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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/net/sunrpc/sched.c
4 *
5 * Scheduling for synchronous and asynchronous RPC requests.
6 *
7 * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
8 *
9 * TCP NFS related read + write fixes
10 * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
11 */
12
13#include <linux/module.h>
14
15#include <linux/sched.h>
16#include <linux/interrupt.h>
17#include <linux/slab.h>
18#include <linux/mempool.h>
19#include <linux/smp.h>
20#include <linux/spinlock.h>
21#include <linux/mutex.h>
22#include <linux/freezer.h>
23#include <linux/sched/mm.h>
24
25#include <linux/sunrpc/clnt.h>
26#include <linux/sunrpc/metrics.h>
27
28#include "sunrpc.h"
29
30#define CREATE_TRACE_POINTS
31#include <trace/events/sunrpc.h>
32
33/*
34 * RPC slabs and memory pools
35 */
36#define RPC_BUFFER_MAXSIZE (2048)
37#define RPC_BUFFER_POOLSIZE (8)
38#define RPC_TASK_POOLSIZE (8)
39static struct kmem_cache *rpc_task_slabp __read_mostly;
40static struct kmem_cache *rpc_buffer_slabp __read_mostly;
41static mempool_t *rpc_task_mempool __read_mostly;
42static mempool_t *rpc_buffer_mempool __read_mostly;
43
44static void rpc_async_schedule(struct work_struct *);
45static void rpc_release_task(struct rpc_task *task);
46static void __rpc_queue_timer_fn(struct work_struct *);
47
48/*
49 * RPC tasks sit here while waiting for conditions to improve.
50 */
51static struct rpc_wait_queue delay_queue;
52
53/*
54 * rpciod-related stuff
55 */
56struct workqueue_struct *rpciod_workqueue __read_mostly;
57struct workqueue_struct *xprtiod_workqueue __read_mostly;
58EXPORT_SYMBOL_GPL(xprtiod_workqueue);
59
60gfp_t rpc_task_gfp_mask(void)
61{
62 if (current->flags & PF_WQ_WORKER)
63 return GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
64 return GFP_KERNEL;
65}
66EXPORT_SYMBOL_GPL(rpc_task_gfp_mask);
67
68bool rpc_task_set_rpc_status(struct rpc_task *task, int rpc_status)
69{
70 if (cmpxchg(&task->tk_rpc_status, 0, rpc_status) == 0)
71 return true;
72 return false;
73}
74
75unsigned long
76rpc_task_timeout(const struct rpc_task *task)
77{
78 unsigned long timeout = READ_ONCE(task->tk_timeout);
79
80 if (timeout != 0) {
81 unsigned long now = jiffies;
82 if (time_before(now, timeout))
83 return timeout - now;
84 }
85 return 0;
86}
87EXPORT_SYMBOL_GPL(rpc_task_timeout);
88
89/*
90 * Disable the timer for a given RPC task. Should be called with
91 * queue->lock and bh_disabled in order to avoid races within
92 * rpc_run_timer().
93 */
94static void
95__rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
96{
97 if (list_empty(&task->u.tk_wait.timer_list))
98 return;
99 task->tk_timeout = 0;
100 list_del(&task->u.tk_wait.timer_list);
101 if (list_empty(&queue->timer_list.list))
102 cancel_delayed_work(&queue->timer_list.dwork);
103}
104
105static void
106rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
107{
108 unsigned long now = jiffies;
109 queue->timer_list.expires = expires;
110 if (time_before_eq(expires, now))
111 expires = 0;
112 else
113 expires -= now;
114 mod_delayed_work(rpciod_workqueue, &queue->timer_list.dwork, expires);
115}
116
117/*
118 * Set up a timer for the current task.
119 */
120static void
121__rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task,
122 unsigned long timeout)
123{
124 task->tk_timeout = timeout;
125 if (list_empty(&queue->timer_list.list) || time_before(timeout, queue->timer_list.expires))
126 rpc_set_queue_timer(queue, timeout);
127 list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
128}
129
130static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
131{
132 if (queue->priority != priority) {
133 queue->priority = priority;
134 queue->nr = 1U << priority;
135 }
136}
137
138static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
139{
140 rpc_set_waitqueue_priority(queue, queue->maxpriority);
141}
142
143/*
144 * Add a request to a queue list
145 */
146static void
147__rpc_list_enqueue_task(struct list_head *q, struct rpc_task *task)
148{
149 struct rpc_task *t;
150
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.links,
154 &t->u.tk_wait.links);
155 /* Cache the queue head in task->u.tk_wait.list */
156 task->u.tk_wait.list.next = q;
157 task->u.tk_wait.list.prev = NULL;
158 return;
159 }
160 }
161 INIT_LIST_HEAD(&task->u.tk_wait.links);
162 list_add_tail(&task->u.tk_wait.list, q);
163}
164
165/*
166 * Remove request from a queue list
167 */
168static void
169__rpc_list_dequeue_task(struct rpc_task *task)
170{
171 struct list_head *q;
172 struct rpc_task *t;
173
174 if (task->u.tk_wait.list.prev == NULL) {
175 list_del(&task->u.tk_wait.links);
176 return;
177 }
178 if (!list_empty(&task->u.tk_wait.links)) {
179 t = list_first_entry(&task->u.tk_wait.links,
180 struct rpc_task,
181 u.tk_wait.links);
182 /* Assume __rpc_list_enqueue_task() cached the queue head */
183 q = t->u.tk_wait.list.next;
184 list_add_tail(&t->u.tk_wait.list, q);
185 list_del(&task->u.tk_wait.links);
186 }
187 list_del(&task->u.tk_wait.list);
188}
189
190/*
191 * Add new request to a priority queue.
192 */
193static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
194 struct rpc_task *task,
195 unsigned char queue_priority)
196{
197 if (unlikely(queue_priority > queue->maxpriority))
198 queue_priority = queue->maxpriority;
199 __rpc_list_enqueue_task(&queue->tasks[queue_priority], task);
200}
201
202/*
203 * Add new request to wait queue.
204 */
205static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
206 struct rpc_task *task,
207 unsigned char queue_priority)
208{
209 INIT_LIST_HEAD(&task->u.tk_wait.timer_list);
210 if (RPC_IS_PRIORITY(queue))
211 __rpc_add_wait_queue_priority(queue, task, queue_priority);
212 else
213 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
214 task->tk_waitqueue = queue;
215 queue->qlen++;
216 /* barrier matches the read in rpc_wake_up_task_queue_locked() */
217 smp_wmb();
218 rpc_set_queued(task);
219}
220
221/*
222 * Remove request from a priority queue.
223 */
224static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
225{
226 __rpc_list_dequeue_task(task);
227}
228
229/*
230 * Remove request from queue.
231 * Note: must be called with spin lock held.
232 */
233static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
234{
235 __rpc_disable_timer(queue, task);
236 if (RPC_IS_PRIORITY(queue))
237 __rpc_remove_wait_queue_priority(task);
238 else
239 list_del(&task->u.tk_wait.list);
240 queue->qlen--;
241}
242
243static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
244{
245 int i;
246
247 spin_lock_init(&queue->lock);
248 for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
249 INIT_LIST_HEAD(&queue->tasks[i]);
250 queue->maxpriority = nr_queues - 1;
251 rpc_reset_waitqueue_priority(queue);
252 queue->qlen = 0;
253 queue->timer_list.expires = 0;
254 INIT_DELAYED_WORK(&queue->timer_list.dwork, __rpc_queue_timer_fn);
255 INIT_LIST_HEAD(&queue->timer_list.list);
256 rpc_assign_waitqueue_name(queue, qname);
257}
258
259void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
260{
261 __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
262}
263EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
264
265void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
266{
267 __rpc_init_priority_wait_queue(queue, qname, 1);
268}
269EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
270
271void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
272{
273 cancel_delayed_work_sync(&queue->timer_list.dwork);
274}
275EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
276
277static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode)
278{
279 schedule();
280 if (signal_pending_state(mode, current))
281 return -ERESTARTSYS;
282 return 0;
283}
284
285#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) || IS_ENABLED(CONFIG_TRACEPOINTS)
286static void rpc_task_set_debuginfo(struct rpc_task *task)
287{
288 struct rpc_clnt *clnt = task->tk_client;
289
290 /* Might be a task carrying a reverse-direction operation */
291 if (!clnt) {
292 static atomic_t rpc_pid;
293
294 task->tk_pid = atomic_inc_return(&rpc_pid);
295 return;
296 }
297
298 task->tk_pid = atomic_inc_return(&clnt->cl_pid);
299}
300#else
301static inline void rpc_task_set_debuginfo(struct rpc_task *task)
302{
303}
304#endif
305
306static void rpc_set_active(struct rpc_task *task)
307{
308 rpc_task_set_debuginfo(task);
309 set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
310 trace_rpc_task_begin(task, NULL);
311}
312
313/*
314 * Mark an RPC call as having completed by clearing the 'active' bit
315 * and then waking up all tasks that were sleeping.
