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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 | |
28 | asmlinkage void preempt_schedule(void); |
29 | |
30 | #define preempt_disable() \ |
31 | do { \ |
32 | inc_preempt_count(); \ |
33 | barrier(); \ |
34 | } while (0) |
35 | |
36 | #define preempt_enable_no_resched() \ |
37 | do { \ |
38 | barrier(); \ |
39 | dec_preempt_count(); \ |
40 | } while (0) |
41 | |
42 | #define preempt_check_resched() \ |
43 | do { \ |
44 | if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ |
45 | preempt_schedule(); \ |
46 | } while (0) |
47 | |
48 | #define preempt_enable() \ |
49 | do { \ |
50 | preempt_enable_no_resched(); \ |
51 | barrier(); \ |
52 | preempt_check_resched(); \ |
53 | } while (0) |
54 | |
55 | /* 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() \ |
64 | do { \ |
65 | inc_preempt_count_notrace(); \ |
66 | barrier(); \ |
67 | } while (0) |
68 | |
69 | #define preempt_enable_no_resched_notrace() \ |
70 | do { \ |
71 | barrier(); \ |
72 | dec_preempt_count_notrace(); \ |
73 | } while (0) |
74 | |
75 | /* preempt_check_resched is OK to trace */ |
76 | #define preempt_enable_notrace() \ |
77 | do { \ |
78 | preempt_enable_no_resched_notrace(); \ |
79 | barrier(); \ |
80 | preempt_check_resched(); \ |
81 | } while (0) |
82 | |
83 | #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 | |
90 | #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 | |
94 | #endif |
95 | |
96 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
97 | |
98 | struct 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 |
108 | * |
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. |
113 | */ |
114 | struct 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 | */ |
127 | struct preempt_notifier { |
128 | struct hlist_node link; |
129 | struct preempt_ops *ops; |
130 | }; |
131 | |
132 | void preempt_notifier_register(struct preempt_notifier *notifier); |
133 | void preempt_notifier_unregister(struct preempt_notifier *notifier); |
134 | |
135 | static inline void preempt_notifier_init(struct preempt_notifier *notifier, |
136 | struct preempt_ops *ops) |
137 | { |
138 | INIT_HLIST_NODE(¬ifier->link); |
139 | notifier->ops = ops; |
140 | } |
141 | |
142 | #endif |
143 | |
144 | #endif /* __LINUX_PREEMPT_H */ |
145 |
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