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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(unsigned long ptr);
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;
58
59/*
60 * Disable the timer for a given RPC task. Should be called with
61 * queue->lock and bh_disabled in order to avoid races within
62 * rpc_run_timer().
63 */
64static void
65__rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
66{
67 if (task->tk_timeout == 0)
68 return;
69 dprintk("RPC: %5u disabling timer\n", task->tk_pid);
70 task->tk_timeout = 0;
71 list_del(&task->u.tk_wait.timer_list);
72 if (list_empty(&queue->timer_list.list))
73 del_timer(&queue->timer_list.timer);
74}
75
76static void
77rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
78{
79 queue->timer_list.expires = expires;
80 mod_timer(&queue->timer_list.timer, expires);
81}
82
83/*
84 * Set up a timer for the current task.
85 */
86static void
87__rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
88{
89 if (!task->tk_timeout)
90 return;
91
92 dprintk("RPC: %5u setting alarm for %u ms\n",
93 task->tk_pid, jiffies_to_msecs(task->tk_timeout));
94
95 task->u.tk_wait.expires = jiffies + task->tk_timeout;
96 if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
97 rpc_set_queue_timer(queue, task->u.tk_wait.expires);
98 list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
99}
100
101static void rpc_rotate_queue_owner(struct rpc_wait_queue *queue)
102{
103 struct list_head *q = &queue->tasks[queue->priority];
104 struct rpc_task *task;
105
106 if (!list_empty(q)) {
107 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
108 if (task->tk_owner == queue->owner)
109 list_move_tail(&task->u.tk_wait.list, q);
110 }
111}
112
113static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
114{
115 if (queue->priority != priority) {
116 /* Fairness: rotate the list when changing priority */
117 rpc_rotate_queue_owner(queue);
118 queue->priority = priority;
119 }
120}
121
122static void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
123{
124 queue->owner = pid;
125 queue->nr = RPC_BATCH_COUNT;
126}
127
128static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
129{
130 rpc_set_waitqueue_priority(queue, queue->maxpriority);
131 rpc_set_waitqueue_owner(queue, 0);
132}
133
134/*
135 * Add new request to a priority queue.
136 */
137static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
138 struct rpc_task *task,
139 unsigned char queue_priority)
140{
141 struct list_head *q;
142 struct rpc_task *t;
143
144 INIT_LIST_HEAD(&task->u.tk_wait.links);
145 if (unlikely(queue_priority > queue->maxpriority))
146 queue_priority = queue->maxpriority;
147 if (queue_priority > queue->priority)
148 rpc_set_waitqueue_priority(queue, queue_priority);
149 q = &queue->tasks[queue_priority];
150 list_for_each_entry(t, q, u.tk_wait.list) {
151 if (t->tk_owner == task->tk_owner) {
152 list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
153 return;
154 }
155 }
156 list_add_tail(&task->u.tk_wait.list, q);
157}
158
159/*
160 * Add new request to wait queue.
161 *
162 * Swapper tasks always get inserted at the head of the queue.
163 * This should avoid many nasty memory deadlocks and hopefully
164 * improve overall performance.
165 * Everyone else gets appended to the queue to ensure proper FIFO behavior.
166 */
167static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
168 struct rpc_task *task,
169 unsigned char queue_priority)
170{
171 WARN_ON_ONCE(RPC_IS_QUEUED(task));
172 if (RPC_IS_QUEUED(task))
173 return;
174
175 if (RPC_IS_PRIORITY(queue))
176 __rpc_add_wait_queue_priority(queue, task, queue_priority);
177 else if (RPC_IS_SWAPPER(task))
178 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
179 else
180 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
181 task->tk_waitqueue = queue;
182 queue->qlen++;
183 /* barrier matches the read in rpc_wake_up_task_queue_locked() */
184 smp_wmb();
185 rpc_set_queued(task);
186
187 dprintk("RPC: %5u added to queue %p \"%s\"\n",
188 task->tk_pid, queue, rpc_qname(queue));
189}
190
191/*
192 * Remove request from a priority queue.
193 */
194static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
195{
196 struct rpc_task *t;
197
198 if (!list_empty(&task->u.tk_wait.links)) {
199 t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
200 list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
201 list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
202 }
203}
204
205/*
206 * Remove request from queue.
207 * Note: must be called with spin lock held.
208 */
209static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
210{
211 __rpc_disable_timer(queue, task);
212 if (RPC_IS_PRIORITY(queue))
213 __rpc_remove_wait_queue_priority(task);
214 list_del(&task->u.tk_wait.list);
215 queue->qlen--;
216 dprintk("RPC: %5u removed from queue %p \"%s\"\n",
217 task->tk_pid, queue, rpc_qname(queue));
218}
219
220static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
221{
222 int i;
223
224 spin_lock_init(&queue->lock);
225 for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
226 INIT_LIST_HEAD(&queue->tasks[i]);
227 queue->maxpriority = nr_queues - 1;
228 rpc_reset_waitqueue_priority(queue);
229 queue->qlen = 0;
230 setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
231 INIT_LIST_HEAD(&queue->timer_list.list);
232 rpc_assign_waitqueue_name(queue, qname);
233}
234
235void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
236{
237 __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
238}
239EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
240
241void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
242{
243 __rpc_init_priority_wait_queue(queue, qname, 1);
244}
245EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
246
247void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
248{
249 del_timer_sync(&queue->timer_list.timer);
250}
251EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
252
253static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode)
254{
255 freezable_schedule_unsafe();
256 if (signal_pending_state(mode, current))
257 return -ERESTARTSYS;
258 return 0;
259}
260
261#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) || IS_ENABLED(CONFIG_TRACEPOINTS)
262static void rpc_task_set_debuginfo(struct rpc_task *task)
263{
264 static atomic_t rpc_pid;
265
266 task->tk_pid = atomic_inc_return(&rpc_pid);
267}
268#else
269static inline void rpc_task_set_debuginfo(struct rpc_task *task)
270{
271}
272#endif
273
274static void rpc_set_active(struct rpc_task *task)
275{
276 trace_rpc_task_begin(task->tk_client, task, NULL);
277
278 rpc_task_set_debuginfo(task);
279 set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
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->tk_client, 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 rpc_task *task)
333{
334 bool need_wakeup = !rpc_test_and_set_running(task);
335
336 rpc_clear_queued(task);
337 if (!need_wakeup)
338 return;
339 if (RPC_IS_ASYNC(task)) {
340 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
341 queue_work(rpciod_workqueue, &task->u.tk_work);
342 } else
343 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
344}
345
346/*
347 * Prepare for sleeping on a wait queue.
348 * By always appending tasks to the list we ensure FIFO behavior.
349 * NB: An RPC task will only receive interrupt-driven events as long
350 * as it's on a wait queue.
351 */
352static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
353 struct rpc_task *task,
354 rpc_action action,
355 unsigned char queue_priority)
356{
357 dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
358 task->tk_pid, rpc_qname(q), jiffies);
359
360 trace_rpc_task_sleep(task->tk_client, task, q);
361
362 __rpc_add_wait_queue(q, task, queue_priority);
363
364 WARN_ON_ONCE(task->tk_callback != NULL);
365 task->tk_callback = action;
366 __rpc_add_timer(q, task);
367}
368
369void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
370 rpc_action action)
371{
372 /* We shouldn't ever put an inactive task to sleep */
373 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
374 if (!RPC_IS_ACTIVATED(task)) {
375 task->tk_status = -EIO;
376 rpc_put_task_async(task);
377 return;
378 }
379
380 /*
381 * Protect the queue operations.
382 */
383 spin_lock_bh(&q->lock);
384 __rpc_sleep_on_priority(q, task, action, task->tk_priority);
385 spin_unlock_bh(&q->lock);
386}
387EXPORT_SYMBOL_GPL(rpc_sleep_on);
388
389void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
390 rpc_action action, int priority)
391{
392 /* We shouldn't ever put an inactive task to sleep */
393 WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
394 if (!RPC_IS_ACTIVATED(task)) {
395 task->tk_status = -EIO;
396 rpc_put_task_async(task);
397 return;
398 }
399
400 /*
401 * Protect the queue operations.
402 */
403 spin_lock_bh(&q->lock);
404 __rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
405 spin_unlock_bh(&q->lock);
406}
407EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
408
409/**
410 * __rpc_do_wake_up_task - wake up a single rpc_task
411 * @queue: wait queue
412 * @task: task to be woken up
413 *
414 * Caller must hold queue->lock, and have cleared the task queued flag.
