Re: [PATCH v2 3/6] sched: dynamic: Simplify preempt_schedule{,_notrace}()

[Jinjie Ruan]

在 2026/8/4 3:17, Mark Rutland 写道:
> PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
> In either model, both preempt_schedule() and preempt_schedule_notrace()
> are always called and never disabled.
> 
> Remove the unnecessary code for these when PREEMPT_DYNAMIC is selected.
> 
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> Reviewed-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
> Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: John Stultz <jstultz@xxxxxxxxxx>
> Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
> Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
> ---
>  arch/arm64/include/asm/preempt.h | 10 ------
>  arch/s390/include/asm/preempt.h  | 11 -------
>  arch/x86/include/asm/preempt.h   | 28 -----------------
>  include/asm-generic/preempt.h    | 10 ------
>  kernel/sched/core.c              | 52 --------------------------------
>  5 files changed, 111 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h
> index 932ea4b620428..506dab34dddb2 100644
> --- a/arch/arm64/include/asm/preempt.h
> +++ b/arch/arm64/include/asm/preempt.h
> @@ -84,19 +84,9 @@ static inline bool should_resched(int preempt_offset)
>  void preempt_schedule(void);
>  void preempt_schedule_notrace(void);
>  
> -#ifdef CONFIG_PREEMPT_DYNAMIC
> -
> -void dynamic_preempt_schedule(void);
> -#define __preempt_schedule()		dynamic_preempt_schedule()
> -void dynamic_preempt_schedule_notrace(void);
> -#define __preempt_schedule_notrace()	dynamic_preempt_schedule_notrace()
> -
> -#else /* CONFIG_PREEMPT_DYNAMIC */
> -
>  #define __preempt_schedule()		preempt_schedule()
>  #define __preempt_schedule_notrace()	preempt_schedule_notrace()

In both full and lazy modes for PREEMPT_DYNAMIC , "preempt_schedule" and
"preempt_schedule_notrace" are enabled. Therefore, dynamic switching is
not required. we can directly invoke preempt_schedule[_notrace]().

