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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. | |
8f0aa2f2 DH |
10 | * |
11 | * See Documentation/slow-work.txt | |
07fe7cb7 DH |
12 | */ |
13 | ||
14 | #ifndef _LINUX_SLOW_WORK_H | |
15 | #define _LINUX_SLOW_WORK_H | |
16 | ||
17 | #ifdef CONFIG_SLOW_WORK | |
18 | ||
12e22c5e DH |
19 | #include <linux/sysctl.h> |
20 | ||
07fe7cb7 DH |
21 | struct slow_work; |
22 | ||
23 | /* | |
24 | * The operations used to support slow work items | |
25 | */ | |
26 | struct 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 | */ | |
44 | struct 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 | */ | |
61 | static 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 | /** | |
5dd559f0 | 70 | * vslow_work_init - Initialise a very slow work item |
07fe7cb7 DH |
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 | */ | |
78 | static 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 | ||
86 | extern int slow_work_enqueue(struct slow_work *work); | |
87 | extern int slow_work_register_user(void); | |
88 | extern void slow_work_unregister_user(void); | |
89 | ||
12e22c5e DH |
90 | #ifdef CONFIG_SYSCTL |
91 | extern ctl_table slow_work_sysctls[]; | |
92 | #endif | |
07fe7cb7 DH |
93 | |
94 | #endif /* CONFIG_SLOW_WORK */ | |
95 | #endif /* _LINUX_SLOW_WORK_H */ |