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 #include <linux/thread_info.h>
13
14 #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) || \
15 defined(CONFIG_PREEMPT_TRACE)
16 extern void add_preempt_count(int val);
17 extern void sub_preempt_count(int val);
18 #else
19 # define add_preempt_count(val) do { preempt_count() += (val); } while (0)
20 # define sub_preempt_count(val) do { preempt_count() -= (val); } while (0)
21 #endif
22
23 #define inc_preempt_count() add_preempt_count(1)
24 #define dec_preempt_count() sub_preempt_count(1)
25
26 #define preempt_count() (current_thread_info()->preempt_count)
27
28 #ifdef CONFIG_PREEMPT
29
30 asmlinkage void preempt_schedule(void);
31 asmlinkage void preempt_schedule_irq(void);
32
33 #define preempt_disable() \
34 do { \
35 inc_preempt_count(); \
36 barrier(); \
37 } while (0)
38
39 #define __preempt_enable_no_resched() \
40 do { \
41 barrier(); \
42 dec_preempt_count(); \
43 } while (0)
44
45
46 #ifdef CONFIG_DEBUG_PREEMPT
47 extern void notrace preempt_enable_no_resched(void);
48 #else
49 # define preempt_enable_no_resched() __preempt_enable_no_resched()
50 #endif
51
52 #define preempt_check_resched() \
53 do { \
54 if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
55 preempt_schedule(); \
56 } while (0)
57
58 #define preempt_check_resched_delayed() \
59 do { \
60 if (unlikely(test_thread_flag(TIF_NEED_RESCHED_DELAYED))) \
61 preempt_schedule(); \
62 } while (0)
63
64 #define preempt_enable() \
65 do { \
66 __preempt_enable_no_resched(); \
67 barrier(); \
68 preempt_check_resched(); \
69 } while (0)
70
71 /* For debugging and tracer internals only! */
72 #define add_preempt_count_notrace(val) \
73 do { preempt_count() += (val); } while (0)
74 #define sub_preempt_count_notrace(val) \
75 do { preempt_count() -= (val); } while (0)
76 #define inc_preempt_count_notrace() add_preempt_count_notrace(1)
77 #define dec_preempt_count_notrace() sub_preempt_count_notrace(1)
78
79 #define preempt_disable_notrace() \
80 do { \
81 inc_preempt_count_notrace(); \
82 barrier(); \
83 } while (0)
84
85 #define preempt_enable_no_resched_notrace() \
86 do { \
87 barrier(); \
88 dec_preempt_count_notrace(); \
89 } while (0)
90
91 /* preempt_check_resched is OK to trace */
92 #define preempt_enable_notrace() \
93 do { \
94 preempt_enable_no_resched_notrace(); \
95 barrier(); \
96 preempt_check_resched(); \
97 } while (0)
98
99 #else
100
101 #define preempt_disable() do { } while (0)
102 #define preempt_enable_no_resched() do { } while (0)
103 #define __preempt_enable_no_resched() do { } while (0)
104 #define preempt_enable() do { } while (0)
105 #define preempt_check_resched() do { } while (0)
106 #define preempt_check_resched_delayed() do { } while (0)
107
108 #define preempt_disable_notrace() do { } while (0)
109 #define preempt_enable_no_resched_notrace() do { } while (0)
110 #define preempt_enable_notrace() do { } while (0)
111
112 #define preempt_schedule_irq() do { } while (0)
113
114 #endif
115
116 #ifdef CONFIG_PREEMPT_NOTIFIERS
117
118 struct preempt_notifier;
119
120 /**
121 * preempt_ops - notifiers called when a task is preempted and rescheduled
122 * @sched_in: we're about to be rescheduled:
123 * notifier: struct preempt_notifier for the task being scheduled
124 * cpu: cpu we're scheduled on
125 * @sched_out: we've just been preempted
126 * notifier: struct preempt_notifier for the task being preempted
127 * next: the task that's kicking us out
128 */
129 struct preempt_ops {
130 void (*sched_in)(struct preempt_notifier *notifier, int cpu);
131 void (*sched_out)(struct preempt_notifier *notifier,
132 struct task_struct *next);
133 };
134
135 /**
136 * preempt_notifier - key for installing preemption notifiers
137 * @link: internal use
138 * @ops: defines the notifier functions to be called
139 *
140 * Usually used in conjunction with container_of().
141 */
142 struct preempt_notifier {
143 struct hlist_node link;
144 struct preempt_ops *ops;
145 };
146
147 void preempt_notifier_register(struct preempt_notifier *notifier);
148 void preempt_notifier_unregister(struct preempt_notifier *notifier);
149
150 static inline void preempt_notifier_init(struct preempt_notifier *notifier,
151 struct preempt_ops *ops)
152 {
153 INIT_HLIST_NODE(¬ifier->link);
154 notifier->ops = ops;
155 }
156
157 #endif
158
159 #endif /* __LINUX_PREEMPT_H */
160
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