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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 | ||
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 | ||
1da177e4 LT |
45 | #define preempt_disable() \ |
46 | do { \ | |
47 | inc_preempt_count(); \ | |
48 | barrier(); \ | |
49 | } while (0) | |
50 | ||
ba74c144 | 51 | #define sched_preempt_enable_no_resched() \ |
1da177e4 LT |
52 | do { \ |
53 | barrier(); \ | |
54 | dec_preempt_count(); \ | |
55 | } while (0) | |
56 | ||
ba74c144 TG |
57 | #define preempt_enable_no_resched() sched_preempt_enable_no_resched() |
58 | ||
1da177e4 LT |
59 | #define preempt_enable() \ |
60 | do { \ | |
61 | preempt_enable_no_resched(); \ | |
d6f02913 | 62 | barrier(); \ |
1da177e4 LT |
63 | preempt_check_resched(); \ |
64 | } while (0) | |
65 | ||
50282528 SR |
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() \ | |
75 | do { \ | |
76 | inc_preempt_count_notrace(); \ | |
77 | barrier(); \ | |
78 | } while (0) | |
79 | ||
80 | #define preempt_enable_no_resched_notrace() \ | |
81 | do { \ | |
82 | barrier(); \ | |
83 | dec_preempt_count_notrace(); \ | |
84 | } while (0) | |
85 | ||
86 | /* preempt_check_resched is OK to trace */ | |
87 | #define preempt_enable_notrace() \ | |
88 | do { \ | |
89 | preempt_enable_no_resched_notrace(); \ | |
90 | barrier(); \ | |
91 | preempt_check_resched(); \ | |
92 | } while (0) | |
93 | ||
bdd4e85d | 94 | #else /* !CONFIG_PREEMPT_COUNT */ |
1da177e4 | 95 | |
386afc91 LT |
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() | |
50282528 | 110 | |
bdd4e85d | 111 | #endif /* CONFIG_PREEMPT_COUNT */ |
1da177e4 | 112 | |
e107be36 AK |
113 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
114 | ||
115 | struct 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 | |
8592e648 TH |
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. | |
e107be36 AK |
130 | */ |
131 | struct 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 | */ | |
144 | struct preempt_notifier { | |
145 | struct hlist_node link; | |
146 | struct preempt_ops *ops; | |
147 | }; | |
148 | ||
149 | void preempt_notifier_register(struct preempt_notifier *notifier); | |
150 | void preempt_notifier_unregister(struct preempt_notifier *notifier); | |
151 | ||
152 | static 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 | ||
1da177e4 | 161 | #endif /* __LINUX_PREEMPT_H */ |