On Sun, Apr 29, 2018 at 5:57 AM, Ming Lei <tom.leiming@xxxxxxxxx> wrote: > 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. Or one timout_mutex is enough. Thanks, Ming Lei
