[PATCH 1/2] nvme: pci: simplify timeout handling

[jianchao.wang]

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.

Thanks
Jianchao