[PATCH RT 4/5] block: Use cpu_chill() for retry loops
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2012-12-22 04:26:08
Also in:
lkml
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
From: Thomas Gleixner <redacted> 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 <redacted> 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 fb95dd2..6b54201 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; } }
--
1.7.10.4