From: Ming Lei ming.lei@redhat.com
[ Upstream commit 5d05426e2d5fd7df8afc866b78c36b37b00188b7 ]
blk_mq_run_hw_queues() could be run when there isn't queued request and after queue is cleaned up, at that time tagset is freed, because tagset lifetime is covered by driver, and often freed after blk_cleanup_queue() returns.
So don't touch ->tagset for figuring out current default hctx by the mapping built in request queue, so use-after-free on tagset can be avoided. Meantime this way should be fast than retrieving mapping from tagset.
Cc: "yukuai (C)" yukuai3@huawei.com Cc: Jan Kara jack@suse.cz Fixes: b6e68ee82585 ("blk-mq: Improve performance of non-mq IO schedulers with multiple HW queues") Signed-off-by: Ming Lei ming.lei@redhat.com Reviewed-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/20220522122350.743103-1-ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-mq.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c index 82de39926a9f..b70488e4db94 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1642,8 +1642,7 @@ static bool blk_mq_has_sqsched(struct request_queue *q) */ static struct blk_mq_hw_ctx *blk_mq_get_sq_hctx(struct request_queue *q) { - struct blk_mq_hw_ctx *hctx; - + struct blk_mq_ctx *ctx = blk_mq_get_ctx(q); /* * If the IO scheduler does not respect hardware queues when * dispatching, we just don't bother with multiple HW queues and @@ -1651,8 +1650,8 @@ static struct blk_mq_hw_ctx *blk_mq_get_sq_hctx(struct request_queue *q) * just causes lock contention inside the scheduler and pointless cache * bouncing. */ - hctx = blk_mq_map_queue_type(q, HCTX_TYPE_DEFAULT, - raw_smp_processor_id()); + struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, 0, ctx); + if (!blk_mq_hctx_stopped(hctx)) return hctx; return NULL;