Linux 4.13.16
[linux/fpc-iii.git] / net / sunrpc / sched.c
blob0cc83839c13c3621a70a4b9e8ded773217a2edf3
1 /*
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>
25 #include "sunrpc.h"
27 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
28 #define RPCDBG_FACILITY RPCDBG_SCHED
29 #endif
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 __read_mostly;
58 struct workqueue_struct *xprtiod_workqueue __read_mostly;
61 * Disable the timer for a given RPC task. Should be called with
62 * queue->lock and bh_disabled in order to avoid races within
63 * rpc_run_timer().
65 static void
66 __rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
68 if (task->tk_timeout == 0)
69 return;
70 dprintk("RPC: %5u disabling timer\n", task->tk_pid);
71 task->tk_timeout = 0;
72 list_del(&task->u.tk_wait.timer_list);
73 if (list_empty(&queue->timer_list.list))
74 del_timer(&queue->timer_list.timer);
77 static void
78 rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
80 queue->timer_list.expires = expires;
81 mod_timer(&queue->timer_list.timer, expires);
85 * Set up a timer for the current task.
87 static void
88 __rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
90 if (!task->tk_timeout)
91 return;
93 dprintk("RPC: %5u setting alarm for %u ms\n",
94 task->tk_pid, jiffies_to_msecs(task->tk_timeout));
96 task->u.tk_wait.expires = jiffies + task->tk_timeout;
97 if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
98 rpc_set_queue_timer(queue, task->u.tk_wait.expires);
99 list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
102 static void rpc_rotate_queue_owner(struct rpc_wait_queue *queue)
104 struct list_head *q = &queue->tasks[queue->priority];
105 struct rpc_task *task;
107 if (!list_empty(q)) {
108 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
109 if (task->tk_owner == queue->owner)
110 list_move_tail(&task->u.tk_wait.list, q);
114 static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
116 if (queue->priority != priority) {
117 /* Fairness: rotate the list when changing priority */
118 rpc_rotate_queue_owner(queue);
119 queue->priority = priority;
123 static void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
125 queue->owner = pid;
126 queue->nr = RPC_BATCH_COUNT;
129 static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
131 rpc_set_waitqueue_priority(queue, queue->maxpriority);
132 rpc_set_waitqueue_owner(queue, 0);
136 * Add new request to a priority queue.
138 static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
139 struct rpc_task *task,
140 unsigned char queue_priority)
142 struct list_head *q;
143 struct rpc_task *t;
145 INIT_LIST_HEAD(&task->u.tk_wait.links);
146 if (unlikely(queue_priority > queue->maxpriority))
147 queue_priority = queue->maxpriority;
148 if (queue_priority > queue->priority)
149 rpc_set_waitqueue_priority(queue, queue_priority);
150 q = &queue->tasks[queue_priority];
151 list_for_each_entry(t, q, u.tk_wait.list) {
152 if (t->tk_owner == task->tk_owner) {
153 list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
154 return;
157 list_add_tail(&task->u.tk_wait.list, q);
161 * Add new request to wait queue.
163 * Swapper tasks always get inserted at the head of the queue.
164 * This should avoid many nasty memory deadlocks and hopefully
165 * improve overall performance.
166 * Everyone else gets appended to the queue to ensure proper FIFO behavior.
168 static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
169 struct rpc_task *task,
170 unsigned char queue_priority)
172 WARN_ON_ONCE(RPC_IS_QUEUED(task));
173 if (RPC_IS_QUEUED(task))
174 return;
176 if (RPC_IS_PRIORITY(queue))
177 __rpc_add_wait_queue_priority(queue, task, queue_priority);
178 else if (RPC_IS_SWAPPER(task))
179 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
180 else
181 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
182 task->tk_waitqueue = queue;
183 queue->qlen++;
184 /* barrier matches the read in rpc_wake_up_task_queue_locked() */
185 smp_wmb();
186 rpc_set_queued(task);
188 dprintk("RPC: %5u added to queue %p \"%s\"\n",
189 task->tk_pid, queue, rpc_qname(queue));
193 * Remove request from a priority queue.
195 static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
197 struct rpc_task *t;
199 if (!list_empty(&task->u.tk_wait.links)) {
200 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
201 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
202 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
207 * Remove request from queue.
208 * Note: must be called with spin lock held.
