#ifdef CONFIG_SMP
# define WARN_ON_SMP(x) WARN_ON(x)
#else
+/*
+ * Use of ({0;}) because WARN_ON_SMP(x) may be used either as
+ * a stand alone line statement or as a condition in an if ()
+ * statement.
+ * A simple "0" would cause gcc to give a "statement has no effect"
+ * warning.
+ */
# define WARN_ON_SMP(x) ({0;})
#endif