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authorThomas Gleixner <tglx@linutronix.de>2012-12-20 18:28:26 +0100
committerSteven Rostedt <rostedt@goodmis.org>2012-12-21 22:53:33 -0500
commit2752b9c52de75cfcf9b0baad67db971370dbce86 (patch)
tree6b8c711f1eeb3288bf2bf2137457fdb9a2dcad38
parenta85011a2fa7a4050410ba2718f5459f950c69cd3 (diff)
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 <tglx@linutronix.de> Cc: stable-rt@vger.kernel.org
-rw-r--r--block/blk-ioc.c5
1 files 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 <linux/blkdev.h>
#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
#include <linux/slab.h>
+#include <linux/delay.h>
#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;
}
}