2 * linux/net/sunrpc/sched.c
4 * Scheduling for synchronous and asynchronous RPC requests.
6 * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
8 * TCP NFS related read + write fixes
9 * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
12 #include <linux/module.h>
14 #include <linux/sched.h>
15 #include <linux/interrupt.h>
16 #include <linux/slab.h>
17 #include <linux/mempool.h>
18 #include <linux/smp.h>
19 #include <linux/spinlock.h>
20 #include <linux/mutex.h>
21 #include <linux/freezer.h>
23 #include <linux/sunrpc/clnt.h>
28 #define RPCDBG_FACILITY RPCDBG_SCHED
31 #define CREATE_TRACE_POINTS
32 #include <trace/events/sunrpc.h>
35 * RPC slabs and memory pools
37 #define RPC_BUFFER_MAXSIZE (2048)
38 #define RPC_BUFFER_POOLSIZE (8)
39 #define RPC_TASK_POOLSIZE (8)
40 static struct kmem_cache *rpc_task_slabp __read_mostly;
41 static struct kmem_cache *rpc_buffer_slabp __read_mostly;
42 static mempool_t *rpc_task_mempool __read_mostly;
43 static mempool_t *rpc_buffer_mempool __read_mostly;
45 static void rpc_async_schedule(struct work_struct *);
46 static void rpc_release_task(struct rpc_task *task);
47 static void __rpc_queue_timer_fn(unsigned long ptr);
50 * RPC tasks sit here while waiting for conditions to improve.
52 static struct rpc_wait_queue delay_queue;
55 * rpciod-related stuff
57 struct workqueue_struct *rpciod_workqueue;
60 * Disable the timer for a given RPC task. Should be called with
61 * queue->lock and bh_disabled in order to avoid races within
65 __rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
67 if (task->tk_timeout == 0)
69 dprintk("RPC: %5u disabling timer\n", task->tk_pid);
71 list_del(&task->u.tk_wait.timer_list);
72 if (list_empty(&queue->timer_list.list))
73 del_timer(&queue->timer_list.timer);
77 rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
79 queue->timer_list.expires = expires;
80 mod_timer(&queue->timer_list.timer, expires);
84 * Set up a timer for the current task.
87 __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
89 if (!task->tk_timeout)
92 dprintk("RPC: %5u setting alarm for %lu ms\n",
93 task->tk_pid, task->tk_timeout * 1000 / HZ);
95 task->u.tk_wait.expires = jiffies + task->tk_timeout;
96 if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
97 rpc_set_queue_timer(queue, task->u.tk_wait.expires);
98 list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
101 static void rpc_rotate_queue_owner(struct rpc_wait_queue *queue)
103 struct list_head *q = &queue->tasks[queue->priority];
104 struct rpc_task *task;
106 if (!list_empty(q)) {
107 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
108 if (task->tk_owner == queue->owner)
109 list_move_tail(&task->u.tk_wait.list, q);
113 static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
115 if (queue->priority != priority) {
116 /* Fairness: rotate the list when changing priority */
117 rpc_rotate_queue_owner(queue);
118 queue->priority = priority;
122 static void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
125 queue->nr = RPC_BATCH_COUNT;
128 static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
130 rpc_set_waitqueue_priority(queue, queue->maxpriority);
131 rpc_set_waitqueue_owner(queue, 0);
135 * Add new request to a priority queue.
137 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
138 struct rpc_task *task,
139 unsigned char queue_priority)
144 INIT_LIST_HEAD(&task->u.tk_wait.links);
145 if (unlikely(queue_priority > queue->maxpriority))
146 queue_priority = queue->maxpriority;
147 if (queue_priority > queue->priority)
148 rpc_set_waitqueue_priority(queue, queue_priority);
149 q = &queue->tasks[queue_priority];
150 list_for_each_entry(t, q, u.tk_wait.list) {
151 if (t->tk_owner == task->tk_owner) {
152 list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
156 list_add_tail(&task->u.tk_wait.list, q);
160 * Add new request to wait queue.
