1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_SCHED_IDLE_H
3#define _LINUX_SCHED_IDLE_H
4
5#include <linux/sched.h>
6
7enum cpu_idle_type {
8 __CPU_NOT_IDLE = 0,
9 CPU_IDLE,
10 CPU_NEWLY_IDLE,
11 CPU_MAX_IDLE_TYPES
12};
13
14extern void wake_up_if_idle(int cpu);
15
16/*
17 * Idle thread specific functions to determine the need_resched
18 * polling state.
19 */
20#ifdef TIF_POLLING_NRFLAG
21
22#ifdef _ASM_GENERIC_BITOPS_INSTRUMENTED_ATOMIC_H
23
24static __always_inline void __current_set_polling(void)
25{
26 arch_set_bit(TIF_POLLING_NRFLAG,
27 addr: (unsigned long *)(&current_thread_info()->flags));
28}
29
30static __always_inline void __current_clr_polling(void)
31{
32 arch_clear_bit(TIF_POLLING_NRFLAG,
33 addr: (unsigned long *)(&current_thread_info()->flags));
34}
35
36#else
37
38static __always_inline void __current_set_polling(void)
39{
40 set_bit(TIF_POLLING_NRFLAG,
41 (unsigned long *)(&current_thread_info()->flags));
42}
43
44static __always_inline void __current_clr_polling(void)
45{
46 clear_bit(TIF_POLLING_NRFLAG,
47 (unsigned long *)(&current_thread_info()->flags));
48}
49
50#endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_ATOMIC_H */
51
52static __always_inline bool __must_check current_set_polling_and_test(void)
53{
54 __current_set_polling();
55
56 /*
57 * Polling state must be visible before we test NEED_RESCHED,
58 * paired by resched_curr()
59 */
60 smp_mb__after_atomic();
61
62 return unlikely(tif_need_resched());
63}
64
65static __always_inline bool __must_check current_clr_polling_and_test(void)
66{
67 __current_clr_polling();
68
69 /*
70 * Polling state must be visible before we test NEED_RESCHED,
71 * paired by resched_curr()
72 */
73 smp_mb__after_atomic();
74
75 return unlikely(tif_need_resched());
76}
77
78static __always_inline void current_clr_polling(void)
79{
80 __current_clr_polling();
81
82 /*
83 * Ensure we check TIF_NEED_RESCHED after we clear the polling bit.
84 * Once the bit is cleared, we'll get IPIs with every new
85 * TIF_NEED_RESCHED and the IPI handler, scheduler_ipi(), will also
86 * fold.
87 */
88 smp_mb__after_atomic(); /* paired with resched_curr() */
89
90 preempt_fold_need_resched();
91}
92
93#else
94static inline void __current_set_polling(void) { }
95static inline void __current_clr_polling(void) { }
96
97static inline bool __must_check current_set_polling_and_test(void)
98{
99 return unlikely(tif_need_resched());
100}
101static inline bool __must_check current_clr_polling_and_test(void)
102{
103 return unlikely(tif_need_resched());
104}
105
106static __always_inline void current_clr_polling(void)
107{
108 __current_clr_polling();
109
110 smp_mb(); /* paired with resched_curr() */
111
112 preempt_fold_need_resched();
113}
114#endif
115
116#endif /* _LINUX_SCHED_IDLE_H */
117

source code of linux/include/linux/sched/idle.h