Linux kernel mirror (for testing)
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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
14#ifdef CONFIG_SMP
15extern void wake_up_if_idle(int cpu);
16#else
17static inline void wake_up_if_idle(int cpu) { }
18#endif
19
20/*
21 * Idle thread specific functions to determine the need_resched
22 * polling state.
23 */
24#ifdef TIF_POLLING_NRFLAG
25
26static inline void __current_set_polling(void)
27{
28 set_thread_flag(TIF_POLLING_NRFLAG);
29}
30
31static inline bool __must_check current_set_polling_and_test(void)
32{
33 __current_set_polling();
34
35 /*
36 * Polling state must be visible before we test NEED_RESCHED,
37 * paired by resched_curr()
38 */
39 smp_mb__after_atomic();
40
41 return unlikely(tif_need_resched());
42}
43
44static inline void __current_clr_polling(void)
45{
46 clear_thread_flag(TIF_POLLING_NRFLAG);
47}
48
49static inline bool __must_check current_clr_polling_and_test(void)
50{
51 __current_clr_polling();
52
53 /*
54 * Polling state must be visible before we test NEED_RESCHED,
55 * paired by resched_curr()
56 */
57 smp_mb__after_atomic();
58
59 return unlikely(tif_need_resched());
60}
61
62#else
63static inline void __current_set_polling(void) { }
64static inline void __current_clr_polling(void) { }
65
66static inline bool __must_check current_set_polling_and_test(void)
67{
68 return unlikely(tif_need_resched());
69}
70static inline bool __must_check current_clr_polling_and_test(void)
71{
72 return unlikely(tif_need_resched());
73}
74#endif
75
76static inline void current_clr_polling(void)
77{
78 __current_clr_polling();
79
80 /*
81 * Ensure we check TIF_NEED_RESCHED after we clear the polling bit.
82 * Once the bit is cleared, we'll get IPIs with every new
83 * TIF_NEED_RESCHED and the IPI handler, scheduler_ipi(), will also
84 * fold.
85 */
86 smp_mb(); /* paired with resched_curr() */
87
88 preempt_fold_need_resched();
89}
90
91#endif /* _LINUX_SCHED_IDLE_H */