On Fri, 9 Mar 2018 15:16:35 +0800
Jason Wang <jasow...@redhat.com> wrote:
> On 2018年03月08日 23:16, Jesper Dangaard Brouer wrote:
> > Hi Jason,
> >
> > Please see below FIXME, which is actually a question to you.
> >
> > On Thu, 08 Mar 2018 14:08:11 +0100 Jesper Dangaard Brouer
> > <bro...@redhat.com> wrote:
> >
> >> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> >> index 475088f947bb..cd046cf31b77 100644
> >> --- a/drivers/net/tun.c
> >> +++ b/drivers/net/tun.c
> > [...]
> >
> >> @@ -1290,17 +1290,18 @@ static const struct net_device_ops tun_netdev_ops
> >> = {
> >> static int tun_xdp_xmit(struct net_device *dev, struct xdp_buff *xdp)
> >> {
> >> struct tun_struct *tun = netdev_priv(dev);
> >> - struct xdp_buff *buff = xdp->data_hard_start;
> >> - int headroom = xdp->data - xdp->data_hard_start;
> >> + struct xdp_frame *frame;
> >> struct tun_file *tfile;
> >> u32 numqueues;
> >> int ret = 0;
> >>
> >> - /* Assure headroom is available and buff is properly aligned */
> >> - if (unlikely(headroom < sizeof(*xdp) || tun_is_xdp_buff(xdp)))
> >> - return -ENOSPC;
> >> + /* FIXME: Explain why this check is the needed! */
> >> + if (unlikely(tun_is_xdp_frame(xdp)))
> >> + return -EBADRQC;
> >>
> >> - *buff = *xdp;
> >> + frame = convert_to_xdp_frame(xdp);
> >> + if (unlikely(!frame))
> >> + return -EOVERFLOW;
> > To Jason, in the FIXME, I'm inheriting a check you put in, but I don't
> > understand why this check was needed?
> >
>
> Sorry for the late reply.
>
> I think it was used to make sure to not use misaligned or invalid
> pointer that caller passed to us.
Okay, but I don't think this can happen, thus I'm going to remove this
check in V3.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