316 */
317static int rpc_complete_task(struct rpc_task *task)
318{
319 void *m = &task->tk_runstate;
320 wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
321 struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
322 unsigned long flags;
323 int ret;
324
325 trace_rpc_task_complete(task, NULL);
326
327 spin_lock_irqsave(&wq->lock, flags);
328 clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
329 ret = atomic_dec_and_test(&task->tk_count);
330 if (waitqueue_active(wq))
331 __wake_up_locked_key(wq, TASK_NORMAL, &k);
332 spin_unlock_irqrestore(&wq->lock, flags);
333 return ret;
334}
335
336/*
337 * Allow callers to wait for completion of an RPC call
338 *
339 * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
340 * to enforce taking of the wq->lock and hence avoid races with
341 * rpc_complete_task().
342 */
343int rpc_wait_for_completion_task(struct rpc_task *task)
344{
345 return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
346 rpc_wait_bit_killable, TASK_KILLABLE|TASK_FREEZABLE_UNSAFE);
347}
348EXPORT_SYMBOL_GPL(rpc_wait_for_completion_task);
349
350/*
351 * Make an RPC task runnable.
352 *
353 * Note: If the task is ASYNC, and is being made runnable after sitting on an
354 * rpc_wait_queue, this must be called with the queue spinlock held to protect
355 * the wait queue operation.
356 * Note the ordering of rpc_test_and_set_running() and rpc_clear_queued(),
357 * which is needed to ensure that __rpc_execute() doesn't loop (due to the
358 * lockless RPC_IS_QUEUED() test) before we've had a chance to test
359 * the RPC_TASK_RUNNING flag.
360 */
361static void rpc_make_runnable(struct workqueue_struct *wq,
362 struct rpc_task *task)
363{
364 bool need_wakeup = !rpc_test_and_set_running(task);
365
366 rpc_clear_queued(task);
367 if (!need_wakeup)
368 return;
369 if (RPC_IS_ASYNC(task)) {
370 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
371 queue_work(wq, &task->u.tk_work);
372 } else
373 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
374}
375
376/*
377 * Prepare for sleeping on a wait queue.
378 * By always appending tasks to the list we ensure FIFO behavior.
379 * NB: An RPC task will only receive interrupt-driven events as long
380 * as it's on a wait queue.
381 */
382static void __rpc_do_sleep_on_priority(struct rpc_wait_queue *q,
383 struct rpc_task *task,
384 unsigned char queue_priority)
385{
386 trace_rpc_task_sleep(task, q);
387
388 __rpc_add_wait_queue(q, task, queue_priority);
389}
390
391static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
392 struct rpc_task *task,
393 unsigned char queue_priority)
394{
395 if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
396 return;
397 __rpc_do_sleep_on_priority(q, task, queue_priority);
398}
399
400static void __rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
401 struct rpc_task *task, unsigned long timeout,
402 unsigned char queue_priority)
403{
404 if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
405 return;
406 if (time_is_after_jiffies(timeout)) {
407 __rpc_do_sleep_on_priority(q, task, queue_priority);
408 __rpc_add_timer(q, task, timeout);
409 } else
410 task->tk_status = -ETIMEDOUT;
411}
412
413static void rpc_set_tk_callback(struct rpc_task *task, rpc_action action)
414{
415 if (action && !WARN_ON_ONCE(task->tk_callback != NULL))
416 task->tk_callback = action;
417}
418
419static bool rpc_sleep_check_activated(struct rpc_task *task)
420{
421 /* We shouldn't ever put an inactive task to sleep */
422 if (WARN_ON_ONCE(!RPC_IS_ACTIVATED(task))) {
423 task->tk_status = -EIO;
424 rpc_put_task_async(task);
425 return false;
426 }
427 return true;
428}
429
430void rpc_sleep_on_timeout(struct rpc_wait_queue *q, struct rpc_task *task,
431 rpc_action action, unsigned long timeout)
432{
433 if (!rpc_sleep_check_activated(task))
434 return;
435
436 rpc_set_tk_callback(task, action);
437
438 /*
439 * Protect the queue operations.
440 */
441 spin_lock(&q->lock);
442 __rpc_sleep_on_priority_timeout(q, task, timeout, task->tk_priority);
443 spin_unlock(&q->lock);
444}
445EXPORT_SYMBOL_GPL(rpc_sleep_on_timeout);
446
447void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
448 rpc_action action)
449{
450 if (!rpc_sleep_check_activated(task))
451 return;
452
453 rpc_set_tk_callback(task, action);
454
455 WARN_ON_ONCE(task->tk_timeout != 0);
456 /*
457 * Protect the queue operations.
458 */
459 spin_lock(&q->lock);
460 __rpc_sleep_on_priority(q, task, task->tk_priority);
461 spin_unlock(&q->lock);
462}
463EXPORT_SYMBOL_GPL(rpc_sleep_on);
464
465void rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
466 struct rpc_task *task, unsigned long timeout, int priority)
467{
468 if (!rpc_sleep_check_activated(task))
469 return;
470
471 priority -= RPC_PRIORITY_LOW;
472 /*
473 * Protect the queue operations.
474 */
475 spin_lock(&q->lock);
476 __rpc_sleep_on_priority_timeout(q, task, timeout, priority);
477 spin_unlock(&q->lock);
478}
479EXPORT_SYMBOL_GPL(rpc_sleep_on_priority_timeout);
480
481void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
482 int priority)
483{
484 if (!rpc_sleep_check_activated(task))
485 return;
486
487 WARN_ON_ONCE(task->tk_timeout != 0);
488 priority -= RPC_PRIORITY_LOW;
489 /*
490 * Protect the queue operations.
491 */
492 spin_lock(&q->lock);
493 __rpc_sleep_on_priority(q, task, priority);
494 spin_unlock(&q->lock);
495}
496EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
497
498/**
499 * __rpc_do_wake_up_task_on_wq - wake up a single rpc_task
500 * @wq: workqueue on which to run task
501 * @queue: wait queue
502 * @task: task to be woken up
503 *
504 * Caller must hold queue->lock, and have cleared the task queued flag.
505 */
506static void __rpc_do_wake_up_task_on_wq(struct workqueue_struct *wq,
507 struct rpc_wait_queue *queue,
508 struct rpc_task *task)
509{
510 /* Has the task been executed yet? If not, we cannot wake it up! */
511 if (!RPC_IS_ACTIVATED(task)) {
512 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
513 return;
514 }
515
516 trace_rpc_task_wakeup(task, queue);
517
518 __rpc_remove_wait_queue(queue, task);
519
520 rpc_make_runnable(wq, task);
521}
522
523/*
524 * Wake up a queued task while the queue lock is being held
525 */
526static struct rpc_task *
527rpc_wake_up_task_on_wq_queue_action_locked(struct workqueue_struct *wq,
528 struct rpc_wait_queue *queue, struct rpc_task *task,
529 bool (*action)(struct rpc_task *, void *), void *data)
530{
531 if (RPC_IS_QUEUED(task)) {
532 smp_rmb();
533 if (task->tk_waitqueue == queue) {
534 if (action == NULL || action(task, data)) {
535 __rpc_do_wake_up_task_on_wq(wq, queue, task);
536 return task;
537 }
538 }
539 }
540 return NULL;
541}
542
543/*
544 * Wake up a queued task while the queue lock is being held
545 */
546static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue,
547 struct rpc_task *task)
548{
549 rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
550 task, NULL, NULL);
551}
552
553/*
554 * Wake up a task on a specific queue
555 */
556void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
557{
558 if (!RPC_IS_QUEUED(task))
559 return;
560 spin_lock(&queue->lock);
561 rpc_wake_up_task_queue_locked(queue, task);
562 spin_unlock(&queue->lock);
563}
564EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
565
566static bool rpc_task_action_set_status(struct rpc_task *task, void *status)
567{
568 task->tk_status = *(int *)status;
569 return true;
570}
571
572static void
573rpc_wake_up_task_queue_set_status_locked(struct rpc_wait_queue *queue,
574 struct rpc_task *task, int status)
575{
576 rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
577 task, rpc_task_action_set_status, &status);
578}
579
580/**
581 * rpc_wake_up_queued_task_set_status - wake up a task and set task->tk_status
582 * @queue: pointer to rpc_wait_queue
583 * @task: pointer to rpc_task
584 * @status: integer error value
585 *
586 * If @task is queued on @queue, then it is woken up, and @task->tk_status is
587 * set to the value of @status.
588 */
589void
590rpc_wake_up_queued_task_set_status(struct rpc_wait_queue *queue,
591 struct rpc_task *task, int status)
592{
593 if (!RPC_IS_QUEUED(task))
594 return;
595 spin_lock(&queue->lock);
596 rpc_wake_up_task_queue_set_status_locked(queue, task, status);
597 spin_unlock(&queue->lock);
598}
599
600/*
601 * Wake up the next task on a priority queue.
602 */
603static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
604{
605 struct list_head *q;
606 struct rpc_task *task;
607
608 /*
609 * Service the privileged queue.
610 */
611 q = &queue->tasks[RPC_NR_PRIORITY - 1];
612 if (queue->maxpriority > RPC_PRIORITY_PRIVILEGED && !list_empty(q)) {
613 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
614 goto out;
615 }
616
617 /*
618 * Service a batch of tasks from a single owner.
619 */
620 q = &queue->tasks[queue->priority];
621 if (!list_empty(q) && queue->nr) {
622 queue->nr--;
623 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
624 goto out;
625 }
626
627 /*
628 * Service the next queue.
