On Fri, 10 Jan 2020 at 16:30, Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote:
>
> Björn Töpel <bjorn.topel@xxxxxxxxx> writes:
>
[...]
> >
> > After these changes, does the noinline (commit 47b123ed9e99 ("xdp:
> > split code for map vs non-map redirect")) still make sense?
>
> Hmm, good question. The two code paths are certainly close to one
> another; and I guess they could be consolidated further.
>
> The best case would be if we had a way to lookup the ifindex directly in
> the helper. Do you know if there's a way to get the current net
> namespace from the helper? Can we use current->nsproxy->net_ns in that
> context?
>
Nope, interrupt context. :-( Another (ugly) way is adding a netns
member to the bpf_redirect_info, that is populated by the driver
(driver changes everywhere -- ick). So no.
(And *if* one would go the route of changing all drivers, I think the
percpu bpf_redirect_info should be replaced a by a context that is
passed from the driver to the XDP program execution and
xdp_do_redirect/flush. But that's a much bigger patch. :-))
Björn
> If we can, and if we don't mind merging the two different tracepoints,
> the xdp_do_redirect() function could be made quite a bit leaner...
>
> -Toke
>
