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Subject: Re: [PATCH 2/2] sched: Move the sleeping while atomic checks early
 in cond_resched()
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>
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	 <1247237391-5352-2-git-send-email-fweisbec@gmail.com>
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Date: Fri, 10 Jul 2009 16:59:55 +0200
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On Fri, 2009-07-10 at 16:49 +0200, Frederic Weisbecker wrote:

> index 0cb0d8d..e357dc7 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -2279,11 +2279,13 @@ extern int _cond_resched(void);
>  #ifdef CONFIG_PREEMPT_BKL
>  static inline int cond_resched(void)
>  {
> +	might_sleep();
>  	return 0;
>  }
>  #else
>  static inline int cond_resched(void)
>  {
> +	might_sleep();
>  	return _cond_resched();
>  }
>  #endif

# define might_resched() _cond_resched()

# define might_sleep() \
	do { __might_sleep(__FILE__, __LINE__); might_resched(); } while (0)


Doesn't seem to make it any better that, but yeah, moving that
__might_sleep() did occur to me earlier today when I touched that code.

> diff --git a/kernel/sched.c b/kernel/sched.c
> index 87ecac1..c22804b 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -6605,9 +6605,6 @@ SYSCALL_DEFINE0(sched_yield)
>  
>  static void __cond_resched(void)
>  {
> -#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
> -	__might_sleep(__FILE__, __LINE__);
> -#endif
>  	/*
>  	 * The BKS might be reacquired before we have dropped
>  	 * PREEMPT_ACTIVE, which could trigger a second