summaryrefslogtreecommitdiffstats
path: root/include/asm-generic/preempt.h
blob: c3046c9200630b15f9ced04213c8415258dd1c81 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_PREEMPT_H
#define __ASM_PREEMPT_H

#include <linux/thread_info.h>

#define PREEMPT_ENABLED	(0)

static __always_inline int preempt_count(void)
{
	return READ_ONCE(current_thread_info()->preempt_count);
}

static __always_inline volatile int *preempt_count_ptr(void)
{
	return &current_thread_info()->preempt_count;
}

static __always_inline void preempt_count_set(int pc)
{
	*preempt_count_ptr() = pc;
}

/*
 * must be macros to avoid header recursion hell
 */
#define init_task_preempt_count(p) do { \
	task_thread_info(p)->preempt_count = FORK_PREEMPT_COUNT; \
} while (0)

#define init_idle_preempt_count(p, cpu) do { \
	task_thread_info(p)->preempt_count = PREEMPT_ENABLED; \
} while (0)

static __always_inline void set_preempt_need_resched(void)
{
}

static __always_inline void clear_preempt_need_resched(void)
{
}

static __always_inline bool test_preempt_need_resched(void)
{
	return false;
}

/*
 * The various preempt_count add/sub methods
 */

static __always_inline void __preempt_count_add(int val)
{
	*preempt_count_ptr() += val;
}

static __always_inline void __preempt_count_sub(int val)
{
	*preempt_count_ptr() -= val;
}

static __always_inline bool __preempt_count_dec_and_test(void)
{
	/*
	 * Because of load-store architectures cannot do per-cpu atomic
	 * operations; we cannot use PREEMPT_NEED_RESCHED because it might get
	 * lost.
	 */
	return !--*preempt_count_ptr() && tif_need_resched();
}

/*
 * Returns true when we need to resched and can (barring IRQ state).
 */
static __always_inline bool should_resched(int preempt_offset)
{
	return unlikely(preempt_count() == preempt_offset &&
			tif_need_resched());
}

#ifdef CONFIG_PREEMPT
extern asmlinkage void preempt_schedule(void);
#define __preempt_schedule() preempt_schedule()
extern asmlinkage void preempt_schedule_notrace(void);
#define __preempt_schedule_notrace() preempt_schedule_notrace()
#endif /* CONFIG_PREEMPT */

#endif /* __ASM_PREEMPT_H */