Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/include/linux/rcu.h b/tools/include/linux/rcu.h
index 7d02527..9554d3f 100644
--- a/tools/include/linux/rcu.h
+++ b/tools/include/linux/rcu.h
@@ -19,7 +19,7 @@
 	return false;
 }
 
-#define rcu_assign_pointer(p, v) ((p) = (v))
-#define RCU_INIT_POINTER(p, v) p=(v)
+#define rcu_assign_pointer(p, v)	do { (p) = (v); } while (0)
+#define RCU_INIT_POINTER(p, v)	do { (p) = (v); } while (0)
 
 #endif