943                 if (!(rovr->tk_flags & RPC_TASK_KILLED)) {
944                         rovr->tk_flags |= RPC_TASK_KILLED;
945                         rpc_exit(rovr, -EIO);
946                         rpc_wake_up_task(rovr);
947                 }
948         }
949         spin_unlock(&clnt->cl_lock);
950 }
951 EXPORT_SYMBOL_GPL(rpc_killall_tasks);
952
953 int rpciod_up(void)
954 {
955         return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
956 }
957
958 void rpciod_down(void)
959 {
960         module_put(THIS_MODULE);
961 }
962
963 /*
964  * Start up the rpciod workqueue.
965  */
966 static int rpciod_start(void)
967 {
968         struct workqueue_struct *wq;
969
970         /*
971          * Create the rpciod thread and wait for it to start.
972          */
973         dprintk("RPC:       creating workqueue rpciod\n");
974         wq = create_workqueue("rpciod");
975         rpciod_workqueue = wq;
976         return rpciod_workqueue != NULL;
977 }
978
979 static void rpciod_stop(void)
980 {
981         struct workqueue_struct *wq = NULL;
982
983         if (rpciod_workqueue == NULL)
984                 return;
985         dprintk("RPC:       destroying workqueue rpciod\n");
986
987         wq = rpciod_workqueue;
988         rpciod_workqueue = NULL;
989         destroy_workqueue(wq);
990 }
991
992 void
993 rpc_destroy_mempool(void)
994 {
995         rpciod_stop();
996         if (rpc_buffer_mempool)
997                 mempool_destroy(rpc_buffer_mempool);
998         if (rpc_task_mempool)
999                 mempool_destroy(rpc_task_mempool);
1000         if (rpc_task_slabp)
1001                 kmem_cache_destroy(rpc_task_slabp);
1002         if (rpc_buffer_slabp)
1003                 kmem_cache_destroy(rpc_buffer_slabp);
1004         rpc_destroy_wait_queue(&delay_queue);
1005 }
1006
1007 int
1008 rpc_init_mempool(void)
1009 {
1010         /*
1011          * The following is not strictly a mempool initialisation,
1012          * but there is no harm in doing it here
1013          */
1014         rpc_init_wait_queue(&delay_queue, "delayq");
1015         if (!rpciod_start())
1016                 goto err_nomem;
1017
1018         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1019                                              sizeof(struct rpc_task),
1020                                              0, SLAB_HWCACHE_ALIGN,
1021                                              NULL);
1022         if (!rpc_task_slabp)
1023                 goto err_nomem;
1024         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1025                                              RPC_BUFFER_MAXSIZE,
1026                                              0, SLAB_HWCACHE_ALIGN,
1027                                              NULL);
1028         if (!rpc_buffer_slabp)
1029                 goto err_nomem;
1030         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1031                                                     rpc_task_slabp);
1032         if (!rpc_task_mempool)
1033                 goto err_nomem;
1034         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1035                                                       rpc_buffer_slabp);
1036         if (!rpc_buffer_mempool)
1037                 goto err_nomem;
1038         return 0;
1039 err_nomem:
1040         rpc_destroy_mempool();
1041         return -ENOMEM;
1042 }