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author | Bart Van Assche <bvanassche@acm.org> | 2012-12-06 14:32:01 +0100 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2012-12-06 14:32:01 +0100 |
commit | c246e80d86736312933646896c4157daf511dadc (patch) | |
tree | 183119080e120f5a3e98edf5bb824e940e5b8f18 /block | |
parent | block: Let blk_drain_queue() caller obtain the queue lock (diff) | |
download | linux-c246e80d86736312933646896c4157daf511dadc.tar.xz linux-c246e80d86736312933646896c4157daf511dadc.zip |
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 <bvanassche@acm.org>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Chanho Min <chanho.min@lge.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r-- | block/blk-core.c | 31 | ||||
-rw-r--r-- | block/blk-exec.c | 2 | ||||
-rw-r--r-- | block/blk.h | 2 |
3 files changed, 30 insertions, 5 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index a182b586b06a..f52d05ff5d24 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -293,6 +293,25 @@ void blk_sync_queue(struct request_queue *q) EXPORT_SYMBOL(blk_sync_queue); /** + * __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))) + return; + + q->request_fn(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) if (unlikely(blk_queue_stopped(q))) return; - q->request_fn(q); + __blk_run_queue_uncond(q); } EXPORT_SYMBOL(__blk_run_queue); @@ -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) spin_unlock_irq(lock); mutex_unlock(&q->sysfs_lock); - /* 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. + */ spin_lock_irq(lock); __blk_drain_queue(q, true); + queue_flag_set(QUEUE_FLAG_DEAD, q); spin_unlock_irq(lock); /* @q won't process any more request, flush async actions */ diff --git a/block/blk-exec.c b/block/blk-exec.c index 4aec98df7ba5..1320e74d79b8 100644 --- a/block/blk-exec.c +++ b/block/blk-exec.c @@ -72,7 +72,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, __blk_run_queue(q); /* the queue is stopped so it won't be run */ if (rq->cmd_type == REQ_TYPE_PM_RESUME) - q->request_fn(q); + __blk_run_queue_uncond(q); spin_unlock_irq(q->queue_lock); } EXPORT_SYMBOL_GPL(blk_execute_rq_nowait); diff --git a/block/blk.h b/block/blk.h index 2218a8a78292..47fdfdd41520 100644 --- a/block/blk.h +++ b/block/blk.h @@ -145,6 +145,8 @@ int blk_try_merge(struct request *rq, struct bio *bio); void blk_queue_congestion_threshold(struct request_queue *q); +void __blk_run_queue_uncond(struct request_queue *q); + int blk_dev_init(void); |