linux-kernel - Re: [RFC][PATCH 08/11] sched: Simplify preempt

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Message-ID: <20150929114227.653226aa@gandalf.local.home>
Date:	Tue, 29 Sep 2015 11:42:27 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	mingo@...nel.org, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, fweisbec@...il.com, oleg@...hat.com,
	umgwanakikbuti@...il.com, tglx@...utronix.de
Subject: Re: [RFC][PATCH 08/11] sched: Simplify preempt_count tests

On Tue, 29 Sep 2015 11:28:33 +0200
Peter Zijlstra <peterz@...radead.org> wrote:

> Since we stopped setting PREEMPT_ACTIVE, there is no need to mask it
> out of preempt_count() tests.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---

Reviewed-by: Steven Rostedt <rostedt@...dmis.org>

-- Steve

>  include/linux/preempt.h |    3 +--
>  kernel/sched/core.c     |    2 +-
>  2 files changed, 2 insertions(+), 3 deletions(-)
> 
> --- a/include/linux/preempt.h
> +++ b/include/linux/preempt.h
> @@ -126,8 +126,7 @@
>   * Check whether we were atomic before we did preempt_disable():
>   * (used by the scheduler)
>   */
> -#define in_atomic_preempt_off() \
> -		((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_DISABLE_OFFSET)
> +#define in_atomic_preempt_off() (preempt_count() != PREEMPT_DISABLE_OFFSET)
>  
>  #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
>  extern void preempt_count_add(int val);
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -7472,7 +7472,7 @@ void __init sched_init(void)
>  #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
>  static inline int preempt_count_equals(int preempt_offset)
>  {
> -	int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();
> +	int nested = preempt_count() + rcu_preempt_depth();
>  
>  	return (nested == preempt_offset);
>  }
> 

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