162 * Swapper tasks always get inserted at the head of the queue.
163 * This should avoid many nasty memory deadlocks and hopefully
164 * improve overall performance.
165 * Everyone else gets appended to the queue to ensure proper FIFO behavior.
167 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
168 struct rpc_task *task,
169 unsigned char queue_priority)
171 WARN_ON_ONCE(RPC_IS_QUEUED(task));
172 if (RPC_IS_QUEUED(task))
175 if (RPC_IS_PRIORITY(queue))
176 __rpc_add_wait_queue_priority(queue, task, queue_priority);
177 else if (RPC_IS_SWAPPER(task))
178 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
180 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
181 task->tk_waitqueue = queue;
183 /* barrier matches the read in rpc_wake_up_task_queue_locked() */
185 rpc_set_queued(task);
187 dprintk("RPC: %5u added to queue %p \"%s\"\n",
188 task->tk_pid, queue, rpc_qname(queue));
192 * Remove request from a priority queue.
194 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
198 if (!list_empty(&task->u.tk_wait.links)) {
199 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
200 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
201 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
206 * Remove request from queue.
207 * Note: must be called with spin lock held.
209 static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
211 __rpc_disable_timer(queue, task);
212 if (RPC_IS_PRIORITY(queue))
213 __rpc_remove_wait_queue_priority(task);
214 list_del(&task->u.tk_wait.list);
216 dprintk("RPC: %5u removed from queue %p \"%s\"\n",
217 task->tk_pid, queue, rpc_qname(queue));
220 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
224 spin_lock_init(&queue->lock);
225 for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
226 INIT_LIST_HEAD(&queue->tasks[i]);
227 queue->maxpriority = nr_queues - 1;
228 rpc_reset_waitqueue_priority(queue);
230 setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
231 INIT_LIST_HEAD(&queue->timer_list.list);
232 rpc_assign_waitqueue_name(queue, qname);
235 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
237 __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
239 EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
241 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
243 __rpc_init_priority_wait_queue(queue, qname, 1);
245 EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
247 void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
249 del_timer_sync(&queue->timer_list.timer);
251 EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
253 static int rpc_wait_bit_killable(void *word)
255 if (fatal_signal_pending(current))
257 freezable_schedule();
262 static void rpc_task_set_debuginfo(struct rpc_task *task)
264 static atomic_t rpc_pid;
266 task->tk_pid = atomic_inc_return(&rpc_pid);
269 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
274 static void rpc_set_active(struct rpc_task *task)
276 trace_rpc_task_begin(task->tk_client, task, NULL);
278 rpc_task_set_debuginfo(task);
279 set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
283 * Mark an RPC call as having completed by clearing the 'active' bit
284 * and then waking up all tasks that were sleeping.
286 static int rpc_complete_task(struct rpc_task *task)
288 void *m = &task->tk_runstate;
289 wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
290 struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
294 trace_rpc_task_complete(task->tk_client, task, NULL);
296 spin_lock_irqsave(&wq->lock, flags);
297 clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
298 ret = atomic_dec_and_test(&task->tk_count);
299 if (waitqueue_active(wq))
300 __wake_up_locked_key(wq, TASK_NORMAL, &k);
301 spin_unlock_irqrestore(&wq->lock, flags);
306 * Allow callers to wait for completion of an RPC call
308 * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
309 * to enforce taking of the wq->lock and hence avoid races with
310 * rpc_complete_task().
312 int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
315 action = rpc_wait_bit_killable;
316 return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
317 action, TASK_KILLABLE);
319 EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
322 * Make an RPC task runnable.
324 * Note: If the task is ASYNC, and is being made runnable after sitting on an
325 * rpc_wait_queue, this must be called with the queue spinlock held to protect
326 * the wait queue operation.
327 * Note the ordering of rpc_test_and_set_running() and rpc_clear_queued(),
328 * which is needed to ensure that __rpc_execute() doesn't loop (due to the
329 * lockless RPC_IS_QUEUED() test) before we've had a chance to test
330 * the RPC_TASK_RUNNING flag.
