apparmor: Replace spin_is_locked() with lockdep

lockdep_assert_held() is better suited to checking locking requirements,
since it won't get confused when someone else holds the lock. This is
also a step towards possibly removing spin_is_locked().

Signed-off-by: Lance Roy <ldr709@gmail.com>
Cc: John Johansen <john.johansen@canonical.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: <linux-security-module@vger.kernel.org>
Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/file.c

@@ -496,7 +496,7 @@ static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
 	/* update caching of label on file_ctx */
 	spin_lock(&fctx->lock);
 	old = rcu_dereference_protected(fctx->label,
-					spin_is_locked(&fctx->lock));
+					lockdep_is_held(&fctx->lock));
 	l = aa_label_merge(old, label, GFP_ATOMIC);
 	if (l) {
 		if (l != old) {