Merge pull request #29 from OwenSmith/master

Protect Netio imports with a mutex.
Avoid duplicate entries in the IP address table

Duplicates are useless and actually cause problems overflowing xenstore's
quota. Also, we should not bother looking at the MIB address table unless
the frontend is CONNECTED or ENABLED since our NetLuid is not necessarily
valid unless we are in one of those states.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Merge pull request #30 from pauldu/master

Avoid duplicate entries in the IP address table
Use new XENBUS CACHE interface rather than local pool code

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Remove much code duplication

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Use new GNTTAB interface

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Merge pull request #32 from pauldu/gnttab

Updated GNTTAB interface
Change Cache lifecycle to match ring lifecycle.
Ensure caches are destroyed when device transitions to D3 to prevent
assertion failure in xenbus.

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