|author||Bart Van Assche <firstname.lastname@example.org>||2012-12-06 14:32:01 +0100|
|committer||Jens Axboe <email@example.com>||2012-12-06 14:32:01 +0100|
block: Avoid that request_fn is invoked on a dead queue
A block driver may start cleaning up resources needed by its request_fn as soon as blk_cleanup_queue() finished, so request_fn must not be invoked after draining finished. This is important when blk_run_queue() is invoked without any requests in progress. As an example, if blk_drain_queue() and scsi_run_queue() run in parallel, blk_drain_queue() may have finished all requests after scsi_run_queue() has taken a SCSI device off the starved list but before that last function has had a chance to run the queue. Signed-off-by: Bart Van Assche <firstname.lastname@example.org> Cc: James Bottomley <JBottomley@Parallels.com> Cc: Mike Christie <email@example.com> Cc: Chanho Min <firstname.lastname@example.org> Acked-by: Tejun Heo <email@example.com> Signed-off-by: Jens Axboe <firstname.lastname@example.org>
Diffstat (limited to 'block/blk-core.c')
1 files changed, 27 insertions, 4 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index a182b586b06a..f52d05ff5d24 100644
@@ -293,6 +293,25 @@ void blk_sync_queue(struct request_queue *q)
+ * __blk_run_queue_uncond - run a queue whether or not it has been stopped
+ * @q: The queue to run
+ * Description:
+ * Invoke request handling on a queue if there are any pending requests.
+ * May be used to restart request handling after a request has completed.
+ * This variant runs the queue whether or not the queue has been
+ * stopped. Must be called with the queue lock held and interrupts
+ * disabled. See also @blk_run_queue.
+inline void __blk_run_queue_uncond(struct request_queue *q)
+ if (unlikely(blk_queue_dead(q)))
* __blk_run_queue - run a single device queue
* @q: The queue to run
@@ -305,7 +324,7 @@ void __blk_run_queue(struct request_queue *q)
@@ -477,8 +496,8 @@ EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
* blk_cleanup_queue - shutdown a request queue
* @q: request queue to shutdown
- * Mark @q DYING, drain all pending requests, destroy and put it. All
- * future requests will be failed immediately with -ENODEV.
+ * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
+ * put it. All future requests will be failed immediately with -ENODEV.
void blk_cleanup_queue(struct request_queue *q)
@@ -507,9 +526,13 @@ void blk_cleanup_queue(struct request_queue *q)
- /* drain all requests queued before DYING marking */
+ * Drain all requests queued before DYING marking. Set DEAD flag to
+ * prevent that q->request_fn() gets invoked after draining finished.
+ queue_flag_set(QUEUE_FLAG_DEAD, q);
/* @q won't process any more request, flush async actions */