sched.c

   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		smp_mb__after_atomic();
 374		wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
 375	}
 376}
 377
 378/*
 379 * Prepare for sleeping on a wait queue.
 380 * By always appending tasks to the list we ensure FIFO behavior.
 381 * NB: An RPC task will only receive interrupt-driven events as long
 382 * as it's on a wait queue.
 383 */
 384static void __rpc_do_sleep_on_priority(struct rpc_wait_queue *q,
 385		struct rpc_task *task,
 386		unsigned char queue_priority)
 387{
 388	trace_rpc_task_sleep(task, q);
 389
 390	__rpc_add_wait_queue(q, task, queue_priority);
 391}
 392
 393static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
 394		struct rpc_task *task,
 395		unsigned char queue_priority)
 396{
 397	if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
 398		return;
 399	__rpc_do_sleep_on_priority(q, task, queue_priority);
 400}
 401
 402static void __rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
 403		struct rpc_task *task, unsigned long timeout,
 404		unsigned char queue_priority)
 405{
 406	if (WARN_ON_ONCE(RPC_IS_QUEUED(task)))
 407		return;
 408	if (time_is_after_jiffies(timeout)) {
 409		__rpc_do_sleep_on_priority(q, task, queue_priority);
 410		__rpc_add_timer(q, task, timeout);
 411	} else
 412		task->tk_status = -ETIMEDOUT;
 413}
 414
 415static void rpc_set_tk_callback(struct rpc_task *task, rpc_action action)
 416{
 417	if (action && !WARN_ON_ONCE(task->tk_callback != NULL))
 418		task->tk_callback = action;
 419}
 420
 421static bool rpc_sleep_check_activated(struct rpc_task *task)
 422{
 423	/* We shouldn't ever put an inactive task to sleep */
 424	if (WARN_ON_ONCE(!RPC_IS_ACTIVATED(task))) {
 425		task->tk_status = -EIO;
 426		rpc_put_task_async(task);
 427		return false;
 428	}
 429	return true;
 430}
 431
 432void rpc_sleep_on_timeout(struct rpc_wait_queue *q, struct rpc_task *task,
 433				rpc_action action, unsigned long timeout)
 434{
 435	if (!rpc_sleep_check_activated(task))
 436		return;
 437
 438	rpc_set_tk_callback(task, action);
 439
 440	/*
 441	 * Protect the queue operations.
 442	 */
 443	spin_lock(&q->lock);
 444	__rpc_sleep_on_priority_timeout(q, task, timeout, task->tk_priority);
 445	spin_unlock(&q->lock);
 446}
 447EXPORT_SYMBOL_GPL(rpc_sleep_on_timeout);
 448
 449void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
 450				rpc_action action)
 451{
 452	if (!rpc_sleep_check_activated(task))
 453		return;
 454
 455	rpc_set_tk_callback(task, action);
 456
 457	WARN_ON_ONCE(task->tk_timeout != 0);
 458	/*
 459	 * Protect the queue operations.
 460	 */
 461	spin_lock(&q->lock);
 462	__rpc_sleep_on_priority(q, task, task->tk_priority);
 463	spin_unlock(&q->lock);
 464}
 465EXPORT_SYMBOL_GPL(rpc_sleep_on);
 466
 467void rpc_sleep_on_priority_timeout(struct rpc_wait_queue *q,
 468		struct rpc_task *task, unsigned long timeout, int priority)
 469{
 470	if (!rpc_sleep_check_activated(task))
 471		return;
 472
 473	priority -= RPC_PRIORITY_LOW;
 474	/*
 475	 * Protect the queue operations.
 476	 */
 477	spin_lock(&q->lock);
 478	__rpc_sleep_on_priority_timeout(q, task, timeout, priority);
 479	spin_unlock(&q->lock);
 480}
 481EXPORT_SYMBOL_GPL(rpc_sleep_on_priority_timeout);
 482
 483void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
 484		int priority)
 485{
 486	if (!rpc_sleep_check_activated(task))
 487		return;
 488
 489	WARN_ON_ONCE(task->tk_timeout != 0);
 490	priority -= RPC_PRIORITY_LOW;
 491	/*
 492	 * Protect the queue operations.
