mac80211: fix notify_mac function
[linux-2.6.git] / net / sunrpc / sched.c
1 /*
2  * linux/net/sunrpc/sched.c
3  *
4  * Scheduling for synchronous and asynchronous RPC requests.
5  *
6  * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
7  *
8  * TCP NFS related read + write fixes
9  * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
10  */
11
12 #include <linux/module.h>
13
14 #include <linux/sched.h>
15 #include <linux/interrupt.h>
16 #include <linux/slab.h>
17 #include <linux/mempool.h>
18 #include <linux/smp.h>
19 #include <linux/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         /* We might have raced */
297         if (RPC_IS_QUEUED(task)) {
298                 rpc_clear_running(task);
299                 return;
300         }
301         if (RPC_IS_ASYNC(task)) {
302                 int status;
303
304                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
305                 status = queue_work(rpciod_workqueue, &task->u.tk_work);
306                 if (status < 0) {
307                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
308                         task->tk_status = status;
309                         return;
310                 }
311         } else
312                 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
313 }
314
315 /*
316  * Prepare for sleeping on a wait queue.
317  * By always appending tasks to the list we ensure FIFO behavior.
318  * NB: An RPC task will only receive interrupt-driven events as long
319  * as it's on a wait queue.
320  */
321 static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
322                         rpc_action action)
323 {
324         dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
325                         task->tk_pid, rpc_qname(q), jiffies);
326
327         if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
328                 printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
329                 return;
330         }
331
332         __rpc_add_wait_queue(q, task);
333
334         BUG_ON(task->tk_callback != NULL);
335         task->tk_callback = action;
336         __rpc_add_timer(q, task);
337 }
338
339 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
340                                 rpc_action action)
341 {
342         /* Mark the task as being activated if so needed */
343         rpc_set_active(task);
344
345         /*
346          * Protect the queue operations.
347          */
348         spin_lock_bh(&q->lock);
349         __rpc_sleep_on(q, task, action);
350         spin_unlock_bh(&q->lock);
351 }
352 EXPORT_SYMBOL_GPL(rpc_sleep_on);
353
354 /**
355  * __rpc_do_wake_up_task - wake up a single rpc_task
356  * @queue: wait queue
357  * @task: task to be woken up
358  *
359  * Caller must hold queue->lock, and have cleared the task queued flag.
360  */
361 static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
362 {
363         dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
364                         task->tk_pid, jiffies);
365
366 #ifdef RPC_DEBUG
367         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
368 #endif
369         /* Has the task been executed yet? If not, we cannot wake it up! */
370         if (!RPC_IS_ACTIVATED(task)) {
371                 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
372                 return;
373         }
374
375         __rpc_remove_wait_queue(queue, task);
376
377         rpc_make_runnable(task);
378
379         dprintk("RPC:       __rpc_wake_up_task done\n");
380 }
381
382 /*
383  * Wake up a queued task while the queue lock is being held
384  */
385 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
386 {
387         if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
388                 __rpc_do_wake_up_task(queue, task);
389 }
390
391 /*
392  * Wake up a task on a specific queue
393  */
394 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
395 {
396         spin_lock_bh(&queue->lock);
397         rpc_wake_up_task_queue_locked(queue, task);
398         spin_unlock_bh(&queue->lock);
399 }
400 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
401
402 /*
403  * Wake up the specified task
404  */
405 static void rpc_wake_up_task(struct rpc_task *task)
406 {
407         rpc_wake_up_queued_task(task->tk_waitqueue, task);
408 }
409
410 /*
411  * Wake up the next task on a priority queue.
412  */
413 static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
414 {
415         struct list_head *q;
416         struct rpc_task *task;
417
418         /*
419          * Service a batch of tasks from a single owner.
