On Tue, Oct 30, 2018 at 11:59 AM Cong Wang [off-list ref] wrote:

I wonder how compiler recognizes it as "never fail" when marked with
__must_check.

__must_check means that you can not ignore the return value of a function.

Here we do use the return value.

Also prior code was not checking skb->length so really my patch does
add explicit
check if in the future skb->len gets wrong after a bug is added in this driver.

(A NULL deref will trap the bug, instead of potentially reading
garbage from skb->data)