1 #ifndef __LINUX_PREEMPT_H
2 #define __LINUX_PREEMPT_H
5 * include/linux/preempt.h - macros for accessing and manipulating
6 * preempt_count (used for kernel preemption, interrupt count, etc.)
9 #include <linux/thread_info.h>
10 #include <linux/linkage.h>
11 #include <linux/list.h>
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
);
17 # define add_preempt_count(val) do { preempt_count() += (val); } while (0)
18 # define sub_preempt_count(val) do { preempt_count() -= (val); } while (0)
21 #define inc_preempt_count() add_preempt_count(1)
22 #define dec_preempt_count() sub_preempt_count(1)
24 #define preempt_count() (current_thread_info()->preempt_count)
28 asmlinkage
void preempt_schedule(void);
30 #define preempt_check_resched() \
32 if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
36 #else /* !CONFIG_PREEMPT */
38 #define preempt_check_resched() do { } while (0)
40 #endif /* CONFIG_PREEMPT */
43 #ifdef CONFIG_PREEMPT_COUNT
45 #define preempt_disable() \
47 inc_preempt_count(); \
51 #define sched_preempt_enable_no_resched() \
54 dec_preempt_count(); \
57 #define preempt_enable_no_resched() sched_preempt_enable_no_resched()
59 #define preempt_enable() \
61 preempt_enable_no_resched(); \
63 preempt_check_resched(); \
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)
74 #define preempt_disable_notrace() \
76 inc_preempt_count_notrace(); \
80 #define preempt_enable_no_resched_notrace() \
83 dec_preempt_count_notrace(); \
86 /* preempt_check_resched is OK to trace */
87 #define preempt_enable_notrace() \
89 preempt_enable_no_resched_notrace(); \
91 preempt_check_resched(); \
94 #else /* !CONFIG_PREEMPT_COUNT */
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
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()
107 #define preempt_disable_notrace() barrier()
108 #define preempt_enable_no_resched_notrace() barrier()
109 #define preempt_enable_notrace() barrier()
111 #endif /* CONFIG_PREEMPT_COUNT */
113 #ifdef CONFIG_PREEMPT_NOTIFIERS
115 struct preempt_notifier
;
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
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.
132 void (*sched_in
)(struct preempt_notifier
*notifier
, int cpu
);
133 void (*sched_out
)(struct preempt_notifier
*notifier
,
134 struct task_struct
*next
);
138 * preempt_notifier - key for installing preemption notifiers
139 * @link: internal use
140 * @ops: defines the notifier functions to be called
142 * Usually used in conjunction with container_of().
144 struct preempt_notifier
{
145 struct hlist_node link
;
146 struct preempt_ops
*ops
;
149 void preempt_notifier_register(struct preempt_notifier
*notifier
);
150 void preempt_notifier_unregister(struct preempt_notifier
*notifier
);
152 static inline void preempt_notifier_init(struct preempt_notifier
*notifier
,
153 struct preempt_ops
*ops
)
155 INIT_HLIST_NODE(¬ifier
->link
);
161 #endif /* __LINUX_PREEMPT_H */
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