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.
328 static void rpc_make_runnable(struct rpc_task *task)
330 rpc_clear_queued(task);
331 if (rpc_test_and_set_running(task))
333 if (RPC_IS_ASYNC(task)) {
334 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
335 queue_work(rpciod_workqueue, &task->u.tk_work);
337 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
341 * Prepare for sleeping on a wait queue.
342 * By always appending tasks to the list we ensure FIFO behavior.
343 * NB: An RPC task will only receive interrupt-driven events as long
344 * as it's on a wait queue.
346 static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
347 struct rpc_task *task,
349 unsigned char queue_priority)
351 dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
352 task->tk_pid, rpc_qname(q), jiffies);
354 trace_rpc_task_sleep(task->tk_client, task, q);
356 __rpc_add_wait_queue(q, task, queue_priority);
358 WARN_ON_ONCE(task->tk_callback != NULL);
359 task->tk_callback = action;
360 __rpc_add_timer(q, task);
363 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
366 /* We shouldn't ever put an inactive task to sleep */
367 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
368 if (!RPC_IS_ACTIVATED(task)) {
369 task->tk_status = -EIO;
370 rpc_put_task_async(task);
375 * Protect the queue operations.
377 spin_lock_bh(&q->lock);
378 __rpc_sleep_on_priority(q, task, action, task->tk_priority);
379 spin_unlock_bh(&q->lock);
381 EXPORT_SYMBOL_GPL(rpc_sleep_on);
383 void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
384 rpc_action action, int priority)
386 /* We shouldn't ever put an inactive task to sleep */
387 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
388 if (!RPC_IS_ACTIVATED(task)) {
389 task->tk_status = -EIO;
390 rpc_put_task_async(task);
395 * Protect the queue operations.
397 spin_lock_bh(&q->lock);
398 __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
399 spin_unlock_bh(&q->lock);
401 EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
404 * __rpc_do_wake_up_task - wake up a single rpc_task
406 * @task: task to be woken up
408 * Caller must hold queue->lock, and have cleared the task queued flag.
410 static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
412 dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
413 task->tk_pid, jiffies);
415 /* Has the task been executed yet? If not, we cannot wake it up! */
416 if (!RPC_IS_ACTIVATED(task)) {
417 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
421 trace_rpc_task_wakeup(task->tk_client, task, queue);
423 __rpc_remove_wait_queue(queue, task);
425 rpc_make_runnable(task);
427 dprintk("RPC: __rpc_wake_up_task done\n");
431 * Wake up a queued task while the queue lock is being held
433 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
435 if (RPC_IS_QUEUED(task)) {
437 if (task->tk_waitqueue == queue)
438 __rpc_do_wake_up_task(queue, task);
443 * Tests whether rpc queue is empty
445 int rpc_queue_empty(struct rpc_wait_queue *queue)
449 spin_lock_bh(&queue->lock);
451 spin_unlock_bh(&queue->lock);
454 EXPORT_SYMBOL_GPL(rpc_queue_empty);
457 * Wake up a task on a specific queue
459 void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
461 spin_lock_bh(&queue->lock);
462 rpc_wake_up_task_queue_locked(queue, task);
463 spin_unlock_bh(&queue->lock);
465 EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
468 * Wake up the next task on a priority queue.
470 static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
473 struct rpc_task *task;
476 * Service a batch of tasks from a single owner.
478 q = &queue->tasks[queue->priority];
479 if (!list_empty(q)) {
480 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
481 if (queue->owner == task->tk_owner) {
484 list_move_tail(&task->u.tk_wait.list, q);
487 * Check if we need to switch queues.
493 * Service the next queue.
496 if (q == &queue->tasks[0])
497 q = &queue->tasks[queue->maxpriority];
500 if (!list_empty(q)) {
501 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
504 } while (q != &queue->tasks[queue->priority]);
506 rpc_reset_waitqueue_priority(queue);
510 rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
512 rpc_set_waitqueue_owner(queue, task->tk_owner);
517 static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
519 if (RPC_IS_PRIORITY(queue))
520 return __rpc_find_next_queued_priority(queue);
521 if (!list_empty(&queue->tasks[0]))
522 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
527 * Wake up the first task on the wait queue.
