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/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*
* See Documentation/slow-work.txt
*/
#ifndef _LINUX_SLOW_WORK_H
#define _LINUX_SLOW_WORK_H
#ifdef CONFIG_SLOW_WORK
#include <linux/sysctl.h>
struct slow_work;
/*
* The operations used to support slow work items
*/
struct slow_work_ops {
/* owner */
struct module *owner;
/* get a ref on a work item
* - return 0 if successful, -ve if not
*/
int (*get_ref)(struct slow_work *work);
/* discard a ref to a work item */
void (*put_ref)(struct slow_work *work);
/* execute a work item */
void (*execute)(struct slow_work *work);
};
/*
* A slow work item
* - A reference is held on the parent object by the thread pool when it is
* queued
*/
struct slow_work {
struct module *owner; /* the owning module */
unsigned long flags;
#define SLOW_WORK_PENDING 0 /* item pending (further) execution */
#define SLOW_WORK_EXECUTING 1 /* item currently executing */
#define SLOW_WORK_ENQ_DEFERRED 2 /* item enqueue deferred */
#define SLOW_WORK_VERY_SLOW 3 /* item is very slow */
const struct slow_work_ops *ops; /* operations table for this item */
struct list_head link; /* link in queue */
};
/**
* slow_work_init - Initialise a slow work item
* @work: The work item to initialise
* @ops: The operations to use to handle the slow work item
*
* Initialise a slow work item.
*/
static inline void slow_work_init(struct slow_work *work,
const struct slow_work_ops *ops)
{
work->flags = 0;
work->ops = ops;
INIT_LIST_HEAD(&work->link);
}
/**
* vslow_work_init - Initialise a very slow work item
* @work: The work item to initialise
* @ops: The operations to use to handle the slow work item
*
* Initialise a very slow work item. This item will be restricted such that
* only a certain number of the pool threads will be able to execute items of
* this type.
*/
static inline void vslow_work_init(struct slow_work *work,
const struct slow_work_ops *ops)
{
work->flags = 1 << SLOW_WORK_VERY_SLOW;
work->ops = ops;
INIT_LIST_HEAD(&work->link);
}
extern int slow_work_enqueue(struct slow_work *work);
extern int slow_work_register_user(struct module *owner);
extern void slow_work_unregister_user(struct module *owner);
#ifdef CONFIG_SYSCTL
extern ctl_table slow_work_sysctls[];
#endif
#endif /* CONFIG_SLOW_WORK */
#endif /* _LINUX_SLOW_WORK_H */
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