210 static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
212 __rpc_disable_timer(queue, task);
213 if (RPC_IS_PRIORITY(queue))
214 __rpc_remove_wait_queue_priority(task);
215 list_del(&task->u.tk_wait.list);
216 queue->qlen--;
217 dprintk("RPC: %5u removed from queue %p \"%s\"\n",
218 task->tk_pid, queue, rpc_qname(queue));
221 static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
223 int i;
225 spin_lock_init(&queue->lock);
226 for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
227 INIT_LIST_HEAD(&queue->tasks[i]);
228 queue->maxpriority = nr_queues - 1;
229 rpc_reset_waitqueue_priority(queue);
230 queue->qlen = 0;
231 setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
232 INIT_LIST_HEAD(&queue->timer_list.list);
233 rpc_assign_waitqueue_name(queue, qname);
236 void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
238 __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
240 EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
242 void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
244 __rpc_init_priority_wait_queue(queue, qname, 1);
246 EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
248 void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
250 del_timer_sync(&queue->timer_list.timer);
252 EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
254 static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode)
256 freezable_schedule_unsafe();
257 if (signal_pending_state(mode, current))
258 return -ERESTARTSYS;
259 return 0;
262 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) || IS_ENABLED(CONFIG_TRACEPOINTS)
263 static void rpc_task_set_debuginfo(struct rpc_task *task)
265 static atomic_t rpc_pid;
267 task->tk_pid = atomic_inc_return(&rpc_pid);
269 #else
270 static inline void rpc_task_set_debuginfo(struct rpc_task *task)
273 #endif
275 static void rpc_set_active(struct rpc_task *task)
277 trace_rpc_task_begin(task->tk_client, task, NULL);
279 rpc_task_set_debuginfo(task);
280 set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
284 * Mark an RPC call as having completed by clearing the 'active' bit
285 * and then waking up all tasks that were sleeping.
287 static int rpc_complete_task(struct rpc_task *task)
289 void *m = &task->tk_runstate;
290 wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
291 struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
292 unsigned long flags;
293 int ret;
295 trace_rpc_task_complete(task->tk_client, task, NULL);
297 spin_lock_irqsave(&wq->lock, flags);
298 clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
299 ret = atomic_dec_and_test(&task->tk_count);
300 if (waitqueue_active(wq))
301 __wake_up_locked_key(wq, TASK_NORMAL, &k);
302 spin_unlock_irqrestore(&wq->lock, flags);
303 return ret;
307 * Allow callers to wait for completion of an RPC call
309 * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
310 * to enforce taking of the wq->lock and hence avoid races with
311 * rpc_complete_task().
313 int __rpc_wait_for_completion_task(struct rpc_task *task, wait_bit_action_f *action)
315 if (action == NULL)
316 action = rpc_wait_bit_killable;
317 return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
318 action, TASK_KILLABLE);
320 EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
323 * Make an RPC task runnable.
325 * Note: If the task is ASYNC, and is being made runnable after sitting on an
326 * rpc_wait_queue, this must be called with the queue spinlock held to protect
327 * the wait queue operation.
328 * Note the ordering of rpc_test_and_set_running() and rpc_clear_queued(),
329 * which is needed to ensure that __rpc_execute() doesn't loop (due to the
330 * lockless RPC_IS_QUEUED() test) before we've had a chance to test
331 * the RPC_TASK_RUNNING flag.
333 static void rpc_make_runnable(struct workqueue_struct *wq,
334 struct rpc_task *task)
336 bool need_wakeup = !rpc_test_and_set_running(task);
338 rpc_clear_queued(task);
339 if (!need_wakeup)
340 return;
341 if (RPC_IS_ASYNC(task)) {
342 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
343 queue_work(wq, &task->u.tk_work);
344 } else
345 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
349 * Prepare for sleeping on a wait queue.
350 * By always appending tasks to the list we ensure FIFO behavior.
351 * NB: An RPC task will only receive interrupt-driven events as long
352 * as it's on a wait queue.
354 static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
355 struct rpc_task *task,
356 rpc_action action,
357 unsigned char queue_priority)
359 dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
360 task->tk_pid, rpc_qname(q), jiffies);
362 trace_rpc_task_sleep(task->tk_client, task, q);
364 __rpc_add_wait_queue(q, task, queue_priority);
366 WARN_ON_ONCE(task->tk_callback != NULL);
367 task->tk_callback = action;
368 __rpc_add_timer(q, task);
371 void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
372 rpc_action action)
374 /* We shouldn't ever put an inactive task to sleep */
375 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
376 if (!RPC_IS_ACTIVATED(task)) {
377 task->tk_status = -EIO;
378 rpc_put_task_async(task);
379 return;
383 * Protect the queue operations.