415 */
416static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
417{
418 dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
419 task->tk_pid, jiffies);
420
421 /* Has the task been executed yet? If not, we cannot wake it up! */
422 if (!RPC_IS_ACTIVATED(task)) {
423 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
424 return;
425 }
426
427 trace_rpc_task_wakeup(task->tk_client, task, queue);
428
429 __rpc_remove_wait_queue(queue, task);
430
431 rpc_make_runnable(task);
432
433 dprintk("RPC: __rpc_wake_up_task done\n");
434}
435
436/*
437 * Wake up a queued task while the queue lock is being held
438 */
439static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
440{
441 if (RPC_IS_QUEUED(task)) {
442 smp_rmb();
443 if (task->tk_waitqueue == queue)
444 __rpc_do_wake_up_task(queue, task);
445 }
446}
447
448/*
449 * Wake up a task on a specific queue
450 */
451void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
452{
453 spin_lock_bh(&queue->lock);
454 rpc_wake_up_task_queue_locked(queue, task);
455 spin_unlock_bh(&queue->lock);
456}
457EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
458
459/*
460 * Wake up the next task on a priority queue.
461 */
462static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
463{
464 struct list_head *q;
465 struct rpc_task *task;
466
467 /*
468 * Service a batch of tasks from a single owner.
469 */
470 q = &queue->tasks[queue->priority];
471 if (!list_empty(q)) {
472 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
473 if (queue->owner == task->tk_owner) {
474 if (--queue->nr)
475 goto out;
476 list_move_tail(&task->u.tk_wait.list, q);
477 }
478 /*
479 * Check if we need to switch queues.
480 */
481 goto new_owner;
482 }
483
484 /*
485 * Service the next queue.
486 */
487 do {
488 if (q == &queue->tasks[0])
489 q = &queue->tasks[queue->maxpriority];
490 else
491 q = q - 1;
492 if (!list_empty(q)) {
493 task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
494 goto new_queue;
495 }
496 } while (q != &queue->tasks[queue->priority]);
497
498 rpc_reset_waitqueue_priority(queue);
499 return NULL;
500
501new_queue:
502 rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
503new_owner:
504 rpc_set_waitqueue_owner(queue, task->tk_owner);
505out:
506 return task;
507}
508
509static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
510{
511 if (RPC_IS_PRIORITY(queue))
512 return __rpc_find_next_queued_priority(queue);
513 if (!list_empty(&queue->tasks[0]))
514 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
515 return NULL;
516}
517
518/*
519 * Wake up the first task on the wait queue.
520 */
521struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
522 bool (*func)(struct rpc_task *, void *), void *data)
523{
524 struct rpc_task *task = NULL;
525
526 dprintk("RPC: wake_up_first(%p \"%s\")\n",
527 queue, rpc_qname(queue));
528 spin_lock_bh(&queue->lock);
529 task = __rpc_find_next_queued(queue);
530 if (task != NULL) {
531 if (func(task, data))
532 rpc_wake_up_task_queue_locked(queue, task);
533 else
534 task = NULL;
535 }
536 spin_unlock_bh(&queue->lock);
537
538 return task;
539}
540EXPORT_SYMBOL_GPL(rpc_wake_up_first);
541
542static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
543{
544 return true;
545}
546
547/*
548 * Wake up the next task on the wait queue.
549*/
550struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
551{
552 return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
553}
554EXPORT_SYMBOL_GPL(rpc_wake_up_next);
555
556/**
557 * rpc_wake_up - wake up all rpc_tasks
558 * @queue: rpc_wait_queue on which the tasks are sleeping
559 *
560 * Grabs queue->lock
561 */
562void rpc_wake_up(struct rpc_wait_queue *queue)
563{
564 struct list_head *head;
565
566 spin_lock_bh(&queue->lock);
567 head = &queue->tasks[queue->maxpriority];
568 for (;;) {
569 while (!list_empty(head)) {
570 struct rpc_task *task;
571 task = list_first_entry(head,
572 struct rpc_task,
573 u.tk_wait.list);
574 rpc_wake_up_task_queue_locked(queue, task);
575 }
576 if (head == &queue->tasks[0])
577 break;
578 head--;
579 }
580 spin_unlock_bh(&queue->lock);
581}
582EXPORT_SYMBOL_GPL(rpc_wake_up);
583
584/**
585 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
586 * @queue: rpc_wait_queue on which the tasks are sleeping
587 * @status: status value to set
588 *
589 * Grabs queue->lock
590 */
591void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
592{
593 struct list_head *head;
594
595 spin_lock_bh(&queue->lock);
596 head = &queue->tasks[queue->maxpriority];
597 for (;;) {
598 while (!list_empty(head)) {
599 struct rpc_task *task;
600 task = list_first_entry(head,
601 struct rpc_task,
602 u.tk_wait.list);
603 task->tk_status = status;
604 rpc_wake_up_task_queue_locked(queue, task);
605 }
606 if (head == &queue->tasks[0])
607 break;
608 head--;
609 }
610 spin_unlock_bh(&queue->lock);
611}
612EXPORT_SYMBOL_GPL(rpc_wake_up_status);
613
614static void __rpc_queue_timer_fn(unsigned long ptr)
615{
616 struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
617 struct rpc_task *task, *n;
618 unsigned long expires, now, timeo;
619
620 spin_lock(&queue->lock);
621 expires = now = jiffies;
622 list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
623 timeo = task->u.tk_wait.expires;
624 if (time_after_eq(now, timeo)) {
625 dprintk("RPC: %5u timeout\n", task->tk_pid);
626 task->tk_status = -ETIMEDOUT;
627 rpc_wake_up_task_queue_locked(queue, task);
628 continue;
629 }
630 if (expires == now || time_after(expires, timeo))
631 expires = timeo;
632 }
633 if (!list_empty(&queue->timer_list.list))
634 rpc_set_queue_timer(queue, expires);
635 spin_unlock(&queue->lock);
636}
637
638static void __rpc_atrun(struct rpc_task *task)
639{
640 if (task->tk_status == -ETIMEDOUT)
641 task->tk_status = 0;
642}
643
644/*
645 * Run a task at a later time
646 */
647void rpc_delay(struct rpc_task *task, unsigned long delay)
648{
649 task->tk_timeout = delay;
650 rpc_sleep_on(&delay_queue, task, __rpc_atrun);
651}
652EXPORT_SYMBOL_GPL(rpc_delay);
653
654/*
655 * Helper to call task->tk_ops->rpc_call_prepare
656 */
657void rpc_prepare_task(struct rpc_task *task)
658{
659 task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
660}
661
662static void
663rpc_init_task_statistics(struct rpc_task *task)
664{
665 /* Initialize retry counters */
666 task->tk_garb_retry = 2;
667 task->tk_cred_retry = 2;
668 task->tk_rebind_retry = 2;
669
670 /* starting timestamp */
671 task->tk_start = ktime_get();
672}
673
674static void
675rpc_reset_task_statistics(struct rpc_task *task)
676{
677 task->tk_timeouts = 0;
678 task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
679
680 rpc_init_task_statistics(task);
681}
682
683/*
684 * Helper that calls task->tk_ops->rpc_call_done if it exists
685 */
686void rpc_exit_task(struct rpc_task *task)
687{
688 task->tk_action = NULL;
689 if (task->tk_ops->rpc_call_done != NULL) {
690 task->tk_ops->rpc_call_done(task, task->tk_calldata);
691 if (task->tk_action != NULL) {
692 WARN_ON(RPC_ASSASSINATED(task));
693 /* Always release the RPC slot and buffer memory */
694 xprt_release(task);
695 rpc_reset_task_statistics(task);
696 }
697 }
698}
699
700void rpc_exit(struct rpc_task *task, int status)
701{
702 task->tk_status = status;
703 task->tk_action = rpc_exit_task;
704 if (RPC_IS_QUEUED(task))
705 rpc_wake_up_queued_task(task->tk_waitqueue, task);
706}
707EXPORT_SYMBOL_GPL(rpc_exit);
708
709void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
710{
711 if (ops->rpc_release != NULL)
712 ops->rpc_release(calldata);
713}
714
715/*
716 * This is the RPC `scheduler' (or rather, the finite state machine).
717 */
718static void __rpc_execute(struct rpc_task *task)
719{
720 struct rpc_wait_queue *queue;
721 int task_is_async = RPC_IS_ASYNC(task);
722 int status = 0;
723
724 dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
725 task->tk_pid, task->tk_flags);
726
727 WARN_ON_ONCE(RPC_IS_QUEUED(task));
728 if (RPC_IS_QUEUED(task))
729 return;
730
731 for (;;) {
732 void (*do_action)(struct rpc_task *);
733
734 /*
735 * Execute any pending callback first.
