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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | #ifndef __LINUX_PREEMPT_H |
3 | #define __LINUX_PREEMPT_H | |
4 | ||
5 | /* | |
6 | * include/linux/preempt.h - macros for accessing and manipulating | |
7 | * preempt_count (used for kernel preemption, interrupt count, etc.) | |
8 | */ | |
9 | ||
1da177e4 | 10 | #include <linux/linkage.h> |
e107be36 | 11 | #include <linux/list.h> |
1da177e4 | 12 | |
92cf2118 FW |
13 | /* |
14 | * We put the hardirq and softirq counter into the preemption | |
15 | * counter. The bitmask has the following meaning: | |
16 | * | |
17 | * - bits 0-7 are the preemption count (max preemption depth: 256) | |
18 | * - bits 8-15 are the softirq count (max # of softirqs: 256) | |
19 | * | |
20 | * The hardirq count could in theory be the same as the number of | |
21 | * interrupts in the system, but we run all interrupt handlers with | |
22 | * interrupts disabled, so we cannot have nesting interrupts. Though | |
23 | * there are a few palaeontologic drivers which reenable interrupts in | |
24 | * the handler, so we need more than one bit here. | |
25 | * | |
2e10e71c FW |
26 | * PREEMPT_MASK: 0x000000ff |
27 | * SOFTIRQ_MASK: 0x0000ff00 | |
28 | * HARDIRQ_MASK: 0x000f0000 | |
29 | * NMI_MASK: 0x00100000 | |
2e10e71c | 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 | ||
d04b0ad3 IM |
56 | #define PREEMPT_DISABLED (PREEMPT_DISABLE_OFFSET + PREEMPT_ENABLED) |
57 | ||
58 | /* | |
59 | * Disable preemption until the scheduler is running -- use an unconditional | |
60 | * value so that it also works on !PREEMPT_COUNT kernels. | |
61 | * | |
62 | * Reset by start_kernel()->sched_init()->init_idle()->init_idle_preempt_count(). | |
63 | */ | |
64 | #define INIT_PREEMPT_COUNT PREEMPT_OFFSET | |
65 | ||
66 | /* | |
67 | * Initial preempt_count value; reflects the preempt_count schedule invariant | |
68 | * which states that during context switches: | |
69 | * | |
70 | * preempt_count() == 2*PREEMPT_DISABLE_OFFSET | |
71 | * | |
72 | * Note: PREEMPT_DISABLE_OFFSET is 0 for !PREEMPT_COUNT kernels. | |
73 | * Note: See finish_task_switch(). | |
74 | */ | |
75 | #define FORK_PREEMPT_COUNT (2*PREEMPT_DISABLE_OFFSET + PREEMPT_ENABLED) | |
76 | ||
2e10e71c FW |
77 | /* preempt_count() and related functions, depends on PREEMPT_NEED_RESCHED */ |
78 | #include <asm/preempt.h> | |
79 | ||
92cf2118 FW |
80 | #define hardirq_count() (preempt_count() & HARDIRQ_MASK) |
81 | #define softirq_count() (preempt_count() & SOFTIRQ_MASK) | |
82 | #define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \ | |
83 | | NMI_MASK)) | |
84 | ||
85 | /* | |
86 | * Are we doing bottom half or hardware interrupt processing? | |
7c478895 PZ |
87 | * |
88 | * in_irq() - We're in (hard) IRQ context | |
89 | * in_softirq() - We have BH disabled, or are processing softirqs | |
90 | * in_interrupt() - We're in NMI,IRQ,SoftIRQ context or have BH disabled | |
91 | * in_serving_softirq() - We're in softirq context | |
92 | * in_nmi() - We're in NMI context | |
93 | * in_task() - We're in task context | |
94 | * | |
95 | * Note: due to the BH disabled confusion: in_softirq(),in_interrupt() really | |
96 | * should not be used in new code. | |
92cf2118 FW |
97 | */ |
98 | #define in_irq() (hardirq_count()) | |
99 | #define in_softirq() (softirq_count()) | |
100 | #define in_interrupt() (irq_count()) | |
101 | #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) | |
7c478895 PZ |
102 | #define in_nmi() (preempt_count() & NMI_MASK) |
103 | #define in_task() (!(preempt_count() & \ | |
104 | (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET))) | |
92cf2118 | 105 | |
fe32d3cd KK |
106 | /* |
107 | * The preempt_count offset after preempt_disable(); | |
108 | */ | |
92cf2118 | 109 | #if defined(CONFIG_PREEMPT_COUNT) |
fe32d3cd | 110 | # define PREEMPT_DISABLE_OFFSET PREEMPT_OFFSET |
92cf2118 | 111 | #else |
fe32d3cd | 112 | # define PREEMPT_DISABLE_OFFSET 0 |
92cf2118 FW |
113 | #endif |
114 | ||
fe32d3cd KK |
115 | /* |
116 | * The preempt_count offset after spin_lock() | |
117 | */ | |
