Subject: Re: [PATCH net-next] tuntap: Fallback to automq on TUNSETSTEERINGEBPF prog negative return

From: "Michael S. Tsirkin" <[email-masked]>
Date: Wed, 25 Sep 2019 06:33:43 -0400

On Sun, Sep 22, 2019 at 03:46:19PM -0700, Matt Cover wrote:
> Unless of course we can simply state via
> documentation that any negative return
> for which a define doesn't exist is
> undefined behavior. In which case,
> there is no old vs new behavior and
> no need for an ioctl. Simply the
> understanding provided by the
> documentation.

Unfortunately this isn't sufficient: software can easily return a wrong
value by mistake, and become dependent on an undefined behaviour.

-- 
MST