736 */
737 do_action = task->tk_callback;
738 task->tk_callback = NULL;
739 if (do_action == NULL) {
740 /*
741 * Perform the next FSM step.
742 * tk_action may be NULL if the task has been killed.
743 * In particular, note that rpc_killall_tasks may
744 * do this at any time, so beware when dereferencing.
745 */
746 do_action = task->tk_action;
747 if (do_action == NULL)
748 break;
749 }
750 trace_rpc_task_run_action(task->tk_client, task, task->tk_action);
751 do_action(task);
752
753 /*
754 * Lockless check for whether task is sleeping or not.
755 */
756 if (!RPC_IS_QUEUED(task))
757 continue;
758 /*
759 * The queue->lock protects against races with
760 * rpc_make_runnable().
761 *
762 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
763 * rpc_task, rpc_make_runnable() can assign it to a
764 * different workqueue. We therefore cannot assume that the
765 * rpc_task pointer may still be dereferenced.
766 */
767 queue = task->tk_waitqueue;
768 spin_lock_bh(&queue->lock);
769 if (!RPC_IS_QUEUED(task)) {
770 spin_unlock_bh(&queue->lock);
771 continue;
772 }
773 rpc_clear_running(task);
774 spin_unlock_bh(&queue->lock);
775 if (task_is_async)
776 return;
777
778 /* sync task: sleep here */
779 dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
780 status = out_of_line_wait_on_bit(&task->tk_runstate,
781 RPC_TASK_QUEUED, rpc_wait_bit_killable,
782 TASK_KILLABLE);
783 if (status == -ERESTARTSYS) {
784 /*
785 * When a sync task receives a signal, it exits with
786 * -ERESTARTSYS. In order to catch any callbacks that
787 * clean up after sleeping on some queue, we don't
788 * break the loop here, but go around once more.
789 */
790 dprintk("RPC: %5u got signal\n", task->tk_pid);
791 task->tk_flags |= RPC_TASK_KILLED;
792 rpc_exit(task, -ERESTARTSYS);
793 }
794 dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
795 }
796
797 dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
798 task->tk_status);
799 /* Release all resources associated with the task */
800 rpc_release_task(task);
801}
802
803/*
804 * User-visible entry point to the scheduler.
805 *
806 * This may be called recursively if e.g. an async NFS task updates
807 * the attributes and finds that dirty pages must be flushed.
808 * NOTE: Upon exit of this function the task is guaranteed to be
809 * released. In particular note that tk_release() will have
810 * been called, so your task memory may have been freed.
811 */
812void rpc_execute(struct rpc_task *task)
813{
814 bool is_async = RPC_IS_ASYNC(task);
815
816 rpc_set_active(task);
817 rpc_make_runnable(task);
818 if (!is_async)
819 __rpc_execute(task);
820}
821
822static void rpc_async_schedule(struct work_struct *work)
823{
824 __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
825}
826
827/**
828 * rpc_malloc - allocate an RPC buffer
829 * @task: RPC task that will use this buffer
830 * @size: requested byte size
831 *
832 * To prevent rpciod from hanging, this allocator never sleeps,
833 * returning NULL and suppressing warning if the request cannot be serviced
834 * immediately.
835 * The caller can arrange to sleep in a way that is safe for rpciod.
836 *
837 * Most requests are 'small' (under 2KiB) and can be serviced from a
838 * mempool, ensuring that NFS reads and writes can always proceed,
839 * and that there is good locality of reference for these buffers.
840 *
841 * In order to avoid memory starvation triggering more writebacks of
842 * NFS requests, we avoid using GFP_KERNEL.
843 */
844void *rpc_malloc(struct rpc_task *task, size_t size)
845{
846 struct rpc_buffer *buf;
847 gfp_t gfp = GFP_NOIO | __GFP_NOWARN;
848
849 if (RPC_IS_SWAPPER(task))
850 gfp = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN;
851
852 size += sizeof(struct rpc_buffer);
853 if (size <= RPC_BUFFER_MAXSIZE)
854 buf = mempool_alloc(rpc_buffer_mempool, gfp);
855 else
856 buf = kmalloc(size, gfp);
857
858 if (!buf)
859 return NULL;
860
861 buf->len = size;
862 dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
863 task->tk_pid, size, buf);
864 return &buf->data;
865}
866EXPORT_SYMBOL_GPL(rpc_malloc);
867
868/**
869 * rpc_free - free buffer allocated via rpc_malloc
870 * @buffer: buffer to free
871 *
872 */
873void rpc_free(void *buffer)
874{
875 size_t size;
876 struct rpc_buffer *buf;
877
878 if (!buffer)
879 return;
880
881 buf = container_of(buffer, struct rpc_buffer, data);
882 size = buf->len;
883
884 dprintk("RPC: freeing buffer of size %zu at %p\n",
885 size, buf);
886
887 if (size <= RPC_BUFFER_MAXSIZE)
888 mempool_free(buf, rpc_buffer_mempool);
889 else
890 kfree(buf);
891}
892EXPORT_SYMBOL_GPL(rpc_free);
893
894/*
895 * Creation and deletion of RPC task structures
896 */
897static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
898{
899 memset(task, 0, sizeof(*task));
900 atomic_set(&task->tk_count, 1);
901 task->tk_flags = task_setup_data->flags;
902 task->tk_ops = task_setup_data->callback_ops;
903 task->tk_calldata = task_setup_data->callback_data;
904 INIT_LIST_HEAD(&task->tk_task);
905
906 task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
907 task->tk_owner = current->tgid;
908
909 /* Initialize workqueue for async tasks */
910 task->tk_workqueue = task_setup_data->workqueue;
911
912 task->tk_xprt = xprt_get(task_setup_data->rpc_xprt);
913
914 if (task->tk_ops->rpc_call_prepare != NULL)
915 task->tk_action = rpc_prepare_task;
916
917 rpc_init_task_statistics(task);
918
919 dprintk("RPC: new task initialized, procpid %u\n",
920 task_pid_nr(current));
921}
922
923static struct rpc_task *
924rpc_alloc_task(void)
925{
926 return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO);
927}
928
929/*
930 * Create a new task for the specified client.
931 */
932struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
933{
934 struct rpc_task *task = setup_data->task;
935 unsigned short flags = 0;
936
937 if (task == NULL) {
938 task = rpc_alloc_task();
939 if (task == NULL) {
940 rpc_release_calldata(setup_data->callback_ops,
941 setup_data->callback_data);
942 return ERR_PTR(-ENOMEM);
943 }
944 flags = RPC_TASK_DYNAMIC;
945 }
946
947 rpc_init_task(task, setup_data);
948 task->tk_flags |= flags;
949 dprintk("RPC: allocated task %p\n", task);
950 return task;
951}
952
953/*
954 * rpc_free_task - release rpc task and perform cleanups
955 *
956 * Note that we free up the rpc_task _after_ rpc_release_calldata()
957 * in order to work around a workqueue dependency issue.
958 *
959 * Tejun Heo states:
960 * "Workqueue currently considers two work items to be the same if they're
961 * on the same address and won't execute them concurrently - ie. it
962 * makes a work item which is queued again while being executed wait
963 * for the previous execution to complete.
964 *
965 * If a work function frees the work item, and then waits for an event
966 * which should be performed by another work item and *that* work item
967 * recycles the freed work item, it can create a false dependency loop.
968 * There really is no reliable way to detect this short of verifying
969 * every memory free."
970 *
971 */
972static void rpc_free_task(struct rpc_task *task)
973{
974 unsigned short tk_flags = task->tk_flags;
975
976 rpc_release_calldata(task->tk_ops, task->tk_calldata);
977
978 if (tk_flags & RPC_TASK_DYNAMIC) {
979 dprintk("RPC: %5u freeing task\n", task->tk_pid);
980 mempool_free(task, rpc_task_mempool);
981 }
982}
983
984static void rpc_async_release(struct work_struct *work)
985{
986 rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
987}
988
989static void rpc_release_resources_task(struct rpc_task *task)
990{
991 xprt_release(task);
992 if (task->tk_msg.rpc_cred) {
993 put_rpccred(task->tk_msg.rpc_cred);
994 task->tk_msg.rpc_cred = NULL;
995 }
996 rpc_task_release_client(task);
997}
998
999static void rpc_final_put_task(struct rpc_task *task,
1000 struct workqueue_struct *q)
1001{
1002 if (q != NULL) {
1003 INIT_WORK(&task->u.tk_work, rpc_async_release);
1004 queue_work(q, &task->u.tk_work);
1005 } else
1006 rpc_free_task(task);
1007}
1008
1009static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1010{
1011 if (atomic_dec_and_test(&task->tk_count)) {
1012 rpc_release_resources_task(task);
1013 rpc_final_put_task(task, q);
1014 }
1015}
1016
1017void rpc_put_task(struct rpc_task *task)
1018{
1019 rpc_do_put_task(task, NULL);
1020}
1021EXPORT_SYMBOL_GPL(rpc_put_task);
1022
1023void rpc_put_task_async(struct rpc_task *task)
1024{
1025 rpc_do_put_task(task, task->tk_workqueue);
1026}
1027EXPORT_SYMBOL_GPL(rpc_put_task_async);
1028
1029static void rpc_release_task(struct rpc_task *task)
1030{
1031 dprintk("RPC: %5u release task\n", task->tk_pid);
1032
1033 WARN_ON_ONCE(RPC_IS_QUEUED(task));
1034
1035 rpc_release_resources_task(task);
1036
1037 /*
1038 * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1039 * so it should be safe to use task->tk_count as a test for whether
1040 * or not any other processes still hold references to our rpc_task.
