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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 | ||
1da177e4 | 9 | #include <linux/linkage.h> |
e107be36 | 10 | #include <linux/list.h> |
1da177e4 | 11 | |
f27dde8d PZ |
12 | /* |
13 | * We use the MSB mostly because its available; see <linux/preempt_mask.h> for | |
14 | * the other bits -- can't include that header due to inclusion hell. | |
15 | */ | |
16 | #define PREEMPT_NEED_RESCHED 0x80000000 | |
17 | ||
a7878709 | 18 | #include <asm/preempt.h> |
f27dde8d | 19 | |
6cd8a4bb | 20 | #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) |
bdb43806 PZ |
21 | extern void preempt_count_add(int val); |
22 | extern void preempt_count_sub(int val); | |
23 | #define preempt_count_dec_and_test() ({ preempt_count_sub(1); should_resched(); }) | |
1da177e4 | 24 | #else |
bdb43806 PZ |
25 | #define preempt_count_add(val) __preempt_count_add(val) |
26 | #define preempt_count_sub(val) __preempt_count_sub(val) | |
27 | #define preempt_count_dec_and_test() __preempt_count_dec_and_test() | |
1da177e4 LT |
28 | #endif |
29 | ||
bdb43806 PZ |
30 | #define __preempt_count_inc() __preempt_count_add(1) |
31 | #define __preempt_count_dec() __preempt_count_sub(1) | |
bdd4e85d | 32 | |
bdb43806 PZ |
33 | #define preempt_count_inc() preempt_count_add(1) |
34 | #define preempt_count_dec() preempt_count_sub(1) | |
bdd4e85d FW |
35 | |
36 | #ifdef CONFIG_PREEMPT_COUNT | |
37 | ||
1da177e4 LT |
38 | #define preempt_disable() \ |
39 | do { \ | |
bdb43806 | 40 | preempt_count_inc(); \ |
1da177e4 LT |
41 | barrier(); \ |
42 | } while (0) | |
43 | ||
ba74c144 | 44 | #define sched_preempt_enable_no_resched() \ |
1da177e4 LT |
45 | do { \ |
46 | barrier(); \ | |
bdb43806 | 47 | preempt_count_dec(); \ |
1da177e4 LT |
48 | } while (0) |
49 | ||
bdb43806 | 50 | #define preempt_enable_no_resched() sched_preempt_enable_no_resched() |
ba74c144 | 51 | |
bdb43806 | 52 | #ifdef CONFIG_PREEMPT |
1da177e4 LT |
53 | #define preempt_enable() \ |
54 | do { \ | |
bdb43806 PZ |
55 | barrier(); \ |
56 | if (unlikely(preempt_count_dec_and_test())) \ | |
1a338ac3 | 57 | __preempt_schedule(); \ |
1da177e4 LT |
58 | } while (0) |
59 | ||
bdb43806 PZ |
60 | #define preempt_check_resched() \ |
61 | do { \ | |
62 | if (should_resched()) \ | |
1a338ac3 | 63 | __preempt_schedule(); \ |
bdb43806 PZ |
64 | } while (0) |
65 | ||
66 | #else | |
67 | #define preempt_enable() preempt_enable_no_resched() | |
68 | #define preempt_check_resched() do { } while (0) | |
69 | #endif | |
50282528 SR |
70 | |
71 | #define preempt_disable_notrace() \ | |
72 | do { \ | |
bdb43806 | 73 | __preempt_count_inc(); \ |
50282528 SR |
74 | barrier(); \ |
75 | } while (0) | |
76 | ||
77 | #define preempt_enable_no_resched_notrace() \ | |
78 | do { \ | |
79 | barrier(); \ | |
bdb43806 | 80 | __preempt_count_dec(); \ |
50282528 SR |
81 | } while (0) |
82 | ||
bdb43806 PZ |
83 | #ifdef CONFIG_PREEMPT |
84 | ||
1a338ac3 PZ |
85 | #ifndef CONFIG_CONTEXT_TRACKING |
86 | #define __preempt_schedule_context() __preempt_schedule() | |
bdb43806 PZ |
87 | #endif |
88 | ||
50282528 SR |
89 | #define preempt_enable_notrace() \ |
90 | do { \ | |
bdb43806 PZ |
91 | barrier(); \ |