LGTM
Reviewed-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>

>  
> -#endif /* CONFIG_PREEMPT_DYNAMIC */
>  #endif /* CONFIG_PREEMPTION */
>  
>  #endif /* __ASM_PREEMPT_H */
> diff --git a/arch/s390/include/asm/preempt.h b/arch/s390/include/asm/preempt.h
> index 6e5821bb047e2..797efcbfe394a 100644
> --- a/arch/s390/include/asm/preempt.h
> +++ b/arch/s390/include/asm/preempt.h
> @@ -148,20 +148,9 @@ static __always_inline bool should_resched(int preempt_offset)
>  void preempt_schedule(void);
>  void preempt_schedule_notrace(void);
>  
> -#ifdef CONFIG_PREEMPT_DYNAMIC
> -
> -void dynamic_preempt_schedule(void);
> -void dynamic_preempt_schedule_notrace(void);
> -#define __preempt_schedule()		dynamic_preempt_schedule()
> -#define __preempt_schedule_notrace()	dynamic_preempt_schedule_notrace()
> -
> -#else /* CONFIG_PREEMPT_DYNAMIC */
> -
>  #define __preempt_schedule()		preempt_schedule()
>  #define __preempt_schedule_notrace()	preempt_schedule_notrace()
>  
> -#endif /* CONFIG_PREEMPT_DYNAMIC */
> -
>  #endif /* CONFIG_PREEMPTION */
>  
>  #endif /* __ASM_PREEMPT_H */
> diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
> index 578441db09f0b..14002c2abff44 100644
> --- a/arch/x86/include/asm/preempt.h
> +++ b/arch/x86/include/asm/preempt.h
> @@ -109,43 +109,15 @@ static __always_inline bool should_resched(int preempt_offset)
>  extern asmlinkage void preempt_schedule(void);
>  extern asmlinkage void preempt_schedule_thunk(void);
>  
> -#define preempt_schedule_dynamic_enabled	preempt_schedule_thunk
> -#define preempt_schedule_dynamic_disabled	NULL
> -
>  extern asmlinkage void preempt_schedule_notrace(void);
>  extern asmlinkage void preempt_schedule_notrace_thunk(void);
>  
> -#define preempt_schedule_notrace_dynamic_enabled	preempt_schedule_notrace_thunk
> -#define preempt_schedule_notrace_dynamic_disabled	NULL
> -
> -#ifdef CONFIG_PREEMPT_DYNAMIC
> -
> -DECLARE_STATIC_CALL(preempt_schedule, preempt_schedule_dynamic_enabled);
> -
> -#define __preempt_schedule() \
> -do { \
> -	__STATIC_CALL_MOD_ADDRESSABLE(preempt_schedule); \
> -	asm volatile ("call " STATIC_CALL_TRAMP_STR(preempt_schedule) : ASM_CALL_CONSTRAINT); \
> -} while (0)
> -
> -DECLARE_STATIC_CALL(preempt_schedule_notrace, preempt_schedule_notrace_dynamic_enabled);
> -
> -#define __preempt_schedule_notrace() \
> -do { \
> -	__STATIC_CALL_MOD_ADDRESSABLE(preempt_schedule_notrace); \
> -	asm volatile ("call " STATIC_CALL_TRAMP_STR(preempt_schedule_notrace) : ASM_CALL_CONSTRAINT); \
> -} while (0)
> -
> -#else /* PREEMPT_DYNAMIC */
> -
>  #define __preempt_schedule() \
>  	asm volatile ("call preempt_schedule_thunk" : ASM_CALL_CONSTRAINT);
>  
>  #define __preempt_schedule_notrace() \
>  	asm volatile ("call preempt_schedule_notrace_thunk" : ASM_CALL_CONSTRAINT);
>  
> -#endif /* PREEMPT_DYNAMIC */
> -
>  #endif /* PREEMPTION */
>  
>  #endif /* __ASM_PREEMPT_H */
> diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h
> index 51f8f3881523a..26309df2a42f3 100644
> --- a/include/asm-generic/preempt.h
> +++ b/include/asm-generic/preempt.h
> @@ -82,19 +82,9 @@ static __always_inline bool should_resched(int preempt_offset)
>  extern asmlinkage void preempt_schedule(void);
>  extern asmlinkage void preempt_schedule_notrace(void);
>  
> -#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
> -
> -void dynamic_preempt_schedule(void);
> -void dynamic_preempt_schedule_notrace(void);
> -#define __preempt_schedule()		dynamic_preempt_schedule()
> -#define __preempt_schedule_notrace()	dynamic_preempt_schedule_notrace()
> -
> -#else /* !CONFIG_PREEMPT_DYNAMIC || !CONFIG_HAVE_PREEMPT_DYNAMIC_KEY*/
> -
>  #define __preempt_schedule() preempt_schedule()
>  #define __preempt_schedule_notrace() preempt_schedule_notrace()
>  
> -#endif /* CONFIG_PREEMPT_DYNAMIC && CONFIG_HAVE_PREEMPT_DYNAMIC_KEY*/
>  #endif /* CONFIG_PREEMPTION */