420          */
421         q = &queue->tasks[queue->priority];
422         if (!list_empty(q)) {
423                 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
424                 if (queue->owner == task->tk_owner) {
425                         if (--queue->nr)
426                                 goto out;
427                         list_move_tail(&task->u.tk_wait.list, q);
428                 }
429                 /*
430                  * Check if we need to switch queues.
431                  */
432                 if (--queue->count)
433                         goto new_owner;
434         }
435
436         /*
437          * Service the next queue.
438          */
439         do {
440                 if (q == &queue->tasks[0])
441                         q = &queue->tasks[queue->maxpriority];
442                 else
443                         q = q - 1;
444                 if (!list_empty(q)) {
445                         task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
446                         goto new_queue;
447                 }
448         } while (q != &queue->tasks[queue->priority]);
449
450         rpc_reset_waitqueue_priority(queue);
451         return NULL;
452
453 new_queue:
454         rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
455 new_owner:
456         rpc_set_waitqueue_owner(queue, task->tk_owner);
457 out:
458         rpc_wake_up_task_queue_locked(queue, task);
459         return task;
460 }
461
462 /*
463  * Wake up the next task on the wait queue.
464  */
465 struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
466 {
467         struct rpc_task *task = NULL;
468
469         dprintk("RPC:       wake_up_next(%p \"%s\")\n",
470                         queue, rpc_qname(queue));
471         spin_lock_bh(&queue->lock);
472         if (RPC_IS_PRIORITY(queue))
473                 task = __rpc_wake_up_next_priority(queue);
474         else {
475                 task_for_first(task, &queue->tasks[0])
476                         rpc_wake_up_task_queue_locked(queue, task);
477         }
478         spin_unlock_bh(&queue->lock);
479
480         return task;
481 }
482 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
483
484 /**
485  * rpc_wake_up - wake up all rpc_tasks
486  * @queue: rpc_wait_queue on which the tasks are sleeping
487  *
488  * Grabs queue->lock
489  */
490 void rpc_wake_up(struct rpc_wait_queue *queue)
491 {
492         struct rpc_task *task, *next;
493         struct list_head *head;
494
495         spin_lock_bh(&queue->lock);
496         head = &queue->tasks[queue->maxpriority];
497         for (;;) {
498                 list_for_each_entry_safe(task, next, head, u.tk_wait.list)
499                         rpc_wake_up_task_queue_locked(queue, task);
500                 if (head == &queue->tasks[0])
501                         break;
502                 head--;
503         }
504         spin_unlock_bh(&queue->lock);
505 }
506 EXPORT_SYMBOL_GPL(rpc_wake_up);
507
508 /**
509  * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
510  * @queue: rpc_wait_queue on which the tasks are sleeping
511  * @status: status value to set
512  *
513  * Grabs queue->lock
514  */
515 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
516 {
517         struct rpc_task *task, *next;
518         struct list_head *head;
519
520         spin_lock_bh(&queue->lock);
521         head = &queue->tasks[queue->maxpriority];
522         for (;;) {
523                 list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
524                         task->tk_status = status;
525                         rpc_wake_up_task_queue_locked(queue, task);
526                 }
527                 if (head == &queue->tasks[0])
528                         break;
529                 head--;
530         }
531         spin_unlock_bh(&queue->lock);
532 }
533 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
534
535 static void __rpc_queue_timer_fn(unsigned long ptr)
536 {
537         struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
538         struct rpc_task *task, *n;
539         unsigned long expires, now, timeo;
540
541         spin_lock(&queue->lock);
542         expires = now = jiffies;
543         list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
544                 timeo = task->u.tk_wait.expires;
545                 if (time_after_eq(now, timeo)) {
546                         dprintk("RPC: %5u timeout\n", task->tk_pid);
547                         task->tk_status = -ETIMEDOUT;
548                         rpc_wake_up_task_queue_locked(queue, task);
549                         continue;
550                 }
551                 if (expires == now || time_after(expires, timeo))
552                         expires = timeo;
553         }
554         if (!list_empty(&queue->timer_list.list))
555                 rpc_set_queue_timer(queue, expires);
