From 2752b9c52de75cfcf9b0baad67db971370dbce86 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 20 Dec 2012 18:28:26 +0100 Subject: block: Use cpu_chill() for retry loops Retry loops on RT might loop forever when the modifying side was preempted. Steven also observed a live lock when there was a concurrent priority boosting going on. Use cpu_chill() instead of cpu_relax() to let the system make progress. Signed-off-by: Thomas Gleixner Cc: stable-rt@vger.kernel.org --- block/blk-ioc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/block/blk-ioc.c b/block/blk-ioc.c index fb95dd2f889a..6b542018ed1e 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -8,6 +8,7 @@ #include #include /* for max_pfn/max_low_pfn */ #include +#include #include "blk.h" @@ -110,7 +111,7 @@ static void ioc_release_fn(struct work_struct *work) spin_unlock(q->queue_lock); } else { spin_unlock_irqrestore(&ioc->lock, flags); - cpu_relax(); + cpu_chill(); spin_lock_irqsave_nested(&ioc->lock, flags, 1); } } @@ -188,7 +189,7 @@ retry: spin_unlock(icq->q->queue_lock); } else { spin_unlock_irqrestore(&ioc->lock, flags); - cpu_relax(); + cpu_chill(); goto retry; } } -- cgit v1.2.3