385 spin_lock_bh(&q->lock);
386 __rpc_sleep_on_priority(q, task, action, task->tk_priority);
387 spin_unlock_bh(&q->lock);
389 EXPORT_SYMBOL_GPL(rpc_sleep_on);
391 void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
392 rpc_action action, int priority)
394 /* We shouldn't ever put an inactive task to sleep */
395 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
396 if (!RPC_IS_ACTIVATED(task)) {
397 task->tk_status = -EIO;
398 rpc_put_task_async(task);
399 return;
403 * Protect the queue operations.
405 spin_lock_bh(&q->lock);
406 __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
407 spin_unlock_bh(&q->lock);
409 EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
412 * __rpc_do_wake_up_task_on_wq - wake up a single rpc_task
413 * @wq: workqueue on which to run task
414 * @queue: wait queue
415 * @task: task to be woken up
417 * Caller must hold queue->lock, and have cleared the task queued flag.
419 static void __rpc_do_wake_up_task_on_wq(struct workqueue_struct *wq,
420 struct rpc_wait_queue *queue,
421 struct rpc_task *task)
423 dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
424 task->tk_pid, jiffies);
426 /* Has the task been executed yet? If not, we cannot wake it up! */
427 if (!RPC_IS_ACTIVATED(task)) {
428 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
429 return;
432 trace_rpc_task_wakeup(task->tk_client, task, queue);
434 __rpc_remove_wait_queue(queue, task);
436 rpc_make_runnable(wq, task);
438 dprintk("RPC: __rpc_wake_up_task done\n");
442 * Wake up a queued task while the queue lock is being held
444 static void rpc_wake_up_task_on_wq_queue_locked(struct workqueue_struct *wq,
445 struct rpc_wait_queue *queue, struct rpc_task *task)
447 if (RPC_IS_QUEUED(task)) {
448 smp_rmb();
449 if (task->tk_waitqueue == queue)
450 __rpc_do_wake_up_task_on_wq(wq, queue, task);
455 * Wake up a queued task while the queue lock is being held
457 static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
459 rpc_wake_up_task_on_wq_queue_locked(rpciod_workqueue, queue, task);
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)
478 struct list_head *q;
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) {
488 if (--queue->nr)
489 goto out;
490 list_move_tail(&task->u.tk_wait.list, q);
493 * Check if we need to switch queues.
495 goto new_owner;
499 * Service the next queue.
501 do {
502 if (q == &queue->tasks[0])
503 q = &queue->tasks[queue->maxpriority];
504 else
505 q = q - 1;
506 if (!list_empty(q)) {
507 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
508 goto new_queue;
510 } while (q != &queue->tasks[queue->priority]);
512 rpc_reset_waitqueue_priority(queue);
513 return NULL;
515 new_queue:
516 rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
517 new_owner:
518 rpc_set_waitqueue_owner(queue, task->tk_owner);
519 out:
520 return task;
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);
529 return NULL;
533 * Wake up the first task on the wait queue.
535 struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq,
536 struct rpc_wait_queue *queue,
537 bool (*func)(struct rpc_task *, void *), void *data)
539 struct rpc_task *task = NULL;
541 dprintk("RPC: wake_up_first(%p \"%s\")\n",
542 queue, rpc_qname(queue));
543 spin_lock_bh(&queue->lock);
544 task = __rpc_find_next_queued(queue);
545 if (task != NULL) {
546 if (func(task, data))
547 rpc_wake_up_task_on_wq_queue_locked(wq, queue, task);
548 else
549 task = NULL;
551 spin_unlock_bh(&queue->lock);
553 return task;
557 * Wake up the first task on the wait queue.
559 struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
560 bool (*func)(struct rpc_task *, void *), void *data)
562 return rpc_wake_up_first_on_wq(rpciod_workqueue, queue, func, data);
564 EXPORT_SYMBOL_GPL(rpc_wake_up_first);
566 static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
568 return true;
572 * Wake up the next task on the wait queue.
