Linux kernel mirror (for testing)
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linux
1#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
9#include <linux/thread_info.h>
10#include <linux/linkage.h>
11#include <linux/list.h>
12
13#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
14 extern void add_preempt_count(int val);
15 extern void sub_preempt_count(int val);
16#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_check_resched() \
31do { \
32 if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
33 preempt_schedule(); \
34} while (0)
35
36#else /* !CONFIG_PREEMPT */
37
38#define preempt_check_resched() do { } while (0)
39
40#endif /* CONFIG_PREEMPT */
41
42
43#ifdef CONFIG_PREEMPT_COUNT
44
45#define preempt_disable() \
46do { \
47 inc_preempt_count(); \
48 barrier(); \
49} while (0)
50
51#define sched_preempt_enable_no_resched() \
52do { \
53 barrier(); \
54 dec_preempt_count(); \
55} while (0)
56
57#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
58
59#define preempt_enable() \
60do { \
61 preempt_enable_no_resched(); \
62 barrier(); \
63 preempt_check_resched(); \
64} while (0)
65
66/* For debugging and tracer internals only! */
67#define add_preempt_count_notrace(val) \
68 do { preempt_count() += (val); } while (0)
69#define sub_preempt_count_notrace(val) \
70 do { preempt_count() -= (val); } while (0)
71#define inc_preempt_count_notrace() add_preempt_count_notrace(1)
72#define dec_preempt_count_notrace() sub_preempt_count_notrace(1)
73
74#define preempt_disable_notrace() \
75do { \
76 inc_preempt_count_notrace(); \
77 barrier(); \
78} while (0)
79
80#define preempt_enable_no_resched_notrace() \
81do { \
82 barrier(); \
83 dec_preempt_count_notrace(); \
84} while (0)
85
86/* preempt_check_resched is OK to trace */
87#define preempt_enable_notrace() \
88do { \
89 preempt_enable_no_resched_notrace(); \
90 barrier(); \
91 preempt_check_resched(); \
92} while (0)
93
94#else /* !CONFIG_PREEMPT_COUNT */
95
96/*
97 * Even if we don't have any preemption, we need preempt disable/enable
98 * to be barriers, so that we don't have things like get_user/put_user
99 * that can cause faults and scheduling migrate into our preempt-protected
100 * region.
101 */
102#define preempt_disable() barrier()
103#define sched_preempt_enable_no_resched() barrier()
104#define preempt_enable_no_resched() barrier()
105#define preempt_enable() barrier()
106
107#define preempt_disable_notrace() barrier()
108#define preempt_enable_no_resched_notrace() barrier()
109#define preempt_enable_notrace() barrier()
110
111#endif /* CONFIG_PREEMPT_COUNT */
112
113#ifdef CONFIG_PREEMPT_NOTIFIERS
114
115struct preempt_notifier;
116
117/**
118 * preempt_ops - notifiers called when a task is preempted and rescheduled
119 * @sched_in: we're about to be rescheduled:
120 * notifier: struct preempt_notifier for the task being scheduled
121 * cpu: cpu we're scheduled on
122 * @sched_out: we've just been preempted
123 * notifier: struct preempt_notifier for the task being preempted
124 * next: the task that's kicking us out
125 *
126 * Please note that sched_in and out are called under different
127 * contexts. sched_out is called with rq lock held and irq disabled
128 * while sched_in is called without rq lock and irq enabled. This
129 * difference is intentional and depended upon by its users.
130 */
131struct preempt_ops {
132 void (*sched_in)(struct preempt_notifier *notifier, int cpu);
133 void (*sched_out)(struct preempt_notifier *notifier,
134 struct task_struct *next);
135};
136
137/**
138 * preempt_notifier - key for installing preemption notifiers
139 * @link: internal use
140 * @ops: defines the notifier functions to be called
141 *
142 * Usually used in conjunction with container_of().
143 */
144struct preempt_notifier {
145 struct hlist_node link;
146 struct preempt_ops *ops;
147};
148
149void preempt_notifier_register(struct preempt_notifier *notifier);
150void preempt_notifier_unregister(struct preempt_notifier *notifier);
151
152static inline void preempt_notifier_init(struct preempt_notifier *notifier,
153 struct preempt_ops *ops)
154{
155 INIT_HLIST_NODE(¬ifier->link);
156 notifier->ops = ops;
157}
158
159#endif
160
161#endif /* __LINUX_PREEMPT_H */