device_rename only performs useful and race free validity checking at the optional sysfs level so depending on it for all of the validity checking in cfg80211_dev_rename is racy. Instead implement all of the needed validity checking and locking in cfg80211_dev_rename. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>