This breaks kernel ABI on KDEBUG builds (but not non-KDEBUG builds),
but it does so in order to resolve a long-standing incompatibility
between them: until now, any kernel add-ons built against one which
made use of these lock facilities could not be run on the other;
instead you would get hangs and/or crashes.
After this change, kernel add-ons built with a KDEBUG configuration
should work on a non-KDEBUG kernel, while add-ons built with a
non-KDEBUG configuration will fail to load on a KDEBUG kernel
with unresolved symbols, preventing incorrect and broken operation.
Augustin Cavalier
f4e0ce8d61