Hi ming Thanks for your detailed response. That's really appreciated. On 01/27/2018 09:31 PM, Ming Lei wrote: >> But nvme_dev_disable may run with nvme_timeout in parallel or race with it. > But that doesn't mean it is a race, blk_mq_complete_request() can avoid race > between timeout and other completions, such as cancel. > Yes, I know blk_mq_complete_request could avoid the a request is accessed by timeout path and other completion path concurrently. :) What's I worry about is the timeout path could hold the expired request, so when nvme_dev_disable return, we cannot ensure all the previous outstanding requests has been handled. That's really bad. >> The best way to fix this is to ensure the timeout path has been completed before cancel the >> previously outstanding requests. (Just ignore the case where the nvme_timeout will invoke nvme_dev_disable, >> it has to be fixed by other way.) > Maybe your approach looks a bit clean and simplify the implementation, but seems > it isn't necessary. > > So could you explain a bit what the exact issue you are worrying about? deadlock? > or others? There is indeed potential issue. But it is in very narrow window. Please refer to https://lkml.org/lkml/2018/1/19/68 As you said, the approach looks a bit clean and simplify the implementation. That's what I really want, break the complicated relationship between nvme_timeout and nvme_dev_diable. Thanks Jianchao