529 struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
530 bool (*func)(struct rpc_task *, void *), void *data)
532 struct rpc_task *task = NULL;
534 dprintk("RPC: wake_up_first(%p \"%s\")\n",
535 queue, rpc_qname(queue));
536 spin_lock_bh(&queue->lock);
537 task = __rpc_find_next_queued(queue);
539 if (func(task, data))
540 rpc_wake_up_task_queue_locked(queue, task);
544 spin_unlock_bh(&queue->lock);
548 EXPORT_SYMBOL_GPL(rpc_wake_up_first);
550 static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
556 * Wake up the next task on the wait queue.
558 struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
560 return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
562 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
565 * rpc_wake_up - wake up all rpc_tasks
566 * @queue: rpc_wait_queue on which the tasks are sleeping
570 void rpc_wake_up(struct rpc_wait_queue *queue)
572 struct list_head *head;
574 spin_lock_bh(&queue->lock);
575 head = &queue->tasks[queue->maxpriority];
577 while (!list_empty(head)) {
578 struct rpc_task *task;
579 task = list_first_entry(head,
582 rpc_wake_up_task_queue_locked(queue, task);
584 if (head == &queue->tasks[0])
588 spin_unlock_bh(&queue->lock);
590 EXPORT_SYMBOL_GPL(rpc_wake_up);
593 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
594 * @queue: rpc_wait_queue on which the tasks are sleeping
595 * @status: status value to set
599 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
601 struct list_head *head;
603 spin_lock_bh(&queue->lock);
604 head = &queue->tasks[queue->maxpriority];
606 while (!list_empty(head)) {
607 struct rpc_task *task;
608 task = list_first_entry(head,
611 task->tk_status = status;
612 rpc_wake_up_task_queue_locked(queue, task);
614 if (head == &queue->tasks[0])
618 spin_unlock_bh(&queue->lock);
620 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
622 static void __rpc_queue_timer_fn(unsigned long ptr)
624 struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
625 struct rpc_task *task, *n;
626 unsigned long expires, now, timeo;
628 spin_lock(&queue->lock);
629 expires = now = jiffies;
630 list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
631 timeo = task->u.tk_wait.expires;
632 if (time_after_eq(now, timeo)) {
633 dprintk("RPC: %5u timeout\n", task->tk_pid);
634 task->tk_status = -ETIMEDOUT;
635 rpc_wake_up_task_queue_locked(queue, task);
638 if (expires == now || time_after(expires, timeo))
641 if (!list_empty(&queue->timer_list.list))
642 rpc_set_queue_timer(queue, expires);
643 spin_unlock(&queue->lock);
646 static void __rpc_atrun(struct rpc_task *task)
652 * Run a task at a later time
654 void rpc_delay(struct rpc_task *task, unsigned long delay)
656 task->tk_timeout = delay;
657 rpc_sleep_on(&delay_queue, task, __rpc_atrun);
659 EXPORT_SYMBOL_GPL(rpc_delay);
662 * Helper to call task->tk_ops->rpc_call_prepare
664 void rpc_prepare_task(struct rpc_task *task)
666 task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
670 rpc_init_task_statistics(struct rpc_task *task)
672 /* Initialize retry counters */
673 task->tk_garb_retry = 2;
674 task->tk_cred_retry = 2;
675 task->tk_rebind_retry = 2;
677 /* starting timestamp */
678 task->tk_start = ktime_get();
682 rpc_reset_task_statistics(struct rpc_task *task)
684 task->tk_timeouts = 0;
685 task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
687 rpc_init_task_statistics(task);
691 * Helper that calls task->tk_ops->rpc_call_done if it exists
693 void rpc_exit_task(struct rpc_task *task)
695 task->tk_action = NULL;
696 if (task->tk_ops->rpc_call_done != NULL) {
697 task->tk_ops->rpc_call_done(task, task->tk_calldata);
698 if (task->tk_action != NULL) {
699 WARN_ON(RPC_ASSASSINATED(task));
700 /* Always release the RPC slot and buffer memory */
702 rpc_reset_task_statistics(task);
707 void rpc_exit(struct rpc_task *task, int status)
709 task->tk_status = status;
710 task->tk_action = rpc_exit_task;
711 if (RPC_IS_QUEUED(task))
712 rpc_wake_up_queued_task(task->tk_waitqueue, task);
714 EXPORT_SYMBOL_GPL(rpc_exit);
716 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
718 if (ops->rpc_release != NULL)
719 ops->rpc_release(calldata);
723 * This is the RPC `scheduler' (or rather, the finite state machine).