1041 */
1042 if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1043 /* Wake up anyone who may be waiting for task completion */
1044 if (!rpc_complete_task(task))
1045 return;
1046 } else {
1047 if (!atomic_dec_and_test(&task->tk_count))
1048 return;
1049 }
1050 rpc_final_put_task(task, task->tk_workqueue);
1051}
1052
1053int rpciod_up(void)
1054{
1055 return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1056}
1057
1058void rpciod_down(void)
1059{
1060 module_put(THIS_MODULE);
1061}
1062
1063/*
1064 * Start up the rpciod workqueue.
1065 */
1066static int rpciod_start(void)
1067{
1068 struct workqueue_struct *wq;
1069
1070 /*
1071 * Create the rpciod thread and wait for it to start.
1072 */
1073 dprintk("RPC: creating workqueue rpciod\n");
1074 /* Note: highpri because network receive is latency sensitive */
1075 wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1076 rpciod_workqueue = wq;
1077 return rpciod_workqueue != NULL;
1078}
1079
1080static void rpciod_stop(void)
1081{
1082 struct workqueue_struct *wq = NULL;
1083
1084 if (rpciod_workqueue == NULL)
1085 return;
1086 dprintk("RPC: destroying workqueue rpciod\n");
1087
1088 wq = rpciod_workqueue;
1089 rpciod_workqueue = NULL;
1090 destroy_workqueue(wq);
1091}
1092
1093void
1094rpc_destroy_mempool(void)
1095{
1096 rpciod_stop();
1097 mempool_destroy(rpc_buffer_mempool);
1098 mempool_destroy(rpc_task_mempool);
1099 kmem_cache_destroy(rpc_task_slabp);
1100 kmem_cache_destroy(rpc_buffer_slabp);
1101 rpc_destroy_wait_queue(&delay_queue);
1102}
1103
1104int
1105rpc_init_mempool(void)
1106{
1107 /*
1108 * The following is not strictly a mempool initialisation,
1109 * but there is no harm in doing it here
1110 */
1111 rpc_init_wait_queue(&delay_queue, "delayq");
1112 if (!rpciod_start())
1113 goto err_nomem;
1114
1115 rpc_task_slabp = kmem_cache_create("rpc_tasks",
1116 sizeof(struct rpc_task),
1117 0, SLAB_HWCACHE_ALIGN,
1118 NULL);
1119 if (!rpc_task_slabp)
1120 goto err_nomem;
1121 rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1122 RPC_BUFFER_MAXSIZE,
1123 0, SLAB_HWCACHE_ALIGN,
1124 NULL);
1125 if (!rpc_buffer_slabp)
1126 goto err_nomem;
1127 rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1128 rpc_task_slabp);
1129 if (!rpc_task_mempool)
1130 goto err_nomem;
1131 rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1132 rpc_buffer_slabp);
1133 if (!rpc_buffer_mempool)
1134 goto err_nomem;
1135 return 0;
1136err_nomem:
1137 rpc_destroy_mempool();
1138 return -ENOMEM;
1139}
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
60unsigned long
61rpc_task_timeout(const struct rpc_task *task)
62{
63 unsigned long timeout = READ_ONCE(task->tk_timeout);
64
65 if (timeout != 0) {
66 unsigned long now = jiffies;
67 if (time_before(now, timeout))
68 return timeout - now;
69 }
70 return 0;
71}
72EXPORT_SYMBOL_GPL(rpc_task_timeout);
73
74/*
75 * Disable the timer for a given RPC task. Should be called with
76 * queue->lock and bh_disabled in order to avoid races within
77 * rpc_run_timer().
78 */
79static void
80__rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
81{
82 if (list_empty(&task->u.tk_wait.timer_list))
83 return;
84 task->tk_timeout = 0;
85 list_del(&task->u.tk_wait.timer_list);
86 if (list_empty(&queue->timer_list.list))
87 cancel_delayed_work(&queue->timer_list.dwork);
88}
89
90static void
91rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
92{
93 unsigned long now = jiffies;
94 queue->timer_list.expires = expires;
95 if (time_before_eq(expires, now))
96 expires = 0;
97 else
98 expires -= now;
99 mod_delayed_work(rpciod_workqueue, &queue->timer_list.dwork, expires);
100}
101
102/*
103 * Set up a timer for the current task.
104 */
105static void
106__rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task,
107 unsigned long timeout)
108{
109 task->tk_timeout = timeout;
110 if (list_empty(&queue->timer_list.list) || time_before(timeout, queue->timer_list.expires))
111 rpc_set_queue_timer(queue, timeout);
112 list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
113}
114
115static void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
116{
117 if (queue->priority != priority) {
118 queue->priority = priority;
119 queue->nr = 1U << priority;
120 }
121}
122
123static void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
124{
125 rpc_set_waitqueue_priority(queue, queue->maxpriority);
126}
127
128/*
129 * Add a request to a queue list
130 */
131static void
132__rpc_list_enqueue_task(struct list_head *q, struct rpc_task *task)
133{
134 struct rpc_task *t;
135
136 list_for_each_entry(t, q, u.tk_wait.list) {
137 if (t->tk_owner == task->tk_owner) {
138 list_add_tail(&task->u.tk_wait.links,
139 &t->u.tk_wait.links);
140 /* Cache the queue head in task->u.tk_wait.list */
141 task->u.tk_wait.list.next = q;
142 task->u.tk_wait.list.prev = NULL;
143 return;
144 }
145 }
146 INIT_LIST_HEAD(&task->u.tk_wait.links);
147 list_add_tail(&task->u.tk_wait.list, q);
148}
149
150/*
151 * Remove request from a queue list
152 */
153static void
154__rpc_list_dequeue_task(struct rpc_task *task)
155{
156 struct list_head *q;
157 struct rpc_task *t;
158
159 if (task->u.tk_wait.list.prev == NULL) {
160 list_del(&task->u.tk_wait.links);
161 return;
162 }
163 if (!list_empty(&task->u.tk_wait.links)) {
164 t = list_first_entry(&task->u.tk_wait.links,
165 struct rpc_task,
166 u.tk_wait.links);
167 /* Assume __rpc_list_enqueue_task() cached the queue head */
168 q = t->u.tk_wait.list.next;
169 list_add_tail(&t->u.tk_wait.list, q);
170 list_del(&task->u.tk_wait.links);
171 }
172 list_del(&task->u.tk_wait.list);
173}
174
175/*
176 * Add new request to a priority queue.
177 */
178static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue,
179 struct rpc_task *task,
180 unsigned char queue_priority)
181{
182 if (unlikely(queue_priority > queue->maxpriority))
183 queue_priority = queue->maxpriority;
184 __rpc_list_enqueue_task(&queue->tasks[queue_priority], task);
185}
186
187/*
188 * Add new request to wait queue.
189 *
190 * Swapper tasks always get inserted at the head of the queue.
191 * This should avoid many nasty memory deadlocks and hopefully
192 * improve overall performance.
193 * Everyone else gets appended to the queue to ensure proper FIFO behavior.
194 */
195static void __rpc_add_wait_queue(struct rpc_wait_queue *queue,
196 struct rpc_task *task,
197 unsigned char queue_priority)
198{
199 INIT_LIST_HEAD(&task->u.tk_wait.timer_list);
200 if (RPC_IS_PRIORITY(queue))
201 __rpc_add_wait_queue_priority(queue, task, queue_priority);
202 else if (RPC_IS_SWAPPER(task))
203 list_add(&task->u.tk_wait.list, &queue->tasks[0]);
204 else
205 list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
206 task->tk_waitqueue = queue;
207 queue->qlen++;
208 /* barrier matches the read in rpc_wake_up_task_queue_locked() */
209 smp_wmb();
210 rpc_set_queued(task);
211}
212
213/*
214 * Remove request from a priority queue.
