Author: Julia Lawall <julia@diku.dk> device and acpi_driver_data(device) were tested just a few lines above. A simplified version of the semantic match that finds this problem is as follows: (http://www.emn.fr/x-info/coccinelle/) // @r exists@ local idexpression x; expression E; @@ if (x == NULL || …) { … when forall return …; } .. when != \(x=E\|x–\|x++\|–x\|++x\|x-=E\|x+=E\|x|=E\|x&=E\|&x\) …