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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. |
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 | #include <linux/timer.h> |
21 | |
22 | struct slow_work; |
23 | #ifdef CONFIG_SLOW_WORK_DEBUG |
24 | struct seq_file; |
25 | #endif |
26 | |
27 | /* |
28 | * The operations used to support slow work items |
29 | */ |
30 | struct slow_work_ops { |
31 | /* owner */ |
32 | struct module *owner; |
33 | |
34 | /* get a ref on a work item |
35 | * - return 0 if successful, -ve if not |
36 | */ |
37 | int (*get_ref)(struct slow_work *work); |
38 | |
39 | /* discard a ref to a work item */ |
40 | void (*put_ref)(struct slow_work *work); |
41 | |
42 | /* execute a work item */ |
43 | void (*execute)(struct slow_work *work); |
44 | |
45 | #ifdef CONFIG_SLOW_WORK_DEBUG |
46 | /* describe a work item for debugfs */ |
47 | void (*desc)(struct slow_work *work, struct seq_file *m); |
48 | #endif |
49 | }; |
50 | |
51 | /* |
52 | * A slow work item |
53 | * - A reference is held on the parent object by the thread pool when it is |
54 | * queued |
55 | */ |
56 | struct slow_work { |
57 | struct module *owner; /* the owning module */ |
58 | unsigned long flags; |
59 | #define SLOW_WORK_PENDING 0 /* item pending (further) execution */ |
60 | #define SLOW_WORK_EXECUTING 1 /* item currently executing */ |
61 | #define SLOW_WORK_ENQ_DEFERRED 2 /* item enqueue deferred */ |
62 | #define SLOW_WORK_VERY_SLOW 3 /* item is very slow */ |
63 | #define SLOW_WORK_CANCELLING 4 /* item is being cancelled, don't enqueue */ |
64 | #define SLOW_WORK_DELAYED 5 /* item is struct delayed_slow_work with active timer */ |
65 | const struct slow_work_ops *ops; /* operations table for this item */ |
66 | struct list_head link; /* link in queue */ |
67 | #ifdef CONFIG_SLOW_WORK_DEBUG |
68 | struct timespec mark; /* jiffies at which queued or exec begun */ |
69 | #endif |
70 | }; |
71 | |
72 | struct delayed_slow_work { |
73 | struct slow_work work; |
74 | struct timer_list timer; |
75 | }; |
76 | |
77 | /** |
78 | * slow_work_init - Initialise a slow work item |
79 | * @work: The work item to initialise |
80 | * @ops: The operations to use to handle the slow work item |
81 | * |
82 | * Initialise a slow work item. |
83 | */ |
84 | static inline void slow_work_init(struct slow_work *work, |
85 | const struct slow_work_ops *ops) |
86 | { |
87 | work->flags = 0; |
88 | work->ops = ops; |
89 | INIT_LIST_HEAD(&work->link); |
90 | } |
91 | |
92 | /** |
93 | * slow_work_init - Initialise a delayed slow work item |
94 | * @work: The work item to initialise |
95 | * @ops: The operations to use to handle the slow work item |
96 | * |
97 | * Initialise a delayed slow work item. |
98 | */ |
99 | static inline void delayed_slow_work_init(struct delayed_slow_work *dwork, |
100 | const struct slow_work_ops *ops) |
101 | { |
102 | init_timer(&dwork->timer); |
103 | slow_work_init(&dwork->work, ops); |
104 | } |
105 | |
106 | /** |
107 | * vslow_work_init - Initialise a very slow work item |
108 | * @work: The work item to initialise |
109 | * @ops: The operations to use to handle the slow work item |
110 | * |
111 | * Initialise a very slow work item. This item will be restricted such that |
112 | * only a certain number of the pool threads will be able to execute items of |
113 | * this type. |
114 | */ |
115 | static inline void vslow_work_init(struct slow_work *work, |
116 | const struct slow_work_ops *ops) |
117 | { |
118 | work->flags = 1 << SLOW_WORK_VERY_SLOW; |
119 | work->ops = ops; |
120 | INIT_LIST_HEAD(&work->link); |
121 | } |
122 | |
123 | /** |
124 | * slow_work_is_queued - Determine if a slow work item is on the work queue |
125 | * work: The work item to test |
126 | * |
127 | * Determine if the specified slow-work item is on the work queue. This |
128 | * returns true if it is actually on the queue. |
129 | * |
130 | * If the item is executing and has been marked for requeue when execution |
131 | * finishes, then false will be returned. |
132 | * |
133 | * Anyone wishing to wait for completion of execution can wait on the |
134 | * SLOW_WORK_EXECUTING bit. |
135 | */ |
136 | static inline bool slow_work_is_queued(struct slow_work *work) |
137 | { |
138 | unsigned long flags = work->flags; |
139 | return flags & SLOW_WORK_PENDING && !(flags & SLOW_WORK_EXECUTING); |
140 | } |
141 | |
142 | extern int slow_work_enqueue(struct slow_work *work); |
143 | extern void slow_work_cancel(struct slow_work *work); |
144 | extern int slow_work_register_user(struct module *owner); |
145 | extern void slow_work_unregister_user(struct module *owner); |
146 | |
147 | extern int delayed_slow_work_enqueue(struct delayed_slow_work *dwork, |
148 | unsigned long delay); |
149 | |
150 | static inline void delayed_slow_work_cancel(struct delayed_slow_work *dwork) |
151 | { |
152 | slow_work_cancel(&dwork->work); |
153 | } |
154 | |
155 | extern bool slow_work_sleep_till_thread_needed(struct slow_work *work, |
156 | signed long *_timeout); |
157 | |
158 | #ifdef CONFIG_SYSCTL |
159 | extern ctl_table slow_work_sysctls[]; |
160 | #endif |
161 | |
162 | #endif /* CONFIG_SLOW_WORK */ |
163 | #endif /* _LINUX_SLOW_WORK_H */ |
164 |
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