 493	 */
 494	spin_lock(&q->lock);
 495	__rpc_sleep_on_priority(q, task, priority);
 496	spin_unlock(&q->lock);
 497}
 498EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);
 499
 500/**
 501 * __rpc_do_wake_up_task_on_wq - wake up a single rpc_task
 502 * @wq: workqueue on which to run task
 503 * @queue: wait queue
 504 * @task: task to be woken up
 505 *
 506 * Caller must hold queue->lock, and have cleared the task queued flag.
 507 */
 508static void __rpc_do_wake_up_task_on_wq(struct workqueue_struct *wq,
 509		struct rpc_wait_queue *queue,
 510		struct rpc_task *task)
 511{
 512	/* Has the task been executed yet? If not, we cannot wake it up! */
 513	if (!RPC_IS_ACTIVATED(task)) {
 514		printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
 515		return;
 516	}
 517
 518	trace_rpc_task_wakeup(task, queue);
 519
 520	__rpc_remove_wait_queue(queue, task);
 521
 522	rpc_make_runnable(wq, task);
 523}
 524
 525/*
 526 * Wake up a queued task while the queue lock is being held
 527 */
 528static struct rpc_task *
 529rpc_wake_up_task_on_wq_queue_action_locked(struct workqueue_struct *wq,
 530		struct rpc_wait_queue *queue, struct rpc_task *task,
 531		bool (*action)(struct rpc_task *, void *), void *data)
 532{
 533	if (RPC_IS_QUEUED(task)) {
 534		smp_rmb();
 535		if (task->tk_waitqueue == queue) {
 536			if (action == NULL || action(task, data)) {
 537				__rpc_do_wake_up_task_on_wq(wq, queue, task);
 538				return task;
 539			}
 540		}
 541	}
 542	return NULL;
 543}
 544
 545/*
 546 * Wake up a queued task while the queue lock is being held
 547 */
 548static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue,
 549					  struct rpc_task *task)
 550{
 551	rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
 552						   task, NULL, NULL);
 553}
 554
 555/*
 556 * Wake up a task on a specific queue
 557 */
 558void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
 559{
 560	if (!RPC_IS_QUEUED(task))
 561		return;
 562	spin_lock(&queue->lock);
 563	rpc_wake_up_task_queue_locked(queue, task);
 564	spin_unlock(&queue->lock);
 565}
 566EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
 567
 568static bool rpc_task_action_set_status(struct rpc_task *task, void *status)
 569{
 570	task->tk_status = *(int *)status;
 571	return true;
 572}
 573
 574static void
 575rpc_wake_up_task_queue_set_status_locked(struct rpc_wait_queue *queue,
 576		struct rpc_task *task, int status)
 577{
 578	rpc_wake_up_task_on_wq_queue_action_locked(rpciod_workqueue, queue,
 579			task, rpc_task_action_set_status, &status);
 580}
 581
 582/**
 583 * rpc_wake_up_queued_task_set_status - wake up a task and set task->tk_status
 584 * @queue: pointer to rpc_wait_queue
 585 * @task: pointer to rpc_task
 586 * @status: integer error value
 587 *
 588 * If @task is queued on @queue, then it is woken up, and @task->tk_status is
 589 * set to the value of @status.
 590 */
 591void
 592rpc_wake_up_queued_task_set_status(struct rpc_wait_queue *queue,
 593		struct rpc_task *task, int status)
 594{
 595	if (!RPC_IS_QUEUED(task))
 596		return;
 597	spin_lock(&queue->lock);
 598	rpc_wake_up_task_queue_set_status_locked(queue, task, status);
 599	spin_unlock(&queue->lock);
 600}
 601
 602/*
 603 * Wake up the next task on a priority queue.
 604 */
 605static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *queue)
 606{
 607	struct list_head *q;
 608	struct rpc_task *task;
 609
 610	/*
 611	 * Service the privileged queue.
 612	 */
 613	q = &queue->tasks[RPC_NR_PRIORITY - 1];
 614	if (queue->maxpriority > RPC_PRIORITY_PRIVILEGED && !list_empty(q)) {
 615		task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
 616		goto out;
 617	}
 618
 619	/*
 620	 * Service a batch of tasks from a single owner.
 621	 */
 622	q = &queue->tasks[queue->priority];
 623	if (!list_empty(q) && queue->nr) {
 624		queue->nr--;
 625		task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
 626		goto out;
 627	}
 628
 629	/*
 630	 * Service the next queue.