332 static void rpc_make_runnable(struct rpc_task *task)
334 bool need_wakeup = !rpc_test_and_set_running(task);
336 rpc_clear_queued(task);
339 if (RPC_IS_ASYNC(task)) {
340 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
341 queue_work(rpciod_workqueue, &task->u.tk_work);
343 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
347 * Prepare for sleeping on a wait queue.
348 * By always appending tasks to the list we ensure FIFO behavior.
349 * NB: An RPC task will only receive interrupt-driven events as long
350 * as it's on a wait queue.
352 static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
353 struct rpc_task *task,
355 unsigned char queue_priority)
357 dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
358 task->tk_pid, rpc_qname(q), jiffies);
360 trace_rpc_task_sleep(task->tk_client, task, q);
362 __rpc_add_wait_queue(q, task, queue_priority);
364 WARN_ON_ONCE(task->tk_callback != NULL);
365 task->tk_callback = action;
366 __rpc_add_timer(q, task);
369 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
372 /* We shouldn't ever put an inactive task to sleep */
373 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
374 if (!RPC_IS_ACTIVATED(task)) {
375 task->tk_status = -EIO;
376 rpc_put_task_async(task);
381 * Protect the queue operations.
383 spin_lock_bh(&q->lock);
384 __rpc_sleep_on_priority(q, task, action, task->tk_priority);
385 spin_unlock_bh(&q->lock);
387 EXPORT_SYMBOL_GPL(rpc_sleep_on);
389 void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
390 rpc_action action, int priority)
392 /* We shouldn't ever put an inactive task to sleep */
393 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
394 if (!RPC_IS_ACTIVATED(task)) {
395 task->tk_status = -EIO;
396 rpc_put_task_async(task);
401 * Protect the queue operations.
403 spin_lock_bh(&q->lock);
404 __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
405 spin_unlock_bh(&q->lock);
407 EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
410 * __rpc_do_wake_up_task - wake up a single rpc_task
412 * @task: task to be woken up
414 * Caller must hold queue->lock, and have cleared the task queued flag.
416 static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
418 dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
419 task->tk_pid, jiffies);
421 /* Has the task been executed yet? If not, we cannot wake it up! */
422 if (!RPC_IS_ACTIVATED(task)) {
423 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
427 trace_rpc_task_wakeup(task->tk_client, task, queue);
429 __rpc_remove_wait_queue(queue, task);
431 rpc_make_runnable(task);
433 dprintk("RPC: __rpc_wake_up_task done\n");
437 * Wake up a queued task while the queue lock is being held
439 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
441 if (RPC_IS_QUEUED(task)) {
443 if (task->tk_waitqueue == queue)
444 __rpc_do_wake_up_task(queue, task);
449 * Tests whether rpc queue is empty
451 int rpc_queue_empty(struct rpc_wait_queue *queue)
455 spin_lock_bh(&queue->lock);
457 spin_unlock_bh(&queue->lock);
460 EXPORT_SYMBOL_GPL(rpc_queue_empty);
463 * Wake up a task on a specific queue
465 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
467 spin_lock_bh(&queue->lock);
468 rpc_wake_up_task_queue_locked(queue, task);
469 spin_unlock_bh(&queue->lock);
471 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
474 * Wake up the next task on a priority queue.
476 static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
479 struct rpc_task *task;
482 * Service a batch of tasks from a single owner.
484 q = &queue->tasks[queue->priority];
485 if (!list_empty(q)) {
486 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
487 if (queue->owner == task->tk_owner) {
490 list_move_tail(&task->u.tk_wait.list, q);
493 * Check if we need to switch queues.
499 * Service the next queue.
