Re: [PATCH bpf-next 2/2] xdp: Use bulking for non-map XDP_REDIRECT

Björn Töpel [off-list ref] writes:

On Fri, 10 Jan 2020 at 16:30, Toke Høiland-Jørgensen [off-list ref] wrote:

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Björn Töpel [off-list ref] writes:

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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.

Yup, that's what I thought. OK, too bad; I'll see what other
consolidation I can do with the current code, then.

(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. :-))

Yeah, let's leave that until the next time we figure out we have to
change all the drivers, then ;)

-Toke