Re: [PATCH 2/2] sched: Move the sleeping while atomic checks early in cond_resched()

Peter Zijlstra
2009-07-10T15:00:15Z

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