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