On Sat, Apr 28, 2018 at 10:00 PM, jianchao.wang <jianchao.w.wang@xxxxxxxxxx> wrote: > Hi ming > > On 04/27/2018 10:57 PM, Ming Lei wrote: >> I may not understand your point, once blk_sync_queue() returns, the >> timer itself is deactivated, meantime the synced .nvme_timeout() only >> returns EH_NOT_HANDLED before the deactivation. >> >> That means this timer won't be expired any more, so could you explain >> a bit why timeout can come again after blk_sync_queue() returns > > Please consider the following case: > > blk_sync_queue > -> del_timer_sync > blk_mq_timeout_work > -> blk_mq_check_expired // return the timeout value > -> blk_mq_terninate_expired > -> .timeout //return EH_NOT_HANDLED > -> mod_timer // setup the timer again based on the result of blk_mq_check_expired > -> cancel_work_sync > So after the blk_sync_queue, the timer may come back again, then the timeout work. OK, I was trying to avoid to use blk_abort_request(), but looks we may have to depend on it or similar way. BTW, that means blk_sync_queue() has been broken, even though the uses in blk_cleanup_queue(). Another approach is to introduce one perpcu_ref of 'q->timeout_usage_counter' for syncing timeout, seems a bit over-kill too, but simpler in both theory and implement. Thanks, Ming Lei
