| Subject: rt: Introduce cpu_chill() |
| From: Thomas Gleixner <tglx@linutronix.de> |
| Date: Wed, 07 Mar 2012 20:51:03 +0100 |
| |
| 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 <tglx@linutronix.de> |
| Cc: stable-rt@vger.kernel.org |
| --- |
| include/linux/delay.h | 6 ++++++ |
| 1 file changed, 6 insertions(+) |
| |
| --- a/include/linux/delay.h |
| +++ b/include/linux/delay.h |
| @@ -52,4 +52,10 @@ static inline void ssleep(unsigned int s |
| 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) */ |