The root cause of the panic is the race between the resume and reconnect to the backend.
Clearing the 'update_wanted' flag of xenfb before disconnecting from the
backend fixes this issue.
Signed-off-by: Joe Jin <joe.jin@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Tested-by: Gurudas Pai <gurudas.pai@oracle.com> Acked-by: Ian Campbell <ian.campbell@citrix.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Andrew Morton <akpm@linux-foundation.org>