Fix a NULL pointer deref in the user-defined key type whereby updating a
negative key into a fully instantiated key will cause an oops to occur
when the code attempts to free the non-existent old payload.
This results in an oops that looks something like the following:
Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Jeff Layton <jlayton@redhat.com> Acked-by: Neil Horman <nhorman@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[PG: pre-3.0 kernels dont have kfree_rcu, so tweak accordingly] Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>