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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 | |
92cf2118 FW |
12 | /* |
13 | * We put the hardirq and softirq counter into the preemption | |
14 | * counter. The bitmask has the following meaning: | |
15 | * | |
16 | * - bits 0-7 are the preemption count (max preemption depth: 256) | |
17 | * - bits 8-15 are the softirq count (max # of softirqs: 256) | |
18 | * | |
19 | * The hardirq count could in theory be the same as the number of | |
20 | * interrupts in the system, but we run all interrupt handlers with | |
21 | * interrupts disabled, so we cannot have nesting interrupts. Though | |
22 | * there are a few palaeontologic drivers which reenable interrupts in | |
23 | * the handler, so we need more than one bit here. | |
24 | * | |
2e10e71c FW |
25 | * PREEMPT_MASK: 0x000000ff |
26 | * SOFTIRQ_MASK: 0x0000ff00 | |
27 | * HARDIRQ_MASK: 0x000f0000 | |
28 | * NMI_MASK: 0x00100000 | |
29 | * PREEMPT_ACTIVE: 0x00200000 | |
30 | * PREEMPT_NEED_RESCHED: 0x80000000 | |
92cf2118 FW |
31 | */ |
32 | #define PREEMPT_BITS 8 | |
33 | #define SOFTIRQ_BITS 8 | |
34 | #define HARDIRQ_BITS 4 | |
35 | #define NMI_BITS 1 | |
36 | ||
37 | #define PREEMPT_SHIFT 0 | |
38 | #define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS) | |
39 | #define HARDIRQ_SHIFT (SOFTIRQ_SHIFT + SOFTIRQ_BITS) | |
40 | #define NMI_SHIFT (HARDIRQ_SHIFT + HARDIRQ_BITS) | |
41 | ||
42 | #define __IRQ_MASK(x) ((1UL << (x))-1) | |
43 | ||
44 | #define PREEMPT_MASK (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT) | |
45 | #define SOFTIRQ_MASK (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT) | |
46 | #define HARDIRQ_MASK (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT) | |
47 | #define NMI_MASK (__IRQ_MASK(NMI_BITS) << NMI_SHIFT) | |
48 | ||
49 | #define PREEMPT_OFFSET (1UL << PREEMPT_SHIFT) | |
50 | #define SOFTIRQ_OFFSET (1UL << SOFTIRQ_SHIFT) | |
51 | #define HARDIRQ_OFFSET (1UL << HARDIRQ_SHIFT) | |
52 | #define NMI_OFFSET (1UL << NMI_SHIFT) | |
53 | ||
54 | #define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET) | |
55 | ||
56 | #define PREEMPT_ACTIVE_BITS 1 | |
57 | #define PREEMPT_ACTIVE_SHIFT (NMI_SHIFT + NMI_BITS) | |
58 | #define PREEMPT_ACTIVE (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT) | |
59 | ||
2e10e71c FW |
60 | /* We use the MSB mostly because its available */ |
61 | #define PREEMPT_NEED_RESCHED 0x80000000 | |
62 | ||
63 | /* preempt_count() and related functions, depends on PREEMPT_NEED_RESCHED */ | |
64 | #include <asm/preempt.h> | |
65 | ||
92cf2118 FW |
66 | #define hardirq_count() (preempt_count() & HARDIRQ_MASK) |
67 | #define softirq_count() (preempt_count() & SOFTIRQ_MASK) | |
68 | #define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \ | |
69 | | NMI_MASK)) | |
70 | ||
71 | /* | |
72 | * Are we doing bottom half or hardware interrupt processing? | |
73 | * Are we in a softirq context? Interrupt context? | |
74 | * in_softirq - Are we currently processing softirq or have bh disabled? | |
75 | * in_serving_softirq - Are we currently processing softirq? | |
76 | */ | |
77 | #define in_irq() (hardirq_count()) | |
78 | #define in_softirq() (softirq_count()) | |
79 | #define in_interrupt() (irq_count()) | |
80 | #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) | |
81 | ||
82 | /* | |
83 | * Are we in NMI context? | |
84 | */ | |
85 | #define in_nmi() (preempt_count() & NMI_MASK) | |
86 | ||
87 | #if defined(CONFIG_PREEMPT_COUNT) | |
90b62b51 | 88 | # define PREEMPT_DISABLE_OFFSET 1 |
92cf2118 | 89 | #else |
90b62b51 | 90 | # define PREEMPT_DISABLE_OFFSET 0 |
92cf2118 FW |
91 | #endif |
92 | ||
93 | /* | |
94 | * The preempt_count offset needed for things like: | |
95 | * | |
96 | * spin_lock_bh() | |
97 | * | |
98 | * Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and | |
99 | * softirqs, such that unlock sequences of: | |
100 | * | |
101 | * spin_unlock(); | |
102 | * local_bh_enable(); | |
