trimming task_work: kill ->data

get rid of the only user of ->data; this is _not_ the final variant - in the
end we'll have task_work and rcu_head identical and just use cred->rcu,
at which point the separate allocation will be gone completely.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 4ad54ee..c9b07c9 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -837,9 +837,10 @@
 void key_change_session_keyring(struct task_work *twork)
 {
 	const struct cred *old = current_cred();
-	struct cred *new = twork->data;
+	struct kludge *p = container_of(twork, struct kludge, twork);
+	struct cred *new = p->cred;
 
-	kfree(twork);
+	kfree(p);
 	if (unlikely(current->flags & PF_EXITING)) {
 		put_cred(new);
 		return;