[PATCH 1/2] NVMe: Lock out shutdown during pci init

[Keith Busch]

On Sat, Feb 13, 2016 at 01:58:51AM -0800, Christoph Hellwig wrote:
> Seems like we should be holding the lock over the call
> to nvme_dev_disable to get protection for the whole execution,
> e.g. by adding a __nvme_dev_disable variant that expects the lock
> to be held.
> 
> Maybe it's also worth renaming shutdown_lock to register_mutex
> or similar to better document what it protects.

Perhaps we shouldn't unmap the registers on a reset. That'd fix several
problems, including this one and writing queue doorbells.