Messages in this thread Patch in this message | | | Date | Fri, 21 Dec 2012 23:25:19 -0500 | From | Steven Rostedt <> | Subject | [PATCH RT 4/5] block: Use cpu_chill() for retry loops |
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From: Thomas Gleixner <tglx@linutronix.de>
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 --- 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
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