path: root/net/sunrpc/sched.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/net/sunrpc/sched.c
 *
 * Scheduling for synchronous and asynchronous RPC requests.
 *
 * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
 *
 * TCP NFS related read + write fixes
 * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
 */

#include <linux/module.h>

#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/mempool.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/sched/mm.h>

#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/metrics.h>

#include "sunrpc.h"

#define CREATE_TRACE_POINTS
#include <trace/events/sunrpc.h>

/*
 * RPC slabs and memory pools
 */
#define RPC_BUFFER_MAXSIZE	(2048)
#define RPC_BUFFER_POOLSIZE	(8)
#define RPC_TASK_POOLSIZE	(8)
static struct kmem_cache	*rpc_task_slabp __read_mostly;
static struct kmem_cache	*rpc_buffer_slabp __read_mostly;
static mempool_t	*rpc_task_mempool __read_mostly;
static mempool_t	*rpc_buffer_mempool __read_mostly;

static void			rpc_async_schedule(struct work_struct *);
static void			 rpc_release_task(struct rpc_task *task);
static void __rpc_queue_timer_fn(struct work_struct *);

/*
 * RPC tasks sit here while waiting for conditions to improve.
 */
static struct rpc_wait_queue delay_queue;

/*
 * rpciod-related stuff
 */
struct workqueue_struct *rpciod_workqueue __read_mostly;
struct workqueue_struct *xprtiod_workqueue __read_mostly;
EXPORT_SYMBOL_GPL(xprtiod_workqueue);

unsigned long
rpc_task_timeout(const struct rpc_task *task)
{
	unsigned long timeout = READ_ONCE(task->tk_timeout);

	if (timeout != 0) {
		unsigned long now = jiffies;
		if (time_before(now, timeout))
			return timeout - now;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(rpc_task_timeout);

/*
 * Disable the timer for a given RPC task. Should be called with
 * queue->lock and bh_disabled in order to avoid races within
 * rpc_run_timer().
 */
static void
__rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
{
	if (list_empty(&task->u.tk_wait.timer_list))
		return;
	task->tk_timeout = 0;
	list_del(&task->u.tk_wait.timer_list);
	if (list_empty(&queue->timer_list.list))
		cancel_delayed_work(&queue->timer_list.dwork);
}

static void
rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
{
	unsigned long now = jiffies;
	queue->timer_list.expires = expires;
	if (time_before_eq(expires, now))
		expires = 0;
	else
		expires -= now;
	mod_delayed_work(rpciod_workqueue, &queue->timer_list.dwork, expires);
}

/*
 * Set up a timer for the current task.
 */
static void
__rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task,
		unsigned long timeout)
{
	task->tk_timeout = timeout;
	if (list_empty(&queue->timer_list.list) || time_before(timeout, queue->timer_list.expires))
		rpc_set_queue_timer(queue, timeout);
	list_add(&task->