From f4560231ec42092c6662acccabb28c6cac9f5dfb Mon Sep 17 00:00:00 2001 From: Jianchao Wang Date: Tue, 17 Apr 2018 11:46:20 +0800 Subject: blk-mq: start request gstate with gen 1 rq->gstate and rq->aborted_gstate both are zero before rqs are allocated. If we have a small timeout, when the timer fires, there could be rqs that are never allocated, and also there could be rq that has been allocated but not initialized and started. At the moment, the rq->gstate and rq->aborted_gstate both are 0, thus the blk_mq_terminate_expired will identify the rq is timed out and invoke .timeout early. For scsi, this will cause scsi_times_out to be invoked before the scsi_cmnd is not initialized, scsi_cmnd->device is still NULL at the moment, then we will get crash. Cc: Bart Van Assche Cc: Tejun Heo Cc: Ming Lei Cc: Martin Steigerwald Cc: stable@vger.kernel.org Signed-off-by: Jianchao Wang Signed-off-by: Jens Axboe --- block/blk-core.c | 4 ++++ block/blk-mq.c | 7 +++++++ 2 files changed, 11 insertions(+) (limited to 'block') diff --git a/block/blk-core.c b/block/blk-core.c index 3e77409e5a84..85909b431eb0 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -201,6 +201,10 @@ void blk_rq_init(struct request_queue *q, struct request *rq) rq->part = NULL; seqcount_init(&rq->gstate_seq); u64_stats_init(&rq->aborted_gstate_sync); + /* + * See comment of blk_mq_init_request + */ + WRITE_ONCE(rq->gstate, MQ_RQ_GEN_INC); } EXPORT_SYMBOL(blk_rq_init); diff --git a/block/blk-mq.c b/block/blk-mq.c index 0dc9e341c2a7..e4aa36817367 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2042,6 +2042,13 @@ static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq, seqcount_init(&rq->gstate_seq); u64_stats_init(&rq->aborted_gstate_sync); + /* + * start gstate with gen 1 instead of 0, otherwise it will be equal + * to aborted_gstate, and be identified timed out by + * blk_mq_terminate_expired. + */ + WRITE_ONCE(rq->gstate, MQ_RQ_GEN_INC); + return 0; } -- cgit v1.2.3