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> > > -Toke