502 if (q == &queue->tasks[0])
503 q = &queue->tasks[queue->maxpriority];
506 if (!list_empty(q)) {
507 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
510 } while (q != &queue->tasks[queue->priority]);
512 rpc_reset_waitqueue_priority(queue);
516 rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
518 rpc_set_waitqueue_owner(queue, task->tk_owner);
523 static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
525 if (RPC_IS_PRIORITY(queue))
526 return __rpc_find_next_queued_priority(queue);
527 if (!list_empty(&queue->tasks[0]))
528 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
533 * Wake up the first task on the wait queue.
535 struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
536 bool (*func)(struct rpc_task *, void *), void *data)
538 struct rpc_task *task = NULL;
540 dprintk("RPC: wake_up_first(%p \"%s\")\n",
541 queue, rpc_qname(queue));
542 spin_lock_bh(&queue->lock);
543 task = __rpc_find_next_queued(queue);
545 if (func(task, data))
546 rpc_wake_up_task_queue_locked(queue, task);
550 spin_unlock_bh(&queue->lock);
554 EXPORT_SYMBOL_GPL(rpc_wake_up_first);
556 static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
562 * Wake up the next task on the wait queue.
564 struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
566 return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
568 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
571 * rpc_wake_up - wake up all rpc_tasks
572 * @queue: rpc_wait_queue on which the tasks are sleeping
576 void rpc_wake_up(struct rpc_wait_queue *queue)
578 struct list_head *head;
580 spin_lock_bh(&queue->lock);
581 head = &queue->tasks[queue->maxpriority];
583 while (!list_empty(head)) {
584 struct rpc_task *task;
585 task = list_first_entry(head,
588 rpc_wake_up_task_queue_locked(queue, task);
590 if (head == &queue->tasks[0])
594 spin_unlock_bh(&queue->lock);
596 EXPORT_SYMBOL_GPL(rpc_wake_up);
599 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
600 * @queue: rpc_wait_queue on which the tasks are sleeping
601 * @status: status value to set
605 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
607 struct list_head *head;
609 spin_lock_bh(&queue->lock);
610 head = &queue->tasks[queue->maxpriority];
612 while (!list_empty(head)) {
613 struct rpc_task *task;
614 task = list_first_entry(head,
617 task->tk_status = status;
618 rpc_wake_up_task_queue_locked(queue, task);
620 if (head == &queue->tasks[0])
624 spin_unlock_bh(&queue->lock);
626 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
628 static void __rpc_queue_timer_fn(unsigned long ptr)
630 struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
631 struct rpc_task *task, *n;
632 unsigned long expires, now, timeo;
634 spin_lock(&queue->lock);
635 expires = now = jiffies;
636 list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
637 timeo = task->u.tk_wait.expires;
638 if (time_after_eq(now, timeo)) {
639 dprintk("RPC: %5u timeout\n", task->tk_pid);
640 task->tk_status = -ETIMEDOUT;
641 rpc_wake_up_task_queue_locked(queue, task);
644 if (expires == now || time_after(expires, timeo))
647 if (!list_empty(&queue->timer_list.list))
648 rpc_set_queue_timer(queue, expires);
649 spin_unlock(&queue->lock);
652 static void __rpc_atrun(struct rpc_task *task)
658 * Run a task at a later time
660 void rpc_delay(struct rpc_task *task, unsigned long delay)
662 task->tk_timeout = delay;
663 rpc_sleep_on(&delay_queue, task, __rpc_atrun);
665 EXPORT_SYMBOL_GPL(rpc_delay);
668 * Helper to call task->tk_ops->rpc_call_prepare
670 void rpc_prepare_task(struct rpc_task *task)
672 task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
676 rpc_init_task_statistics(struct rpc_task *task)
678 /* Initialize retry counters */
679 task->tk_garb_retry = 2;
680 task->tk_cred_retry = 2;
681 task->tk_rebind_retry = 2;
683 /* starting timestamp */
684 task->tk_start = ktime_get();
688 rpc_reset_task_statistics(struct rpc_task *task)
690 task->tk_timeouts = 0;
691 task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
693 rpc_init_task_statistics(task);
697 * Helper that calls task->tk_ops->rpc_call_done if it exists
699 void rpc_exit_task(struct rpc_task *task)
701 task->tk_action = NULL;
702 if (task->tk_ops->rpc_call_done != NULL) {
703 task->tk_ops->rpc_call_done(task, task->tk_calldata);
704 if (task->tk_action != NULL) {
705 WARN_ON(RPC_ASSASSINATED(task));
706 /* Always release the RPC slot and buffer memory */
708 rpc_reset_task_statistics(task);
713 void rpc_exit(struct rpc_task *task, int status)
715 task->tk_status = status;
716 task->tk_action = rpc_exit_task;
717 if (RPC_IS_QUEUED(task))
718 rpc_wake_up_queued_task(task->tk_waitqueue, task);
720 EXPORT_SYMBOL_GPL(rpc_exit);
722 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
724 if (ops->rpc_release != NULL)
725 ops->rpc_release(calldata);
729 * This is the RPC `scheduler' (or rather, the finite state machine).