629 */
630 do {
631 if (q == &queue->tasks[0])
632 q = &queue->tasks[queue->maxpriority];
633 else
634 q = q - 1;
635 if (!list_empty(q)) {
636 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
637 goto new_queue;
638 }
639 } while (q != &queue->tasks[queue->priority]);
640
641 rpc_reset_waitqueue_priority(queue);
642 return NULL;
643
644new_queue:
645 rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
646out:
647 return task;
648}
649
650static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
651{
652 if (RPC_IS_PRIORITY(queue))
653 return __rpc_find_next_queued_priority(queue);
654 if (!list_empty(&queue->tasks[0]))
655 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
656 return NULL;
657}
658
659/*
660 * Wake up the first task on the wait queue.
661 */
662struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq,
663 struct rpc_wait_queue *queue,
664 bool (*func)(struct rpc_task *, void *), void *data)
665{
666 struct rpc_task *task = NULL;
667
668 spin_lock(&queue->lock);
669 task = __rpc_find_next_queued(queue);
670 if (task != NULL)
671 task = rpc_wake_up_task_on_wq_queue_action_locked(wq, queue,
672 task, func, data);
673 spin_unlock(&queue->lock);
674
675 return task;
676}
677
678/*
679 * Wake up the first task on the wait queue.
680 */
681struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
682 bool (*func)(struct rpc_task *, void *), void *data)
683{
684 return rpc_wake_up_first_on_wq(rpciod_workqueue, queue, func, data);
685}
686EXPORT_SYMBOL_GPL(rpc_wake_up_first);
687
688static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
689{
690 return true;
691}
692
693/*
694 * Wake up the next task on the wait queue.
695*/
696struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
697{
698 return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
699}
700EXPORT_SYMBOL_GPL(rpc_wake_up_next);
701
702/**
703 * rpc_wake_up_locked - wake up all rpc_tasks
704 * @queue: rpc_wait_queue on which the tasks are sleeping
705 *
706 */
707static void rpc_wake_up_locked(struct rpc_wait_queue *queue)
708{
709 struct rpc_task *task;
710
711 for (;;) {
712 task = __rpc_find_next_queued(queue);
713 if (task == NULL)
714 break;
715 rpc_wake_up_task_queue_locked(queue, task);
716 }
717}
718
719/**
720 * rpc_wake_up - wake up all rpc_tasks
721 * @queue: rpc_wait_queue on which the tasks are sleeping
722 *
723 * Grabs queue->lock
724 */
725void rpc_wake_up(struct rpc_wait_queue *queue)
726{
727 spin_lock(&queue->lock);
728 rpc_wake_up_locked(queue);
729 spin_unlock(&queue->lock);
730}
731EXPORT_SYMBOL_GPL(rpc_wake_up);
732
733/**
734 * rpc_wake_up_status_locked - wake up all rpc_tasks and set their status value.
735 * @queue: rpc_wait_queue on which the tasks are sleeping
736 * @status: status value to set
737 */
738static void rpc_wake_up_status_locked(struct rpc_wait_queue *queue, int status)
739{
740 struct rpc_task *task;
741
742 for (;;) {
743 task = __rpc_find_next_queued(queue);
744 if (task == NULL)
745 break;
746 rpc_wake_up_task_queue_set_status_locked(queue, task, status);
747 }
748}
749
750/**
751 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
752 * @queue: rpc_wait_queue on which the tasks are sleeping
753 * @status: status value to set
754 *
755 * Grabs queue->lock
756 */
757void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
758{
759 spin_lock(&queue->lock);
760 rpc_wake_up_status_locked(queue, status);
761 spin_unlock(&queue->lock);
762}
763EXPORT_SYMBOL_GPL(rpc_wake_up_status);
764
765static void __rpc_queue_timer_fn(struct work_struct *work)
766{
767 struct rpc_wait_queue *queue = container_of(work,
768 struct rpc_wait_queue,
769 timer_list.dwork.work);
770 struct rpc_task *task, *n;
771 unsigned long expires, now, timeo;
772
773 spin_lock(&queue->lock);
774 expires = now = jiffies;
775 list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
776 timeo = task->tk_timeout;
777 if (time_after_eq(now, timeo)) {
778 trace_rpc_task_timeout(task, task->tk_action);
779 task->tk_status = -ETIMEDOUT;
780 rpc_wake_up_task_queue_locked(queue, task);
781 continue;
782 }
783 if (expires == now || time_after(expires, timeo))
784 expires = timeo;
785 }
786 if (!list_empty(&queue->timer_list.list))
787 rpc_set_queue_timer(queue, expires);
788 spin_unlock(&queue->lock);
789}
790
791static void __rpc_atrun(struct rpc_task *task)
792{
793 if (task->tk_status == -ETIMEDOUT)
794 task->tk_status = 0;
795}
796
797/*
798 * Run a task at a later time
799 */
800void rpc_delay(struct rpc_task *task, unsigned long delay)
801{
802 rpc_sleep_on_timeout(&delay_queue, task, __rpc_atrun, jiffies + delay);
803}
804EXPORT_SYMBOL_GPL(rpc_delay);
805
806/*
807 * Helper to call task->tk_ops->rpc_call_prepare
808 */
809void rpc_prepare_task(struct rpc_task *task)
810{
811 task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
812}
813
814static void
815rpc_init_task_statistics(struct rpc_task *task)
816{
817 /* Initialize retry counters */
818 task->tk_garb_retry = 2;
819 task->tk_cred_retry = 2;
820
821 /* starting timestamp */
822 task->tk_start = ktime_get();
823}
824
825static void
826rpc_reset_task_statistics(struct rpc_task *task)
827{
828 task->tk_timeouts = 0;
829 task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_SENT);
830 rpc_init_task_statistics(task);
831}
832
833/*
834 * Helper that calls task->tk_ops->rpc_call_done if it exists
835 */
836void rpc_exit_task(struct rpc_task *task)
837{
838 trace_rpc_task_end(task, task->tk_action);
839 task->tk_action = NULL;
840 if (task->tk_ops->rpc_count_stats)
841 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
842 else if (task->tk_client)
843 rpc_count_iostats(task, task->tk_client->cl_metrics);
844 if (task->tk_ops->rpc_call_done != NULL) {
845 trace_rpc_task_call_done(task, task->tk_ops->rpc_call_done);
846 task->tk_ops->rpc_call_done(task, task->tk_calldata);
847 if (task->tk_action != NULL) {
848 /* Always release the RPC slot and buffer memory */
849 xprt_release(task);
850 rpc_reset_task_statistics(task);
851 }
852 }
853}
854
855void rpc_signal_task(struct rpc_task *task)
856{
857 struct rpc_wait_queue *queue;
858
859 if (!RPC_IS_ACTIVATED(task))
860 return;
861
862 if (!rpc_task_set_rpc_status(task, -ERESTARTSYS))
863 return;
864 trace_rpc_task_signalled(task, task->tk_action);
865 set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
866 smp_mb__after_atomic();
867 queue = READ_ONCE(task->tk_waitqueue);
868 if (queue)
869 rpc_wake_up_queued_task(queue, task);
870}
871
872void rpc_task_try_cancel(struct rpc_task *task, int error)
873{
874 struct rpc_wait_queue *queue;
875
876 if (!rpc_task_set_rpc_status(task, error))
877 return;
878 queue = READ_ONCE(task->tk_waitqueue);
879 if (queue)
880 rpc_wake_up_queued_task(queue, task);
881}
882
883void rpc_exit(struct rpc_task *task, int status)
884{
885 task->tk_status = status;
886 task->tk_action = rpc_exit_task;
887 rpc_wake_up_queued_task(task->tk_waitqueue, task);
888}
889EXPORT_SYMBOL_GPL(rpc_exit);
890
891void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
892{
893 if (ops->rpc_release != NULL)
894 ops->rpc_release(calldata);
895}
896
897static bool xprt_needs_memalloc(struct rpc_xprt *xprt, struct rpc_task *tk)
898{
899 if (!xprt)
900 return false;
901 if (!atomic_read(&xprt->swapper))
902 return false;
903 return test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == tk;
904}
905
906/*
907 * This is the RPC `scheduler' (or rather, the finite state machine).
908 */
909static void __rpc_execute(struct rpc_task *task)
910{
911 struct rpc_wait_queue *queue;
912 int task_is_async = RPC_IS_ASYNC(task);
913 int status = 0;
914 unsigned long pflags = current->flags;
915
916 WARN_ON_ONCE(RPC_IS_QUEUED(task));
917 if (RPC_IS_QUEUED(task))
918 return;
919
920 for (;;) {
921 void (*do_action)(struct rpc_task *);
922
923 /*
924 * Perform the next FSM step or a pending callback.
925 *
926 * tk_action may be NULL if the task has been killed.