103 | * | |
104 | * Work as expected. | |
105 | */ | |
90b62b51 | 106 | #define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_DISABLE_OFFSET) |
92cf2118 FW |
107 | |
108 | /* | |
109 | * Are we running in atomic context? WARNING: this macro cannot | |
110 | * always detect atomic context; in particular, it cannot know about | |
111 | * held spinlocks in non-preemptible kernels. Thus it should not be | |
112 | * used in the general case to determine whether sleeping is possible. | |
113 | * Do not use in_atomic() in driver code. | |
114 | */ | |
115 | #define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != 0) | |
116 | ||
117 | /* | |
118 | * Check whether we were atomic before we did preempt_disable(): | |
119 | * (used by the scheduler, *after* releasing the kernel lock) | |
120 | */ | |
121 | #define in_atomic_preempt_off() \ | |
90b62b51 | 122 | ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_DISABLE_OFFSET) |
92cf2118 | 123 | |
6cd8a4bb | 124 | #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) |
bdb43806 PZ |
125 | extern void preempt_count_add(int val); |
126 | extern void preempt_count_sub(int val); | |
127 | #define preempt_count_dec_and_test() ({ preempt_count_sub(1); should_resched(); }) | |
1da177e4 | 128 | #else |
bdb43806 PZ |
129 | #define preempt_count_add(val) __preempt_count_add(val) |
130 | #define preempt_count_sub(val) __preempt_count_sub(val) | |
131 | #define preempt_count_dec_and_test() __preempt_count_dec_and_test() | |
1da177e4 LT |
132 | #endif |
133 | ||
bdb43806 PZ |
134 | #define __preempt_count_inc() __preempt_count_add(1) |
135 | #define __preempt_count_dec() __preempt_count_sub(1) | |
bdd4e85d | 136 | |
bdb43806 PZ |
137 | #define preempt_count_inc() preempt_count_add(1) |
138 | #define preempt_count_dec() preempt_count_sub(1) | |
bdd4e85d FW |
139 | |
140 | #ifdef CONFIG_PREEMPT_COUNT | |
141 | ||
1da177e4 LT |
142 | #define preempt_disable() \ |
143 | do { \ | |
bdb43806 | 144 | preempt_count_inc(); \ |
1da177e4 LT |
145 | barrier(); \ |
146 | } while (0) | |
147 | ||
ba74c144 | 148 | #define sched_preempt_enable_no_resched() \ |
1da177e4 LT |
149 | do { \ |
150 | barrier(); \ | |
bdb43806 | 151 | preempt_count_dec(); \ |
1da177e4 LT |
152 | } while (0) |
153 | ||
bdb43806 | 154 | #define preempt_enable_no_resched() sched_preempt_enable_no_resched() |
ba74c144 | 155 | |
2e10e71c FW |
156 | #define preemptible() (preempt_count() == 0 && !irqs_disabled()) |
157 | ||
bdb43806 | 158 | #ifdef CONFIG_PREEMPT |
1da177e4 LT |
159 | #define preempt_enable() \ |
160 | do { \ | |
bdb43806 PZ |
161 | barrier(); \ |
162 | if (unlikely(preempt_count_dec_and_test())) \ | |
1a338ac3 | 163 | __preempt_schedule(); \ |
1da177e4 LT |
164 | } while (0) |
165 | ||
bdb43806 PZ |
166 | #define preempt_check_resched() \ |
167 | do { \ | |
168 | if (should_resched()) \ | |
1a338ac3 | 169 | __preempt_schedule(); \ |
bdb43806 PZ |
170 | } while (0) |
171 | ||
172 | #else | |
62b94a08 PZ |
173 | #define preempt_enable() \ |
174 | do { \ | |
175 | barrier(); \ | |
176 | preempt_count_dec(); \ | |
177 | } while (0) | |
bdb43806 PZ |
178 | #define preempt_check_resched() do { } while (0) |
179 | #endif | |
50282528 SR |
180 | |
181 | #define preempt_disable_notrace() \ | |
182 | do { \ | |
bdb43806 | 183 | __preempt_count_inc(); \ |
50282528 SR |
184 | barrier(); \ |
185 | } while (0) | |
186 | ||
187 | #define preempt_enable_no_resched_notrace() \ | |
188 | do { \ | |
189 | barrier(); \ | |
bdb43806 | 190 | __preempt_count_dec(); \ |
50282528 SR |
191 | } while (0) |
192 | ||
bdb43806 PZ |
193 | #ifdef CONFIG_PREEMPT |
194 | ||
1a338ac3 PZ |
195 | #ifndef CONFIG_CONTEXT_TRACKING |
196 | #define __preempt_schedule_context() __preempt_schedule() | |
bdb43806 PZ |
197 | #endif |
198 | ||
50282528 SR |
199 | #define preempt_enable_notrace() \ |
200 | do { \ | |
bdb43806 PZ |
201 | barrier(); \ |
202 | if (unlikely(__preempt_count_dec_and_test())) \ | |
