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1da177e4 LT |
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 | ||
f037360f | 9 | #include <linux/thread_info.h> |
1da177e4 | 10 | #include <linux/linkage.h> |
e107be36 | 11 | #include <linux/list.h> |
1da177e4 | 12 | |
6cd8a4bb | 13 | #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) |
ec701584 HH |
14 | extern void add_preempt_count(int val); |
15 | extern void sub_preempt_count(int val); | |
1da177e4 LT |
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 | ||
28 | asmlinkage void preempt_schedule(void); | |
29 | ||
bdd4e85d FW |
30 | #define preempt_check_resched() \ |
31 | do { \ | |
32 | if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ | |
33 | preempt_schedule(); \ | |
34 | } while (0) | |
35 | ||
29bb9e5a SR |
36 | #ifdef CONFIG_CONTEXT_TRACKING |
37 | ||
38 | void preempt_schedule_context(void); | |
39 | ||
40 | #define preempt_check_resched_context() \ | |
41 | do { \ | |
42 | if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ | |
43 | preempt_schedule_context(); \ | |
44 | } while (0) | |
45 | #else | |
46 | ||
47 | #define preempt_check_resched_context() preempt_check_resched() | |
48 | ||
49 | #endif /* CONFIG_CONTEXT_TRACKING */ | |
50 | ||
bdd4e85d FW |
51 | #else /* !CONFIG_PREEMPT */ |
52 | ||
53 | #define preempt_check_resched() do { } while (0) | |
29bb9e5a | 54 | #define preempt_check_resched_context() do { } while (0) |
bdd4e85d FW |
55 | |
56 | #endif /* CONFIG_PREEMPT */ | |
57 | ||
58 | ||
59 | #ifdef CONFIG_PREEMPT_COUNT | |
60 | ||
1da177e4 LT |
61 | #define preempt_disable() \ |
62 | do { \ | |
63 | inc_preempt_count(); \ | |
64 | barrier(); \ | |
65 | } while (0) | |
66 | ||
ba74c144 | 67 | #define sched_preempt_enable_no_resched() \ |
1da177e4 LT |
68 | do { \ |
69 | barrier(); \ | |
70 | dec_preempt_count(); \ | |
71 | } while (0) | |
72 | ||
ba74c144 TG |
73 | #define preempt_enable_no_resched() sched_preempt_enable_no_resched() |
74 | ||
1da177e4 LT |
75 | #define preempt_enable() \ |
76 | do { \ | |
77 | preempt_enable_no_resched(); \ | |
d6f02913 | 78 | barrier(); \ |
1da177e4 LT |
79 | preempt_check_resched(); \ |
80 | } while (0) | |
81 | ||
50282528 SR |
82 | /* For debugging and tracer internals only! */ |
83 | #define add_preempt_count_notrace(val) \ | |
84 | do { preempt_count() += (val); } while (0) | |
85 | #define sub_preempt_count_notrace(val) \ | |
86 | do { preempt_count() -= (val); } while (0) | |
87 | #define inc_preempt_count_notrace() add_preempt_count_notrace(1) | |
88 | #define dec_preempt_count_notrace() sub_preempt_count_notrace(1) | |
89 | ||
90 | #define preempt_disable_notrace() \ | |
91 | do { \ | |
92 | inc_preempt_count_notrace(); \ | |
93 | barrier(); \ | |
94 | } while (0) | |
95 | ||
96 | #define preempt_enable_no_resched_notrace() \ | |
97 | do { \ | |
98 | barrier(); \ | |
99 | dec_preempt_count_notrace(); \ | |
100 | } while (0) | |
101 | ||
102 | /* preempt_check_resched is OK to trace */ | |
103 | #define preempt_enable_notrace() \ | |
104 | do { \ | |
105 | preempt_enable_no_resched_notrace(); \ | |
106 | barrier(); \ | |
29bb9e5a | 107 | preempt_check_resched_context(); \ |
50282528 SR |
108 | } while (0) |
109 | ||
bdd4e85d | 110 | #else /* !CONFIG_PREEMPT_COUNT */ |
1da177e4 | 111 | |
386afc91 LT |
112 | /* |
113 | * Even if we don't have any preemption, we need preempt disable/enable | |
114 | * to be barriers, so that we don't have things like get_user/put_user | |
115 | * that can cause faults and scheduling migrate into our preempt-protected | |
116 | * region. | |
117 | */ | |
118 | #define preempt_disable() barrier() | |
119 | #define sched_preempt_enable_no_resched() barrier() | |
120 | #define preempt_enable_no_resched() barrier() | |
121 | #define preempt_enable() barrier() | |
122 | ||
123 | #define preempt_disable_notrace() barrier() | |
124 | #define preempt_enable_no_resched_notrace() barrier() | |
125 | #define preempt_enable_notrace() barrier() | |
50282528 | 126 | |
bdd4e85d | 127 | #endif /* CONFIG_PREEMPT_COUNT */ |
1da177e4 | 128 | |
e107be36 AK |
129 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
130 | ||
131 | struct preempt_notifier; | |
132 | ||
133 | /** | |
134 | * preempt_ops - notifiers called when a task is preempted and rescheduled | |
135 | * @sched_in: we're about to be rescheduled: | |
136 | * notifier: struct preempt_notifier for the task being scheduled | |
137 | * cpu: cpu we're scheduled on | |
138 | * @sched_out: we've just been preempted | |
139 | * notifier: struct preempt_notifier for the task being preempted | |
140 | * next: the task that's kicking us out | |
8592e648 TH |
141 | * |
142 | * Please note that sched_in and out are called under different | |
143 | * contexts. sched_out is called with rq lock held and irq disabled | |
144 | * while sched_in is called without rq lock and irq enabled. This | |
145 | * difference is intentional and depended upon by its users. | |
e107be36 AK |
146 | */ |
147 | struct preempt_ops { | |
148 | void (*sched_in)(struct preempt_notifier *notifier, int cpu); | |
149 | void (*sched_out)(struct preempt_notifier *notifier, | |
150 | struct task_struct *next); | |
151 | }; | |
152 | ||
153 | /** | |
154 | * preempt_notifier - key for installing preemption notifiers | |
155 | * @link: internal use | |
156 | * @ops: defines the notifier functions to be called | |
157 | * | |
158 | * Usually used in conjunction with container_of(). | |
159 | */ | |
160 | struct preempt_notifier { | |
161 | struct hlist_node link; | |
162 | struct preempt_ops *ops; | |
163 | }; | |
164 | ||
165 | void preempt_notifier_register(struct preempt_notifier *notifier); | |
166 | void preempt_notifier_unregister(struct preempt_notifier *notifier); | |
167 | ||
168 | static inline void preempt_notifier_init(struct preempt_notifier *notifier, | |
169 | struct preempt_ops *ops) | |
170 | { | |
171 | INIT_HLIST_NODE(¬ifier->link); | |
172 | notifier->ops = ops; | |
173 | } | |
174 | ||
175 | #endif | |
176 | ||
1da177e4 | 177 | #endif /* __LINUX_PREEMPT_H */ |