| Message ID | 20200924171705.3803628-1-andriin@fb.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf] libbpf: fix XDP program load regression for old kernels | expand |
On Thu, Sep 24, 2020 at 10:18 AM Andrii Nakryiko <andriin@fb.com> wrote: > > Fix regression in libbpf, introduced by XDP link change, which causes XDP > programs to fail to be loaded into kernel due to specified BPF_XDP > expected_attach_type. While kernel doesn't enforce expected_attach_type for > BPF_PROG_TYPE_XDP, some old kernels already support XDP program, but they > don't yet recognize expected_attach_type field in bpf_attr, so setting it to > non-zero value causes program load to fail. > > Luckily, libbpf already has a mechanism to deal with such cases, so just make > expected_attach_type optional for XDP programs. > > Reported-by: Nikita Shirokov <tehnerd@tehnerd.com> > Reported-by: Udip Pant <udippant@fb.com> > Fixes: dc8698cac7aa ("libbpf: Add support for BPF XDP link") > Signed-off-by: Andrii Nakryiko <andriin@fb.com> Applied. Thanks Looks like libbpf CI needs to add a few old kernels.
On Thu, Sep 24, 2020 at 10:34 AM Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote: > > On Thu, Sep 24, 2020 at 10:18 AM Andrii Nakryiko <andriin@fb.com> wrote: > > > > Fix regression in libbpf, introduced by XDP link change, which causes XDP > > programs to fail to be loaded into kernel due to specified BPF_XDP > > expected_attach_type. While kernel doesn't enforce expected_attach_type for > > BPF_PROG_TYPE_XDP, some old kernels already support XDP program, but they > > don't yet recognize expected_attach_type field in bpf_attr, so setting it to > > non-zero value causes program load to fail. > > > > Luckily, libbpf already has a mechanism to deal with such cases, so just make > > expected_attach_type optional for XDP programs. > > > > Reported-by: Nikita Shirokov <tehnerd@tehnerd.com> > > Reported-by: Udip Pant <udippant@fb.com> > > Fixes: dc8698cac7aa ("libbpf: Add support for BPF XDP link") > > Signed-off-by: Andrii Nakryiko <andriin@fb.com> > > Applied. Thanks Thanks! > > Looks like libbpf CI needs to add a few old kernels. Yeah. We have 4.9 which is very old and only a few selftests can even succeed there. Then we jump to 5.5, which is too recent to detect this issue. This issue happened on 4.15, would that be a good version to stick to? Any opinions?
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 7253b833576c..e493d6048143 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -6925,7 +6925,7 @@ static const struct bpf_sec_def section_defs[] = { BPF_XDP_DEVMAP), BPF_EAPROG_SEC("xdp_cpumap/", BPF_PROG_TYPE_XDP, BPF_XDP_CPUMAP), - BPF_EAPROG_SEC("xdp", BPF_PROG_TYPE_XDP, + BPF_APROG_SEC("xdp", BPF_PROG_TYPE_XDP, BPF_XDP), BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT), BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN),
Fix regression in libbpf, introduced by XDP link change, which causes XDP programs to fail to be loaded into kernel due to specified BPF_XDP expected_attach_type. While kernel doesn't enforce expected_attach_type for BPF_PROG_TYPE_XDP, some old kernels already support XDP program, but they don't yet recognize expected_attach_type field in bpf_attr, so setting it to non-zero value causes program load to fail. Luckily, libbpf already has a mechanism to deal with such cases, so just make expected_attach_type optional for XDP programs. Reported-by: Nikita Shirokov <tehnerd@tehnerd.com> Reported-by: Udip Pant <udippant@fb.com> Fixes: dc8698cac7aa ("libbpf: Add support for BPF XDP link") Signed-off-by: Andrii Nakryiko <andriin@fb.com> --- tools/lib/bpf/libbpf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)