 631	 */
 632	do {
 633		if (q == &queue->tasks[0])
 634			q = &queue->tasks[queue->maxpriority];
 635		else
 636			q = q - 1;
 637		if (!list_empty(q)) {
 638			task = list_first_entry(q, struct rpc_task, u.tk_wait.list);
 639			goto new_queue;
 640		}
 641	} while (q != &queue->tasks[queue->priority]);
 642
 643	rpc_reset_waitqueue_priority(queue);
 644	return NULL;
 645
 646new_queue:
 647	rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
 648out:
 649	return task;
 650}
 651
 652static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue)
 653{
 654	if (RPC_IS_PRIORITY(queue))
 655		return __rpc_find_next_queued_priority(queue);
 656	if (!list_empty(&queue->tasks[0]))
 657		return list_first_entry(&queue->tasks[0], struct rpc_task, u.tk_wait.list);
 658	return NULL;
 659}
 660
 661/*
 662 * Wake up the first task on the wait queue.
 663 */
 664struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq,
 665		struct rpc_wait_queue *queue,
 666		bool (*func)(struct rpc_task *, void *), void *data)
 667{
 668	struct rpc_task	*task = NULL;
 669
 670	spin_lock(&queue->lock);
 671	task = __rpc_find_next_queued(queue);
 672	if (task != NULL)
 673		task = rpc_wake_up_task_on_wq_queue_action_locked(wq, queue,
 674				task, func, data);
 675	spin_unlock(&queue->lock);
 676
 677	return task;
 678}
 679
 680/*
 681 * Wake up the first task on the wait queue.
 682 */
 683struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue,
 684		bool (*func)(struct rpc_task *, void *), void *data)
 685{
 686	return rpc_wake_up_first_on_wq(rpciod_workqueue, queue, func, data);
 687}
 688EXPORT_SYMBOL_GPL(rpc_wake_up_first);
 689
 690static bool rpc_wake_up_next_func(struct rpc_task *task, void *data)
 691{
 692	return true;
 693}
 694
 695/*
 696 * Wake up the next task on the wait queue.
 697*/
 698struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *queue)
 699{
 700	return rpc_wake_up_first(queue, rpc_wake_up_next_func, NULL);
 701}
 702EXPORT_SYMBOL_GPL(rpc_wake_up_next);
 703
 704/**
 705 * rpc_wake_up_locked - wake up all rpc_tasks
 706 * @queue: rpc_wait_queue on which the tasks are sleeping
 707 *
 708 */
 709static void rpc_wake_up_locked(struct rpc_wait_queue *queue)
 710{
 711	struct rpc_task *task;
 712
 713	for (;;) {
 714		task = __rpc_find_next_queued(queue);
 715		if (task == NULL)
 716			break;
 717		rpc_wake_up_task_queue_locked(queue, task);
 718	}
 719}
 720
 721/**
 722 * rpc_wake_up - wake up all rpc_tasks
 723 * @queue: rpc_wait_queue on which the tasks are sleeping
 724 *
 725 * Grabs queue->lock
 726 */
 727void rpc_wake_up(struct rpc_wait_queue *queue)
 728{
 729	spin_lock(&queue->lock);
 730	rpc_wake_up_locked(queue);
 731	spin_unlock(&queue->lock);
 732}
 733EXPORT_SYMBOL_GPL(rpc_wake_up);
 734
 735/**
 736 * rpc_wake_up_status_locked - wake up all rpc_tasks and set their status value.