927 */
928 do_action = task->tk_action;
929 /* Tasks with an RPC error status should exit */
930 if (do_action && do_action != rpc_exit_task &&
931 (status = READ_ONCE(task->tk_rpc_status)) != 0) {
932 task->tk_status = status;
933 do_action = rpc_exit_task;
934 }
935 /* Callbacks override all actions */
936 if (task->tk_callback) {
937 do_action = task->tk_callback;
938 task->tk_callback = NULL;
939 }
940 if (!do_action)
941 break;
942 if (RPC_IS_SWAPPER(task) ||
943 xprt_needs_memalloc(task->tk_xprt, task))
944 current->flags |= PF_MEMALLOC;
945
946 trace_rpc_task_run_action(task, do_action);
947 do_action(task);
948
949 /*
950 * Lockless check for whether task is sleeping or not.
951 */
952 if (!RPC_IS_QUEUED(task)) {
953 cond_resched();
954 continue;
955 }
956
957 /*
958 * The queue->lock protects against races with
959 * rpc_make_runnable().
960 *
961 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
962 * rpc_task, rpc_make_runnable() can assign it to a
963 * different workqueue. We therefore cannot assume that the
964 * rpc_task pointer may still be dereferenced.
965 */
966 queue = task->tk_waitqueue;
967 spin_lock(&queue->lock);
968 if (!RPC_IS_QUEUED(task)) {
969 spin_unlock(&queue->lock);
970 continue;
971 }
972 /* Wake up any task that has an exit status */
973 if (READ_ONCE(task->tk_rpc_status) != 0) {
974 rpc_wake_up_task_queue_locked(queue, task);
975 spin_unlock(&queue->lock);
976 continue;
977 }
978 rpc_clear_running(task);
979 spin_unlock(&queue->lock);
980 if (task_is_async)
981 goto out;
982
983 /* sync task: sleep here */
984 trace_rpc_task_sync_sleep(task, task->tk_action);
985 status = out_of_line_wait_on_bit(&task->tk_runstate,
986 RPC_TASK_QUEUED, rpc_wait_bit_killable,
987 TASK_KILLABLE|TASK_FREEZABLE);
988 if (status < 0) {
989 /*
990 * When a sync task receives a signal, it exits with
991 * -ERESTARTSYS. In order to catch any callbacks that
992 * clean up after sleeping on some queue, we don't
993 * break the loop here, but go around once more.
994 */
995 rpc_signal_task(task);
996 }
997 trace_rpc_task_sync_wake(task, task->tk_action);
998 }
999
1000 /* Release all resources associated with the task */
1001 rpc_release_task(task);
1002out:
1003 current_restore_flags(pflags, PF_MEMALLOC);
1004}
1005
1006/*
1007 * User-visible entry point to the scheduler.
1008 *
1009 * This may be called recursively if e.g. an async NFS task updates
1010 * the attributes and finds that dirty pages must be flushed.
1011 * NOTE: Upon exit of this function the task is guaranteed to be
1012 * released. In particular note that tk_release() will have
1013 * been called, so your task memory may have been freed.
1014 */
1015void rpc_execute(struct rpc_task *task)
1016{
1017 bool is_async = RPC_IS_ASYNC(task);
1018
1019 rpc_set_active(task);
1020 rpc_make_runnable(rpciod_workqueue, task);
1021 if (!is_async) {
1022 unsigned int pflags = memalloc_nofs_save();
1023 __rpc_execute(task);
1024 memalloc_nofs_restore(pflags);
1025 }
1026}
1027
1028static void rpc_async_schedule(struct work_struct *work)
1029{
1030 unsigned int pflags = memalloc_nofs_save();
1031
1032 __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
1033 memalloc_nofs_restore(pflags);
1034}
1035
1036/**
1037 * rpc_malloc - allocate RPC buffer resources
1038 * @task: RPC task
1039 *
1040 * A single memory region is allocated, which is split between the
1041 * RPC call and RPC reply that this task is being used for. When
1042 * this RPC is retired, the memory is released by calling rpc_free.
1043 *
1044 * To prevent rpciod from hanging, this allocator never sleeps,
1045 * returning -ENOMEM and suppressing warning if the request cannot
1046 * be serviced immediately. The caller can arrange to sleep in a
1047 * way that is safe for rpciod.
1048 *
1049 * Most requests are 'small' (under 2KiB) and can be serviced from a
1050 * mempool, ensuring that NFS reads and writes can always proceed,
1051 * and that there is good locality of reference for these buffers.
1052 */
1053int rpc_malloc(struct rpc_task *task)
1054{
1055 struct rpc_rqst *rqst = task->tk_rqstp;
1056 size_t size = rqst->rq_callsize + rqst->rq_rcvsize;
1057 struct rpc_buffer *buf;
1058 gfp_t gfp = rpc_task_gfp_mask();
1059
1060 size += sizeof(struct rpc_buffer);
1061 if (size <= RPC_BUFFER_MAXSIZE) {
1062 buf = kmem_cache_alloc(rpc_buffer_slabp, gfp);
1063 /* Reach for the mempool if dynamic allocation fails */
1064 if (!buf && RPC_IS_ASYNC(task))
1065 buf = mempool_alloc(rpc_buffer_mempool, GFP_NOWAIT);
1066 } else
1067 buf = kmalloc(size, gfp);
1068
1069 if (!buf)
1070 return -ENOMEM;
1071
1072 buf->len = size;
1073 rqst->rq_buffer = buf->data;
1074 rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_callsize;
1075 return 0;
1076}
1077EXPORT_SYMBOL_GPL(rpc_malloc);
1078
1079/**
1080 * rpc_free - free RPC buffer resources allocated via rpc_malloc
1081 * @task: RPC task
1082 *
1083 */
1084void rpc_free(struct rpc_task *task)
1085{
1086 void *buffer = task->tk_rqstp->rq_buffer;
1087 size_t size;
1088 struct rpc_buffer *buf;
1089
1090 buf = container_of(buffer, struct rpc_buffer, data);
1091 size = buf->len;
1092
1093 if (size <= RPC_BUFFER_MAXSIZE)
1094 mempool_free(buf, rpc_buffer_mempool);
1095 else
1096 kfree(buf);
1097}
1098EXPORT_SYMBOL_GPL(rpc_free);
1099
1100/*
1101 * Creation and deletion of RPC task structures
1102 */
1103static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
1104{
1105 memset(task, 0, sizeof(*task));
1106 atomic_set(&task->tk_count, 1);
1107 task->tk_flags = task_setup_data->flags;
1108 task->tk_ops = task_setup_data->callback_ops;
1109 task->tk_calldata = task_setup_data->callback_data;
1110 INIT_LIST_HEAD(&task->tk_task);
1111
1112 task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
1113 task->tk_owner = current->tgid;
1114
1115 /* Initialize workqueue for async tasks */
1116 task->tk_workqueue = task_setup_data->workqueue;
1117
1118 task->tk_xprt = rpc_task_get_xprt(task_setup_data->rpc_client,
1119 xprt_get(task_setup_data->rpc_xprt));
1120
1121 task->tk_op_cred = get_rpccred(task_setup_data->rpc_op_cred);
1122
1123 if (task->tk_ops->rpc_call_prepare != NULL)
1124 task->tk_action = rpc_prepare_task;
1125
1126 rpc_init_task_statistics(task);
1127}
1128
1129static struct rpc_task *rpc_alloc_task(void)
1130{
1131 struct rpc_task *task;
1132
1133 task = kmem_cache_alloc(rpc_task_slabp, rpc_task_gfp_mask());
1134 if (task)
1135 return task;
1136 return mempool_alloc(rpc_task_mempool, GFP_NOWAIT);
1137}
1138
1139/*
1140 * Create a new task for the specified client.
1141 */
1142struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
1143{
1144 struct rpc_task *task = setup_data->task;
1145 unsigned short flags = 0;
1146
1147 if (task == NULL) {
1148 task = rpc_alloc_task();
1149 if (task == NULL) {
1150 rpc_release_calldata(setup_data->callback_ops,
1151 setup_data->callback_data);
1152 return ERR_PTR(-ENOMEM);
1153 }
1154 flags = RPC_TASK_DYNAMIC;
1155 }
1156
1157 rpc_init_task(task, setup_data);
1158 task->tk_flags |= flags;
1159 return task;
1160}
1161
1162/*
1163 * rpc_free_task - release rpc task and perform cleanups
1164 *
1165 * Note that we free up the rpc_task _after_ rpc_release_calldata()
1166 * in order to work around a workqueue dependency issue.
1167 *
1168 * Tejun Heo states:
1169 * "Workqueue currently considers two work items to be the same if they're
1170 * on the same address and won't execute them concurrently - ie. it
1171 * makes a work item which is queued again while being executed wait
1172 * for the previous execution to complete.
1173 *
1174 * If a work function frees the work item, and then waits for an event
1175 * which should be performed by another work item and *that* work item
1176 * recycles the freed work item, it can create a false dependency loop.
1177 * There really is no reliable way to detect this short of verifying
1178 * every memory free."
