Author: Julia Lawall <julia@diku.dk> Test the just-initialized value rather than some other one. The semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/) // @r@ identifier x,y,f!={PTR_ERR,ERR_PTR,ERR_CAST}; statement S; @@ x = f(…); ( if (\(x == NULL\|IS_ERR(x)\)) S | *if (\(y == NULL\|IS_ERR(y)\)) { … when != x return …; } ) // …