725 static void __rpc_execute(struct rpc_task *task)
727 struct rpc_wait_queue *queue;
728 int task_is_async = RPC_IS_ASYNC(task);
731 dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
732 task->tk_pid, task->tk_flags);
734 WARN_ON_ONCE(RPC_IS_QUEUED(task));
735 if (RPC_IS_QUEUED(task))
739 void (*do_action)(struct rpc_task *);
742 * Execute any pending callback first.
744 do_action = task->tk_callback;
745 task->tk_callback = NULL;
746 if (do_action == NULL) {
748 * Perform the next FSM step.
749 * tk_action may be NULL if the task has been killed.
750 * In particular, note that rpc_killall_tasks may
751 * do this at any time, so beware when dereferencing.
753 do_action = task->tk_action;
754 if (do_action == NULL)
757 trace_rpc_task_run_action(task->tk_client, task, task->tk_action);
761 * Lockless check for whether task is sleeping or not.
763 if (!RPC_IS_QUEUED(task))
766 * The queue->lock protects against races with
767 * rpc_make_runnable().
769 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
770 * rpc_task, rpc_make_runnable() can assign it to a
771 * different workqueue. We therefore cannot assume that the
772 * rpc_task pointer may still be dereferenced.
774 queue = task->tk_waitqueue;
775 spin_lock_bh(&queue->lock);
776 if (!RPC_IS_QUEUED(task)) {
777 spin_unlock_bh(&queue->lock);
780 rpc_clear_running(task);
781 spin_unlock_bh(&queue->lock);
785 /* sync task: sleep here */
786 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
787 status = out_of_line_wait_on_bit(&task->tk_runstate,
788 RPC_TASK_QUEUED, rpc_wait_bit_killable,
790 if (status == -ERESTARTSYS) {
792 * When a sync task receives a signal, it exits with
793 * -ERESTARTSYS. In order to catch any callbacks that
794 * clean up after sleeping on some queue, we don't
795 * break the loop here, but go around once more.
797 dprintk("RPC: %5u got signal\n", task->tk_pid);
798 task->tk_flags |= RPC_TASK_KILLED;
799 rpc_exit(task, -ERESTARTSYS);
801 rpc_set_running(task);
802 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
805 dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
807 /* Release all resources associated with the task */
808 rpc_release_task(task);
812 * User-visible entry point to the scheduler.
814 * This may be called recursively if e.g. an async NFS task updates
815 * the attributes and finds that dirty pages must be flushed.
816 * NOTE: Upon exit of this function the task is guaranteed to be
817 * released. In particular note that tk_release() will have
818 * been called, so your task memory may have been freed.
820 void rpc_execute(struct rpc_task *task)
822 rpc_set_active(task);
823 rpc_make_runnable(task);
824 if (!RPC_IS_ASYNC(task))
828 static void rpc_async_schedule(struct work_struct *work)
830 current->flags |= PF_FSTRANS;
831 __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
832 current->flags &= ~PF_FSTRANS;
836 * rpc_malloc - allocate an RPC buffer
837 * @task: RPC task that will use this buffer
838 * @size: requested byte size
840 * To prevent rpciod from hanging, this allocator never sleeps,
841 * returning NULL if the request cannot be serviced immediately.
