Author: Julia Lawall <julia@diku.dk> Function _sr_lookup, defined in the same file, returns ERR_PTR not NULL in an error case. The semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/) // @r@ identifier f; @@ f(…) { … return ERR_PTR(…); } @@ identifier r.f, fld; expression x; statement S1,S2; @@ x = f(…) … when …