215 */
216static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
217{
218 __rpc_list_dequeue_task(task);
219}
220
221/*
222 * Remove request from queue.
223 * Note: must be called with spin lock held.
224 */
225static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
226{
227 __rpc_disable_timer(queue, task);
228 if (RPC_IS_PRIORITY(queue))
229 __rpc_remove_wait_queue_priority(task);
230 else
231 list_del(&task->u.tk_wait.list);
232 queue->qlen--;
233}
234
235static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
236{
237 int i;
238
239 spin_lock_init(&queue->lock);
240 for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
241 INIT_LIST_HEAD(&queue->tasks[i]);
242 queue->maxpriority = nr_queues - 1;
243 rpc_reset_waitqueue_priority(queue);
244 queue->qlen = 0;
245 queue->timer_list.expires = 0;
246 INIT_DELAYED_WORK(&queue->timer_list.dwork, __rpc_queue_timer_fn);
247 INIT_LIST_HEAD(&queue->timer_list.list);
248 rpc_assign_waitqueue_name(queue, qname);
249}
250
251void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
252{
253 __rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
254}
255EXPORT_SYMBOL_GPL(rpc_init_priority_wait_queue);
256
257void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
258{
259 __rpc_init_priority_wait_queue(queue, qname, 1);
260}
261EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
262
263void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
264{
265 cancel_delayed_work_sync(&queue->timer_list.dwork);
266}
267EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
268
269static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode)
270{
271 freezable_schedule_unsafe();
272 if (signal_pending_state(mode, current))
273 return -ERESTARTSYS;
274 return 0;
275}
276
277#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) || IS_ENABLED(CONFIG_TRACEPOINTS)
278static void rpc_task_set_debuginfo(struct rpc_task *task)
279{
280 static atomic_t rpc_pid;
281
282 task->tk_pid = atomic_inc_return(&rpc_pid);
283}
284#else
285static inline void rpc_task_set_debuginfo(struct rpc_task *task)
286{
287}
288#endif
289
290static void rpc_set_active(struct rpc_task *task)
291{
292 rpc_task_set_debuginfo(task);
293 set_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
294 trace_rpc_task_begin(task, NULL);
295}
296
297/*
298 * Mark an RPC call as having completed by clearing the 'active' bit
299 * and then waking up all tasks that were sleeping.
300 */
301static int rpc_complete_task(struct rpc_task *task)
302{
303 void *m = &task->tk_runstate;
304 wait_queue_head_t *wq = bit_waitqueue(m, RPC_TASK_ACTIVE);
305 struct wait_bit_key k = __WAIT_BIT_KEY_INITIALIZER(m, RPC_TASK_ACTIVE);
306 unsigned long flags;
307 int ret;
308
309 trace_rpc_task_complete(task, NULL);
310
311 spin_lock_irqsave(&wq->lock, flags);
312 clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
313 ret = atomic_dec_and_test(&task->tk_count);
314 if (waitqueue_active(wq))
315 __wake_up_locked_key(wq, TASK_NORMAL, &k);
316 spin_unlock_irqrestore(&wq->lock, flags);
317 return ret;
318}
319
320/*
321 * Allow callers to wait for completion of an RPC call
322 *
323 * Note the use of out_of_line_wait_on_bit() rather than wait_on_bit()
324 * to enforce taking of the wq->lock and hence avoid races with
325 * rpc_complete_task().
326 */
327int __rpc_wait_for_completion_task(struct rpc_task *task, wait_bit_action_f *action)
328{
329 if (action == NULL)
330 action = rpc_wait_bit_killable;
331 return out_of_line_wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
332 action, TASK_KILLABLE);
333}
334EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
335
336/*
337 * Make an RPC task runnable.
338 *
339 * Note: If the task is ASYNC, and is being made runnable after sitting on an
340 * rpc_wait_queue, this must be called with the queue spinlock held to protect
341 * the wait queue operation.
342 * Note the ordering of rpc_test_and_set_running() and rpc_clear_queued(),
343 * which is needed to ensure that __rpc_execute() doesn't loop (due to the
344 * lockless RPC_IS_QUEUED() test) before we've had a chance to test
345 * the RPC_TASK_RUNNING flag.
346 */
347static void rpc_make_runnable(struct workqueue_struct *wq,
348 struct rpc_task *task)
349{
350 bool need_wakeup = !rpc_test_and_set_running(task);
351
352 rpc_clear_queued(task);
353 if (!need_wakeup)
354 return;
355 if (RPC_IS_ASYNC(task)) {
356 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
357 queue_work(wq, &task->u.tk_work);
358 } else
359 wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
360}
361
362/*
363 * Prepare for sleeping on a wait queue.
364 * By always appending tasks to the list we ensure FIFO behavior.
365 * NB: An RPC task will only receive interrupt-driven events as long
366 * as it's on a wait queue.
367 */
368static void __rpc_do_sleep_on_priority(struct rpc_wait_queue *q,
369 struct rpc_task *task,
370 unsigned char queue_priority)
371{
372 trace_rpc_task_sleep(task, q);
373
374 __rpc_add_wait_queue(q, task, queue_priority);
375}
376
377static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
378 struct rpc_task *task,
379 unsigned char queue_priority)
380{
381 if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
382 return;
383 __rpc_do_sleep_on_priority(q, task, queue_priority);
384}
385
386static void __rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
387 struct rpc_task *task, unsigned long timeout,
388 unsigned char queue_priority)
389{
390 if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
391 return;
392 if (time_is_after_jiffies(timeout)) {
393 __rpc_do_sleep_on_priority(q, task, queue_priority);
394 __rpc_add_timer(q, task, timeout);
395 } else
396 task->tk_status = -ETIMEDOUT;
397}
398
399static void rpc_set_tk_callback(struct rpc_task *task, rpc_action action)
400{
401 if (action && !WARN_ON_ONCE(task->tk_callback != NULL))
402 task->tk_callback = action;
403}
404
405static bool rpc_sleep_check_activated(struct rpc_task *task)
406{
407 /* We shouldn't ever put an inactive task to sleep */
408 if (WARN_ON_ONCE(!RPC_IS_ACTIVATED(task))) {
409 task->tk_status = -EIO;
410 rpc_put_task_async(task);
411 return false;
412 }
413 return true;
414}
415
416void rpc_sleep_on_timeout(struct rpc_wait_queue *q, struct rpc_task *task,
417 rpc_action action, unsigned long timeout)
418{
419 if (!rpc_sleep_check_activated(task))
420 return;
421
422 rpc_set_tk_callback(task, action);
423
424 /*
425 * Protect the queue operations.
426 */
427 spin_lock(&q->lock);
428 __rpc_sleep_on_priority_timeout(q, task, timeout, task->tk_priority);
429 spin_unlock(&q->lock);
430}
431EXPORT_SYMBOL_GPL(rpc_sleep_on_timeout);
432
433void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
434 rpc_action action)
435{
436 if (!rpc_sleep_check_activated(task))
437 return;
438
439 rpc_set_tk_callback(task, action);
440
441 WARN_ON_ONCE(task->tk_timeout != 0);
442 /*
443 * Protect the queue operations.
444 */
445 spin_lock(&q->lock);
446 __rpc_sleep_on_priority(q, task, task->tk_priority);
447 spin_unlock(&q->lock);
448}
449EXPORT_SYMBOL_GPL(rpc_sleep_on);
450
451void rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
452 struct rpc_task *task, unsigned long timeout, int priority)
453{
454 if (!rpc_sleep_check_activated(task))
455 return;
456
457 priority -= RPC_PRIORITY_LOW;
458 /*
459 * Protect the queue operations.
460 */
461 spin_lock(&q->lock);
462 __rpc_sleep_on_priority_timeout(q, task, timeout, priority);
463 spin_unlock(&q->lock);
464}
465EXPORT_SYMBOL_GPL(rpc_sleep_on_priority_timeout);
466
467void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
468 int priority)
469{
470 if (!rpc_sleep_check_activated(task))
471 return;
472
473 WARN_ON_ONCE(task->tk_timeout != 0);
474 priority -= RPC_PRIORITY_LOW;
475 /*
476 * Protect the queue operations.