842 * The caller can arrange to sleep in a way that is safe for rpciod.
844 * Most requests are 'small' (under 2KiB) and can be serviced from a
845 * mempool, ensuring that NFS reads and writes can always proceed,
846 * and that there is good locality of reference for these buffers.
848 * In order to avoid memory starvation triggering more writebacks of
849 * NFS requests, we avoid using GFP_KERNEL.
851 void *rpc_malloc(struct rpc_task *task, size_t size)
853 struct rpc_buffer *buf;
854 gfp_t gfp = GFP_NOWAIT;
856 if (RPC_IS_SWAPPER(task))
857 gfp |= __GFP_MEMALLOC;
859 size += sizeof(struct rpc_buffer);
860 if (size <= RPC_BUFFER_MAXSIZE)
861 buf = mempool_alloc(rpc_buffer_mempool, gfp);
863 buf = kmalloc(size, gfp);
869 dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
870 task->tk_pid, size, buf);
873 EXPORT_SYMBOL_GPL(rpc_malloc);
876 * rpc_free - free buffer allocated via rpc_malloc
877 * @buffer: buffer to free
880 void rpc_free(void *buffer)
883 struct rpc_buffer *buf;
888 buf = container_of(buffer, struct rpc_buffer, data);
891 dprintk("RPC: freeing buffer of size %zu at %p\n",
894 if (size <= RPC_BUFFER_MAXSIZE)
895 mempool_free(buf, rpc_buffer_mempool);
899 EXPORT_SYMBOL_GPL(rpc_free);
902 * Creation and deletion of RPC task structures
904 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
906 memset(task, 0, sizeof(*task));
907 atomic_set(&task->tk_count, 1);
908 task->tk_flags = task_setup_data->flags;
909 task->tk_ops = task_setup_data->callback_ops;
910 task->tk_calldata = task_setup_data->callback_data;
911 INIT_LIST_HEAD(&task->tk_task);
913 task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
914 task->tk_owner = current->tgid;
916 /* Initialize workqueue for async tasks */
917 task->tk_workqueue = task_setup_data->workqueue;
919 if (task->tk_ops->rpc_call_prepare != NULL)
920 task->tk_action = rpc_prepare_task;
922 rpc_init_task_statistics(task);
924 dprintk("RPC: new task initialized, procpid %u\n",
925 task_pid_nr(current));
928 static struct rpc_task *
931 return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO);
935 * Create a new task for the specified client.
937 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
939 struct rpc_task *task = setup_data->task;
940 unsigned short flags = 0;
943 task = rpc_alloc_task();
945 rpc_release_calldata(setup_data->callback_ops,
946 setup_data->callback_data);
947 return ERR_PTR(-ENOMEM);
949 flags = RPC_TASK_DYNAMIC;
952 rpc_init_task(task, setup_data);
953 task->tk_flags |= flags;
954 dprintk("RPC: allocated task %p\n", task);
959 * rpc_free_task - release rpc task and perform cleanups
961 * Note that we free up the rpc_task _after_ rpc_release_calldata()
962 * in order to work around a workqueue dependency issue.
965 * "Workqueue currently considers two work items to be the same if they're
966 * on the same address and won't execute them concurrently - ie. it
967 * makes a work item which is queued again while being executed wait
968 * for the previous execution to complete.
970 * If a work function frees the work item, and then waits for an event
971 * which should be performed by another work item and *that* work item
972 * recycles the freed work item, it can create a false dependency loop.
973 * There really is no reliable way to detect this short of verifying
974 * every memory free."
