Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 6ab8c1b..c309f43 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -19,6 +19,7 @@
 	struct rw_semaphore rwsem;
 	struct idr ipcs_idr;
 	int max_idx;
+	int last_idx;	/* For wrap around detection */
 #ifdef CONFIG_CHECKPOINT_RESTORE
 	int next_id;
 #endif