574 struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
576 return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
578 EXPORT_SYMBOL_GPL(rpc_wake_up_next);
581 * rpc_wake_up - wake up all rpc_tasks
582 * @queue: rpc_wait_queue on which the tasks are sleeping
584 * Grabs queue->lock
586 void rpc_wake_up(struct rpc_wait_queue *queue)
588 struct list_head *head;
590 spin_lock_bh(&queue->lock);
591 head = &queue->tasks[queue->maxpriority];
592 for (;;) {
593 while (!list_empty(head)) {
594 struct rpc_task *task;
595 task = list_first_entry(head,
596 struct rpc_task,
597 u.tk_wait.list);
598 rpc_wake_up_task_queue_locked(queue, task);
600 if (head == &queue->tasks[0])
601 break;
602 head--;
604 spin_unlock_bh(&queue->lock);
606 EXPORT_SYMBOL_GPL(rpc_wake_up);
609 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
610 * @queue: rpc_wait_queue on which the tasks are sleeping
611 * @status: status value to set
613 * Grabs queue->lock
615 void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
617 struct list_head *head;
619 spin_lock_bh(&queue->lock);
620 head = &queue->tasks[queue->maxpriority];
621 for (;;) {
622 while (!list_empty(head)) {
623 struct rpc_task *task;
624 task = list_first_entry(head,
625 struct rpc_task,
626 u.tk_wait.list);
627 task->tk_status = status;
628 rpc_wake_up_task_queue_locked(queue, task);
630 if (head == &queue->tasks[0])
631 break;
632 head--;
634 spin_unlock_bh(&queue->lock);
636 EXPORT_SYMBOL_GPL(rpc_wake_up_status);
638 static void __rpc_queue_timer_fn(unsigned long ptr)
640 struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
641 struct rpc_task *task, *n;
642 unsigned long expires, now, timeo;
644 spin_lock(&queue->lock);
645 expires = now = jiffies;
646 list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
647 timeo = task->u.tk_wait.expires;
648 if (time_after_eq(now, timeo)) {
649 dprintk("RPC: %5u timeout\n", task->tk_pid);
650 task->tk_status = -ETIMEDOUT;
651 rpc_wake_up_task_queue_locked(queue, task);
652 continue;
654 if (expires == now || time_after(expires, timeo))
655 expires = timeo;
657 if (!list_empty(&queue->timer_list.list))
658 rpc_set_queue_timer(queue, expires);
659 spin_unlock(&queue->lock);
662 static void __rpc_atrun(struct rpc_task *task)
664 if (task->tk_status == -ETIMEDOUT)
665 task->tk_status = 0;
669 * Run a task at a later time
671 void rpc_delay(struct rpc_task *task, unsigned long delay)
673 task->tk_timeout = delay;
674 rpc_sleep_on(&delay_queue, task, __rpc_atrun);
676 EXPORT_SYMBOL_GPL(rpc_delay);
679 * Helper to call task->tk_ops->rpc_call_prepare
681 void rpc_prepare_task(struct rpc_task *task)
683 task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
686 static void
687 rpc_init_task_statistics(struct rpc_task *task)
689 /* Initialize retry counters */
690 task->tk_garb_retry = 2;
691 task->tk_cred_retry = 2;
692 task->tk_rebind_retry = 2;
694 /* starting timestamp */
695 task->tk_start = ktime_get();
698 static void
699 rpc_reset_task_statistics(struct rpc_task *task)
701 task->tk_timeouts = 0;
702 task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
704 rpc_init_task_statistics(task);
708 * Helper that calls task->tk_ops->rpc_call_done if it exists
710 void rpc_exit_task(struct rpc_task *task)
712 task->tk_action = NULL;
713 if (task->tk_ops->rpc_call_done != NULL) {
714 task->tk_ops->rpc_call_done(task, task->tk_calldata);
715 if (task->tk_action != NULL) {
716 WARN_ON(RPC_ASSASSINATED(task));
717 /* Always release the RPC slot and buffer memory */
718 xprt_release(task);
719 rpc_reset_task_statistics(task);
724 void rpc_exit(struct rpc_task *task, int status)
726 task->tk_status = status;
727 task->tk_action = rpc_exit_task;
728 if (RPC_IS_QUEUED(task))
729 rpc_wake_up_queued_task(task->tk_waitqueue, task);
731 EXPORT_SYMBOL_GPL(rpc_exit);
733 void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
735 if (ops->rpc_release != NULL)
736 ops->rpc_release(calldata);
740 * This is the RPC `scheduler' (or rather, the finite state machine).
