Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
2 *
3 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 *
11 * See Documentation/slow-work.txt
12 */
13
14#ifndef _LINUX_SLOW_WORK_H
15#define _LINUX_SLOW_WORK_H
16
17#ifdef CONFIG_SLOW_WORK
18
19#include <linux/sysctl.h>
20
21struct slow_work;
22
23/*
24 * The operations used to support slow work items
25 */
26struct slow_work_ops {
27 /* get a ref on a work item
28 * - return 0 if successful, -ve if not
29 */
30 int (*get_ref)(struct slow_work *work);
31
32 /* discard a ref to a work item */
33 void (*put_ref)(struct slow_work *work);
34
35 /* execute a work item */
36 void (*execute)(struct slow_work *work);
37};
38
39/*
40 * A slow work item
41 * - A reference is held on the parent object by the thread pool when it is
42 * queued
43 */
44struct slow_work {
45 unsigned long flags;
46#define SLOW_WORK_PENDING 0 /* item pending (further) execution */
47#define SLOW_WORK_EXECUTING 1 /* item currently executing */
48#define SLOW_WORK_ENQ_DEFERRED 2 /* item enqueue deferred */
49#define SLOW_WORK_VERY_SLOW 3 /* item is very slow */
50 const struct slow_work_ops *ops; /* operations table for this item */
51 struct list_head link; /* link in queue */
52};
53
54/**
55 * slow_work_init - Initialise a slow work item
56 * @work: The work item to initialise
57 * @ops: The operations to use to handle the slow work item
58 *
59 * Initialise a slow work item.
60 */
61static inline void slow_work_init(struct slow_work *work,
62 const struct slow_work_ops *ops)
63{
64 work->flags = 0;
65 work->ops = ops;
66 INIT_LIST_HEAD(&work->link);
67}
68
69/**
70 * vslow_work_init - Initialise a very slow work item
71 * @work: The work item to initialise
72 * @ops: The operations to use to handle the slow work item
73 *
74 * Initialise a very slow work item. This item will be restricted such that
75 * only a certain number of the pool threads will be able to execute items of
76 * this type.
77 */
78static inline void vslow_work_init(struct slow_work *work,
79 const struct slow_work_ops *ops)
80{
81 work->flags = 1 << SLOW_WORK_VERY_SLOW;
82 work->ops = ops;
83 INIT_LIST_HEAD(&work->link);
84}
85
86extern int slow_work_enqueue(struct slow_work *work);
87extern int slow_work_register_user(void);
88extern void slow_work_unregister_user(void);
89
90#ifdef CONFIG_SYSCTL
91extern ctl_table slow_work_sysctls[];
92#endif
93
94#endif /* CONFIG_SLOW_WORK */
95#endif /* _LINUX_SLOW_WORK_H */