1179 *
1180 */
1181static void rpc_free_task(struct rpc_task *task)
1182{
1183 unsigned short tk_flags = task->tk_flags;
1184
1185 put_rpccred(task->tk_op_cred);
1186 rpc_release_calldata(task->tk_ops, task->tk_calldata);
1187
1188 if (tk_flags & RPC_TASK_DYNAMIC)
1189 mempool_free(task, rpc_task_mempool);
1190}
1191
1192static void rpc_async_release(struct work_struct *work)
1193{
1194 unsigned int pflags = memalloc_nofs_save();
1195
1196 rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
1197 memalloc_nofs_restore(pflags);
1198}
1199
1200static void rpc_release_resources_task(struct rpc_task *task)
1201{
1202 xprt_release(task);
1203 if (task->tk_msg.rpc_cred) {
1204 if (!(task->tk_flags & RPC_TASK_CRED_NOREF))
1205 put_cred(task->tk_msg.rpc_cred);
1206 task->tk_msg.rpc_cred = NULL;
1207 }
1208 rpc_task_release_client(task);
1209}
1210
1211static void rpc_final_put_task(struct rpc_task *task,
1212 struct workqueue_struct *q)
1213{
1214 if (q != NULL) {
1215 INIT_WORK(&task->u.tk_work, rpc_async_release);
1216 queue_work(q, &task->u.tk_work);
1217 } else
1218 rpc_free_task(task);
1219}
1220
1221static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1222{
1223 if (atomic_dec_and_test(&task->tk_count)) {
1224 rpc_release_resources_task(task);
1225 rpc_final_put_task(task, q);
1226 }
1227}
1228
1229void rpc_put_task(struct rpc_task *task)
1230{
1231 rpc_do_put_task(task, NULL);
1232}
1233EXPORT_SYMBOL_GPL(rpc_put_task);
1234
1235void rpc_put_task_async(struct rpc_task *task)
1236{
1237 rpc_do_put_task(task, task->tk_workqueue);
1238}
1239EXPORT_SYMBOL_GPL(rpc_put_task_async);
1240
1241static void rpc_release_task(struct rpc_task *task)
1242{
1243 WARN_ON_ONCE(RPC_IS_QUEUED(task));
1244
1245 rpc_release_resources_task(task);
1246
1247 /*
1248 * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1249 * so it should be safe to use task->tk_count as a test for whether
1250 * or not any other processes still hold references to our rpc_task.
1251 */
1252 if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1253 /* Wake up anyone who may be waiting for task completion */
1254 if (!rpc_complete_task(task))
1255 return;
1256 } else {
1257 if (!atomic_dec_and_test(&task->tk_count))
1258 return;
1259 }
1260 rpc_final_put_task(task, task->tk_workqueue);
1261}
1262
1263int rpciod_up(void)
1264{
1265 return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1266}
1267
1268void rpciod_down(void)
1269{
1270 module_put(THIS_MODULE);
1271}
1272
1273/*
1274 * Start up the rpciod workqueue.
1275 */
1276static int rpciod_start(void)
1277{
1278 struct workqueue_struct *wq;
1279
1280 /*
1281 * Create the rpciod thread and wait for it to start.
1282 */
1283 wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
1284 if (!wq)
1285 goto out_failed;
1286 rpciod_workqueue = wq;
1287 wq = alloc_workqueue("xprtiod", WQ_UNBOUND | WQ_MEM_RECLAIM, 0);
1288 if (!wq)
1289 goto free_rpciod;
1290 xprtiod_workqueue = wq;
1291 return 1;
1292free_rpciod:
1293 wq = rpciod_workqueue;
1294 rpciod_workqueue = NULL;
1295 destroy_workqueue(wq);
1296out_failed:
1297 return 0;
1298}
1299
1300static void rpciod_stop(void)
1301{
1302 struct workqueue_struct *wq = NULL;
1303
1304 if (rpciod_workqueue == NULL)
1305 return;
1306
1307 wq = rpciod_workqueue;
1308 rpciod_workqueue = NULL;
1309 destroy_workqueue(wq);
1310 wq = xprtiod_workqueue;
1311 xprtiod_workqueue = NULL;
1312 destroy_workqueue(wq);
1313}
1314
1315void
1316rpc_destroy_mempool(void)
1317{
1318 rpciod_stop();
1319 mempool_destroy(rpc_buffer_mempool);
1320 mempool_destroy(rpc_task_mempool);
1321 kmem_cache_destroy(rpc_task_slabp);
1322 kmem_cache_destroy(rpc_buffer_slabp);
1323 rpc_destroy_wait_queue(&delay_queue);
1324}
1325
1326int
1327rpc_init_mempool(void)
1328{
1329 /*
1330 * The following is not strictly a mempool initialisation,
1331 * but there is no harm in doing it here
1332 */
1333 rpc_init_wait_queue(&delay_queue, "delayq");
1334 if (!rpciod_start())
1335 goto err_nomem;
1336
1337 rpc_task_slabp = kmem_cache_create("rpc_tasks",
1338 sizeof(struct rpc_task),
1339 0, SLAB_HWCACHE_ALIGN,
1340 NULL);
1341 if (!rpc_task_slabp)
1342 goto err_nomem;
1343 rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1344 RPC_BUFFER_MAXSIZE,
1345 0, SLAB_HWCACHE_ALIGN,
1346 NULL);
1347 if (!rpc_buffer_slabp)
1348 goto err_nomem;
1349 rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1350 rpc_task_slabp);
1351 if (!rpc_task_mempool)
1352 goto err_nomem;
1353 rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1354 rpc_buffer_slabp);
1355 if (!rpc_buffer_mempool)
1356 goto err_nomem;
1357 return 0;
1358err_nomem:
1359 rpc_destroy_mempool();
1360 return -ENOMEM;
1361}
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/spinlock.h>
20#include <linux/mutex.h>
21#include <linux/freezer.h>
22
23#include <linux/sunrpc/clnt.h>
24
25#include "sunrpc.h"
26
27#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
28#define RPCDBG_FACILITY RPCDBG_SCHED
29#endif
30
31#define CREATE_TRACE_POINTS
32#include <trace/events/sunrpc.h>
33
34/*
35 * RPC slabs and memory pools
36 */
37#define RPC_BUFFER_MAXSIZE (2048)
38#define RPC_BUFFER_POOLSIZE (8)
39#define RPC_TASK_POOLSIZE (8)
40static struct kmem_cache *rpc_task_slabp __read_mostly;
41static struct kmem_cache *rpc_buffer_slabp __read_mostly;
42static mempool_t *rpc_task_mempool __read_mostly;
43static mempool_t *rpc_buffer_mempool __read_mostly;
44
45static void rpc_async_schedule(struct work_struct *);
46static void rpc_release_task(struct rpc_task *task);
47static void __rpc_queue_timer_fn(struct timer_list *t);
48
49/*
50 * RPC tasks sit here while waiting for conditions to improve.
51 */
52static struct rpc_wait_queue delay_queue;
53
54/*
55 * rpciod-related stuff
56 */
57struct workqueue_struct *rpciod_workqueue __read_mostly;
58struct workqueue_struct *xprtiod_workqueue __read_mostly;
59
60/*
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().
64 */
65static void
66__rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
67{
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);
75}
76
77static void
78rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
79{
80 queue->timer_list.expires = expires;
81 mod_timer(&queue->timer_list.timer, expires);
82}
83
84/*
85 * Set up a timer for the current task.
86 */
87static void
88__rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
89{
90 if (!task->tk_timeout)
91 return;
92
93 dprintk("RPC: %5u setting alarm for %u ms\n",
94 task->tk_pid, jiffies_to_msecs(task->tk_timeout));
95
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);
100}
101
102static void rpc_rotate_queue_owner(struct rpc_wait_queue *queue)
103{
104 struct list_head *q = &queue->tasks[queue->priority];
105 struct rpc_task *task;
106
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);
111 }
112}
113
114static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
115{
116 if (queue->priority != priority) {
117 /* Fairness: rotate the list when changing priority */
118 rpc_rotate_queue_owner(queue);
119 queue->priority = priority;
120 }
121}
122
123static void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
124{
125 queue->owner = pid;
126 queue->nr = RPC_BATCH_COUNT;
127}
128
129static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
130{
131 rpc_set_waitqueue_priority(queue, queue->maxpriority);
132 rpc_set_waitqueue_owner(queue, 0);
133}
134
135/*
136 * Add new request to a priority queue.
137 */
138static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
139 struct rpc_task *task,
140 unsigned char queue_priority)
141{
142 struct list_head *q;
143 struct rpc_task *t;
144
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;
155 }
156 }
157 list_add_tail(&task->u.tk_wait.list, q);
158}
159
160/*
161 * Add new request to wait queue.
162 *
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.
167 */
168static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
169 struct rpc_task *task,
170 unsigned char queue_priority)
171{
172 WARN_ON_ONCE(RPC_IS_QUEUED(task));
173 if (RPC_IS_QUEUED(task))
174 return;
175
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);
187
188 dprintk("RPC: %5u added to queue %p \"%s\"\n",
189 task->tk_pid, queue, rpc_qname(queue));
190}
191
192/*
193 * Remove request from a priority queue.
194 */
195static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
196{
197 struct rpc_task *t;
198
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);
203 }
204}
205
206/*
207 * Remove request from queue.
208 * Note: must be called with spin lock held.
