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authorBart Van Assche <bvanassche@acm.org>2012-11-28 13:45:56 +0100
committerJens Axboe <axboe@kernel.dk>2012-12-06 14:32:30 +0100
commit704605711ef048a7c6ad2ec599f15d2e0baf86b2 (patch)
tree16620b55d00b289a9a343d1d2c150684fbb1661c /block/blk-core.c
parentc246e80d86736312933646896c4157daf511dadc (diff)
downloadlinux-linaro-stable-704605711ef048a7c6ad2ec599f15d2e0baf86b2.tar.gz
block: Avoid scheduling delayed work on a dead queue
Running a queue must continue after it has been marked dying until it has been marked dead. So the function blk_run_queue_async() must not schedule delayed work after blk_cleanup_queue() has marked a queue dead. Hence add a test for that queue state in blk_run_queue_async() and make sure that queue_unplugged() invokes that function with the queue lock held. This avoids that the queue state can change after it has been tested and before mod_delayed_work() is invoked. Drop the queue dying test in queue_unplugged() since it is now superfluous: __blk_run_queue() already tests whether or not the queue is dead. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Cc: Mike Christie <michaelc@cs.wisc.edu> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-core.c')
-rw-r--r--block/blk-core.c33
1 files changed, 9 insertions, 24 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index f52d05ff5d24..9fb23537c7ad 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -219,12 +219,13 @@ static void blk_delay_work(struct work_struct *work)
* Description:
* Sometimes queueing needs to be postponed for a little while, to allow
* resources to come back. This function will make sure that queueing is
- * restarted around the specified time.
+ * restarted around the specified time. Queue lock must be held.
*/
void blk_delay_queue(struct request_queue *q, unsigned long msecs)
{
- queue_delayed_work(kblockd_workqueue, &q->delay_work,
- msecs_to_jiffies(msecs));
+ if (likely(!blk_queue_dead(q)))
+ queue_delayed_work(kblockd_workqueue, &q->delay_work,
+ msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_delay_queue);
@@ -334,11 +335,11 @@ EXPORT_SYMBOL(__blk_run_queue);
*
* Description:
* Tells kblockd to perform the equivalent of @blk_run_queue on behalf
- * of us.
+ * of us. The caller must hold the queue lock.
*/
void blk_run_queue_async(struct request_queue *q)
{
- if (likely(!blk_queue_stopped(q)))
+ if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
}
EXPORT_SYMBOL(blk_run_queue_async);
@@ -2913,27 +2914,11 @@ static void queue_unplugged(struct request_queue *q, unsigned int depth,
{
trace_block_unplug(q, depth, !from_schedule);
- /*
- * Don't mess with a dying queue.
- */
- if (unlikely(blk_queue_dying(q))) {
- spin_unlock(q->queue_lock);
- return;
- }
-
- /*
- * If we are punting this to kblockd, then we can safely drop
- * the queue_lock before waking kblockd (which needs to take
- * this lock).
- */
- if (from_schedule) {
- spin_unlock(q->queue_lock);
+ if (from_schedule)
blk_run_queue_async(q);
- } else {
+ else
__blk_run_queue(q);
- spin_unlock(q->queue_lock);
- }
-
+ spin_unlock(q->queue_lock);
}
static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)