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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 | |
62b94a08 PZ |
67 | #define preempt_enable() \ |
68 | do { \ | |
69 | barrier(); \ | |
70 | preempt_count_dec(); \ | |
71 | } while (0) | |
bdb43806 PZ |
72 | #define preempt_check_resched() do { } while (0) |
73 | #endif | |
50282528 SR |
74 | |
75 | #define preempt_disable_notrace() \ | |
76 | do { \ | |
bdb43806 | 77 | __preempt_count_inc(); \ |
50282528 SR |
78 | barrier(); \ |
79 | } while (0) | |
80 | ||
81 | #define preempt_enable_no_resched_notrace() \ | |
82 | do { \ | |
83 | barrier(); \ | |
bdb43806 | 84 | __preempt_count_dec(); \ |
50282528 SR |
85 | } while (0) |
86 | ||
bdb43806 PZ |
87 | #ifdef CONFIG_PREEMPT |
88 | ||
1a338ac3 PZ |
89 | #ifndef CONFIG_CONTEXT_TRACKING |
90 | #define __preempt_schedule_context() __preempt_schedule() | |
bdb43806 PZ |
91 | #endif |
92 | ||
50282528 SR |
93 | #define preempt_enable_notrace() \ |
94 | do { \ | |
bdb43806 PZ |
95 | barrier(); \ |
96 | if (unlikely(__preempt_count_dec_and_test())) \ | |
1a338ac3 | 97 | __preempt_schedule_context(); \ |
50282528 | 98 | } while (0) |
bdb43806 | 99 | #else |
62b94a08 PZ |
100 | #define preempt_enable_notrace() \ |
101 | do { \ | |
102 | barrier(); \ | |
103 | __preempt_count_dec(); \ | |
104 | } while (0) | |
bdb43806 | 105 | #endif |
50282528 | 106 | |
bdd4e85d | 107 | #else /* !CONFIG_PREEMPT_COUNT */ |
1da177e4 | 108 | |
386afc91 LT |
109 | /* |
110 | * Even if we don't have any preemption, we need preempt disable/enable | |
111 | * to be barriers, so that we don't have things like get_user/put_user | |
112 | * that can cause faults and scheduling migrate into our preempt-protected | |
113 | * region. | |
114 | */ | |
bdb43806 | 115 | #define preempt_disable() barrier() |
386afc91 | 116 | #define sched_preempt_enable_no_resched() barrier() |
bdb43806 PZ |
117 | #define preempt_enable_no_resched() barrier() |
118 | #define preempt_enable() barrier() | |
119 | #define preempt_check_resched() do { } while (0) | |
386afc91 LT |
120 | |
121 | #define preempt_disable_notrace() barrier() | |
122 | #define preempt_enable_no_resched_notrace() barrier() | |
123 | #define preempt_enable_notrace() barrier() | |
50282528 | 124 | |
bdd4e85d | 125 | #endif /* CONFIG_PREEMPT_COUNT */ |
1da177e4 | 126 | |
62b94a08 PZ |
127 | #ifdef MODULE |
128 | /* | |
129 | * Modules have no business playing preemption tricks. | |
130 | */ | |
131 | #undef sched_preempt_enable_no_resched | |
132 | #undef preempt_enable_no_resched | |
133 | #undef preempt_enable_no_resched_notrace | |
134 | #undef preempt_check_resched | |
135 | #endif | |
136 | ||
8cb75e0c PZ |
137 | #define preempt_set_need_resched() \ |
138 | do { \ | |
139 | set_preempt_need_resched(); \ | |
140 | } while (0) | |
141 | #define preempt_fold_need_resched() \ | |
142 | do { \ | |
143 | if (tif_need_resched()) \ | |
144 | set_preempt_need_resched(); \ | |
145 | } while (0) | |
8cb75e0c | 146 | |
e107be36 AK |
147 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
148 | ||
149 | struct preempt_notifier; | |
150 | ||
151 | /** | |
152 | * preempt_ops - notifiers called when a task is preempted and rescheduled | |
153 | * @sched_in: we're about to be rescheduled: | |
154 | * notifier: struct preempt_notifier for the task being scheduled | |
155 | * cpu: cpu we're scheduled on | |
156 | * @sched_out: we've just been preempted | |
157 | * notifier: struct preempt_notifier for the task being preempted | |
158 | * next: the task that's kicking us out | |
8592e648 TH |
159 | * |
160 | * Please note that sched_in and out are called under different | |
161 | * contexts. sched_out is called with rq lock held and irq disabled | |
162 | * while sched_in is called without rq lock and irq enabled. This | |
163 | * difference is intentional and depended upon by its users. | |
e107be36 AK |
164 | */ |
165 | struct preempt_ops { | |
166 | void (*sched_in)(struct preempt_notifier *notifier, int cpu); | |
167 | void (*sched_out)(struct preempt_notifier *notifier, | |
168 | struct task_struct *next); | |
169 | }; | |
170 | ||
171 | /** | |
172 | * preempt_notifier - key for installing preemption notifiers | |
173 | * @link: internal use | |
174 | * @ops: defines the notifier functions to be called | |
175 | * | |
176 | * Usually used in conjunction with container_of(). | |
177 | */ | |
178 | struct preempt_notifier { | |
179 | struct hlist_node link; | |
180 | struct preempt_ops *ops; | |
181 | }; | |
182 | ||
183 | void preempt_notifier_register(struct preempt_notifier *notifier); | |
184 | void preempt_notifier_unregister(struct preempt_notifier *notifier); | |
185 | ||
186 | static inline void preempt_notifier_init(struct preempt_notifier *notifier, | |
187 | struct preempt_ops *ops) | |
188 | { | |
189 | INIT_HLIST_NODE(¬ifier->link); | |
190 | notifier->ops = ops; | |
191 | } | |
192 | ||
193 | #endif | |
194 | ||
1da177e4 | 195 | #endif /* __LINUX_PREEMPT_H */ |