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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef __LINUX_PREEMPT_H
2#define __LINUX_PREEMPT_H
3
4/*
5 * include/linux/preempt.h - macros for accessing and manipulating
6 * preempt_count (used for kernel preemption, interrupt count, etc.)
7 */
8
Al Virof0373602005-11-13 16:06:57 -08009#include <linux/thread_info.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/linkage.h>
Avi Kivitye107be32007-07-26 13:40:43 +020011#include <linux/list.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012
Steven Rostedt6cd8a4b2008-05-12 21:20:42 +020013#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
Harvey Harrisonec701582008-02-08 04:19:55 -080014 extern void add_preempt_count(int val);
15 extern void sub_preempt_count(int val);
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#else
17# define add_preempt_count(val) do { preempt_count() += (val); } while (0)
18# define sub_preempt_count(val) do { preempt_count() -= (val); } while (0)
19#endif
20
21#define inc_preempt_count() add_preempt_count(1)
22#define dec_preempt_count() sub_preempt_count(1)
23
24#define preempt_count() (current_thread_info()->preempt_count)
25
26#ifdef CONFIG_PREEMPT
27
28asmlinkage void preempt_schedule(void);
29
30#define preempt_disable() \
31do { \
32 inc_preempt_count(); \
33 barrier(); \
34} while (0)
35
36#define preempt_enable_no_resched() \
37do { \
38 barrier(); \
39 dec_preempt_count(); \
40} while (0)
41
42#define preempt_check_resched() \
43do { \
44 if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
45 preempt_schedule(); \
46} while (0)
47
48#define preempt_enable() \
49do { \
50 preempt_enable_no_resched(); \
Nicolas Pitred6f02912005-12-21 12:26:25 -050051 barrier(); \
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 preempt_check_resched(); \
53} while (0)
54
Steven Rostedt50282522008-05-12 21:20:41 +020055/* For debugging and tracer internals only! */
56#define add_preempt_count_notrace(val) \
57 do { preempt_count() += (val); } while (0)
58#define sub_preempt_count_notrace(val) \
59 do { preempt_count() -= (val); } while (0)
60#define inc_preempt_count_notrace() add_preempt_count_notrace(1)
61#define dec_preempt_count_notrace() sub_preempt_count_notrace(1)
62
63#define preempt_disable_notrace() \
64do { \
65 inc_preempt_count_notrace(); \
66 barrier(); \
67} while (0)
68
69#define preempt_enable_no_resched_notrace() \
70do { \
71 barrier(); \
72 dec_preempt_count_notrace(); \
73} while (0)
74
75/* preempt_check_resched is OK to trace */
76#define preempt_enable_notrace() \
77do { \
78 preempt_enable_no_resched_notrace(); \
79 barrier(); \
80 preempt_check_resched(); \
81} while (0)
82
Linus Torvalds1da177e2005-04-16 15:20:36 -070083#else
84
85#define preempt_disable() do { } while (0)
86#define preempt_enable_no_resched() do { } while (0)
87#define preempt_enable() do { } while (0)
88#define preempt_check_resched() do { } while (0)
89
Steven Rostedt50282522008-05-12 21:20:41 +020090#define preempt_disable_notrace() do { } while (0)
91#define preempt_enable_no_resched_notrace() do { } while (0)
92#define preempt_enable_notrace() do { } while (0)
93
Linus Torvalds1da177e2005-04-16 15:20:36 -070094#endif
95
Avi Kivitye107be32007-07-26 13:40:43 +020096#ifdef CONFIG_PREEMPT_NOTIFIERS
97
98struct preempt_notifier;
99
100/**
101 * preempt_ops - notifiers called when a task is preempted and rescheduled
102 * @sched_in: we're about to be rescheduled:
103 * notifier: struct preempt_notifier for the task being scheduled
104 * cpu: cpu we're scheduled on
105 * @sched_out: we've just been preempted
106 * notifier: struct preempt_notifier for the task being preempted
107 * next: the task that's kicking us out
Tejun Heo8592e642009-12-02 12:56:46 +0900108 *
109 * Please note that sched_in and out are called under different
110 * contexts. sched_out is called with rq lock held and irq disabled
111 * while sched_in is called without rq lock and irq enabled. This
112 * difference is intentional and depended upon by its users.
Avi Kivitye107be32007-07-26 13:40:43 +0200113 */
114struct preempt_ops {
115 void (*sched_in)(struct preempt_notifier *notifier, int cpu);
116 void (*sched_out)(struct preempt_notifier *notifier,
117 struct task_struct *next);
118};
119
120/**
121 * preempt_notifier - key for installing preemption notifiers
122 * @link: internal use
123 * @ops: defines the notifier functions to be called
124 *
125 * Usually used in conjunction with container_of().
126 */
127struct preempt_notifier {
128 struct hlist_node link;
129 struct preempt_ops *ops;
130};
131
132void preempt_notifier_register(struct preempt_notifier *notifier);
133void preempt_notifier_unregister(struct preempt_notifier *notifier);
134
135static inline void preempt_notifier_init(struct preempt_notifier *notifier,
136 struct preempt_ops *ops)
137{
138 INIT_HLIST_NODE(&notifier->link);
139 notifier->ops = ops;
140}
141
142#endif
143
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144#endif /* __LINUX_PREEMPT_H */