On Mon, Mar 25, 2019 at 01:38:37PM +0800, Jianchao Wang wrote: > blk_mq_tagset_inflight_iter is not safe that it could get stale request > in tags->rqs[]. Use blk_mq_queue_tag_inflight_iter here. A new helper > interface nvme_iterate_inflight_rqs is introduced to iterate > all of the ns under a ctrl. Nak, NVMe only iterates tags when new requests can't enter, allocated requests can't dispatch, and dispatched commands can't complete. So it is perfectly safe to iterate if the driver takes reasonable steps beforehand. Further, for M tags and N namespaces, we complete teardown in O(M) time, but this makes in O(M*N) without gaining anything.