 737 * @queue: rpc_wait_queue on which the tasks are sleeping
 738 * @status: status value to set
 739 */
 740static void rpc_wake_up_status_locked(struct rpc_wait_queue *queue, int status)
 741{
 742	struct rpc_task *task;
 743
 744	for (;;) {
 745		task = __rpc_find_next_queued(queue);
 746		if (task == NULL)
 747			break;
 748		rpc_wake_up_task_queue_set_status_locked(queue, task, status);
 749	}
 750}
 751
 752/**
 753 * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
 754 * @queue: rpc_wait_queue on which the tasks are sleeping
 755 * @status: status value to set
 756 *
 757 * Grabs queue->lock
 758 */
 759void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
 760{
 761	spin_lock(&queue->lock);
 762	rpc_wake_up_status_locked(queue, status);
 763	spin_unlock(&queue->lock);
 764}
 765EXPORT_SYMBOL_GPL(rpc_wake_up_status);
 766
 767static void __rpc_queue_timer_fn(struct work_struct *work)
 768{
 769	struct rpc_wait_queue *queue = container_of(work,
 770			struct rpc_wait_queue,
 771			timer_list.dwork.work);
 772	struct rpc_task *task, *n;
 773	unsigned long expires, now, timeo;
 774
 775	spin_lock(&queue->lock);
 776	expires = now = jiffies;
 777	list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
 778		timeo = task->tk_timeout;
 779		if (time_after_eq(now, timeo)) {
 780			trace_rpc_task_timeout(task, task->tk_action);
 781			task->tk_status = -ETIMEDOUT;
 782			rpc_wake_up_task_queue_locked(queue, task);
 783			continue;
 784		}
 785		if (expires == now || time_after(expires, timeo))
 786			expires = timeo;
 787	}
 788	if (!list_empty(&queue->timer_list.list))
 789		rpc_set_queue_timer(queue, expires);
 790	spin_unlock(&queue->lock);
 791}
 792
 793static void __rpc_atrun(struct rpc_task *task)
 794{
 795	if (task->tk_status == -ETIMEDOUT)
 796		task->tk_status = 0;
 797}
 798
 799/*
 800 * Run a task at a later time
 801 */
 802void rpc_delay(struct rpc_task *task, unsigned long delay)
 803{
 804	rpc_sleep_on_timeout(&delay_queue, task, __rpc_atrun, jiffies + delay);
 805}
 806EXPORT_SYMBOL_GPL(rpc_delay);
 807
 808/*
 809 * Helper to call task->tk_ops->rpc_call_prepare
 810 */
 811void rpc_prepare_task(struct rpc_task *task)
 812{
 813	task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
 814}
 815
 816static void
 817rpc_init_task_statistics(struct rpc_task *task)
 818{
 819	/* Initialize retry counters */
 820	task->tk_garb_retry = 2;
 821	task->tk_cred_retry = 2;
 822
 823	/* starting timestamp */
 824	task->tk_start = ktime_get();
 825}
 826
 827static void
 828rpc_reset_task_statistics(struct rpc_task *task)
 829{
 830	task->tk_timeouts = 0;
 831	task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_SENT);
 832	rpc_init_task_statistics(task);
 833}
 834
 835/*
 836 * Helper that calls task->tk_ops->rpc_call_done if it exists
 837 */
 838void rpc_exit_task(struct rpc_task *task)
 839{
 840	trace_rpc_task_end(task, task->tk_action);
 841	task->tk_action = NULL;
 842	if (task->tk_ops->rpc_count_stats)
 843		task->tk_ops->rpc_count_stats(task, task->tk_calldata);
 844	else if (task->tk_client)
 845		rpc_count_iostats(task, task->tk_client->cl_metrics);
 846	if (task->tk_ops->rpc_call_done != NULL) {
 847		trace_rpc_task_call_done(task, task->tk_ops->rpc_call_done);
 848		task->tk_ops->rpc_call_done(task, task->tk_calldata);
 849		if (task->tk_action != NULL) {
 850			/* Always release the RPC slot and buffer memory */
 851			xprt_release(task);
 852			rpc_reset_task_statistics(task);
 853		}
 854	}
 855}
 856
 857void rpc_signal_task(struct rpc_task *task)
 858{
 859	struct rpc_wait_queue *queue;
 860
 861	if (!RPC_IS_ACTIVATED(task))
 862		return;
 863
 864	if (!rpc_task_set_rpc_status(task, -ERESTARTSYS))
 865		return;
 866	trace_rpc_task_signalled(task, task->tk_action);
 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}
1077
1078/**
1079 * rpc_free - free RPC buffer resources allocated via rpc_malloc
1080 * @task: RPC task
1081 *
1082 */
1083void rpc_free(struct rpc_task *task)
1084{
1085	void *buffer = task->tk_rqstp->rq_buffer;
1086	size_t size;
1087	struct rpc_buffer *buf;
1088
1089	buf = container_of(buffer, struct rpc_buffer, data);
1090	size = buf->len;
1091
1092	if (size <= RPC_BUFFER_MAXSIZE)
1093		mempool_free(buf, rpc_buffer_mempool);
1094	else
1095		kfree(buf);
1096}
1097
1098/*
1099 * Creation and deletion of RPC task structures
1100 */
1101static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
1102{
1103	memset(task, 0, sizeof(*task));
1104	atomic_set(&task->tk_count, 1);
1105	task->tk_flags  = task_setup_data->flags;
1106	task->tk_ops = task_setup_data->callback_ops;
1107	task->tk_calldata = task_setup_data->callback_data;
1108	INIT_LIST_HEAD(&task->tk_task);
1109
1110	task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
1111	task->tk_owner = current->tgid;
1112
1113	/* Initialize workqueue for async tasks */
1114	task->tk_workqueue = task_setup_data->workqueue;
1115
1116	task->tk_xprt = rpc_task_get_xprt(task_setup_data->rpc_client,
1117			xprt_get(task_setup_data->rpc_xprt));
1118
1119	task->tk_op_cred = get_rpccred(task_setup_data->rpc_op_cred);
1120
1121	if (task->tk_ops->rpc_call_prepare != NULL)
1122		task->tk_action = rpc_prepare_task;
1123
1124	rpc_init_task_statistics(task);
1125}
1126
1127static struct rpc_task *rpc_alloc_task(void)
1128{
1129	struct rpc_task *task;
1130
1131	task = kmem_cache_alloc(rpc_task_slabp, rpc_task_gfp_mask());
1132	if (task)
1133		return task;
1134	return mempool_alloc(rpc_task_mempool, GFP_NOWAIT);
1135}
1136
1137/*
1138 * Create a new task for the specified client.