556         spin_unlock(&queue->lock);
557 }
558
559 static void __rpc_atrun(struct rpc_task *task)
560 {
561         task->tk_status = 0;
562 }
563
564 /*
565  * Run a task at a later time
566  */
567 void rpc_delay(struct rpc_task *task, unsigned long delay)
568 {
569         task->tk_timeout = delay;
570         rpc_sleep_on(&delay_queue, task, __rpc_atrun);
571 }
572 EXPORT_SYMBOL_GPL(rpc_delay);
573
574 /*
575  * Helper to call task->tk_ops->rpc_call_prepare
576  */
577 static void rpc_prepare_task(struct rpc_task *task)
578 {
579         task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
580 }
581
582 /*
583  * Helper that calls task->tk_ops->rpc_call_done if it exists
584  */
585 void rpc_exit_task(struct rpc_task *task)
586 {
587         task->tk_action = NULL;
588         if (task->tk_ops->rpc_call_done != NULL) {
589                 task->tk_ops->rpc_call_done(task, task->tk_calldata);
590                 if (task->tk_action != NULL) {
591                         WARN_ON(RPC_ASSASSINATED(task));
592                         /* Always release the RPC slot and buffer memory */
593                         xprt_release(task);
594                 }
595         }
596 }
597 EXPORT_SYMBOL_GPL(rpc_exit_task);
598
599 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
600 {
601         if (ops->rpc_release != NULL)
602                 ops->rpc_release(calldata);
603 }
604
605 /*
606  * This is the RPC `scheduler' (or rather, the finite state machine).
607  */
608 static void __rpc_execute(struct rpc_task *task)
609 {
610         int             status = 0;
611
612         dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
613                         task->tk_pid, task->tk_flags);
614
615         BUG_ON(RPC_IS_QUEUED(task));
616
617         for (;;) {
618
619                 /*
620                  * Execute any pending callback.
621                  */
622                 if (task->tk_callback) {
623                         void (*save_callback)(struct rpc_task *);
624
625                         /*
626                          * We set tk_callback to NULL before calling it,
627                          * in case it sets the tk_callback field itself:
628                          */
629                         save_callback = task->tk_callback;
630                         task->tk_callback = NULL;
631                         save_callback(task);
632                 }
633
634                 /*
635                  * Perform the next FSM step.
636                  * tk_action may be NULL when the task has been killed
637                  * by someone else.
638                  */
639                 if (!RPC_IS_QUEUED(task)) {
640                         if (task->tk_action == NULL)
641                                 break;
642                         task->tk_action(task);
643                 }
644
645                 /*
646                  * Lockless check for whether task is sleeping or not.
647                  */
648                 if (!RPC_IS_QUEUED(task))
649                         continue;
650                 rpc_clear_running(task);
651                 if (RPC_IS_ASYNC(task)) {
652                         /* Careful! we may have raced... */
653                         if (RPC_IS_QUEUED(task))
654                                 return;
655                         if (rpc_test_and_set_running(task))
656                                 return;
657                         continue;
658                 }
659
660                 /* sync task: sleep here */
661                 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
662                 status = out_of_line_wait_on_bit(&task->tk_runstate,
663                                 RPC_TASK_QUEUED, rpc_wait_bit_killable,
664                                 TASK_KILLABLE);
665                 if (status == -ERESTARTSYS) {
666                         /*
667                          * When a sync task receives a signal, it exits with
668                          * -ERESTARTSYS. In order to catch any callbacks that
669                          * clean up after sleeping on some queue, we don't
670                          * break the loop here, but go around once more.
671                          */
672                         dprintk("RPC: %5u got signal\n", task->tk_pid);
673                         task->tk_flags |= RPC_TASK_KILLED;
674                         rpc_exit(task, -ERESTARTSYS);
675                         rpc_wake_up_task(task);
676                 }
677                 rpc_set_running(task);
678                 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
679         }
680
681         dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
682                         task->tk_status);
683         /* Release all resources associated with the task */
684         rpc_release_task(task);
685 }
686
687 /*
688  * User-visible entry point to the scheduler.