118 | #define PREEMPT_LOCK_OFFSET PREEMPT_DISABLE_OFFSET | |
119 | ||
92cf2118 FW |
120 | /* |
121 | * The preempt_count offset needed for things like: | |
122 | * | |
123 | * spin_lock_bh() | |
124 | * | |
125 | * Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and | |
126 | * softirqs, such that unlock sequences of: | |
127 | * | |
128 | * spin_unlock(); | |
129 | * local_bh_enable(); | |
130 | * | |
131 | * Work as expected. | |
132 | */ | |
fe32d3cd | 133 | #define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_LOCK_OFFSET) |
92cf2118 FW |
134 | |
135 | /* | |
136 | * Are we running in atomic context? WARNING: this macro cannot | |
137 | * always detect atomic context; in particular, it cannot know about | |
138 | * held spinlocks in non-preemptible kernels. Thus it should not be | |
139 | * used in the general case to determine whether sleeping is possible. | |
140 | * Do not use in_atomic() in driver code. | |
141 | */ | |
3e51f3c4 | 142 | #define in_atomic() (preempt_count() != 0) |
92cf2118 FW |
143 | |
144 | /* | |
145 | * Check whether we were atomic before we did preempt_disable(): | |
e017cf21 | 146 | * (used by the scheduler) |
92cf2118 | 147 | */ |
da7142e2 | 148 | #define in_atomic_preempt_off() (preempt_count() != PREEMPT_DISABLE_OFFSET) |
92cf2118 | 149 | |
c3bc8fd6 | 150 | #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_TRACE_PREEMPT_TOGGLE) |
bdb43806 PZ |
151 | extern void preempt_count_add(int val); |
152 | extern void preempt_count_sub(int val); | |
fe32d3cd KK |
153 | #define preempt_count_dec_and_test() \ |
154 | ({ preempt_count_sub(1); should_resched(0); }) | |
1da177e4 | 155 | #else |
bdb43806 PZ |
156 | #define preempt_count_add(val) __preempt_count_add(val) |
157 | #define preempt_count_sub(val) __preempt_count_sub(val) | |
158 | #define preempt_count_dec_and_test() __preempt_count_dec_and_test() | |
1da177e4 LT |
159 | #endif |
160 | ||
bdb43806 PZ |
161 | #define __preempt_count_inc() __preempt_count_add(1) |
162 | #define __preempt_count_dec() __preempt_count_sub(1) | |
bdd4e85d | 163 | |
bdb43806 PZ |
164 | #define preempt_count_inc() preempt_count_add(1) |
165 | #define preempt_count_dec() preempt_count_sub(1) | |
bdd4e85d FW |
166 | |
167 | #ifdef CONFIG_PREEMPT_COUNT | |
168 | ||
1da177e4 LT |
169 | #define preempt_disable() \ |
170 | do { \ | |
bdb43806 | 171 | preempt_count_inc(); \ |
1da177e4 LT |
172 | barrier(); \ |
173 | } while (0) | |
174 | ||
ba74c144 | 175 | #define sched_preempt_enable_no_resched() \ |
1da177e4 LT |
176 | do { \ |
177 | barrier(); \ | |
bdb43806 | 178 | preempt_count_dec(); \ |
1da177e4 LT |
179 | } while (0) |
180 | ||
bdb43806 | 181 | #define preempt_enable_no_resched() sched_preempt_enable_no_resched() |
ba74c144 | 182 | |
2e10e71c FW |
183 | #define preemptible() (preempt_count() == 0 && !irqs_disabled()) |
184 | ||
bdb43806 | 185 | #ifdef CONFIG_PREEMPT |
1da177e4 LT |
186 | #define preempt_enable() \ |
187 | do { \ | |
bdb43806 PZ |
188 | barrier(); \ |
189 | if (unlikely(preempt_count_dec_and_test())) \ | |
1a338ac3 | 190 | __preempt_schedule(); \ |
1da177e4 LT |
191 | } while (0) |
192 | ||
9a92e3dc FW |
193 | #define preempt_enable_notrace() \ |
194 | do { \ | |
195 | barrier(); \ | |
196 | if (unlikely(__preempt_count_dec_and_test())) \ | |
197 | __preempt_schedule_notrace(); \ | |
198 | } while (0) | |
199 | ||
bdb43806 PZ |
200 | #define preempt_check_resched() \ |
201 | do { \ | |
fe32d3cd | 202 | if (should_resched(0)) \ |
1a338ac3 | 203 | __preempt_schedule(); \ |
bdb43806 PZ |
204 | } while (0) |
205 | ||
9a92e3dc | 206 | #else /* !CONFIG_PREEMPT */ |
62b94a08 PZ |
207 | #define preempt_enable() \ |
208 | do { \ | |
209 | barrier(); \ | |
210 | preempt_count_dec(); \ | |
211 | } while (0) | |
50282528 | 212 | |
9a92e3dc | 213 | #define preempt_enable_notrace() \ |
50282528 SR |
214 | do { \ |
215 | barrier(); \ | |
bdb43806 | 216 | __preempt_count_dec(); \ |
50282528 SR |
217 | } while (0) |
218 | ||
9a92e3dc FW |
219 | #define preempt_check_resched() do { } while (0) |
220 | #endif /* CONFIG_PREEMPT */ | |
bdb43806 | 221 | |
9a92e3dc | 222 | #define preempt_disable_notrace() \ |
