Line data    Source code

       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_IDLE,
       9             :         CPU_NOT_IDLE,
      10             :         CPU_NEWLY_IDLE,
      11             :         CPU_MAX_IDLE_TYPES
      12             : };
      13             : 
      14             : #ifdef CONFIG_SMP
      15             : extern void wake_up_if_idle(int cpu);
      16             : #else
      17             : static 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             : 
      26             : static inline void __current_set_polling(void)
      27             : {
      28             :         set_thread_flag(TIF_POLLING_NRFLAG);
      29             : }
      30             : 
      31             : static 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             : 
      44             : static inline void __current_clr_polling(void)
      45             : {
      46             :         clear_thread_flag(TIF_POLLING_NRFLAG);
      47             : }
      48             : 
      49             : static 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
      63             : static inline void __current_set_polling(void) { }
      64             : static inline void __current_clr_polling(void) { }
      65             : 
      66             : static inline bool __must_check current_set_polling_and_test(void)
      67             : {
      68             :         return unlikely(tif_need_resched());
      69             : }
      70             : static inline bool __must_check current_clr_polling_and_test(void)
      71             : {
      72           0 :         return unlikely(tif_need_resched());
      73             : }
      74             : #endif
      75             : 
      76             : static 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 */