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_IDLE,
9 CPU_NOT_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
22static inline void __current_set_polling(void)
23{
24 set_thread_flag(TIF_POLLING_NRFLAG);
25}
26
27static inline bool __must_check current_set_polling_and_test(void)
28{
29 __current_set_polling();
30
31 /*
32 * Polling state must be visible before we test NEED_RESCHED,
33 * paired by resched_curr()
34 */
35 smp_mb__after_atomic();
36
37 return unlikely(tif_need_resched());
38}
39
40static inline void __current_clr_polling(void)
41{
42 clear_thread_flag(TIF_POLLING_NRFLAG);
43}
44
45static inline bool __must_check current_clr_polling_and_test(void)
46{
47 __current_clr_polling();
48
49 /*
50 * Polling state must be visible before we test NEED_RESCHED,
51 * paired by resched_curr()
52 */
53 smp_mb__after_atomic();
54
55 return unlikely(tif_need_resched());
56}
57
58#else
59static inline void __current_set_polling(void) { }
60static inline void __current_clr_polling(void) { }
61
62static inline bool __must_check current_set_polling_and_test(void)
63{
64 return unlikely(tif_need_resched());
65}
66static inline bool __must_check current_clr_polling_and_test(void)
67{
68 return unlikely(tif_need_resched());
69}
70#endif
71
72static inline void current_clr_polling(void)
73{
74 __current_clr_polling();
75
76 /*
77 * Ensure we check TIF_NEED_RESCHED after we clear the polling bit.
78 * Once the bit is cleared, we'll get IPIs with every new
79 * TIF_NEED_RESCHED and the IPI handler, scheduler_ipi(), will also
80 * fold.
81 */
82 smp_mb(); /* paired with resched_curr() */
83
84 preempt_fold_need_resched();
85}
86
87#endif /* _LINUX_SCHED_IDLE_H */
88