209 */
210static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
211{
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));
219}
220
221static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
222{
223 int i;
224
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 timer_setup(&queue->timer_list.timer, __rpc_queue_timer_fn, 0);
232 INIT_LIST_HEAD(&queue->timer_list.list);
233 rpc_assign_waitqueue_name(queue, qname);
234}
235
236void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
237{
238 __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
239}
240EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
241
242void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
243{
244 __rpc_init_priority_wait_queue(queue, qname, 1);
245}
246EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
247
248void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
249{
250 del_timer_sync(&queue->timer_list.timer);
251}
252EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
253
254static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode)
255{
256 freezable_schedule_unsafe();
257 if (signal_pending_state(mode, current))
258 return -ERESTARTSYS;
259 return 0;
260}
261
262#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) || IS_ENABLED(CONFIG_TRACEPOINTS)
263static void rpc_task_set_debuginfo(struct rpc_task *task)
264{
265 static atomic_t rpc_pid;
266
267 task->tk_pid = atomic_inc_return(&rpc_pid);
268}
269#else
270static inline void rpc_task_set_debuginfo(struct rpc_task *task)
271{
272}
273#endif
274
275static void rpc_set_active(struct rpc_task *task)
276{
277 rpc_task_set_debuginfo(task);
278 set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
279 trace_rpc_task_begin(task, NULL);
280}
281
282/*
283 * Mark an RPC call as having completed by clearing the 'active' bit
284 * and then waking up all tasks that were sleeping.
285 */
286static int rpc_complete_task(struct rpc_task *task)
287{
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);
291 unsigned long flags;
292 int ret;
293
294 trace_rpc_task_complete(task, NULL);
295
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);
302 return ret;
303}
304
305/*
306 * Allow callers to wait for completion of an RPC call
307 *
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().
311 */
312int __rpc_wait_for_completion_task(struct rpc_task *task, wait_bit_action_f *action)
313{
314 if (action == NULL)
315 action = rpc_wait_bit_killable;
316 return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
317 action, TASK_KILLABLE);
318}
319EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
320
321/*
322 * Make an RPC task runnable.
323 *
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.
331 */
332static void rpc_make_runnable(struct workqueue_struct *wq,
333 struct rpc_task *task)
334{
335 bool need_wakeup = !rpc_test_and_set_running(task);
336
337 rpc_clear_queued(task);
338 if (!need_wakeup)
339 return;
340 if (RPC_IS_ASYNC(task)) {
341 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
342 queue_work(wq, &task->u.tk_work);
343 } else
344 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
345}
346
347/*
348 * Prepare for sleeping on a wait queue.
349 * By always appending tasks to the list we ensure FIFO behavior.
350 * NB: An RPC task will only receive interrupt-driven events as long
351 * as it's on a wait queue.
352 */
353static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
354 struct rpc_task *task,
355 rpc_action action,
356 unsigned char queue_priority)
357{
358 dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
359 task->tk_pid, rpc_qname(q), jiffies);
360
361 trace_rpc_task_sleep(task, q);
362
363 __rpc_add_wait_queue(q, task, queue_priority);
364
365 WARN_ON_ONCE(task->tk_callback != NULL);
366 task->tk_callback = action;
367 __rpc_add_timer(q, task);
368}
369
370void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
371 rpc_action action)
372{
373 /* We shouldn't ever put an inactive task to sleep */
374 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
375 if (!RPC_IS_ACTIVATED(task)) {
376 task->tk_status = -EIO;
377 rpc_put_task_async(task);
378 return;
379 }
380
381 /*
382 * Protect the queue operations.
383 */
384 spin_lock_bh(&q->lock);
385 __rpc_sleep_on_priority(q, task, action, task->tk_priority);
386 spin_unlock_bh(&q->lock);
387}
388EXPORT_SYMBOL_GPL(rpc_sleep_on);
389
390void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
391 rpc_action action, int priority)
392{
393 /* We shouldn't ever put an inactive task to sleep */
394 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
395 if (!RPC_IS_ACTIVATED(task)) {
396 task->tk_status = -EIO;
397 rpc_put_task_async(task);
398 return;
399 }
400
401 /*
402 * Protect the queue operations.
403 */
404 spin_lock_bh(&q->lock);
405 __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
406 spin_unlock_bh(&q->lock);
407}
408EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
409
410/**
411 * __rpc_do_wake_up_task_on_wq - wake up a single rpc_task
412 * @wq: workqueue on which to run task
413 * @queue: wait queue
414 * @task: task to be woken up
415 *
416 * Caller must hold queue->lock, and have cleared the task queued flag.
417 */
418static void __rpc_do_wake_up_task_on_wq(struct workqueue_struct *wq,
419 struct rpc_wait_queue *queue,
420 struct rpc_task *task)
421{
422 dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
423 task->tk_pid, jiffies);
424
425 /* Has the task been executed yet? If not, we cannot wake it up! */
426 if (!RPC_IS_ACTIVATED(task)) {
427 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
428 return;
429 }
430
431 trace_rpc_task_wakeup(task, queue);
432
433 __rpc_remove_wait_queue(queue, task);
434
435 rpc_make_runnable(wq, task);
436
437 dprintk("RPC: __rpc_wake_up_task done\n");
438}
439
440/*
441 * Wake up a queued task while the queue lock is being held
442 */
443static void rpc_wake_up_task_on_wq_queue_locked(struct workqueue_struct *wq,
444 struct rpc_wait_queue *queue, struct rpc_task *task)
445{
446 if (RPC_IS_QUEUED(task)) {
447 smp_rmb();
448 if (task->tk_waitqueue == queue)
449 __rpc_do_wake_up_task_on_wq(wq, queue, task);
450 }
451}
452
453/*
454 * Wake up a queued task while the queue lock is being held
455 */
456static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
457{
458 rpc_wake_up_task_on_wq_queue_locked(rpciod_workqueue, queue, task);
459}
460
461/*
462 * Wake up a task on a specific queue
463 */
464void rpc_wake_up_queued_task_on_wq(struct workqueue_struct *wq,
465 struct rpc_wait_queue *queue,
466 struct rpc_task *task)
467{
468 spin_lock_bh(&queue->lock);
469 rpc_wake_up_task_on_wq_queue_locked(wq, queue, task);
470 spin_unlock_bh(&queue->lock);
471}
472
473/*
474 * Wake up a task on a specific queue
475 */
476void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
477{
478 spin_lock_bh(&queue->lock);
479 rpc_wake_up_task_queue_locked(queue, task);
480 spin_unlock_bh(&queue->lock);
481}
482EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
483
484/*
485 * Wake up the next task on a priority queue.
486 */
487static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
488{
489 struct list_head *q;
490 struct rpc_task *task;
491
492 /*
493 * Service a batch of tasks from a single owner.
494 */
495 q = &queue->tasks[queue->priority];
496 if (!list_empty(q)) {
497 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
498 if (queue->owner == task->tk_owner) {
499 if (--queue->nr)
500 goto out;
501 list_move_tail(&task->u.tk_wait.list, q);
502 }
503 /*
504 * Check if we need to switch queues.
505 */
506 goto new_owner;
507 }
508
509 /*
510 * Service the next queue.
511 */
512 do {
513 if (q == &queue->tasks[0])
514 q = &queue->tasks[queue->maxpriority];
515 else
516 q = q - 1;
517 if (!list_empty(q)) {
518 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
519 goto new_queue;
520 }
521 } while (q != &queue->tasks[queue->priority]);
522
523 rpc_reset_waitqueue_priority(queue);
524 return NULL;
525
526new_queue:
527 rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
528new_owner:
529 rpc_set_waitqueue_owner(queue, task->tk_owner);
530out:
531 return task;
532}
533
534static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
535{
536 if (RPC_IS_PRIORITY(queue))
537 return __rpc_find_next_queued_priority(queue);
538 if (!list_empty(&queue->tasks[0]))
539 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
540 return NULL;
541}
542
543/*
544 * Wake up the first task on the wait queue.
545 */
546struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq,
547 struct rpc_wait_queue *queue,
548 bool (*func)(struct rpc_task *, void *), void *data)
549{
550 struct rpc_task *task = NULL;
551
552 dprintk("RPC: wake_up_first(%p \"%s\")\n",
553 queue, rpc_qname(queue));
554 spin_lock_bh(&queue->lock);
555 task = __rpc_find_next_queued(queue);
556 if (task != NULL) {
557 if (func(task, data))
558 rpc_wake_up_task_on_wq_queue_locked(wq, queue, task);
559 else
560 task = NULL;
561 }
562 spin_unlock_bh(&queue->lock);
563
564 return task;
565}
566
567/*
568 * Wake up the first task on the wait queue.
569 */
570struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
571 bool (*func)(struct rpc_task *, void *), void *data)
572{
573 return rpc_wake_up_first_on_wq(rpciod_workqueue, queue, func, data);
574}
575EXPORT_SYMBOL_GPL(rpc_wake_up_first);
576
577static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
578{
579 return true;
580}
581
582/*
583 * Wake up the next task on the wait queue.
