[PATCHv2 2/2] nvme: Complete all stuck requests

[Sagi Grimberg]

On 24/02/17 02:36, Keith Busch wrote:
> If the block layer has entered requests and gets a CPU hot plug event
> prior to the resume event, it will wait for those requests to exit. If
> the nvme driver is shutting down, it will not start the queues back up,
> preventing forward progress.
>
> To fix that, this patch freezes the request queues when the driver intends
> to shut down the controller so that no new requests may enter.  After the
> controller has been disabled, the queues will be restarted to force all
> entered requests to end in failure so that blk-mq's hot cpu notifier may
> progress. To ensure the queue usage count is 0 on a shutdown, the driver
> waits for freeze to complete before completing the controller shutdown.

Keith, can you explain (again) for me why is the freeze_wait must happen
after the controller has been disabled, instead of starting the queues
and waiting right after freeze start?