Andrii Nakryiko <andrii.nakry...@gmail.com> writes: > On Mon, Jun 24, 2019 at 12:38 PM Toke Høiland-Jørgensen <t...@redhat.com> > wrote: >> >> Andrii Nakryiko <andrii.nakry...@gmail.com> writes: >> >> > On Sat, Jun 22, 2019 at 7:19 PM Toke Høiland-Jørgensen <t...@redhat.com> >> > wrote: >> >> >> >> When using the bpf_redirect_map() helper to redirect packets from XDP, >> >> the eBPF >> >> program cannot currently know whether the redirect will succeed, which >> >> makes it >> >> impossible to gracefully handle errors. To properly fix this will probably >> >> require deeper changes to the way TX resources are allocated, but one >> >> thing that >> >> is fairly straight forward to fix is to allow lookups into devmaps, so >> >> programs >> >> can at least know when a redirect is *guaranteed* to fail because there >> >> is no >> >> entry in the map. Currently, programs work around this by keeping a >> >> shadow map >> >> of another type which indicates whether a map index is valid. >> >> >> >> This series contains two changes that are complementary ways to fix this >> >> issue: >> >> >> >> - Moving the map lookup into the bpf_redirect_map() helper (and caching >> >> the >> >> result), so the helper can return an error if no value is found in the >> >> map. >> >> This includes a refactoring of the devmap and cpumap code to not care >> >> about >> >> the index on enqueue. >> >> >> >> - Allowing regular lookups into devmaps from eBPF programs, using the >> >> read-only >> >> flag to make sure they don't change the values. >> >> >> >> The performance impact of the series is negligible, in the sense that I >> >> cannot >> >> measure it because the variance between test runs is higher than the >> >> difference >> >> pre/post series. >> >> >> >> Changelog: >> >> >> >> v5: >> >> - Rebase on latest bpf-next. >> >> - Update documentation for bpf_redirect_map() with the new meaning of >> >> flags. >> >> >> >> v4: >> >> - Fix a few nits from Andrii >> >> - Lose the #defines in bpf.h and just compare the flags argument >> >> directly to >> >> XDP_TX in bpf_xdp_redirect_map(). >> >> >> >> v3: >> >> - Adopt Jonathan's idea of using the lower two bits of the flag value >> >> as the >> >> return code. >> >> - Always do the lookup, and cache the result for use in >> >> xdp_do_redirect(); to >> >> achieve this, refactor the devmap and cpumap code to get rid the >> >> bitmap for >> >> selecting which devices to flush. >> >> >> >> v2: >> >> - For patch 1, make it clear that the change works for any map type. >> >> - For patch 2, just use the new BPF_F_RDONLY_PROG flag to make the >> >> return >> >> value read-only. >> >> >> >> --- >> >> >> >> Toke Høiland-Jørgensen (3): >> >> devmap/cpumap: Use flush list instead of bitmap >> >> bpf_xdp_redirect_map: Perform map lookup in eBPF helper >> >> devmap: Allow map lookups from eBPF >> >> >> >> >> >> include/linux/filter.h | 1 >> >> include/uapi/linux/bpf.h | 7 ++- >> >> kernel/bpf/cpumap.c | 106 >> >> ++++++++++++++++++++----------------------- >> >> kernel/bpf/devmap.c | 113 >> >> ++++++++++++++++++++++------------------------ >> >> kernel/bpf/verifier.c | 7 +-- >> >> net/core/filter.c | 29 +++++------- >> >> 6 files changed, 123 insertions(+), 140 deletions(-) >> >> >> > >> > >> > Looks like you forgot to add my Acked-by's for your patches? >> >> Ah yes, did not carry those forward for the individual patches, my >> apologies. Could you perhaps be persuaded to send a new one (I believe a >> response to the cover letter acking the whole series would suffice)? >> I'll make sure to add the carrying forward of acks into my workflow in >> the future :) > > I don't think patchworks captures ack's from cover letter, but let's > give it a go: > > Acked-by: Andrii Nakryiko <andr...@fb.com>
Thanks! -Toke
