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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - include/linux/preempt.h
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/linkage.h>
10 #include <linux/list.h>
13 * We put the hardirq and softirq counter into the preemption
14 * counter. The bitmask has the following meaning:
16 * - bits 0-7 are the preemption count (max preemption depth: 256)
17 * - bits 8-15 are the softirq count (max # of softirqs: 256)
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.
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
32 #define PREEMPT_BITS 8
33 #define SOFTIRQ_BITS 8
34 #define HARDIRQ_BITS 4
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)
42 #define __IRQ_MASK(x) ((1UL << (x))-1)
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)
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)
54 #define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET)
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)
60 /* We use the MSB mostly because its available */
61 #define PREEMPT_NEED_RESCHED 0x80000000
63 /* preempt_count() and related functions, depends on PREEMPT_NEED_RESCHED */
64 #include <asm/preempt.h>
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 \
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?
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)
83 * Are we in NMI context?
85 #define in_nmi() (preempt_count() & NMI_MASK)
88 * The preempt_count offset after preempt_disable();
90 #if defined(CONFIG_PREEMPT_COUNT)
91 # define PREEMPT_DISABLE_OFFSET PREEMPT_OFFSET
93 # define PREEMPT_DISABLE_OFFSET 0
97 * The preempt_count offset after spin_lock()
99 #define PREEMPT_LOCK_OFFSET PREEMPT_DISABLE_OFFSET
102 * The preempt_count offset needed for things like:
106 * Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and
107 * softirqs, such that unlock sequences of:
114 #define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_LOCK_OFFSET)
117 * Are we running in atomic context? WARNING: this macro cannot
118 * always detect atomic context; in particular, it cannot know about
119 * held spinlocks in non-preemptible kernels. Thus it should not be
120 * used in the general case to determine whether sleeping is possible.
121 * Do not use in_atomic() in driver code.
123 #define in_atomic() (preempt_count() != 0)
126 * Check whether we were atomic before we did preempt_disable():
127 * (used by the scheduler)
129 #define in_atomic_preempt_off() \
130 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_DISABLE_OFFSET)
132 #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
133 extern void preempt_count_add(int val
);
134 extern void preempt_count_sub(int val
);
135 #define preempt_count_dec_and_test() \
136 ({ preempt_count_sub(1); should_resched(0); })
138 #define preempt_count_add(val) __preempt_count_add(val)
139 #define preempt_count_sub(val) __preempt_count_sub(val)
140 #define preempt_count_dec_and_test() __preempt_count_dec_and_test()
143 #define __preempt_count_inc() __preempt_count_add(1)
144 #define __preempt_count_dec() __preempt_count_sub(1)
146 #define preempt_count_inc() preempt_count_add(1)
147 #define preempt_count_dec() preempt_count_sub(1)
149 #define preempt_active_enter() \
151 preempt_count_add(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
155 #define preempt_active_exit() \
158 preempt_count_sub(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
161 #ifdef CONFIG_PREEMPT_COUNT
163 #define preempt_disable() \
165 preempt_count_inc(); \
169 #define sched_preempt_enable_no_resched() \
172 preempt_count_dec(); \
175 #define preempt_enable_no_resched() sched_preempt_enable_no_resched()
177 #define preemptible() (preempt_count() == 0 && !irqs_disabled())
179 #ifdef CONFIG_PREEMPT
180 #define preempt_enable() \
183 if (unlikely(preempt_count_dec_and_test())) \
184 __preempt_schedule(); \
187 #define preempt_enable_notrace() \
190 if (unlikely(__preempt_count_dec_and_test())) \
191 __preempt_schedule_notrace(); \
194 #define preempt_check_resched() \
196 if (should_resched(0)) \
197 __preempt_schedule(); \
200 #else /* !CONFIG_PREEMPT */
201 #define preempt_enable() \
204 preempt_count_dec(); \
207 #define preempt_enable_notrace() \
210 __preempt_count_dec(); \
213 #define preempt_check_resched() do { } while (0)
214 #endif /* CONFIG_PREEMPT */
216 #define preempt_disable_notrace() \
218 __preempt_count_inc(); \
222 #define preempt_enable_no_resched_notrace() \
225 __preempt_count_dec(); \
228 #else /* !CONFIG_PREEMPT_COUNT */
231 * Even if we don't have any preemption, we need preempt disable/enable
232 * to be barriers, so that we don't have things like get_user/put_user
233 * that can cause faults and scheduling migrate into our preempt-protected
236 #define preempt_disable() barrier()
237 #define sched_preempt_enable_no_resched() barrier()
238 #define preempt_enable_no_resched() barrier()
239 #define preempt_enable() barrier()
240 #define preempt_check_resched() do { } while (0)
242 #define preempt_disable_notrace() barrier()
243 #define preempt_enable_no_resched_notrace() barrier()
244 #define preempt_enable_notrace() barrier()
245 #define preemptible() 0
247 #endif /* CONFIG_PREEMPT_COUNT */
251 * Modules have no business playing preemption tricks.
253 #undef sched_preempt_enable_no_resched
254 #undef preempt_enable_no_resched
255 #undef preempt_enable_no_resched_notrace
256 #undef preempt_check_resched
259 #define preempt_set_need_resched() \
261 set_preempt_need_resched(); \
263 #define preempt_fold_need_resched() \
265 if (tif_need_resched()) \
266 set_preempt_need_resched(); \
269 #ifdef CONFIG_PREEMPT_NOTIFIERS
271 struct preempt_notifier
;
274 * preempt_ops - notifiers called when a task is preempted and rescheduled
275 * @sched_in: we're about to be rescheduled:
276 * notifier: struct preempt_notifier for the task being scheduled
277 * cpu: cpu we're scheduled on
278 * @sched_out: we've just been preempted
279 * notifier: struct preempt_notifier for the task being preempted
280 * next: the task that's kicking us out
282 * Please note that sched_in and out are called under different
283 * contexts. sched_out is called with rq lock held and irq disabled
284 * while sched_in is called without rq lock and irq enabled. This
285 * difference is intentional and depended upon by its users.
288 void (*sched_in
)(struct preempt_notifier
*notifier
, int cpu
);
289 void (*sched_out
)(struct preempt_notifier
*notifier
,
290 struct task_struct
*next
);
294 * preempt_notifier - key for installing preemption notifiers
295 * @link: internal use
296 * @ops: defines the notifier functions to be called
298 * Usually used in conjunction with container_of().
300 struct preempt_notifier
{
301 struct hlist_node link
;
302 struct preempt_ops
*ops
;
305 void preempt_notifier_inc(void);
306 void preempt_notifier_dec(void);
307 void preempt_notifier_register(struct preempt_notifier
*notifier
);
308 void preempt_notifier_unregister(struct preempt_notifier
*notifier
);
310 static inline void preempt_notifier_init(struct preempt_notifier
*notifier
,
311 struct preempt_ops
*ops
)
313 INIT_HLIST_NODE(¬ifier
->link
);
319 #endif /* __LINUX_PREEMPT_H */