From b7d98e0dca67caef09caa3a59203f1e60a8af29e Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 7 Mar 2012 20:51:03 +0100 Subject: rt: Introduce cpu_chill() Retry loops on RT might loop forever when the modifying side was preempted. Add cpu_chill() to replace cpu_relax(). cpu_chill() defaults to cpu_relax() for non RT. On RT it puts the looping task to sleep for a tick so the preempted task can make progress. Signed-off-by: Thomas Gleixner Cc: stable-rt@vger.kernel.org --- include/linux/delay.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/delay.h b/include/linux/delay.h index a6ecb34cf547..e23a7c021eeb 100644 --- a/include/linux/delay.h +++ b/include/linux/delay.h @@ -52,4 +52,10 @@ static inline void ssleep(unsigned int seconds) msleep(seconds * 1000); } +#ifdef CONFIG_PREEMPT_RT_FULL +# define cpu_chill() msleep(1) +#else +# define cpu_chill() cpu_relax() +#endif + #endif /* defined(_LINUX_DELAY_H) */ -- cgit v1.2.3