1139 */
1140struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
1141{
1142	struct rpc_task	*task = setup_data->task;
1143	unsigned short flags = 0;
1144
1145	if (task == NULL) {
1146		task = rpc_alloc_task();
1147		if (task == NULL) {
1148			rpc_release_calldata(setup_data->callback_ops,
1149					     setup_data->callback_data);
1150			return ERR_PTR(-ENOMEM);
1151		}
1152		flags = RPC_TASK_DYNAMIC;
1153	}
1154
1155	rpc_init_task(task, setup_data);
1156	task->tk_flags |= flags;
1157	return task;
1158}
1159
1160/*
1161 * rpc_free_task - release rpc task and perform cleanups
1162 *
1163 * Note that we free up the rpc_task _after_ rpc_release_calldata()
1164 * in order to work around a workqueue dependency issue.
1165 *
1166 * Tejun Heo states:
1167 * "Workqueue currently considers two work items to be the same if they're
1168 * on the same address and won't execute them concurrently - ie. it
1169 * makes a work item which is queued again while being executed wait
1170 * for the previous execution to complete.
1171 *
1172 * If a work function frees the work item, and then waits for an event
1173 * which should be performed by another work item and *that* work item
1174 * recycles the freed work item, it can create a false dependency loop.
1175 * There really is no reliable way to detect this short of verifying
1176 * every memory free."
1177 *
1178 */
1179static void rpc_free_task(struct rpc_task *task)
1180{
1181	unsigned short tk_flags = task->tk_flags;
1182
1183	put_rpccred(task->tk_op_cred);
1184	rpc_release_calldata(task->tk_ops, task->tk_calldata);
1185
1186	if (tk_flags & RPC_TASK_DYNAMIC)
1187		mempool_free(task, rpc_task_mempool);
1188}
1189
1190static void rpc_async_release(struct work_struct *work)
1191{
1192	unsigned int pflags = memalloc_nofs_save();
1193
1194	rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
1195	memalloc_nofs_restore(pflags);
1196}
1197
1198static void rpc_release_resources_task(struct rpc_task *task)
1199{
1200	xprt_release(task);
1201	if (task->tk_msg.rpc_cred) {
1202		if (!(task->tk_flags & RPC_TASK_CRED_NOREF))
1203			put_cred(task->tk_msg.rpc_cred);
1204		task->tk_msg.rpc_cred = NULL;
1205	}
1206	rpc_task_release_client(task);
1207}
1208
1209static void rpc_final_put_task(struct rpc_task *task,
1210		struct workqueue_struct *q)
1211{
1212	if (q != NULL) {
1213		INIT_WORK(&task->u.tk_work, rpc_async_release);
1214		queue_work(q, &task->u.tk_work);
1215	} else
1216		rpc_free_task(task);
1217}
1218
1219static void rpc_do_put_task(struct rpc_task *task, struct workqueue_struct *q)
1220{
1221	if (atomic_dec_and_test(&task->tk_count)) {
1222		rpc_release_resources_task(task);
1223		rpc_final_put_task(task, q);
1224	}
1225}
1226
1227void rpc_put_task(struct rpc_task *task)
1228{
1229	rpc_do_put_task(task, NULL);
1230}
1231EXPORT_SYMBOL_GPL(rpc_put_task);
1232
1233void rpc_put_task_async(struct rpc_task *task)
1234{
1235	rpc_do_put_task(task, task->tk_workqueue);
1236}
1237EXPORT_SYMBOL_GPL(rpc_put_task_async);
1238
1239static void rpc_release_task(struct rpc_task *task)
1240{
1241	WARN_ON_ONCE(RPC_IS_QUEUED(task));
1242
1243	rpc_release_resources_task(task);
1244
1245	/*
1246	 * Note: at this point we have been removed from rpc_clnt->cl_tasks,
1247	 * so it should be safe to use task->tk_count as a test for whether
1248	 * or not any other processes still hold references to our rpc_task.