742 static void __rpc_execute(struct rpc_task *task)
744 struct rpc_wait_queue *queue;
745 int task_is_async = RPC_IS_ASYNC(task);
746 int status = 0;
748 dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
749 task->tk_pid, task->tk_flags);
751 WARN_ON_ONCE(RPC_IS_QUEUED(task));
752 if (RPC_IS_QUEUED(task))
753 return;
755 for (;;) {
756 void (*do_action)(struct rpc_task *);
759 * Execute any pending callback first.
761 do_action = task->tk_callback;
762 task->tk_callback = NULL;
763 if (do_action == NULL) {
765 * Perform the next FSM step.
766 * tk_action may be NULL if the task has been killed.
767 * In particular, note that rpc_killall_tasks may
768 * do this at any time, so beware when dereferencing.
770 do_action = task->tk_action;
771 if (do_action == NULL)
772 break;
774 trace_rpc_task_run_action(task->tk_client, task, task->tk_action);
775 do_action(task);
778 * Lockless check for whether task is sleeping or not.
780 if (!RPC_IS_QUEUED(task))
781 continue;
783 * The queue->lock protects against races with
784 * rpc_make_runnable().
786 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
787 * rpc_task, rpc_make_runnable() can assign it to a
788 * different workqueue. We therefore cannot assume that the
789 * rpc_task pointer may still be dereferenced.
791 queue = task->tk_waitqueue;
792 spin_lock_bh(&queue->lock);
793 if (!RPC_IS_QUEUED(task)) {
794 spin_unlock_bh(&queue->lock);
795 continue;
797 rpc_clear_running(task);
798 spin_unlock_bh(&queue->lock);
799 if (task_is_async)
800 return;
802 /* sync task: sleep here */
803 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
804 status = out_of_line_wait_on_bit(&task->tk_runstate,
805 RPC_TASK_QUEUED, rpc_wait_bit_killable,
806 TASK_KILLABLE);
807 if (status == -ERESTARTSYS) {
809 * When a sync task receives a signal, it exits with
810 * -ERESTARTSYS. In order to catch any callbacks that
811 * clean up after sleeping on some queue, we don't
812 * break the loop here, but go around once more.
814 dprintk("RPC: %5u got signal\n", task->tk_pid);
815 task->tk_flags |= RPC_TASK_KILLED;
816 rpc_exit(task, -ERESTARTSYS);
818 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
821 dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
822 task->tk_status);
823 /* Release all resources associated with the task */
824 rpc_release_task(task);
828 * User-visible entry point to the scheduler.
830 * This may be called recursively if e.g. an async NFS task updates
831 * the attributes and finds that dirty pages must be flushed.
832 * NOTE: Upon exit of this function the task is guaranteed to be
833 * released. In particular note that tk_release() will have
834 * been called, so your task memory may have been freed.
836 void rpc_execute(struct rpc_task *task)
838 bool is_async = RPC_IS_ASYNC(task);
840 rpc_set_active(task);
841 rpc_make_runnable(rpciod_workqueue, task);
842 if (!is_async)
843 __rpc_execute(task);
846 static void rpc_async_schedule(struct work_struct *work)
848 __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
852 * rpc_malloc - allocate RPC buffer resources
853 * @task: RPC task
855 * A single memory region is allocated, which is split between the
856 * RPC call and RPC reply that this task is being used for. When
857 * this RPC is retired, the memory is released by calling rpc_free.
859 * To prevent rpciod from hanging, this allocator never sleeps,
860 * returning -ENOMEM and suppressing warning if the request cannot
861 * be serviced immediately. The caller can arrange to sleep in a
862 * way that is safe for rpciod.
864 * Most requests are 'small' (under 2KiB) and can be serviced from a
865 * mempool, ensuring that NFS reads and writes can always proceed,
866 * and that there is good locality of reference for these buffers.
868 * In order to avoid memory starvation triggering more writebacks of
869 * NFS requests, we avoid using GFP_KERNEL.