92 | if (unlikely(__preempt_count_dec_and_test())) \ | |
1a338ac3 | 93 | __preempt_schedule_context(); \ |
50282528 | 94 | } while (0) |
bdb43806 PZ |
95 | #else |
96 | #define preempt_enable_notrace() preempt_enable_no_resched_notrace() | |
97 | #endif | |
50282528 | 98 | |
bdd4e85d | 99 | #else /* !CONFIG_PREEMPT_COUNT */ |
1da177e4 | 100 | |
386afc91 LT |
101 | /* |
102 | * Even if we don't have any preemption, we need preempt disable/enable | |
103 | * to be barriers, so that we don't have things like get_user/put_user | |
104 | * that can cause faults and scheduling migrate into our preempt-protected | |
105 | * region. | |
106 | */ | |
bdb43806 | 107 | #define preempt_disable() barrier() |
386afc91 | 108 | #define sched_preempt_enable_no_resched() barrier() |
bdb43806 PZ |
109 | #define preempt_enable_no_resched() barrier() |
110 | #define preempt_enable() barrier() | |
111 | #define preempt_check_resched() do { } while (0) | |
386afc91 LT |
112 | |
113 | #define preempt_disable_notrace() barrier() | |
114 | #define preempt_enable_no_resched_notrace() barrier() | |
115 | #define preempt_enable_notrace() barrier() | |
50282528 | 116 | |
bdd4e85d | 117 | #endif /* CONFIG_PREEMPT_COUNT */ |
1da177e4 | 118 | |
e107be36 AK |
119 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
120 | ||
121 | struct preempt_notifier; | |
122 | ||
123 | /** | |
124 | * preempt_ops - notifiers called when a task is preempted and rescheduled | |
125 | * @sched_in: we're about to be rescheduled: | |
126 | * notifier: struct preempt_notifier for the task being scheduled | |
127 | * cpu: cpu we're scheduled on | |
128 | * @sched_out: we've just been preempted | |
129 | * notifier: struct preempt_notifier for the task being preempted | |
130 | * next: the task that's kicking us out | |
8592e648 TH |
131 | * |
132 | * Please note that sched_in and out are called under different | |
133 | * contexts. sched_out is called with rq lock held and irq disabled | |
134 | * while sched_in is called without rq lock and irq enabled. This | |
135 | * difference is intentional and depended upon by its users. | |
e107be36 AK |
136 | */ |
137 | struct preempt_ops { | |
138 | void (*sched_in)(struct preempt_notifier *notifier, int cpu); | |
139 | void (*sched_out)(struct preempt_notifier *notifier, | |
140 | struct task_struct *next); | |
141 | }; | |
142 | ||
143 | /** | |
144 | * preempt_notifier - key for installing preemption notifiers | |
145 | * @link: internal use | |
146 | * @ops: defines the notifier functions to be called | |
147 | * | |
148 | * Usually used in conjunction with container_of(). | |
149 | */ | |
150 | struct preempt_notifier { | |
151 | struct hlist_node link; | |
152 | struct preempt_ops *ops; | |
153 | }; | |
154 | ||
155 | void preempt_notifier_register(struct preempt_notifier *notifier); | |
156 | void preempt_notifier_unregister(struct preempt_notifier *notifier); | |
157 | ||
158 | static inline void preempt_notifier_init(struct preempt_notifier *notifier, | |
159 | struct preempt_ops *ops) | |
160 | { | |
161 | INIT_HLIST_NODE(¬ifier->link); | |
162 | notifier->ops = ops; | |
163 | } | |
164 | ||
165 | #endif | |
166 | ||
1da177e4 | 167 | #endif /* __LINUX_PREEMPT_H */ |