689  *
690  * This may be called recursively if e.g. an async NFS task updates
691  * the attributes and finds that dirty pages must be flushed.
692  * NOTE: Upon exit of this function the task is guaranteed to be
693  *       released. In particular note that tk_release() will have
694  *       been called, so your task memory may have been freed.
695  */
696 void rpc_execute(struct rpc_task *task)
697 {
698         rpc_set_active(task);
699         rpc_set_running(task);
700         __rpc_execute(task);
701 }
702
703 static void rpc_async_schedule(struct work_struct *work)
704 {
705         __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
706 }
707
708 struct rpc_buffer {
709         size_t  len;
710         char    data[];
711 };
712
713 /**
714  * rpc_malloc - allocate an RPC buffer
715  * @task: RPC task that will use this buffer
716  * @size: requested byte size
717  *
718  * To prevent rpciod from hanging, this allocator never sleeps,
719  * returning NULL if the request cannot be serviced immediately.
720  * The caller can arrange to sleep in a way that is safe for rpciod.
721  *
722  * Most requests are 'small' (under 2KiB) and can be serviced from a
723  * mempool, ensuring that NFS reads and writes can always proceed,
724  * and that there is good locality of reference for these buffers.
725  *
726  * In order to avoid memory starvation triggering more writebacks of
727  * NFS requests, we avoid using GFP_KERNEL.
728  */
729 void *rpc_malloc(struct rpc_task *task, size_t size)
730 {
731         struct rpc_buffer *buf;
732         gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
733
734         size += sizeof(struct rpc_buffer);
735         if (size <= RPC_BUFFER_MAXSIZE)
736                 buf = mempool_alloc(rpc_buffer_mempool, gfp);
737         else
738                 buf = kmalloc(size, gfp);
739
740         if (!buf)
741                 return NULL;
742
743         buf->len = size;
744         dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
745                         task->tk_pid, size, buf);
746         return &buf->data;
747 }
748 EXPORT_SYMBOL_GPL(rpc_malloc);
749
750 /**
751  * rpc_free - free buffer allocated via rpc_malloc
752  * @buffer: buffer to free
753  *
754  */
755 void rpc_free(void *buffer)
756 {
757         size_t size;
758         struct rpc_buffer *buf;
759
760         if (!buffer)
761                 return;
762
763         buf = container_of(buffer, struct rpc_buffer, data);
764         size = buf->len;
765
766         dprintk("RPC:       freeing buffer of size %zu at %p\n",
767                         size, buf);
768
769         if (size <= RPC_BUFFER_MAXSIZE)
770                 mempool_free(buf, rpc_buffer_mempool);
771         else
772                 kfree(buf);
773 }
774 EXPORT_SYMBOL_GPL(rpc_free);
775
776 /*
777  * Creation and deletion of RPC task structures
778  */
779 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
780 {
781         memset(task, 0, sizeof(*task));
782         atomic_set(&task->tk_count, 1);
783         task->tk_flags  = task_setup_data->flags;
784         task->tk_ops = task_setup_data->callback_ops;
785         task->tk_calldata = task_setup_data->callback_data;
786         INIT_LIST_HEAD(&task->tk_task);
787
788         /* Initialize retry counters */
789         task->tk_garb_retry = 2;
790         task->tk_cred_retry = 2;
791
792         task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
793         task->tk_owner = current->tgid;
794
795         /* Initialize workqueue for async tasks */
796         task->tk_workqueue = task_setup_data->workqueue;
797
798         task->tk_client = task_setup_data->rpc_client;
799         if (task->tk_client != NULL) {
800                 kref_get(&task->tk_client->cl_kref);
801                 if (task->tk_client->cl_softrtry)
802                         task->tk_flags |= RPC_TASK_SOFT;
803         }
804
805         if (task->tk_ops->rpc_call_prepare != NULL)
806                 task->tk_action = rpc_prepare_task;
807
808         if (task_setup_data->rpc_message != NULL) {
809                 task->tk_msg.rpc_proc = task_setup_data->rpc_message->rpc_proc;
810                 task->tk_msg.rpc_argp = task_setup_data->rpc_message->rpc_argp;
811                 task->tk_msg.rpc_resp = task_setup_data->rpc_message->rpc_resp;
812                 /* Bind the user cred */
813                 rpcauth_bindcred(task, task_setup_data->rpc_message->rpc_cred, task_setup_data->flags);
814                 if (task->tk_action == NULL)
815                         rpc_call_start(task);
816         }
817
818         /* starting timestamp */
819         task->tk_start = jiffies;
820
821         dprintk("RPC:       new task initialized, procpid %u\n",
822                                 task_pid_nr(current));
823 }
824
825 static struct rpc_task *
826 rpc_alloc_task(void)
827 {
828         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
829 }
830
831 /*
832  * Create a new task for the specified client.
