[PATCH rfc] nvme-pci: make sure to flush sqe writes before db record update

[Keith Busch]

On Thu, Mar 08, 2018 at 11:36:23AM -0700, Jason Gunthorpe wrote:
> On Thu, Mar 08, 2018 at 07:56:37PM +0200, Sagi Grimberg wrote:
> > If the SQE and DB update have been reordered,
> 
> But that can't happen, the SQE is written before
> nvme_dbbuf_update_and_check_event(), and that function does wmb.

I believe Sagi is talking about the typical controller that doesn't
have shadow db registers (no real nvme device has those), which doesn't
currently go through a path calling wmb().