On Thu, May 28, 2020 at 3:40 PM David Ahern <dsah...@gmail.com> wrote:
>
> On 5/28/20 1:01 AM, Andrii Nakryiko wrote:
> >
> > Please cc b...@vger.kernel.org in the future for patches related to BPF
> > in general.
>
> added to my script
>
> >
> >> include/linux/bpf.h | 5 +++
> >> include/uapi/linux/bpf.h | 5 +++
> >> kernel/bpf/devmap.c | 79 +++++++++++++++++++++++++++++++++-
> >> net/core/dev.c | 18 ++++++++
> >> tools/include/uapi/linux/bpf.h | 5 +++
> >> 5 files changed, 110 insertions(+), 2 deletions(-)
> >>
> >
> > [...]
> >
> >>
> >> +static struct xdp_buff *dev_map_run_prog(struct net_device *dev,
> >> + struct xdp_buff *xdp,
> >> + struct bpf_prog *xdp_prog)
> >> +{
> >> + u32 act;
> >> +
> >> + act = bpf_prog_run_xdp(xdp_prog, xdp);
> >> + switch (act) {
> >> + case XDP_DROP:
> >> + fallthrough;
> >
> > nit: I don't think fallthrough is necessary for cases like:
> >
> > case XDP_DROP:
> > case XDP_PASS:
> > /* do something */
> >
> >> + case XDP_PASS:
> >> + break;
> >> + default:
> >> + bpf_warn_invalid_xdp_action(act);
> >> + fallthrough;
> >> + case XDP_ABORTED:
> >> + trace_xdp_exception(dev, xdp_prog, act);
> >> + act = XDP_DROP;
> >> + break;
> >> + }
> >> +
> >> + if (act == XDP_DROP) {
> >> + xdp_return_buff(xdp);
> >> + xdp = NULL;
> >
> > hm.. if you move XDP_DROP case to after XDP_ABORTED and do fallthrough
> > from XDP_ABORTED, you won't even need to override act and it will just
> > handle all the cases, no?
> >
> > switch (act) {
> > case XDP_PASS:
> > return xdp;
> > default:
> > bpf_warn_invalid_xdp_action(act);
> > fallthrough;
> > case XDP_ABORTED:
> > trace_xdp_exception(dev, xdp_prog, act);
> > fallthrough;
> > case XDP_DROP:
> > xdp_return_buff(xdp);
> > return NULL;
> > }
> >
> > Wouldn't this be simpler?
> >
>
> Switched it to this which captures your intent with a more traditional
> return location.
>
> act = bpf_prog_run_xdp(xdp_prog, xdp);
> switch (act) {
> case XDP_PASS:
> return xdp;
> case XDP_DROP:
> break;
> default:
> bpf_warn_invalid_xdp_action(act);
> fallthrough;
> case XDP_ABORTED:
> trace_xdp_exception(dev, xdp_prog, act);
> break;
> }
>
> xdp_return_buff(xdp);
> return NULL;
looks good as well, thanks
