Hi Ming Thanks for your kindly response. On 06/15/2018 10:56 AM, Ming Lei wrote: >>> IMO, ref-counter is just to fix the blk-mq req life recycle issue. >>> It cannot replace the blk_mark_rq_complete which could avoid the race between >>> timeout and io completion path. >> The .timeout return BLK_EH_DONE doesn't always mean the request has been completed. >> Such as scsi-mid layer, its .timeout callback return BLK_EH_DONE but the timed out >> request is still in abort or eh process. What if a completion irq come during that ? > For blk-mq, it is avoided by the atomic state change in > __blk_mq_complete_request(), > that is why I mentioned the question in my last reply. > but blk_mq_check_expired doesn't do that. do I miss anything ? > But what if the timed-out request has been freed by EH? Then seems > req's ref_counter Thanks Jianchao