833  */
834 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
835 {
836         struct rpc_task *task = setup_data->task;
837         unsigned short flags = 0;
838
839         if (task == NULL) {
840                 task = rpc_alloc_task();
841                 if (task == NULL)
842                         goto out;
843                 flags = RPC_TASK_DYNAMIC;
844         }
845
846         rpc_init_task(task, setup_data);
847
848         task->tk_flags |= flags;
849         dprintk("RPC:       allocated task %p\n", task);
850 out:
851         return task;
852 }
853
854 static void rpc_free_task(struct rpc_task *task)
855 {
856         const struct rpc_call_ops *tk_ops = task->tk_ops;
857         void *calldata = task->tk_calldata;
858
859         if (task->tk_flags & RPC_TASK_DYNAMIC) {
860                 dprintk("RPC: %5u freeing task\n", task->tk_pid);
861                 mempool_free(task, rpc_task_mempool);
862         }
863         rpc_release_calldata(tk_ops, calldata);
864 }
865
866 static void rpc_async_release(struct work_struct *work)
867 {
868         rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
869 }
870
871 void rpc_put_task(struct rpc_task *task)
872 {
873         if (!atomic_dec_and_test(&task->tk_count))
874                 return;
875         /* Release resources */
876         if (task->tk_rqstp)
877                 xprt_release(task);
878         if (task->tk_msg.rpc_cred)
879                 rpcauth_unbindcred(task);
880         if (task->tk_client) {
881                 rpc_release_client(task->tk_client);
882                 task->tk_client = NULL;
883         }
884         if (task->tk_workqueue != NULL) {
885                 INIT_WORK(&task->u.tk_work, rpc_async_release);
886                 queue_work(task->tk_workqueue, &task->u.tk_work);
887         } else
888                 rpc_free_task(task);
889 }
890 EXPORT_SYMBOL_GPL(rpc_put_task);
891
892 static void rpc_release_task(struct rpc_task *task)
893 {
894 #ifdef RPC_DEBUG
895         BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
896 #endif
897         dprintk("RPC: %5u release task\n", task->tk_pid);
898
899         if (!list_empty(&task->tk_task)) {
900                 struct rpc_clnt *clnt = task->tk_client;
901                 /* Remove from client task list */
902                 spin_lock(&clnt->cl_lock);
903                 list_del(&task->tk_task);
904                 spin_unlock(&clnt->cl_lock);
905         }
906         BUG_ON (RPC_IS_QUEUED(task));
907
908 #ifdef RPC_DEBUG
909         task->tk_magic = 0;
910 #endif
911         /* Wake up anyone who is waiting for task completion */
912         rpc_mark_complete_task(task);
913
914         rpc_put_task(task);
915 }
916
917 /*
918  * Kill all tasks for the given client.