871 int rpc_malloc(struct rpc_task *task)
873 struct rpc_rqst *rqst = task->tk_rqstp;
874 size_t size = rqst->rq_callsize + rqst->rq_rcvsize;
875 struct rpc_buffer *buf;
876 gfp_t gfp = GFP_NOIO | __GFP_NOWARN;
878 if (RPC_IS_SWAPPER(task))
879 gfp = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN;
881 size += sizeof(struct rpc_buffer);
882 if (size <= RPC_BUFFER_MAXSIZE)
883 buf = mempool_alloc(rpc_buffer_mempool, gfp);
884 else
885 buf = kmalloc(size, gfp);
887 if (!buf)
888 return -ENOMEM;
890 buf->len = size;
891 dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
892 task->tk_pid, size, buf);
893 rqst->rq_buffer = buf->data;
894 rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_callsize;
895 return 0;
897 EXPORT_SYMBOL_GPL(rpc_malloc);
900 * rpc_free - free RPC buffer resources allocated via rpc_malloc
901 * @task: RPC task
904 void rpc_free(struct rpc_task *task)
906 void *buffer = task->tk_rqstp->rq_buffer;
907 size_t size;
908 struct rpc_buffer *buf;
910 buf = container_of(buffer, struct rpc_buffer, data);
911 size = buf->len;
913 dprintk("RPC: freeing buffer of size %zu at %p\n",
914 size, buf);
916 if (size <= RPC_BUFFER_MAXSIZE)
917 mempool_free(buf, rpc_buffer_mempool);
918 else
919 kfree(buf);
921 EXPORT_SYMBOL_GPL(rpc_free);
924 * Creation and deletion of RPC task structures
926 static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
928 memset(task, 0, sizeof(*task));
929 atomic_set(&task->tk_count, 1);
930 task->tk_flags = task_setup_data->flags;
931 task->tk_ops = task_setup_data->callback_ops;
932 task->tk_calldata = task_setup_data->callback_data;
933 INIT_LIST_HEAD(&task->tk_task);
935 task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
936 task->tk_owner = current->tgid;
938 /* Initialize workqueue for async tasks */
939 task->tk_workqueue = task_setup_data->workqueue;
941 task->tk_xprt = xprt_get(task_setup_data->rpc_xprt);
943 if (task->tk_ops->rpc_call_prepare != NULL)
944 task->tk_action = rpc_prepare_task;
946 rpc_init_task_statistics(task);
948 dprintk("RPC: new task initialized, procpid %u\n",
949 task_pid_nr(current));
952 static struct rpc_task *
953 rpc_alloc_task(void)
955 return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO);
959 * Create a new task for the specified client.
961 struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
963 struct rpc_task *task = setup_data->task;
964 unsigned short flags = 0;
966 if (task == NULL) {
967 task = rpc_alloc_task();
968 flags = RPC_TASK_DYNAMIC;
971 rpc_init_task(task, setup_data);
972 task->tk_flags |= flags;
973 dprintk("RPC: allocated task %p\n", task);
974 return task;
978 * rpc_free_task - release rpc task and perform cleanups
980 * Note that we free up the rpc_task _after_ rpc_release_calldata()
981 * in order to work around a workqueue dependency issue.
983 * Tejun Heo states:
984 * "Workqueue currently considers two work items to be the same if they're
985 * on the same address and won't execute them concurrently - ie. it
986 * makes a work item which is queued again while being executed wait
987 * for the previous execution to complete.
989 * If a work function frees the work item, and then waits for an event
990 * which should be performed by another work item and *that* work item
991 * recycles the freed work item, it can create a false dependency loop.
992 * There really is no reliable way to detect this short of verifying
993 * every memory free."