731 static void __rpc_execute(struct rpc_task *task)
733 struct rpc_wait_queue *queue;
734 int task_is_async = RPC_IS_ASYNC(task);
737 dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
738 task->tk_pid, task->tk_flags);
740 WARN_ON_ONCE(RPC_IS_QUEUED(task));
741 if (RPC_IS_QUEUED(task))
745 void (*do_action)(struct rpc_task *);
748 * Execute any pending callback first.
750 do_action = task->tk_callback;
751 task->tk_callback = NULL;
752 if (do_action == NULL) {
754 * Perform the next FSM step.
755 * tk_action may be NULL if the task has been killed.
756 * In particular, note that rpc_killall_tasks may
757 * do this at any time, so beware when dereferencing.
759 do_action = task->tk_action;
760 if (do_action == NULL)
763 trace_rpc_task_run_action(task->tk_client, task, task->tk_action);
767 * Lockless check for whether task is sleeping or not.
769 if (!RPC_IS_QUEUED(task))
772 * The queue->lock protects against races with
773 * rpc_make_runnable().
775 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
776 * rpc_task, rpc_make_runnable() can assign it to a
777 * different workqueue. We therefore cannot assume that the
778 * rpc_task pointer may still be dereferenced.
780 queue = task->tk_waitqueue;
781 spin_lock_bh(&queue->lock);
782 if (!RPC_IS_QUEUED(task)) {
783 spin_unlock_bh(&queue->lock);
786 rpc_clear_running(task);
787 spin_unlock_bh(&queue->lock);
791 /* sync task: sleep here */
792 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
793 status = out_of_line_wait_on_bit(&task->tk_runstate,
794 RPC_TASK_QUEUED, rpc_wait_bit_killable,
796 if (status == -ERESTARTSYS) {
798 * When a sync task receives a signal, it exits with
799 * -ERESTARTSYS. In order to catch any callbacks that
800 * clean up after sleeping on some queue, we don't
801 * break the loop here, but go around once more.
803 dprintk("RPC: %5u got signal\n", task->tk_pid);
804 task->tk_flags |= RPC_TASK_KILLED;
805 rpc_exit(task, -ERESTARTSYS);
807 rpc_set_running(task);
808 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
811 dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
813 /* Release all resources associated with the task */
814 rpc_release_task(task);
818 * User-visible entry point to the scheduler.
820 * This may be called recursively if e.g. an async NFS task updates
821 * the attributes and finds that dirty pages must be flushed.
822 * NOTE: Upon exit of this function the task is guaranteed to be
823 * released. In particular note that tk_release() will have
824 * been called, so your task memory may have been freed.
826 void rpc_execute(struct rpc_task *task)
828 rpc_set_active(task);
829 rpc_make_runnable(task);
830 if (!RPC_IS_ASYNC(task))
834 static void rpc_async_schedule(struct work_struct *work)
836 current->flags |= PF_FSTRANS;
837 __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
838 current->flags &= ~PF_FSTRANS;
842 * rpc_malloc - allocate an RPC buffer
843 * @task: RPC task that will use this buffer
844 * @size: requested byte size
846 * To prevent rpciod from hanging, this allocator never sleeps,
847 * returning NULL if the request cannot be serviced immediately.
