include/linux/sched/idle.h

   1 #ifndef _LINUX_SCHED_IDLE_H
   2 #define _LINUX_SCHED_IDLE_H
   3
   4 #include <linux/sched.h>
   5
   6 enum cpu_idle_type {
   7         CPU_IDLE,
   8         CPU_NOT_IDLE,
   9         CPU_NEWLY_IDLE,
  10         CPU_MAX_IDLE_TYPES
  11 };
  12
  13 extern void wake_up_if_idle(int cpu);
  14
  15 /*
  16  * Idle thread specific functions to determine the need_resched
  17  * polling state.
  18  */
  19 #ifdef TIF_POLLING_NRFLAG
  20
  21 static inline void __current_set_polling(void)
  22 {
  23         set_thread_flag(TIF_POLLING_NRFLAG);
  24 }
  25
  26 static inline bool __must_check current_set_polling_and_test(void)
  27 {
  28         __current_set_polling();
  29
  30         /*
  31          * Polling state must be visible before we test NEED_RESCHED,
  32          * paired by resched_curr()
  33          */
  34         smp_mb__after_atomic();
  35
  36         return unlikely(tif_need_resched());
  37 }
  38
  39 static inline void __current_clr_polling(void)
  40 {
  41         clear_thread_flag(TIF_POLLING_NRFLAG);
  42 }
  43
  44 static inline bool __must_check current_clr_polling_and_test(void)
  45 {
  46         __current_clr_polling();
  47
  48         /*
  49          * Polling state must be visible before we test NEED_RESCHED,
  50          * paired by resched_curr()
  51          */
  52         smp_mb__after_atomic();
  53
  54         return unlikely(tif_need_resched());
  55 }
  56
  57 #else
  58 static inline void __current_set_polling(void) { }
  59 static inline void __current_clr_polling(void) { }
  60
  61 static inline bool __must_check current_set_polling_and_test(void)
  62 {
  63         return unlikely(tif_need_resched());
  64 }
  65 static inline bool __must_check current_clr_polling_and_test(void)
  66 {
  67         return unlikely(tif_need_resched());
  68 }
  69 #endif
  70
  71 static inline void current_clr_polling(void)
  72 {
  73         __current_clr_polling();
  74
  75         /*
  76          * Ensure we check TIF_NEED_RESCHED after we clear the polling bit.
  77          * Once the bit is cleared, we'll get IPIs with every new
  78          * TIF_NEED_RESCHED and the IPI handler, scheduler_ipi(), will also
  79          * fold.
  80          */
  81         smp_mb(); /* paired with resched_curr() */
  82
  83         preempt_fold_need_resched();
  84 }
  85
  86 #endif /* _LINUX_SCHED_IDLE_H */