Author: Julia Lawall <julia@diku.dk> rtc is clearly does not satisfy IS_ERR at the point where it is tested, so I have changed the test to consider the just initialized rtc->rtc_dev. The semantic match that finds the problem is as follows: (http://www.emn.fr/x-info/coccinelle/) // @match exists@ expression x, E; identifier fld; position p1,p2; @@ ( x = …