996 static void rpc_free_task(struct rpc_task *task)
998 unsigned short tk_flags = task->tk_flags;
1000 rpc_release_calldata(task->tk_ops, task->tk_calldata);
1002 if (tk_flags & RPC_TASK_DYNAMIC) {
1003 dprintk("RPC: %5u freeing task\n", task->tk_pid);
1004 mempool_free(task, rpc_task_mempool);
1008 static void rpc_async_release(struct work_struct *work)
1010 rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
1013 static void rpc_release_resources_task(struct rpc_task *task)
1015 xprt_release(task);
1016 if (task->tk_msg.rpc_cred) {
1017 put_rpccred(task->tk_msg.rpc_cred);
1018 task->tk_msg.rpc_cred = NULL;
1020 rpc_task_release_client(task);
1023 static void rpc_final_put_task(struct rpc_task *task,
1024 struct workqueue_struct *q)
1026 if (q != NULL) {
1027 INIT_WORK(&task->u.tk_work, rpc_async_release);
1028 queue_work(q, &task->u.tk_work);
1029 } else
1030 rpc_free_task(task);
1033 static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1035 if (atomic_dec_and_test(&task->tk_count)) {
1036 rpc_release_resources_task(task);
1037 rpc_final_put_task(task, q);
1041 void rpc_put_task(struct rpc_task *task)
1043 rpc_do_put_task(task, NULL);
1045 EXPORT_SYMBOL_GPL(rpc_put_task);
1047 void rpc_put_task_async(struct rpc_task *task)
1049 rpc_do_put_task(task, task->tk_workqueue);
1051 EXPORT_SYMBOL_GPL(rpc_put_task_async);
1053 static void rpc_release_task(struct rpc_task *task)
1055 dprintk("RPC: %5u release task\n", task->tk_pid);
1057 WARN_ON_ONCE(RPC_IS_QUEUED(task));
1059 rpc_release_resources_task(task);
1062 * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1063 * so it should be safe to use task->tk_count as a test for whether
1064 * or not any other processes still hold references to our rpc_task.
1066 if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1067 /* Wake up anyone who may be waiting for task completion */
1068 if (!rpc_complete_task(task))
1069 return;
1070 } else {
1071 if (!atomic_dec_and_test(&task->tk_count))
1072 return;
1074 rpc_final_put_task(task, task->tk_workqueue);
1077 int rpciod_up(void)
1079 return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1082 void rpciod_down(void)
1084 module_put(THIS_MODULE);
1088 * Start up the rpciod workqueue.
1090 static int rpciod_start(void)
1092 struct workqueue_struct *wq;
1095 * Create the rpciod thread and wait for it to start.
1097 dprintk("RPC: creating workqueue rpciod\n");
1098 wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 0);
1099 if (!wq)
1100 goto out_failed;
1101 rpciod_workqueue = wq;
1102 /* Note: highpri because network receive is latency sensitive */
1103 wq = alloc_workqueue("xprtiod", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1104 if (!wq)
1105 goto free_rpciod;
1106 xprtiod_workqueue = wq;
1107 return 1;
1108 free_rpciod:
1109 wq = rpciod_workqueue;
1110 rpciod_workqueue = NULL;
1111 destroy_workqueue(wq);
1112 out_failed:
1113 return 0;
1116 static void rpciod_stop(void)
1118 struct workqueue_struct *wq = NULL;
1120 if (rpciod_workqueue == NULL)
1121 return;
1122 dprintk("RPC: destroying workqueue rpciod\n");
1124 wq = rpciod_workqueue;
1125 rpciod_workqueue = NULL;
1126 destroy_workqueue(wq);
1127 wq = xprtiod_workqueue;
1128 xprtiod_workqueue = NULL;
1129 destroy_workqueue(wq);
1132 void
1133 rpc_destroy_mempool(void)
1135 rpciod_stop();
1136 mempool_destroy(rpc_buffer_mempool);
1137 mempool_destroy(rpc_task_mempool);
1138 kmem_cache_destroy(rpc_task_slabp);
1139 kmem_cache_destroy(rpc_buffer_slabp);
1140 rpc_destroy_wait_queue(&delay_queue);
1144 rpc_init_mempool(void)
1147 * The following is not strictly a mempool initialisation,
1148 * but there is no harm in doing it here
1150 rpc_init_wait_queue(&delay_queue, "delayq");
1151 if (!rpciod_start())
1152 goto err_nomem;
1154 rpc_task_slabp = kmem_cache_create("rpc_tasks",
1155 sizeof(struct rpc_task),
1156 0, SLAB_HWCACHE_ALIGN,
1157 NULL);
1158 if (!rpc_task_slabp)
1159 goto err_nomem;
1160 rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1161 RPC_BUFFER_MAXSIZE,
1162 0, SLAB_HWCACHE_ALIGN,
1163 NULL);
1164 if (!rpc_buffer_slabp)
1165 goto err_nomem;
1166 rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1167 rpc_task_slabp);
1168 if (!rpc_task_mempool)
1169 goto err_nomem;
1170 rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1171 rpc_buffer_slabp);
1172 if (!rpc_buffer_mempool)
1173 goto err_nomem;
1174 return 0;
1175 err_nomem:
1176 rpc_destroy_mempool();
1177 return -ENOMEM;