We need this helper to fix system stalls. The issue is that the rest
of the system TTYs wait for us to finish waiting. This wasn't an issue
with BKL. BKL used to unlock implicitly.

This is based on the Arnd suggestion.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>