477 */
478 spin_lock(&q->lock);
479 __rpc_sleep_on_priority(q, task, priority);
480 spin_unlock(&q->lock);
481}
482EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
483
484/**
485 * __rpc_do_wake_up_task_on_wq - wake up a single rpc_task
486 * @wq: workqueue on which to run task
487 * @queue: wait queue
488 * @task: task to be woken up
489 *
490 * Caller must hold queue->lock, and have cleared the task queued flag.
491 */
492static void __rpc_do_wake_up_task_on_wq(struct workqueue_struct *wq,
493 struct rpc_wait_queue *queue,
494 struct rpc_task *task)
495{
496 /* Has the task been executed yet? If not, we cannot wake it up! */
497 if (!RPC_IS_ACTIVATED(task)) {
498 printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
499 return;
500 }
501
502 trace_rpc_task_wakeup(task, queue);
503
504 __rpc_remove_wait_queue(queue, task);
505
506 rpc_make_runnable(wq, task);
507}
508
509/*
510 * Wake up a queued task while the queue lock is being held
511 */
512static struct rpc_task *
513rpc_wake_up_task_on_wq_queue_action_locked(struct workqueue_struct *wq,
514 struct rpc_wait_queue *queue, struct rpc_task *task,
515 bool (*action)(struct rpc_task *, void *), void *data)
516{
517 if (RPC_IS_QUEUED(task)) {
518 smp_rmb();
519 if (task->tk_waitqueue == queue) {
520 if (action == NULL || action(task, data)) {
521 __rpc_do_wake_up_task_on_wq(wq, queue, task);
522 return task;
523 }
524 }
525 }
526 return NULL;
527}
528
529/*
530 * Wake up a queued task while the queue lock is being held
531 */
532static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue,
533 struct rpc_task *task)
534{
535 rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
536 task, NULL, NULL);
537}
538
539/*
540 * Wake up a task on a specific queue
541 */
542void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
543{
544 if (!RPC_IS_QUEUED(task))
545 return;
546 spin_lock(&queue->lock);
547 rpc_wake_up_task_queue_locked(queue, task);
548 spin_unlock(&queue->lock);
549}
550EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
551
552static bool rpc_task_action_set_status(struct rpc_task *task, void *status)
553{
554 task->tk_status = *(int *)status;
555 return true;
556}
557
558static void
559rpc_wake_up_task_queue_set_status_locked(struct rpc_wait_queue *queue,
560 struct rpc_task *task, int status)
561{
562 rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
563 task, rpc_task_action_set_status, &status);
564}
565
566/**
567 * rpc_wake_up_queued_task_set_status - wake up a task and set task->tk_status
568 * @queue: pointer to rpc_wait_queue
569 * @task: pointer to rpc_task
570 * @status: integer error value
571 *
572 * If @task is queued on @queue, then it is woken up, and @task->tk_status is
573 * set to the value of @status.
574 */
575void
576rpc_wake_up_queued_task_set_status(struct rpc_wait_queue *queue,
577 struct rpc_task *task, int status)
578{
579 if (!RPC_IS_QUEUED(task))
580 return;
581 spin_lock(&queue->lock);
582 rpc_wake_up_task_queue_set_status_locked(queue, task, status);
583 spin_unlock(&queue->lock);
584}
585
586/*
587 * Wake up the next task on a priority queue.
588 */
589static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
590{
591 struct list_head *q;
592 struct rpc_task *task;
593
594 /*
595 * Service the privileged queue.
596 */
597 q = &queue->tasks[RPC_NR_PRIORITY - 1];
598 if (queue->maxpriority > RPC_PRIORITY_PRIVILEGED && !list_empty(q)) {
599 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
600 goto out;
601 }
602
603 /*
604 * Service a batch of tasks from a single owner.
605 */
606 q = &queue->tasks[queue->priority];
607 if (!list_empty(q) && queue->nr) {
608 queue->nr--;
609 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
610 goto out;
611 }
612
613 /*
614 * Service the next queue.
615 */
616 do {
617 if (q == &queue->tasks[0])
618 q = &queue->tasks[queue->maxpriority];
619 else
620 q = q - 1;
621 if (!list_empty(q)) {
622 task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
623 goto new_queue;
624 }
625 } while (q != &queue->tasks[queue->priority]);
626
627 rpc_reset_waitqueue_priority(queue);
628 return NULL;
629
630new_queue:
631 rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
632out:
633 return task;
634}
635
636static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
637{
638 if (RPC_IS_PRIORITY(queue))
639 return __rpc_find_next_queued_priority(queue);
640 if (!list_empty(&queue->tasks[0]))
641 return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
642 return NULL;
643}
644
645/*
646 * Wake up the first task on the wait queue.
647 */
648struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq,
649 struct rpc_wait_queue *queue,
650 bool (*func)(struct rpc_task *, void *), void *data)
651{
652 struct rpc_task *task = NULL;
653
654 spin_lock(&queue->lock);
655 task = __rpc_find_next_queued(queue);
656 if (task != NULL)
657 task = rpc_wake_up_task_on_wq_queue_action_locked(wq, queue,
658 task, func, data);
659 spin_unlock(&queue->lock);
660
661 return task;
662}
663
664/*
665 * Wake up the first task on the wait queue.
666 */
667struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
668 bool (*func)(struct rpc_task *, void *), void *data)
669{
670 return rpc_wake_up_first_on_wq(rpciod_workqueue, queue, func, data);
671}
672EXPORT_SYMBOL_GPL(rpc_wake_up_first);
673
674static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
675{
676 return true;
677}
678
679/*
680 * Wake up the next task on the wait queue.
681*/
682struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
683{
684 return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
685}
686EXPORT_SYMBOL_GPL(rpc_wake_up_next);
687
688/**
689 * rpc_wake_up_locked - wake up all rpc_tasks
690 * @queue: rpc_wait_queue on which the tasks are sleeping
691 *
692 */
693static void rpc_wake_up_locked(struct rpc_wait_queue *queue)
694{
695 struct rpc_task *task;
696
697 for (;;) {
698 task = __rpc_find_next_queued(queue);
699 if (task == NULL)
700 break;
701 rpc_wake_up_task_queue_locked(queue, task);
702 }
703}
704
705/**
706 * rpc_wake_up - wake up all rpc_tasks
707 * @queue: rpc_wait_queue on which the tasks are sleeping
708 *
709 * Grabs queue->lock
710 */
711void rpc_wake_up(struct rpc_wait_queue *queue)
712{
713 spin_lock(&queue->lock);
714 rpc_wake_up_locked(queue);
715 spin_unlock(&queue->lock);
716}
717EXPORT_SYMBOL_GPL(rpc_wake_up);
718
719/**
720 * rpc_wake_up_status_locked - wake up all rpc_tasks and set their status value.
