LXR linux/include/linux/sched/idle.h

   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