Author: Julien Brunel <brunel@diku.dk> The error test that follows the call to backlight_device_register semms not to concern the right variable. A simplified version of the semantic match that finds this problem is as follows: (http://www.emn.fr/x-info/coccinelle/) // @def0@ expression x; position p0; @@ x@p0 = backlight_device_register(…) @protected@ expression def0.x,E; position def0.p0; position p; statement S; @@ …