721 * @queue: rpc_wait_queue on which the tasks are sleeping
722 * @status: status value to set
723 */
724static void rpc_wake_up_status_locked(struct rpc_wait_queue *queue, int status)
725{
726 struct rpc_task *task;
727
728 for (;;) {
729 task = __rpc_find_next_queued(queue);
730 if (task == NULL)
731 break;
732 rpc_wake_up_task_queue_set_status_locked(queue, task, status);
733 }
734}
735
736/**
737 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
738 * @queue: rpc_wait_queue on which the tasks are sleeping
739 * @status: status value to set
740 *
741 * Grabs queue->lock
742 */
743void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
744{
745 spin_lock(&queue->lock);
746 rpc_wake_up_status_locked(queue, status);
747 spin_unlock(&queue->lock);
748}
749EXPORT_SYMBOL_GPL(rpc_wake_up_status);
750
751static void __rpc_queue_timer_fn(struct work_struct *work)
752{
753 struct rpc_wait_queue *queue = container_of(work,
754 struct rpc_wait_queue,
755 timer_list.dwork.work);
756 struct rpc_task *task, *n;
757 unsigned long expires, now, timeo;
758
759 spin_lock(&queue->lock);
760 expires = now = jiffies;
761 list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
762 timeo = task->tk_timeout;
763 if (time_after_eq(now, timeo)) {
764 trace_rpc_task_timeout(task, task->tk_action);
765 task->tk_status = -ETIMEDOUT;
766 rpc_wake_up_task_queue_locked(queue, task);
767 continue;
768 }
769 if (expires == now || time_after(expires, timeo))
770 expires = timeo;
771 }
772 if (!list_empty(&queue->timer_list.list))
773 rpc_set_queue_timer(queue, expires);
774 spin_unlock(&queue->lock);
775}
776
777static void __rpc_atrun(struct rpc_task *task)
778{
779 if (task->tk_status == -ETIMEDOUT)
780 task->tk_status = 0;
781}
782
783/*
784 * Run a task at a later time
785 */
786void rpc_delay(struct rpc_task *task, unsigned long delay)
787{
788 rpc_sleep_on_timeout(&delay_queue, task, __rpc_atrun, jiffies + delay);
789}
790EXPORT_SYMBOL_GPL(rpc_delay);
791
792/*
793 * Helper to call task->tk_ops->rpc_call_prepare
794 */
795void rpc_prepare_task(struct rpc_task *task)
796{
797 task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
798}
799
800static void
801rpc_init_task_statistics(struct rpc_task *task)
802{
803 /* Initialize retry counters */
804 task->tk_garb_retry = 2;
805 task->tk_cred_retry = 2;
806 task->tk_rebind_retry = 2;
807
808 /* starting timestamp */
809 task->tk_start = ktime_get();
810}
811
812static void
813rpc_reset_task_statistics(struct rpc_task *task)
814{
815 task->tk_timeouts = 0;
816 task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_SENT);
817 rpc_init_task_statistics(task);
818}
819
820/*
821 * Helper that calls task->tk_ops->rpc_call_done if it exists
822 */
823void rpc_exit_task(struct rpc_task *task)
824{
825 trace_rpc_task_end(task, task->tk_action);
826 task->tk_action = NULL;
827 if (task->tk_ops->rpc_count_stats)
828 task->tk_ops->rpc_count_stats(task, task->tk_calldata);
829 else if (task->tk_client)
830 rpc_count_iostats(task, task->tk_client->cl_metrics);
831 if (task->tk_ops->rpc_call_done != NULL) {
832 task->tk_ops->rpc_call_done(task, task->tk_calldata);
833 if (task->tk_action != NULL) {
834 /* Always release the RPC slot and buffer memory */
835 xprt_release(task);
836 rpc_reset_task_statistics(task);
837 }
838 }
839}
840
841void rpc_signal_task(struct rpc_task *task)
842{
843 struct rpc_wait_queue *queue;
844
845 if (!RPC_IS_ACTIVATED(task))
846 return;
847
848 trace_rpc_task_signalled(task, task->tk_action);
849 set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
850 smp_mb__after_atomic();
851 queue = READ_ONCE(task->tk_waitqueue);
852 if (queue)
853 rpc_wake_up_queued_task_set_status(queue, task, -ERESTARTSYS);
854}
855
856void rpc_exit(struct rpc_task *task, int status)
857{
858 task->tk_status = status;
859 task->tk_action = rpc_exit_task;
860 rpc_wake_up_queued_task(task->tk_waitqueue, task);
861}
862EXPORT_SYMBOL_GPL(rpc_exit);
863
864void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
865{
866 if (ops->rpc_release != NULL)
867 ops->rpc_release(calldata);
868}
869
870/*
871 * This is the RPC `scheduler' (or rather, the finite state machine).
872 */
873static void __rpc_execute(struct rpc_task *task)
874{
875 struct rpc_wait_queue *queue;
876 int task_is_async = RPC_IS_ASYNC(task);
877 int status = 0;
878
879 WARN_ON_ONCE(RPC_IS_QUEUED(task));
880 if (RPC_IS_QUEUED(task))
881 return;
882
883 for (;;) {
884 void (*do_action)(struct rpc_task *);
885
886 /*
887 * Perform the next FSM step or a pending callback.
888 *
889 * tk_action may be NULL if the task has been killed.
890 * In particular, note that rpc_killall_tasks may
891 * do this at any time, so beware when dereferencing.
892 */
893 do_action = task->tk_action;
894 if (task->tk_callback) {
895 do_action = task->tk_callback;
896 task->tk_callback = NULL;
897 }
898 if (!do_action)
899 break;
900 trace_rpc_task_run_action(task, do_action);
901 do_action(task);
902
903 /*
904 * Lockless check for whether task is sleeping or not.
905 */
906 if (!RPC_IS_QUEUED(task))
907 continue;
908
909 /*
910 * Signalled tasks should exit rather than sleep.
911 */
912 if (RPC_SIGNALLED(task)) {
913 task->tk_rpc_status = -ERESTARTSYS;
914 rpc_exit(task, -ERESTARTSYS);
915 }
916
917 /*
918 * The queue->lock protects against races with
919 * rpc_make_runnable().
920 *
921 * Note that once we clear RPC_TASK_RUNNING on an asynchronous
922 * rpc_task, rpc_make_runnable() can assign it to a
923 * different workqueue. We therefore cannot assume that the
924 * rpc_task pointer may still be dereferenced.
925 */
926 queue = task->tk_waitqueue;
927 spin_lock(&queue->lock);
928 if (!RPC_IS_QUEUED(task)) {
929 spin_unlock(&queue->lock);
930 continue;
931 }
932 rpc_clear_running(task);
933 spin_unlock(&queue->lock);
934 if (task_is_async)
935 return;
936
937 /* sync task: sleep here */
938 trace_rpc_task_sync_sleep(task, task->tk_action);
939 status = out_of_line_wait_on_bit(&task->tk_runstate,
940 RPC_TASK_QUEUED, rpc_wait_bit_killable,
941 TASK_KILLABLE);
942 if (status < 0) {
943 /*
944 * When a sync task receives a signal, it exits with
945 * -ERESTARTSYS. In order to catch any callbacks that
946 * clean up after sleeping on some queue, we don't
947 * break the loop here, but go around once more.
948 */
949 trace_rpc_task_signalled(task, task->tk_action);
950 set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
951 task->tk_rpc_status = -ERESTARTSYS;
952 rpc_exit(task, -ERESTARTSYS);
953 }
954 trace_rpc_task_sync_wake(task, task->tk_action);
955 }
956
957 /* Release all resources associated with the task */
958 rpc_release_task(task);
959}
960
961/*
962 * User-visible entry point to the scheduler.
963 *
964 * This may be called recursively if e.g. an async NFS task updates
965 * the attributes and finds that dirty pages must be flushed.
966 * NOTE: Upon exit of this function the task is guaranteed to be
967 * released. In particular note that tk_release() will have
968 * been called, so your task memory may have been freed.
969 */
970void rpc_execute(struct rpc_task *task)
971{
972 bool is_async = RPC_IS_ASYNC(task);
973
974 rpc_set_active(task);
975 rpc_make_runnable(rpciod_workqueue, task);
976 if (!is_async) {
977 unsigned int pflags = memalloc_nofs_save();
978 __rpc_execute(task);
979 memalloc_nofs_restore(pflags);
980 }
981}
982
983static void rpc_async_schedule(struct work_struct *work)
984{
985 unsigned int pflags = memalloc_nofs_save();
986
987 __rpc_execute(container_of(work, struct rpc_task, u.tk_work));
988 memalloc_nofs_restore(pflags);
989}
990
991/**
992 * rpc_malloc - allocate RPC buffer resources
993 * @task: RPC task
994 *
995 * A single memory region is allocated, which is split between the
996 * RPC call and RPC reply that this task is being used for. When
997 * this RPC is retired, the memory is released by calling rpc_free.
998 *
999 * To prevent rpciod from hanging, this allocator never sleeps,
1000 * returning -ENOMEM and suppressing warning if the request cannot
1001 * be serviced immediately. The caller can arrange to sleep in a
1002 * way that is safe for rpciod.
1003 *
1004 * Most requests are 'small' (under 2KiB) and can be serviced from a
1005 * mempool, ensuring that NFS reads and writes can always proceed,
1006 * and that there is good locality of reference for these buffers.
