Hi Keith On 3/25/19 9:49 PM, Keith Busch wrote: > 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. nvme_dev_disable just quiesce and freeze the request_queue, but not drain the enters. So there still could be someone escapes the queue freeze checking and tries to allocate request. > Further, for M tags and N namespaces, we complete teardown > in O(M) time, but this makes in O(M*N) without gaining anything. > Yes, it is indeed inefficient. Thanks Jianchao