848 * The caller can arrange to sleep in a way that is safe for rpciod.
850 * Most requests are 'small' (under 2KiB) and can be serviced from a
851 * mempool, ensuring that NFS reads and writes can always proceed,
852 * and that there is good locality of reference for these buffers.
854 * In order to avoid memory starvation triggering more writebacks of
855 * NFS requests, we avoid using GFP_KERNEL.
857 void *rpc_malloc(struct rpc_task *task, size_t size)
859 struct rpc_buffer *buf;
860 gfp_t gfp = GFP_NOWAIT;
862 if (RPC_IS_SWAPPER(task))
863 gfp |= __GFP_MEMALLOC;
865 size += sizeof(struct rpc_buffer);
866 if (size <= RPC_BUFFER_MAXSIZE)
867 buf = mempool_alloc(rpc_buffer_mempool, gfp);
869 buf = kmalloc(size, gfp);
875 dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
876 task->tk_pid, size, buf);
879 EXPORT_SYMBOL_GPL(rpc_malloc);
882 * rpc_free - free buffer allocated via rpc_malloc
883 * @buffer: buffer to free
886 void rpc_free(void *buffer)
889 struct rpc_buffer *buf;
894 buf = container_of(buffer, struct rpc_buffer, data);
897 dprintk("RPC: freeing buffer of size %zu at %p\n",
900 if (size <= RPC_BUFFER_MAXSIZE)
901 mempool_free(buf, rpc_buffer_mempool);
905 EXPORT_SYMBOL_GPL(rpc_free);
908 * Creation and deletion of RPC task structures
910 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
912 memset(task, 0, sizeof(*task));
913 atomic_set(&task->tk_count, 1);
914 task->tk_flags = task_setup_data->flags;
915 task->tk_ops = task_setup_data->callback_ops;
916 task->tk_calldata = task_setup_data->callback_data;
917 INIT_LIST_HEAD(&task->tk_task);
919 task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
920 task->tk_owner = current->tgid;
922 /* Initialize workqueue for async tasks */
923 task->tk_workqueue = task_setup_data->workqueue;
925 if (task->tk_ops->rpc_call_prepare != NULL)
926 task->tk_action = rpc_prepare_task;
928 rpc_init_task_statistics(task);
930 dprintk("RPC: new task initialized, procpid %u\n",
931 task_pid_nr(current));
934 static struct rpc_task *
937 return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO);
941 * Create a new task for the specified client.
943 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
945 struct rpc_task *task = setup_data->task;
946 unsigned short flags = 0;
949 task = rpc_alloc_task();
951 rpc_release_calldata(setup_data->callback_ops,
952 setup_data->callback_data);
953 return ERR_PTR(-ENOMEM);
955 flags = RPC_TASK_DYNAMIC;
958 rpc_init_task(task, setup_data);
959 task->tk_flags |= flags;
960 dprintk("RPC: allocated task %p\n", task);
965 * rpc_free_task - release rpc task and perform cleanups
967 * Note that we free up the rpc_task _after_ rpc_release_calldata()
968 * in order to work around a workqueue dependency issue.
971 * "Workqueue currently considers two work items to be the same if they're
972 * on the same address and won't execute them concurrently - ie. it
973 * makes a work item which is queued again while being executed wait
974 * for the previous execution to complete.
976 * If a work function frees the work item, and then waits for an event
977 * which should be performed by another work item and *that* work item
978 * recycles the freed work item, it can create a false dependency loop.
979 * There really is no reliable way to detect this short of verifying
980 * every memory free."