1007 */
1008int rpc_malloc(struct rpc_task *task)
1009{
1010 struct rpc_rqst *rqst = task->tk_rqstp;
1011 size_t size = rqst->rq_callsize + rqst->rq_rcvsize;
1012 struct rpc_buffer *buf;
1013 gfp_t gfp = GFP_NOFS;
1014
1015 if (RPC_IS_SWAPPER(task))
1016 gfp = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN;
1017
1018 size += sizeof(struct rpc_buffer);
1019 if (size <= RPC_BUFFER_MAXSIZE)
1020 buf = mempool_alloc(rpc_buffer_mempool, gfp);
1021 else
1022 buf = kmalloc(size, gfp);
1023
1024 if (!buf)
1025 return -ENOMEM;
1026
1027 buf->len = size;
1028 rqst->rq_buffer = buf->data;
1029 rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_callsize;
1030 return 0;
1031}
1032EXPORT_SYMBOL_GPL(rpc_malloc);
1033
1034/**
1035 * rpc_free - free RPC buffer resources allocated via rpc_malloc
1036 * @task: RPC task
1037 *
1038 */
1039void rpc_free(struct rpc_task *task)
1040{
1041 void *buffer = task->tk_rqstp->rq_buffer;
1042 size_t size;
1043 struct rpc_buffer *buf;
1044
1045 buf = container_of(buffer, struct rpc_buffer, data);
1046 size = buf->len;
1047
1048 if (size <= RPC_BUFFER_MAXSIZE)
1049 mempool_free(buf, rpc_buffer_mempool);
1050 else
1051 kfree(buf);
1052}
1053EXPORT_SYMBOL_GPL(rpc_free);
1054
1055/*
1056 * Creation and deletion of RPC task structures
1057 */
1058static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
1059{
1060 memset(task, 0, sizeof(*task));
1061 atomic_set(&task->tk_count, 1);
1062 task->tk_flags = task_setup_data->flags;
1063 task->tk_ops = task_setup_data->callback_ops;
1064 task->tk_calldata = task_setup_data->callback_data;
1065 INIT_LIST_HEAD(&task->tk_task);
1066
1067 task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
1068 task->tk_owner = current->tgid;
1069
1070 /* Initialize workqueue for async tasks */
1071 task->tk_workqueue = task_setup_data->workqueue;
1072
1073 task->tk_xprt = rpc_task_get_xprt(task_setup_data->rpc_client,
1074 xprt_get(task_setup_data->rpc_xprt));
1075
1076 task->tk_op_cred = get_rpccred(task_setup_data->rpc_op_cred);
1077
1078 if (task->tk_ops->rpc_call_prepare != NULL)
1079 task->tk_action = rpc_prepare_task;
1080
1081 rpc_init_task_statistics(task);
1082}
1083
1084static struct rpc_task *
1085rpc_alloc_task(void)
1086{
1087 return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
1088}
1089
1090/*
1091 * Create a new task for the specified client.
1092 */
1093struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
1094{
1095 struct rpc_task *task = setup_data->task;
1096 unsigned short flags = 0;
1097
1098 if (task == NULL) {
1099 task = rpc_alloc_task();
1100 flags = RPC_TASK_DYNAMIC;
1101 }
1102
1103 rpc_init_task(task, setup_data);
1104 task->tk_flags |= flags;
1105 return task;
1106}
1107
1108/*
1109 * rpc_free_task - release rpc task and perform cleanups
1110 *
1111 * Note that we free up the rpc_task _after_ rpc_release_calldata()
1112 * in order to work around a workqueue dependency issue.
1113 *
1114 * Tejun Heo states:
1115 * "Workqueue currently considers two work items to be the same if they're
1116 * on the same address and won't execute them concurrently - ie. it
1117 * makes a work item which is queued again while being executed wait
1118 * for the previous execution to complete.
1119 *
1120 * If a work function frees the work item, and then waits for an event
1121 * which should be performed by another work item and *that* work item
1122 * recycles the freed work item, it can create a false dependency loop.
1123 * There really is no reliable way to detect this short of verifying
1124 * every memory free."
1125 *
1126 */
1127static void rpc_free_task(struct rpc_task *task)
1128{
1129 unsigned short tk_flags = task->tk_flags;
1130
1131 put_rpccred(task->tk_op_cred);
1132 rpc_release_calldata(task->tk_ops, task->tk_calldata);
1133
1134 if (tk_flags & RPC_TASK_DYNAMIC)
1135 mempool_free(task, rpc_task_mempool);
1136}
1137
1138static void rpc_async_release(struct work_struct *work)
1139{
1140 unsigned int pflags = memalloc_nofs_save();
1141
1142 rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
1143 memalloc_nofs_restore(pflags);
1144}
1145
1146static void rpc_release_resources_task(struct rpc_task *task)
1147{
1148 xprt_release(task);
1149 if (task->tk_msg.rpc_cred) {
1150 if (!(task->tk_flags & RPC_TASK_CRED_NOREF))
1151 put_cred(task->tk_msg.rpc_cred);
1152 task->tk_msg.rpc_cred = NULL;
1153 }
1154 rpc_task_release_client(task);
1155}
1156
1157static void rpc_final_put_task(struct rpc_task *task,
1158 struct workqueue_struct *q)
1159{
1160 if (q != NULL) {
1161 INIT_WORK(&task->u.tk_work, rpc_async_release);
1162 queue_work(q, &task->u.tk_work);
1163 } else
1164 rpc_free_task(task);
1165}
1166
1167static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1168{
1169 if (atomic_dec_and_test(&task->tk_count)) {
1170 rpc_release_resources_task(task);
1171 rpc_final_put_task(task, q);
1172 }
1173}
1174
1175void rpc_put_task(struct rpc_task *task)
1176{
1177 rpc_do_put_task(task, NULL);
1178}
1179EXPORT_SYMBOL_GPL(rpc_put_task);
1180
1181void rpc_put_task_async(struct rpc_task *task)
1182{
1183 rpc_do_put_task(task, task->tk_workqueue);
1184}
1185EXPORT_SYMBOL_GPL(rpc_put_task_async);
1186
1187static void rpc_release_task(struct rpc_task *task)
1188{
1189 WARN_ON_ONCE(RPC_IS_QUEUED(task));
1190
1191 rpc_release_resources_task(task);
1192
1193 /*
1194 * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1195 * so it should be safe to use task->tk_count as a test for whether
1196 * or not any other processes still hold references to our rpc_task.
1197 */
1198 if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1199 /* Wake up anyone who may be waiting for task completion */
1200 if (!rpc_complete_task(task))
1201 return;
1202 } else {
1203 if (!atomic_dec_and_test(&task->tk_count))
1204 return;
1205 }
1206 rpc_final_put_task(task, task->tk_workqueue);
1207}
1208
1209int rpciod_up(void)
1210{
1211 return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1212}
1213
1214void rpciod_down(void)
1215{
1216 module_put(THIS_MODULE);
1217}
1218
1219/*
1220 * Start up the rpciod workqueue.
1221 */
1222static int rpciod_start(void)
1223{
1224 struct workqueue_struct *wq;
1225
1226 /*
1227 * Create the rpciod thread and wait for it to start.
1228 */
1229 wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
1230 if (!wq)
1231 goto out_failed;
1232 rpciod_workqueue = wq;
1233 /* Note: highpri because network receive is latency sensitive */
1234 wq = alloc_workqueue("xprtiod", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_HIGHPRI, 0);
1235 if (!wq)
1236 goto free_rpciod;
1237 xprtiod_workqueue = wq;
1238 return 1;
1239free_rpciod:
1240 wq = rpciod_workqueue;
1241 rpciod_workqueue = NULL;
1242 destroy_workqueue(wq);
1243out_failed:
1244 return 0;
1245}
1246
1247static void rpciod_stop(void)
1248{
1249 struct workqueue_struct *wq = NULL;
1250
1251 if (rpciod_workqueue == NULL)
1252 return;
1253
1254 wq = rpciod_workqueue;
1255 rpciod_workqueue = NULL;
1256 destroy_workqueue(wq);
1257 wq = xprtiod_workqueue;
1258 xprtiod_workqueue = NULL;
1259 destroy_workqueue(wq);
1260}
1261
1262void
1263rpc_destroy_mempool(void)
1264{
1265 rpciod_stop();
1266 mempool_destroy(rpc_buffer_mempool);
1267 mempool_destroy(rpc_task_mempool);
1268 kmem_cache_destroy(rpc_task_slabp);
1269 kmem_cache_destroy(rpc_buffer_slabp);
1270 rpc_destroy_wait_queue(&delay_queue);
1271}
1272
1273int
1274rpc_init_mempool(void)
1275{
1276 /*
1277 * The following is not strictly a mempool initialisation,
1278 * but there is no harm in doing it here
1279 */
1280 rpc_init_wait_queue(&delay_queue, "delayq");
1281 if (!rpciod_start())
1282 goto err_nomem;
1283
1284 rpc_task_slabp = kmem_cache_create("rpc_tasks",
1285 sizeof(struct rpc_task),
1286 0, SLAB_HWCACHE_ALIGN,
1287 NULL);
1288 if (!rpc_task_slabp)
1289 goto err_nomem;
1290 rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1291 RPC_BUFFER_MAXSIZE,
1292 0, SLAB_HWCACHE_ALIGN,
1293 NULL);
1294 if (!rpc_buffer_slabp)
1295 goto err_nomem;
1296 rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1297 rpc_task_slabp);
1298 if (!rpc_task_mempool)
1299 goto err_nomem;
1300 rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1301 rpc_buffer_slabp);
1302 if (!rpc_buffer_mempool)
1303 goto err_nomem;
1304 return 0;
1305err_nomem:
1306 rpc_destroy_mempool();
1307 return -ENOMEM;
1308}