apparmor: add macro for bug asserts to check that a lock is held

Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/include/lib.h

@@ -19,6 +19,17 @@
 
 #include "match.h"
 
+/* Provide our own test for whether a write lock is held for asserts
+ * this is because on none SMP systems write_can_lock will always
+ * resolve to true, which is what you want for code making decisions
+ * based on it, but wrong for asserts checking that the lock is held
+ */
+#ifdef CONFIG_SMP
+#define write_is_locked(X) !write_can_lock(X)
+#else
+#define write_is_locked(X) (1)
+#endif /* CONFIG_SMP */
+
 /*
  * DEBUG remains global (no per profile flag) since it is mostly used in sysctl
  * which is not related to profile accesses.