>  
>  #endif /* __ASM_PREEMPT_H */
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 84ec93694d718..f88b9ef70a0dd 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -7439,27 +7439,6 @@ asmlinkage __visible void __sched notrace preempt_schedule(void)
>  NOKPROBE_SYMBOL(preempt_schedule);
>  EXPORT_SYMBOL(preempt_schedule);
>  
> -#ifdef CONFIG_PREEMPT_DYNAMIC
> -# ifdef CONFIG_HAVE_PREEMPT_DYNAMIC_CALL
> -#  ifndef preempt_schedule_dynamic_enabled
> -#   define preempt_schedule_dynamic_enabled	preempt_schedule
> -#   define preempt_schedule_dynamic_disabled	NULL
> -#  endif
> -DEFINE_STATIC_CALL(preempt_schedule, preempt_schedule_dynamic_enabled);
> -EXPORT_STATIC_CALL_TRAMP(preempt_schedule);
> -# elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
> -static DEFINE_STATIC_KEY_TRUE(sk_dynamic_preempt_schedule);
> -void __sched notrace dynamic_preempt_schedule(void)
> -{
> -	if (!static_branch_unlikely(&sk_dynamic_preempt_schedule))
> -		return;
> -	preempt_schedule();
> -}
> -NOKPROBE_SYMBOL(dynamic_preempt_schedule);
> -EXPORT_SYMBOL(dynamic_preempt_schedule);
> -# endif
> -#endif /* CONFIG_PREEMPT_DYNAMIC */
> -
>  /**
>   * preempt_schedule_notrace - preempt_schedule called by tracing
>   *
> @@ -7512,27 +7491,6 @@ asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
>  }
>  EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
>  
> -#ifdef CONFIG_PREEMPT_DYNAMIC
> -# if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
> -#  ifndef preempt_schedule_notrace_dynamic_enabled
> -#   define preempt_schedule_notrace_dynamic_enabled	preempt_schedule_notrace
> -#   define preempt_schedule_notrace_dynamic_disabled	NULL
> -#  endif
> -DEFINE_STATIC_CALL(preempt_schedule_notrace, preempt_schedule_notrace_dynamic_enabled);
> -EXPORT_STATIC_CALL_TRAMP(preempt_schedule_notrace);
> -# elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
> -static DEFINE_STATIC_KEY_TRUE(sk_dynamic_preempt_schedule_notrace);
> -void __sched notrace dynamic_preempt_schedule_notrace(void)
> -{
> -	if (!static_branch_unlikely(&sk_dynamic_preempt_schedule_notrace))
> -		return;
> -	preempt_schedule_notrace();
> -}
> -NOKPROBE_SYMBOL(dynamic_preempt_schedule_notrace);
> -EXPORT_SYMBOL(dynamic_preempt_schedule_notrace);
> -# endif
> -#endif
> -
>  #endif /* CONFIG_PREEMPTION */
>  
>  /*
> @@ -7830,8 +7788,6 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
>  # endif
>  
>  /*
> - * SC:preempt_schedule
> - * SC:preempt_schedule_notrace
>   * SC:irqentry_exit_cond_resched
>   *
>   *
> @@ -7842,14 +7798,10 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
>   *   (unselectable)
>   *
>   * FULL:
> - *   preempt_schedule           <- preempt_schedule
> - *   preempt_schedule_notrace   <- preempt_schedule_notrace
>   *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
>   *   dynamic_preempt_lazy       <- false
>   *
>   * LAZY:
> - *   preempt_schedule           <- preempt_schedule
> - *   preempt_schedule_notrace   <- preempt_schedule_notrace
>   *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
>   *   dynamic_preempt_lazy       <- true
>   */
> @@ -7894,8 +7846,6 @@ static void __sched_dynamic_update(int mode)
>  {
>  	switch (mode) {
>  	case preempt_dynamic_full:
> -		preempt_dynamic_enable(preempt_schedule);
> -		preempt_dynamic_enable(preempt_schedule_notrace);
>  		preempt_dynamic_enable(irqentry_exit_cond_resched);
>  		preempt_dynamic_key_disable(preempt_lazy);
>  		if (mode != preempt_dynamic_mode)
> @@ -7903,8 +7853,6 @@ static void __sched_dynamic_update(int mode)
>  		break;
>  
>  	case preempt_dynamic_lazy:
> -		preempt_dynamic_enable(preempt_schedule);
> -		preempt_dynamic_enable(preempt_schedule_notrace);
>  		preempt_dynamic_enable(irqentry_exit_cond_resched);
>  		preempt_dynamic_key_enable(preempt_lazy);
>  		if (mode != preempt_dynamic_mode)