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| author | Bart Van Assche <bvanassche@acm.org> | 2012-11-28 13:46:45 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-12-06 14:33:00 +0100 |
| commit | 24faf6f604efe18236bded4303009fc252913bf0 (patch) | |
| tree | bc4d35a38c44a37ffd718089729ae59b23d50d99 /block/blk-core.c | |
| parent | 704605711ef048a7c6ad2ec599f15d2e0baf86b2 (diff) | |
| download | lwn-24faf6f604efe18236bded4303009fc252913bf0.tar.gz lwn-24faf6f604efe18236bded4303009fc252913bf0.zip | |
block: Make blk_cleanup_queue() wait until request_fn finished
Some request_fn implementations, e.g. scsi_request_fn(), unlock
the queue lock internally. This may result in multiple threads
executing request_fn for the same queue simultaneously. Keep
track of the number of active request_fn calls and make sure that
blk_cleanup_queue() waits until all active request_fn invocations
have finished. A block driver may start cleaning up resources
needed by its request_fn as soon as blk_cleanup_queue() finished,
so blk_cleanup_queue() must wait for all outstanding request_fn
invocations to finish.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reported-by: Chanho Min <chanho.min@lge.com>
Cc: James Bottomley <JBottomley@Parallels.com>
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.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 9fb23537c7ad..473015ee28a2 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -309,7 +309,16 @@ inline void __blk_run_queue_uncond(struct request_queue *q) if (unlikely(blk_queue_dead(q))) return; + /* + * Some request_fn implementations, e.g. scsi_request_fn(), unlock + * the queue lock internally. As a result multiple threads may be + * running such a request function concurrently. Keep track of the + * number of active request_fn invocations such that blk_drain_queue() + * can wait until all these request_fn calls have finished. + */ + q->request_fn_active++; q->request_fn(q); + q->request_fn_active--; } /** @@ -408,6 +417,7 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all) __blk_run_queue(q); drain |= q->nr_rqs_elvpriv; + drain |= q->request_fn_active; /* * Unfortunately, requests are queued at and tracked from |