| From | Paul Gortmaker <> | Subject | [34-longterm 007/179] block: add proper state guards to __elv_next_request | Date | Mon, 14 May 2012 22:11:43 -0400 |
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From: James Bottomley <James.Bottomley@suse.de>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. -------------------
commit 0a58e077eb600d1efd7e54ad9926a75a39d7f8ae upstream.
blk_cleanup_queue() calls elevator_exit() and after this, we can't touch the elevator without oopsing. __elv_next_request() must check for this state because in the refcounted queue model, we can still call it after blk_cleanup_queue() has been called.
This was reported as causing an oops attributable to scsi.
Signed-off-by: James Bottomley <James.Bottomley@suse.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- block/blk.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/blk.h b/block/blk.h index 5ee3d7e..1414836 100644 --- a/block/blk.h +++ b/block/blk.h @@ -62,7 +62,8 @@ static inline struct request *__elv_next_request(struct request_queue *q) return rq; } - if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) + if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) || + !q->elevator->ops->elevator_dispatch_fn(q, 0)) return NULL; } } -- 1.7.9.6
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