983 static void rpc_free_task(struct rpc_task *task)
985 unsigned short tk_flags = task->tk_flags;
987 rpc_release_calldata(task->tk_ops, task->tk_calldata);
989 if (tk_flags & RPC_TASK_DYNAMIC) {
990 dprintk("RPC: %5u freeing task\n", task->tk_pid);
991 mempool_free(task, rpc_task_mempool);
995 static void rpc_async_release(struct work_struct *work)
997 rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
1000 static void rpc_release_resources_task(struct rpc_task *task)
1003 if (task->tk_msg.rpc_cred) {
1004 put_rpccred(task->tk_msg.rpc_cred);
1005 task->tk_msg.rpc_cred = NULL;
1007 rpc_task_release_client(task);
1010 static void rpc_final_put_task(struct rpc_task *task,
1011 struct workqueue_struct *q)
1014 INIT_WORK(&task->u.tk_work, rpc_async_release);
1015 queue_work(q, &task->u.tk_work);
1017 rpc_free_task(task);
1020 static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1022 if (atomic_dec_and_test(&task->tk_count)) {
1023 rpc_release_resources_task(task);
1024 rpc_final_put_task(task, q);
1028 void rpc_put_task(struct rpc_task *task)
1030 rpc_do_put_task(task, NULL);
1032 EXPORT_SYMBOL_GPL(rpc_put_task);
1034 void rpc_put_task_async(struct rpc_task *task)
1036 rpc_do_put_task(task, task->tk_workqueue);
1038 EXPORT_SYMBOL_GPL(rpc_put_task_async);
1040 static void rpc_release_task(struct rpc_task *task)
1042 dprintk("RPC: %5u release task\n", task->tk_pid);
1044 WARN_ON_ONCE(RPC_IS_QUEUED(task));
1046 rpc_release_resources_task(task);
1049 * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1050 * so it should be safe to use task->tk_count as a test for whether
1051 * or not any other processes still hold references to our rpc_task.
1053 if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1054 /* Wake up anyone who may be waiting for task completion */
1055 if (!rpc_complete_task(task))
1058 if (!atomic_dec_and_test(&task->tk_count))
1061 rpc_final_put_task(task, task->tk_workqueue);
1066 return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1069 void rpciod_down(void)
1071 module_put(THIS_MODULE);
1075 * Start up the rpciod workqueue.
1077 static int rpciod_start(void)
1079 struct workqueue_struct *wq;
1082 * Create the rpciod thread and wait for it to start.
1084 dprintk("RPC: creating workqueue rpciod\n");
1085 wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 1);
1086 rpciod_workqueue = wq;
1087 return rpciod_workqueue != NULL;
1090 static void rpciod_stop(void)
1092 struct workqueue_struct *wq = NULL;
1094 if (rpciod_workqueue == NULL)
1096 dprintk("RPC: destroying workqueue rpciod\n");
1098 wq = rpciod_workqueue;
1099 rpciod_workqueue = NULL;
1100 destroy_workqueue(wq);
1104 rpc_destroy_mempool(void)
1107 if (rpc_buffer_mempool)
1108 mempool_destroy(rpc_buffer_mempool);
1109 if (rpc_task_mempool)
1110 mempool_destroy(rpc_task_mempool);
1112 kmem_cache_destroy(rpc_task_slabp);
1113 if (rpc_buffer_slabp)
1114 kmem_cache_destroy(rpc_buffer_slabp);
1115 rpc_destroy_wait_queue(&delay_queue);
1119 rpc_init_mempool(void)
1122 * The following is not strictly a mempool initialisation,
1123 * but there is no harm in doing it here
1125 rpc_init_wait_queue(&delay_queue, "delayq");
1126 if (!rpciod_start())
1129 rpc_task_slabp = kmem_cache_create("rpc_tasks",
1130 sizeof(struct rpc_task),
1131 0, SLAB_HWCACHE_ALIGN,
1133 if (!rpc_task_slabp)
1135 rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1137 0, SLAB_HWCACHE_ALIGN,
1139 if (!rpc_buffer_slabp)
1141 rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1143 if (!rpc_task_mempool)
1145 rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1147 if (!rpc_buffer_mempool)
1151 rpc_destroy_mempool();