commit bb409155 upstream.

Locking mutex in different orders just screams for
deadlocks, and some testing showed that it is actually
quite easy to trigger them.
Signed-off-by: Christian König <deathsimple@vodafone.de>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>