584*/
585struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
586{
587 return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
588}
589EXPORT_SYMBOL_GPL(rpc_wake_up_next);
590
591/**
592 * rpc_wake_up - wake up all rpc_tasks
593 * @queue: rpc_wait_queue on which the tasks are sleeping
594 *
595 * Grabs queue->lock
596 */
597void rpc_wake_up(struct rpc_wait_queue *queue)
598{
599 struct list_head *head;
600
601 spin_lock_bh(&queue->lock);
602 head = &queue->tasks[queue->maxpriority];
603 for (;;) {
604 while (!list_empty(head)) {
605 struct rpc_task *task;
606 task = list_first_entry(head,
607 struct rpc_task,
608 u.tk_wait.list);
609 rpc_wake_up_task_queue_locked(queue, task);
610 }
611 if (head == &queue->tasks[0])
612 break;
613 head--;
614 }
615 spin_unlock_bh(&queue->lock);
616}
617EXPORT_SYMBOL_GPL(rpc_wake_up);
618
619/**
620 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
621 * @queue: rpc_wait_queue on which the tasks are sleeping
622 * @status: status value to set
623 *
624 * Grabs queue->lock
625 */
626void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
627{
628 struct list_head *head;
629
630 spin_lock_bh(&queue->lock);
631 head = &queue->tasks[queue->maxpriority];
632 for (;;) {
633 while (!list_empty(head)) {
634 struct rpc_task *task;
635 task = list_first_entry(head,
636 struct rpc_task,
637 u.tk_wait.list);
638 task->tk_status = status;
639 rpc_wake_up_task_queue_locked(queue, task);
640 }
641 if (head == &queue->tasks[0])
642 break;
643 head--;
644 }
645 spin_unlock_bh(&queue->lock);
646}
647EXPORT_SYMBOL_GPL(rpc_wake_up_status);
648
649static void __rpc_queue_timer_fn(struct timer_list *t)
650{
651 struct rpc_wait_queue *queue = from_timer(queue, t, timer_list.timer);
652 struct rpc_task *task, *n;
653 unsigned long expires, now, timeo;
654
655 spin_lock(&queue->lock);
656 expires = now = jiffies;
657 list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
658 timeo = task->u.tk_wait.expires;
659 if (time_after_eq(now, timeo)) {
660 dprintk("RPC: %5u timeout\n", task->tk_pid);
661 task->tk_status = -ETIMEDOUT;
662 rpc_wake_up_task_queue_locked(queue, task);
663 continue;
664 }
665 if (expires == now || time_after(expires, timeo))
666 expires = timeo;
667 }
668 if (!list_empty(&queue->timer_list.list))
669 rpc_set_queue_timer(queue, expires);
670 spin_unlock(&queue->lock);
671}
672
673static void __rpc_atrun(struct rpc_task *task)
674{
675 if (task->tk_status == -ETIMEDOUT)
676 task->tk_status = 0;
677}
678
679/*
680 * Run a task at a later time
681 */
682void rpc_delay(struct rpc_task *task, unsigned long delay)
683{
684 task->tk_timeout = delay;
685 rpc_sleep_on(&delay_queue, task, __rpc_atrun);
686}
687EXPORT_SYMBOL_GPL(rpc_delay);
688
689/*
690 * Helper to call task->tk_ops->rpc_call_prepare
691 */
692void rpc_prepare_task(struct rpc_task *task)
693{
694 task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
695}
696
697static void
698rpc_init_task_statistics(struct rpc_task *task)
699{
700 /* Initialize retry counters */
701 task->tk_garb_retry = 2;
702 task->tk_cred_retry = 2;
703 task->tk_rebind_retry = 2;
704
705 /* starting timestamp */
706 task->tk_start = ktime_get();
707}
708
709static void
710rpc_reset_task_statistics(struct rpc_task *task)
711{
712 task->tk_timeouts = 0;
713 task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
714
715 rpc_init_task_statistics(task);
716}
717
718/*
719 * Helper that calls task->tk_ops->rpc_call_done if it exists
720 */
721void rpc_exit_task(struct rpc_task *task)
722{
723 task->tk_action = NULL;
724 if (task->tk_ops->rpc_call_done != NULL) {
725 task->tk_ops->rpc_call_done(task, task->tk_calldata);
726 if (task->tk_action != NULL) {
727 WARN_ON(RPC_ASSASSINATED(task));
728 /* Always release the RPC slot and buffer memory */
729 xprt_release(task);
730 rpc_reset_task_statistics(task);
731 }
732 }
733}
734
735void rpc_exit(struct rpc_task *task, int status)
736{
737 task->tk_status = status;
738 task->tk_action = rpc_exit_task;
739 if (RPC_IS_QUEUED(task))
740 rpc_wake_up_queued_task(task->tk_waitqueue, task);
741}
742EXPORT_SYMBOL_GPL(rpc_exit);
743
744void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
745{
746 if (ops->rpc_release != NULL)
747 ops->rpc_release(calldata);
748}
749
750/*
751 * This is the RPC `scheduler' (or rather, the finite state machine).
752 */
753static void __rpc_execute(struct rpc_task *task)
754{
755 struct rpc_wait_queue *queue;
756 int task_is_async = RPC_IS_ASYNC(task);
757 int status = 0;
758
759 dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
760 task->tk_pid, task->tk_flags);
761
762 WARN_ON_ONCE(RPC_IS_QUEUED(task));
763 if (RPC_IS_QUEUED(task))
764 return;
765
766 for (;;) {
767 void (*do_action)(struct rpc_task *);
768
769 /*
770 * Perform the next FSM step or a pending callback.
771 *
772 * tk_action may be NULL if the task has been killed.
773 * In particular, note that rpc_killall_tasks may
774 * do this at any time, so beware when dereferencing.
775 */
776 do_action = task->tk_action;
777 if (task->tk_callback) {
778 do_action = task->tk_callback;
779 task->tk_callback = NULL;
780 }
781 if (!do_action)
782 break;
783 trace_rpc_task_run_action(task, do_action);
784 do_action(task);
785
786 /*
787 * Lockless check for whether task is sleeping or not.
788 */
789 if (!RPC_IS_QUEUED(task))
790 continue;
791 /*
792 * The queue->lock protects against races with
793 * rpc_make_runnable().
794 *
795 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
796 * rpc_task, rpc_make_runnable() can assign it to a
797 * different workqueue. We therefore cannot assume that the
798 * rpc_task pointer may still be dereferenced.
799 */
800 queue = task->tk_waitqueue;
801 spin_lock_bh(&queue->lock);
802 if (!RPC_IS_QUEUED(task)) {
803 spin_unlock_bh(&queue->lock);
804 continue;
805 }
806 rpc_clear_running(task);
807 spin_unlock_bh(&queue->lock);
808 if (task_is_async)
809 return;
810
811 /* sync task: sleep here */
812 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
813 status = out_of_line_wait_on_bit(&task->tk_runstate,
814 RPC_TASK_QUEUED, rpc_wait_bit_killable,
815 TASK_KILLABLE);
816 if (status == -ERESTARTSYS) {
817 /*
818 * When a sync task receives a signal, it exits with
819 * -ERESTARTSYS. In order to catch any callbacks that
820 * clean up after sleeping on some queue, we don't
821 * break the loop here, but go around once more.
822 */
823 dprintk("RPC: %5u got signal\n", task->tk_pid);
824 task->tk_flags |= RPC_TASK_KILLED;
825 rpc_exit(task, -ERESTARTSYS);
826 }
827 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
828 }
829
830 dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
831 task->tk_status);
832 /* Release all resources associated with the task */
833 rpc_release_task(task);
834}
835
836/*
837 * User-visible entry point to the scheduler.
838 *
839 * This may be called recursively if e.g. an async NFS task updates
840 * the attributes and finds that dirty pages must be flushed.
841 * NOTE: Upon exit of this function the task is guaranteed to be
842 * released. In particular note that tk_release() will have
843 * been called, so your task memory may have been freed.
844 */
845void rpc_execute(struct rpc_task *task)
846{
847 bool is_async = RPC_IS_ASYNC(task);
848
849 rpc_set_active(task);
850 rpc_make_runnable(rpciod_workqueue, task);
851 if (!is_async)
852 __rpc_execute(task);
853}
854
855static void rpc_async_schedule(struct work_struct *work)
856{
857 __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
858}
859
860/**
861 * rpc_malloc - allocate RPC buffer resources
862 * @task: RPC task
863 *
864 * A single memory region is allocated, which is split between the
865 * RPC call and RPC reply that this task is being used for. When
866 * this RPC is retired, the memory is released by calling rpc_free.
867 *
868 * To prevent rpciod from hanging, this allocator never sleeps,
869 * returning -ENOMEM and suppressing warning if the request cannot
870 * be serviced immediately. The caller can arrange to sleep in a
871 * way that is safe for rpciod.
872 *
873 * Most requests are 'small' (under 2KiB) and can be serviced from a
874 * mempool, ensuring that NFS reads and writes can always proceed,
875 * and that there is good locality of reference for these buffers.
876 *
877 * In order to avoid memory starvation triggering more writebacks of
878 * NFS requests, we avoid using GFP_KERNEL.
