xen-netback: transition to CLOSED when removing a VIF
xen-netback: transition to CLOSED when removing a VIF

If a guest is destroyed without transitioning its frontend to CLOSED,
the domain becomes a zombie as netback was not grant unmapping the
shared rings.

When removing a VIF, transition the backend to CLOSED so the VIF is
disconnected if necessary (which will unmap the shared rings etc).

This fixes a regression introduced by
279f438e36c0a70b23b86d2090aeec50155034a9 (xen-netback: Don't destroy
the netdev until the vif is shut down).

Signed-off-by: David Vrabel <b9d45bd1f671e508cd8daa63dfc3cabb597562df@citrix.com>
Cc: Ian Campbell <9be92b3dbbd6611e3e4c9209fb3d04b4919e7cca@citrix.com>
Cc: Wei Liu <a5240e9e4c4d742e3a4232ca749f78defd45d722@citrix.com>
Cc: Paul Durrant <cf3f603bfb9e239522183ce023889c661a14dc1b@citrix.com>
Acked-by: Wei Liu <a5240e9e4c4d742e3a4232ca749f78defd45d722@citrix.com>
Reviewed-by:  Paul Durrant <dba6cd059c0054f8a3c62ba902cd9d7238853ee4@citrix.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs