Author: Julia Lawall <julia@diku.dk> Since in each case nothing has been done with the recently allocated urb, it is not necessary to kill it before freeing it. The semantic patch that fixes this problem is as follows: (http://coccinelle.lip6.fr/) // @r exists@ expression urb; statement S; position p1,p2; @@ urb = usb_alloc_urb@p1(…); … when != urb …