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SubjectRe: PATCH V4 0/5 nvme-pci: fixes on nvme_timeout and nvme_dev_disable
Hi Ming

Thanks for your kindly response.

On 04/18/2018 11:40 PM, Ming Lei wrote:
>> Regarding to this patchset, it is mainly to fix the dependency between
>> nvme_timeout and nvme_dev_disable, as your can see:
>> nvme_timeout will invoke nvme_dev_disable, and nvme_dev_disable have to
>> depend on nvme_timeout when controller no response.
> Do you mean nvme_disable_io_queues()? If yes, this one has been handled
> by wait_for_completion_io_timeout() already, and looks the block timeout
> can be disabled simply. Or are there others?
Here is one possible scenario currently

nvme_dev_disable // hold shutdown_lock nvme_timeout
-> nvme_set_host_mem -> nvme_dev_disable
-> nvme_submit_sync_cmd -> try to require shutdown_lock
-> __nvme_submit_sync_cmd
-> blk_execute_rq
//if sysctl_hung_task_timeout_secs == 0
-> wait_for_completion_io
And maybe nvme_dev_disable need to issue other commands in the future.

Even if we could fix these kind of issues as nvme_disable_io_queues,
it is still a risk I think.


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