From: Tejun Heo Subject: block: internal dequeue shouldn't start timer References: bnc#449880 blkdev_dequeue_request() and elv_dequeue_request() are equivalent and both start the timeout timer. Barrier code dequeues the original barrier request but doesn't passes the request itself to lower level driver, only broken down proxy requests; however, as the original barrier code goes through the same dequeue path and timeout timer is started on it. If barrier sequence takes long enough, this timer expires but the low level driver has no idea about this request and oops follows. Timeout timer shouldn't have been started on the original barrier request as it never goes through actual IO. This patch unexports elv_dequeue_request(), which has no external user anyway, and makes it operate on elevator proper w/o adding the timer and make blkdev_dequeue_request() call elv_dequeue_request() and add timer. Internal users which don't pass the request to driver - barrier code and end_that_request_last() - are converted to use elv_dequeue_request(). Signed-off-by: Tejun Heo Cc: Mike Anderson Signed-off-by: Tejun Heo --- block/blk-barrier.c | 4 ++-- block/blk-core.c | 24 +++++++++++++++++++++++- block/elevator.c | 7 ------- include/linux/blkdev.h | 7 ++----- 4 files changed, 27 insertions(+), 15 deletions(-) --- a/block/blk-barrier.c +++ b/block/blk-barrier.c @@ -161,7 +161,7 @@ static inline struct request *start_orde /* * Prep proxy barrier request. */ - blkdev_dequeue_request(rq); + elv_dequeue_request(q, rq); q->orig_bar_rq = rq; rq = &q->bar_rq; blk_rq_init(q, rq); @@ -219,7 +219,7 @@ int blk_do_ordered(struct request_queue * This can happen when the queue switches to * ORDERED_NONE while this request is on it. */ - blkdev_dequeue_request(rq); + elv_dequeue_request(q, rq); if (__blk_end_request(rq, -EOPNOTSUPP, blk_rq_bytes(rq))) BUG(); --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1536,6 +1536,28 @@ void submit_bio(int rw, struct bio *bio) EXPORT_SYMBOL(submit_bio); /** + * blkdev_dequeue_request - dequeue request and start timeout timer + * @req: request to dequeue + * + * Dequeue @req and start timeout timer on it. This hands off the + * request to the driver. + * + * Block internal functions which don't want to start timer should + * call elv_dequeue_request(). + */ +void blkdev_dequeue_request(struct request *req) +{ + elv_dequeue_request(req->q, req); + + /* + * We are now handing the request to the hardware, add the + * timeout handler. + */ + blk_add_timer(req); +} +EXPORT_SYMBOL(blkdev_dequeue_request); + +/** * __end_that_request_first - end I/O on a request * @req: the request being processed * @error: %0 for success, < %0 for error @@ -1670,7 +1692,7 @@ static void end_that_request_last(struct blk_queue_end_tag(req->q, req); if (blk_queued_rq(req)) - blkdev_dequeue_request(req); + elv_dequeue_request(req->q, req); if (unlikely(laptop_mode) && blk_fs_request(req)) laptop_io_completion(); --- a/block/elevator.c +++ b/block/elevator.c @@ -844,14 +844,7 @@ void elv_dequeue_request(struct request_ */ if (blk_account_rq(rq)) q->in_flight++; - - /* - * We are now handing the request to the hardware, add the - * timeout handler. - */ - blk_add_timer(rq); } -EXPORT_SYMBOL(elv_dequeue_request); int elv_queue_empty(struct request_queue *q) { --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -756,6 +756,8 @@ static inline void blk_run_address_space blk_run_backing_dev(mapping->backing_dev_info, NULL); } +extern void blkdev_dequeue_request(struct request *req); + /* * blk_end_request() and friends. * __blk_end_request() and end_request() must be called with @@ -790,11 +792,6 @@ extern void blk_abort_queue(struct reque extern unsigned int blk_rq_bytes(struct request *rq); extern unsigned int blk_rq_cur_bytes(struct request *rq); -static inline void blkdev_dequeue_request(struct request *req) -{ - elv_dequeue_request(req->q, req); -} - /* * Access functions for manipulating queue properties */