919  * XXX: kill their descendants as well?
920  */
921 void rpc_killall_tasks(struct rpc_clnt *clnt)
922 {
923         struct rpc_task *rovr;
924
925
926         if (list_empty(&clnt->cl_tasks))
927                 return;
928         dprintk("RPC:       killing all tasks for client %p\n", clnt);
929         /*
930          * Spin lock all_tasks to prevent changes...
931          */
932         spin_lock(&clnt->cl_lock);
933         list_for_each_entry(rovr, &clnt->cl_tasks, tk_task) {
934                 if (! RPC_IS_ACTIVATED(rovr))
935                         continue;
936                 if (!(rovr->tk_flags & RPC_TASK_KILLED)) {
937                         rovr->tk_flags |= RPC_TASK_KILLED;
938                         rpc_exit(rovr, -EIO);
939                         rpc_wake_up_task(rovr);
940                 }
941         }
942         spin_unlock(&clnt->cl_lock);
943 }
944 EXPORT_SYMBOL_GPL(rpc_killall_tasks);
945
946 int rpciod_up(void)
947 {
948         return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
949 }
950
951 void rpciod_down(void)
952 {
953         module_put(THIS_MODULE);
954 }
955
956 /*
957  * Start up the rpciod workqueue.
958  */
959 static int rpciod_start(void)
960 {
961         struct workqueue_struct *wq;
962
963         /*
964          * Create the rpciod thread and wait for it to start.
965          */
966         dprintk("RPC:       creating workqueue rpciod\n");
967         wq = create_workqueue("rpciod");
968         rpciod_workqueue = wq;
969         return rpciod_workqueue != NULL;
970 }
971
972 static void rpciod_stop(void)
973 {
974         struct workqueue_struct *wq = NULL;
975
976         if (rpciod_workqueue == NULL)
977                 return;
978         dprintk("RPC:       destroying workqueue rpciod\n");
979
980         wq = rpciod_workqueue;
981         rpciod_workqueue = NULL;
982         destroy_workqueue(wq);
983 }
984
985 void
986 rpc_destroy_mempool(void)
987 {
988         rpciod_stop();
989         if (rpc_buffer_mempool)
990                 mempool_destroy(rpc_buffer_mempool);
991         if (rpc_task_mempool)
992                 mempool_destroy(rpc_task_mempool);
993         if (rpc_task_slabp)
994                 kmem_cache_destroy(rpc_task_slabp);
995         if (rpc_buffer_slabp)
996                 kmem_cache_destroy(rpc_buffer_slabp);
997         rpc_destroy_wait_queue(&delay_queue);
998 }
999
1000 int
1001 rpc_init_mempool(void)
1002 {
1003         /*
1004          * The following is not strictly a mempool initialisation,
1005          * but there is no harm in doing it here
1006          */
1007         rpc_init_wait_queue(&delay_queue, "delayq");
1008         if (!rpciod_start())
1009                 goto err_nomem;
1010
1011         rpc_task_slabp = kmem_cache_create("rpc_tasks",
1012                                              sizeof(struct rpc_task),
1013                                              0, SLAB_HWCACHE_ALIGN,
1014                                              NULL);
1015         if (!rpc_task_slabp)
1016                 goto err_nomem;
1017         rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1018                                              RPC_BUFFER_MAXSIZE,
1019                                              0, SLAB_HWCACHE_ALIGN,
1020                                              NULL);
1021         if (!rpc_buffer_slabp)
1022                 goto err_nomem;
1023         rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1024                                                     rpc_task_slabp);
1025         if (!rpc_task_mempool)
1026                 goto err_nomem;
1027         rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1028                                                       rpc_buffer_slabp);
1029         if (!rpc_buffer_mempool)
1030                 goto err_nomem;
1031         return 0;
1032 err_nomem:
1033         rpc_destroy_mempool();
1034         return -ENOMEM;
1035 }