50282528 | 223 | do { \ |
9a92e3dc | 224 | __preempt_count_inc(); \ |
bdb43806 | 225 | barrier(); \ |
50282528 | 226 | } while (0) |
9a92e3dc FW |
227 | |
228 | #define preempt_enable_no_resched_notrace() \ | |
62b94a08 PZ |
229 | do { \ |
230 | barrier(); \ | |
231 | __preempt_count_dec(); \ | |
232 | } while (0) | |
50282528 | 233 | |
bdd4e85d | 234 | #else /* !CONFIG_PREEMPT_COUNT */ |
1da177e4 | 235 | |
386afc91 LT |
236 | /* |
237 | * Even if we don't have any preemption, we need preempt disable/enable | |
238 | * to be barriers, so that we don't have things like get_user/put_user | |
239 | * that can cause faults and scheduling migrate into our preempt-protected | |
240 | * region. | |
241 | */ | |
bdb43806 | 242 | #define preempt_disable() barrier() |
386afc91 | 243 | #define sched_preempt_enable_no_resched() barrier() |
bdb43806 PZ |
244 | #define preempt_enable_no_resched() barrier() |
245 | #define preempt_enable() barrier() | |
246 | #define preempt_check_resched() do { } while (0) | |
386afc91 LT |
247 | |
248 | #define preempt_disable_notrace() barrier() | |
249 | #define preempt_enable_no_resched_notrace() barrier() | |
250 | #define preempt_enable_notrace() barrier() | |
2e10e71c | 251 | #define preemptible() 0 |
50282528 | 252 | |
bdd4e85d | 253 | #endif /* CONFIG_PREEMPT_COUNT */ |
1da177e4 | 254 | |
62b94a08 PZ |
255 | #ifdef MODULE |
256 | /* | |
257 | * Modules have no business playing preemption tricks. | |
258 | */ | |
259 | #undef sched_preempt_enable_no_resched | |
260 | #undef preempt_enable_no_resched | |
261 | #undef preempt_enable_no_resched_notrace | |
262 | #undef preempt_check_resched | |
263 | #endif | |
264 | ||
8cb75e0c PZ |
265 | #define preempt_set_need_resched() \ |
266 | do { \ | |
267 | set_preempt_need_resched(); \ | |
268 | } while (0) | |
269 | #define preempt_fold_need_resched() \ | |
270 | do { \ | |
271 | if (tif_need_resched()) \ | |
272 | set_preempt_need_resched(); \ | |
273 | } while (0) | |
8cb75e0c | 274 | |
e107be36 AK |
275 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
276 | ||
277 | struct preempt_notifier; | |
278 | ||
279 | /** | |
280 | * preempt_ops - notifiers called when a task is preempted and rescheduled | |
281 | * @sched_in: we're about to be rescheduled: | |
282 | * notifier: struct preempt_notifier for the task being scheduled | |
283 | * cpu: cpu we're scheduled on | |
284 | * @sched_out: we've just been preempted | |
285 | * notifier: struct preempt_notifier for the task being preempted | |
286 | * next: the task that's kicking us out | |
8592e648 TH |
287 | * |
288 | * Please note that sched_in and out are called under different | |
289 | * contexts. sched_out is called with rq lock held and irq disabled | |
290 | * while sched_in is called without rq lock and irq enabled. This | |
291 | * difference is intentional and depended upon by its users. | |
e107be36 AK |
292 | */ |
293 | struct preempt_ops { | |
294 | void (*sched_in)(struct preempt_notifier *notifier, int cpu); | |
295 | void (*sched_out)(struct preempt_notifier *notifier, | |
296 | struct task_struct *next); | |
297 | }; | |
298 | ||
299 | /** | |
300 | * preempt_notifier - key for installing preemption notifiers | |
301 | * @link: internal use | |
302 | * @ops: defines the notifier functions to be called | |
303 | * | |
304 | * Usually used in conjunction with container_of(). | |
305 | */ | |
306 | struct preempt_notifier { | |
307 | struct hlist_node link; | |
308 | struct preempt_ops *ops; | |
309 | }; | |
310 | ||
2ecd9d29 PZ |
311 | void preempt_notifier_inc(void); |
312 | void preempt_notifier_dec(void); | |
e107be36 AK |
313 | void preempt_notifier_register(struct preempt_notifier *notifier); |
314 | void preempt_notifier_unregister(struct preempt_notifier *notifier); | |
315 | ||
316 | static inline void preempt_notifier_init(struct preempt_notifier *notifier, | |
317 | struct preempt_ops *ops) | |
318 | { | |
319 | INIT_HLIST_NODE(¬ifier->link); | |
320 | notifier->ops = ops; | |
321 | } | |
322 | ||
323 | #endif | |
324 | ||
1da177e4 | 325 | #endif /* __LINUX_PREEMPT_H */ |