genlmsg_cancel subtracts some constants from its second argument before
calling nlmsg_cancel. nlmsg_cancel then calls nlmsg_trim on the same
arguments. nlmsg_trim tests for NULL before doing any computation, but a
NULL second argument to genlmsg_cancel is no longer NULL due to the initial
subtraction. Nothing else happens in this execution, so the call to
genlmsg_cancel is simply unnecessary in this case.
The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@@
expression data;
@@
if (data == NULL) { ...
* genlmsg_cancel(..., data);
...
return ...;
}
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
efe1cf0c57