Put REQUESTs on the SubmittedReqs list before placing on the ring,
to ensure PdoCompleteRequest has the appropriate request available.

Signed-off-by: Owen Smith <owen.smith@citrix.com>
Use tags for request->id/response->id instead of passing raw pointers.

Signed-off-by: Owen Smith <owen.smith@citrix.com>
Add some more barriers and adjust locking around ring requests.

Signed-off-by: Owen Smith <owen.smith@citrix.com>