977 static void rpc_free_task(struct rpc_task *task)
979 unsigned short tk_flags = task->tk_flags;
981 rpc_release_calldata(task->tk_ops, task->tk_calldata);
983 if (tk_flags & RPC_TASK_DYNAMIC) {
984 dprintk("RPC: %5u freeing task\n", task->tk_pid);
985 mempool_free(task, rpc_task_mempool);
989 static void rpc_async_release(struct work_struct *work)
991 rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
994 static void rpc_release_resources_task(struct rpc_task *task)
997 if (task->tk_msg.rpc_cred) {
998 put_rpccred(task->tk_msg.rpc_cred);
999 task->tk_msg.rpc_cred = NULL;
1001 rpc_task_release_client(task);
1004 static void rpc_final_put_task(struct rpc_task *task,
1005 struct workqueue_struct *q)
1008 INIT_WORK(&task->u.tk_work, rpc_async_release);
1009 queue_work(q, &task->u.tk_work);
1011 rpc_free_task(task);
1014 static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1016 if (atomic_dec_and_test(&task->tk_count)) {
1017 rpc_release_resources_task(task);
1018 rpc_final_put_task(task, q);
1022 void rpc_put_task(struct rpc_task *task)
1024 rpc_do_put_task(task, NULL);
1026 EXPORT_SYMBOL_GPL(rpc_put_task);
1028 void rpc_put_task_async(struct rpc_task *task)
1030 rpc_do_put_task(task, task->tk_workqueue);
1032 EXPORT_SYMBOL_GPL(rpc_put_task_async);
1034 static void rpc_release_task(struct rpc_task *task)
1036 dprintk("RPC: %5u release task\n", task->tk_pid);
1038 WARN_ON_ONCE(RPC_IS_QUEUED(task));
1040 rpc_release_resources_task(task);
1043 * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1044 * so it should be safe to use task->tk_count as a test for whether
1045 * or not any other processes still hold references to our rpc_task.
1047 if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1048 /* Wake up anyone who may be waiting for task completion */
1049 if (!rpc_complete_task(task))
1052 if (!atomic_dec_and_test(&task->tk_count))
1055 rpc_final_put_task(task, task->tk_workqueue);
1060 return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1063 void rpciod_down(void)
1065 module_put(THIS_MODULE);
1069 * Start up the rpciod workqueue.
1071 static int rpciod_start(void)
1073 struct workqueue_struct *wq;
1076 * Create the rpciod thread and wait for it to start.
1078 dprintk("RPC: creating workqueue rpciod\n");
1079 wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 1);
1080 rpciod_workqueue = wq;
1081 return rpciod_workqueue != NULL;
1084 static void rpciod_stop(void)
1086 struct workqueue_struct *wq = NULL;
1088 if (rpciod_workqueue == NULL)
1090 dprintk("RPC: destroying workqueue rpciod\n");
1092 wq = rpciod_workqueue;
1093 rpciod_workqueue = NULL;
1094 destroy_workqueue(wq);
1098 rpc_destroy_mempool(void)
1101 if (rpc_buffer_mempool)
1102 mempool_destroy(rpc_buffer_mempool);
1103 if (rpc_task_mempool)
1104 mempool_destroy(rpc_task_mempool);
1106 kmem_cache_destroy(rpc_task_slabp);
1107 if (rpc_buffer_slabp)
1108 kmem_cache_destroy(rpc_buffer_slabp);
1109 rpc_destroy_wait_queue(&delay_queue);
1113 rpc_init_mempool(void)
1116 * The following is not strictly a mempool initialisation,
1117 * but there is no harm in doing it here
1119 rpc_init_wait_queue(&delay_queue, "delayq");
1120 if (!rpciod_start())
1123 rpc_task_slabp = kmem_cache_create("rpc_tasks",
1124 sizeof(struct rpc_task),
1125 0, SLAB_HWCACHE_ALIGN,
1127 if (!rpc_task_slabp)
1129 rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1131 0, SLAB_HWCACHE_ALIGN,
1133 if (!rpc_buffer_slabp)
1135 rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1137 if (!rpc_task_mempool)
1139 rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1141 if (!rpc_buffer_mempool)
1145 rpc_destroy_mempool();