1a338ac3 | 203 | __preempt_schedule_context(); \ |
50282528 | 204 | } while (0) |
bdb43806 | 205 | #else |
62b94a08 PZ |
206 | #define preempt_enable_notrace() \ |
207 | do { \ | |
208 | barrier(); \ | |
209 | __preempt_count_dec(); \ | |
210 | } while (0) | |
bdb43806 | 211 | #endif |
50282528 | 212 | |
bdd4e85d | 213 | #else /* !CONFIG_PREEMPT_COUNT */ |
1da177e4 | 214 | |
386afc91 LT |
215 | /* |
216 | * Even if we don't have any preemption, we need preempt disable/enable | |
217 | * to be barriers, so that we don't have things like get_user/put_user | |
218 | * that can cause faults and scheduling migrate into our preempt-protected | |
219 | * region. | |
220 | */ | |
bdb43806 | 221 | #define preempt_disable() barrier() |
386afc91 | 222 | #define sched_preempt_enable_no_resched() barrier() |
bdb43806 PZ |
223 | #define preempt_enable_no_resched() barrier() |
224 | #define preempt_enable() barrier() | |
225 | #define preempt_check_resched() do { } while (0) | |
386afc91 LT |
226 | |
227 | #define preempt_disable_notrace() barrier() | |
228 | #define preempt_enable_no_resched_notrace() barrier() | |
229 | #define preempt_enable_notrace() barrier() | |
2e10e71c | 230 | #define preemptible() 0 |
50282528 | 231 | |
bdd4e85d | 232 | #endif /* CONFIG_PREEMPT_COUNT */ |
1da177e4 | 233 | |
62b94a08 PZ |
234 | #ifdef MODULE |
235 | /* | |
236 | * Modules have no business playing preemption tricks. | |
237 | */ | |
238 | #undef sched_preempt_enable_no_resched | |
239 | #undef preempt_enable_no_resched | |
240 | #undef preempt_enable_no_resched_notrace | |
241 | #undef preempt_check_resched | |
242 | #endif | |
243 | ||
8cb75e0c PZ |
244 | #define preempt_set_need_resched() \ |
245 | do { \ | |
246 | set_preempt_need_resched(); \ | |
247 | } while (0) | |
248 | #define preempt_fold_need_resched() \ | |
249 | do { \ | |
250 | if (tif_need_resched()) \ | |
251 | set_preempt_need_resched(); \ | |
252 | } while (0) | |
8cb75e0c | 253 | |
e107be36 AK |
254 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
255 | ||
256 | struct preempt_notifier; | |
257 | ||
258 | /** | |
259 | * preempt_ops - notifiers called when a task is preempted and rescheduled | |
260 | * @sched_in: we're about to be rescheduled: | |
261 | * notifier: struct preempt_notifier for the task being scheduled | |
262 | * cpu: cpu we're scheduled on | |
263 | * @sched_out: we've just been preempted | |
264 | * notifier: struct preempt_notifier for the task being preempted | |
265 | * next: the task that's kicking us out | |
8592e648 TH |
266 | * |
267 | * Please note that sched_in and out are called under different | |
268 | * contexts. sched_out is called with rq lock held and irq disabled | |
269 | * while sched_in is called without rq lock and irq enabled. This | |
270 | * difference is intentional and depended upon by its users. | |
e107be36 AK |
271 | */ |
272 | struct preempt_ops { | |
273 | void (*sched_in)(struct preempt_notifier *notifier, int cpu); | |
274 | void (*sched_out)(struct preempt_notifier *notifier, | |
275 | struct task_struct *next); | |
276 | }; | |
277 | ||
278 | /** | |
279 | * preempt_notifier - key for installing preemption notifiers | |
280 | * @link: internal use | |
281 | * @ops: defines the notifier functions to be called | |
282 | * | |
283 | * Usually used in conjunction with container_of(). | |
284 | */ | |
285 | struct preempt_notifier { | |
286 | struct hlist_node link; | |
287 | struct preempt_ops *ops; | |
288 | }; | |
289 | ||
290 | void preempt_notifier_register(struct preempt_notifier *notifier); | |
291 | void preempt_notifier_unregister(struct preempt_notifier *notifier); | |
292 | ||
293 | static inline void preempt_notifier_init(struct preempt_notifier *notifier, | |
294 | struct preempt_ops *ops) | |
295 | { | |
296 | INIT_HLIST_NODE(¬ifier->link); | |
297 | notifier->ops = ops; | |
298 | } | |
299 | ||
300 | #endif | |
301 | ||
1da177e4 | 302 | #endif /* __LINUX_PREEMPT_H */ |