879 */
880int rpc_malloc(struct rpc_task *task)
881{
882 struct rpc_rqst *rqst = task->tk_rqstp;
883 size_t size = rqst->rq_callsize + rqst->rq_rcvsize;
884 struct rpc_buffer *buf;
885 gfp_t gfp = GFP_NOIO | __GFP_NOWARN;
886
887 if (RPC_IS_SWAPPER(task))
888 gfp = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN;
889
890 size += sizeof(struct rpc_buffer);
891 if (size <= RPC_BUFFER_MAXSIZE)
892 buf = mempool_alloc(rpc_buffer_mempool, gfp);
893 else
894 buf = kmalloc(size, gfp);
895
896 if (!buf)
897 return -ENOMEM;
898
899 buf->len = size;
900 dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
901 task->tk_pid, size, buf);
902 rqst->rq_buffer = buf->data;
903 rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_callsize;
904 return 0;
905}
906EXPORT_SYMBOL_GPL(rpc_malloc);
907
908/**
909 * rpc_free - free RPC buffer resources allocated via rpc_malloc
910 * @task: RPC task
911 *
912 */
913void rpc_free(struct rpc_task *task)
914{
915 void *buffer = task->tk_rqstp->rq_buffer;
916 size_t size;
917 struct rpc_buffer *buf;
918
919 buf = container_of(buffer, struct rpc_buffer, data);
920 size = buf->len;
921
922 dprintk("RPC: freeing buffer of size %zu at %p\n",
923 size, buf);
924
925 if (size <= RPC_BUFFER_MAXSIZE)
926 mempool_free(buf, rpc_buffer_mempool);
927 else
928 kfree(buf);
929}
930EXPORT_SYMBOL_GPL(rpc_free);
931
932/*
933 * Creation and deletion of RPC task structures
934 */
935static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
936{
937 memset(task, 0, sizeof(*task));
938 atomic_set(&task->tk_count, 1);
939 task->tk_flags = task_setup_data->flags;
940 task->tk_ops = task_setup_data->callback_ops;
941 task->tk_calldata = task_setup_data->callback_data;
942 INIT_LIST_HEAD(&task->tk_task);
943
944 task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
945 task->tk_owner = current->tgid;
946
947 /* Initialize workqueue for async tasks */
948 task->tk_workqueue = task_setup_data->workqueue;
949
950 task->tk_xprt = xprt_get(task_setup_data->rpc_xprt);
951
952 if (task->tk_ops->rpc_call_prepare != NULL)
953 task->tk_action = rpc_prepare_task;
954
955 rpc_init_task_statistics(task);
956
957 dprintk("RPC: new task initialized, procpid %u\n",
958 task_pid_nr(current));
959}
960
961static struct rpc_task *
962rpc_alloc_task(void)
963{
964 return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO);
965}
966
967/*
968 * Create a new task for the specified client.
969 */
970struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
971{
972 struct rpc_task *task = setup_data->task;
973 unsigned short flags = 0;
974
975 if (task == NULL) {
976 task = rpc_alloc_task();
977 flags = RPC_TASK_DYNAMIC;
978 }
979
980 rpc_init_task(task, setup_data);
981 task->tk_flags |= flags;
982 dprintk("RPC: allocated task %p\n", task);
983 return task;
984}
985
986/*
987 * rpc_free_task - release rpc task and perform cleanups
988 *
989 * Note that we free up the rpc_task _after_ rpc_release_calldata()
990 * in order to work around a workqueue dependency issue.
991 *
992 * Tejun Heo states:
993 * "Workqueue currently considers two work items to be the same if they're
994 * on the same address and won't execute them concurrently - ie. it
995 * makes a work item which is queued again while being executed wait
996 * for the previous execution to complete.
997 *
998 * If a work function frees the work item, and then waits for an event
999 * which should be performed by another work item and *that* work item
1000 * recycles the freed work item, it can create a false dependency loop.
1001 * There really is no reliable way to detect this short of verifying
1002 * every memory free."
1003 *
1004 */
1005static void rpc_free_task(struct rpc_task *task)
1006{
1007 unsigned short tk_flags = task->tk_flags;
1008
1009 rpc_release_calldata(task->tk_ops, task->tk_calldata);
1010
1011 if (tk_flags & RPC_TASK_DYNAMIC) {
1012 dprintk("RPC: %5u freeing task\n", task->tk_pid);
1013 mempool_free(task, rpc_task_mempool);
1014 }
1015}
1016
1017static void rpc_async_release(struct work_struct *work)
1018{
1019 rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
1020}
1021
1022static void rpc_release_resources_task(struct rpc_task *task)
1023{
1024 xprt_release(task);
1025 if (task->tk_msg.rpc_cred) {
1026 put_rpccred(task->tk_msg.rpc_cred);
1027 task->tk_msg.rpc_cred = NULL;
1028 }
1029 rpc_task_release_client(task);
1030}
1031
1032static void rpc_final_put_task(struct rpc_task *task,
1033 struct workqueue_struct *q)
1034{
1035 if (q != NULL) {
1036 INIT_WORK(&task->u.tk_work, rpc_async_release);
1037 queue_work(q, &task->u.tk_work);
1038 } else
1039 rpc_free_task(task);
1040}
1041
1042static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1043{
1044 if (atomic_dec_and_test(&task->tk_count)) {
1045 rpc_release_resources_task(task);
1046 rpc_final_put_task(task, q);
1047 }
1048}
1049
1050void rpc_put_task(struct rpc_task *task)
1051{
1052 rpc_do_put_task(task, NULL);
1053}
1054EXPORT_SYMBOL_GPL(rpc_put_task);
1055
1056void rpc_put_task_async(struct rpc_task *task)
1057{
1058 rpc_do_put_task(task, task->tk_workqueue);
1059}
1060EXPORT_SYMBOL_GPL(rpc_put_task_async);
1061
1062static void rpc_release_task(struct rpc_task *task)
1063{
1064 dprintk("RPC: %5u release task\n", task->tk_pid);
1065
1066 WARN_ON_ONCE(RPC_IS_QUEUED(task));
1067
1068 rpc_release_resources_task(task);
1069
1070 /*
1071 * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1072 * so it should be safe to use task->tk_count as a test for whether
1073 * or not any other processes still hold references to our rpc_task.
1074 */
1075 if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1076 /* Wake up anyone who may be waiting for task completion */
1077 if (!rpc_complete_task(task))
1078 return;
1079 } else {
1080 if (!atomic_dec_and_test(&task->tk_count))
1081 return;
1082 }
1083 rpc_final_put_task(task, task->tk_workqueue);
1084}
1085
1086int rpciod_up(void)
1087{
1088 return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1089}
1090
1091void rpciod_down(void)
1092{
1093 module_put(THIS_MODULE);
1094}
1095
1096/*
1097 * Start up the rpciod workqueue.
1098 */
1099static int rpciod_start(void)
1100{
1101 struct workqueue_struct *wq;
1102
1103 /*
1104 * Create the rpciod thread and wait for it to start.
1105 */
1106 dprintk("RPC: creating workqueue rpciod\n");
1107 wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
1108 if (!wq)
1109 goto out_failed;
1110 rpciod_workqueue = wq;
1111 /* Note: highpri because network receive is latency sensitive */
1112 wq = alloc_workqueue("xprtiod", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_HIGHPRI, 0);
1113 if (!wq)
1114 goto free_rpciod;
1115 xprtiod_workqueue = wq;
1116 return 1;
1117free_rpciod:
1118 wq = rpciod_workqueue;
1119 rpciod_workqueue = NULL;
1120 destroy_workqueue(wq);
1121out_failed:
1122 return 0;
1123}
1124
1125static void rpciod_stop(void)
1126{
1127 struct workqueue_struct *wq = NULL;
1128
1129 if (rpciod_workqueue == NULL)
1130 return;
1131 dprintk("RPC: destroying workqueue rpciod\n");
1132
1133 wq = rpciod_workqueue;
1134 rpciod_workqueue = NULL;
1135 destroy_workqueue(wq);
1136 wq = xprtiod_workqueue;
1137 xprtiod_workqueue = NULL;
1138 destroy_workqueue(wq);
1139}
1140
1141void
1142rpc_destroy_mempool(void)
1143{
1144 rpciod_stop();
1145 mempool_destroy(rpc_buffer_mempool);
1146 mempool_destroy(rpc_task_mempool);
1147 kmem_cache_destroy(rpc_task_slabp);
1148 kmem_cache_destroy(rpc_buffer_slabp);
1149 rpc_destroy_wait_queue(&delay_queue);
1150}
1151
1152int
1153rpc_init_mempool(void)
1154{
1155 /*
1156 * The following is not strictly a mempool initialisation,
1157 * but there is no harm in doing it here
1158 */
1159 rpc_init_wait_queue(&delay_queue, "delayq");
1160 if (!rpciod_start())
1161 goto err_nomem;
1162
1163 rpc_task_slabp = kmem_cache_create("rpc_tasks",
1164 sizeof(struct rpc_task),
1165 0, SLAB_HWCACHE_ALIGN,
1166 NULL);
1167 if (!rpc_task_slabp)
1168 goto err_nomem;
1169 rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1170 RPC_BUFFER_MAXSIZE,
1171 0, SLAB_HWCACHE_ALIGN,
1172 NULL);
1173 if (!rpc_buffer_slabp)
1174 goto err_nomem;
1175 rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1176 rpc_task_slabp);
1177 if (!rpc_task_mempool)
1178 goto err_nomem;
1179 rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1180 rpc_buffer_slabp);
1181 if (!rpc_buffer_mempool)
1182 goto err_nomem;
1183 return 0;
1184err_nomem:
1185 rpc_destroy_mempool();
1186 return -ENOMEM;
1187}