1249	 */
1250	if (atomic_read(&task->tk_count) != 1 + !RPC_IS_ASYNC(task)) {
1251		/* Wake up anyone who may be waiting for task completion */
1252		if (!rpc_complete_task(task))
1253			return;
1254	} else {
1255		if (!atomic_dec_and_test(&task->tk_count))
1256			return;
1257	}
1258	rpc_final_put_task(task, task->tk_workqueue);
1259}
1260
1261int rpciod_up(void)
1262{
1263	return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
1264}
1265
1266void rpciod_down(void)
1267{
1268	module_put(THIS_MODULE);
1269}
1270
1271/*
1272 * Start up the rpciod workqueue.
1273 */
1274static int rpciod_start(void)
1275{
1276	struct workqueue_struct *wq;
1277
1278	/*
1279	 * Create the rpciod thread and wait for it to start.
1280	 */
1281	wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
1282	if (!wq)
1283		goto out_failed;
1284	rpciod_workqueue = wq;
1285	wq = alloc_workqueue("xprtiod", WQ_UNBOUND | WQ_MEM_RECLAIM, 0);
1286	if (!wq)
1287		goto free_rpciod;
1288	xprtiod_workqueue = wq;
1289	return 1;
1290free_rpciod:
1291	wq = rpciod_workqueue;
1292	rpciod_workqueue = NULL;
1293	destroy_workqueue(wq);
1294out_failed:
1295	return 0;
1296}
1297
1298static void rpciod_stop(void)
1299{
1300	struct workqueue_struct *wq = NULL;
1301
1302	if (rpciod_workqueue == NULL)
1303		return;
1304
1305	wq = rpciod_workqueue;
1306	rpciod_workqueue = NULL;
1307	destroy_workqueue(wq);
1308	wq = xprtiod_workqueue;
1309	xprtiod_workqueue = NULL;
1310	destroy_workqueue(wq);
1311}
1312
1313void
1314rpc_destroy_mempool(void)
1315{
1316	rpciod_stop();
1317	mempool_destroy(rpc_buffer_mempool);
1318	mempool_destroy(rpc_task_mempool);
1319	kmem_cache_destroy(rpc_task_slabp);
1320	kmem_cache_destroy(rpc_buffer_slabp);
1321	rpc_destroy_wait_queue(&delay_queue);
1322}
1323
1324int
1325rpc_init_mempool(void)
1326{
1327	/*
1328	 * The following is not strictly a mempool initialisation,
1329	 * but there is no harm in doing it here
1330	 */
1331	rpc_init_wait_queue(&delay_queue, "delayq");
1332	if (!rpciod_start())
1333		goto err_nomem;
1334
1335	rpc_task_slabp = kmem_cache_create("rpc_tasks",
1336					     sizeof(struct rpc_task),
1337					     0, SLAB_HWCACHE_ALIGN,
1338					     NULL);
1339	if (!rpc_task_slabp)
1340		goto err_nomem;
1341	rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
1342					     RPC_BUFFER_MAXSIZE,
1343					     0, SLAB_HWCACHE_ALIGN,
1344					     NULL);
1345	if (!rpc_buffer_slabp)
1346		goto err_nomem;
1347	rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
1348						    rpc_task_slabp);
1349	if (!rpc_task_mempool)
1350		goto err_nomem;
1351	rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
1352						      rpc_buffer_slabp);
1353	if (!rpc_buffer_mempool)
1354		goto err_nomem;
1355	return 0;
1356err_nomem:
1357	rpc_destroy_mempool();
1358	return -ENOMEM;
1359}