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
7 enum cpu_idle_type {
8 __CPU_NOT_IDLE = 0,
9 CPU_IDLE,
10 CPU_NEWLY_IDLE,
11 CPU_MAX_IDLE_TYPES
12 };
13
14 extern 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
__current_set_polling(void)24 static __always_inline void __current_set_polling(void)
25 {
26 arch_set_bit(TIF_POLLING_NRFLAG,
27 (unsigned long *)(¤t_thread_info()->flags));
28 }
29
__current_clr_polling(void)30 static __always_inline void __current_clr_polling(void)
31 {
32 arch_clear_bit(TIF_POLLING_NRFLAG,
33 (unsigned long *)(¤t_thread_info()->flags));
34 }
35
36 #else
37
__current_set_polling(void)38 static __always_inline void __current_set_polling(void)
39 {
40 set_bit(TIF_POLLING_NRFLAG,
41 (unsigned long *)(¤t_thread_info()->flags));
42 }
43
__current_clr_polling(void)44 static __always_inline void __current_clr_polling(void)
45 {
46 clear_bit(TIF_POLLING_NRFLAG,
47 (unsigned long *)(¤t_thread_info()->flags));
48 }
49
50 #endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_ATOMIC_H */
51
current_set_polling_and_test(void)52 static __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
current_clr_polling_and_test(void)65 static __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
current_clr_polling(void)78 static __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
__current_set_polling(void)94 static inline void __current_set_polling(void) { }
__current_clr_polling(void)95 static inline void __current_clr_polling(void) { }
96
current_set_polling_and_test(void)97 static inline bool __must_check current_set_polling_and_test(void)
98 {
99 return unlikely(tif_need_resched());
100 }
current_clr_polling_and_test(void)101 static inline bool __must_check current_clr_polling_and_test(void)
102 {
103 return unlikely(tif_need_resched());
104 }
105
current_clr_polling(void)106 static __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