On 10/30/24 9:31 AM, Matthieu Baerts wrote:
Hi Tao, BPF maintainers,
On 30/10/2024 12:12, Tao Chen wrote:
在 2024/10/30 18:49, Matthieu Baerts 写道:
Hi Tao Chen,
Thank you for having shared this patch.
On 30/10/2024 11:01, Tao Chen wrote:
Fix compile error when MPTCP feature not support, though eBPF core check
already done which seems invalid in this situation, the error info like:
progs/mptcp_sock.c:49:40: error: no member named 'is_mptcp' in 'struct
tcp_sock'
49 | is_mptcp = bpf_core_field_exists(tsk->is_mptcp) ?
The filed created in new definitions with eBPF core feature to solve
this build problem, and test case result still ok in MPTCP kernel.
176/1 mptcp/base:OK
176/2 mptcp/mptcpify:OK
176 mptcp:OK
Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED
Fixes: 8039d353217c ("selftests/bpf: Add MPTCP test base")
The commit you mentioned here is more than 2 years old, and as far as I
can see, nobody else reported this compilation issue. I guess that's
because people used tools/testing/selftests/bpf/config file as expected
to populate the kernel config, and I suppose you didn't, right?
Hi Matt, thank you for your reply, as you said, i did not use tools/
testing/selftests/bpf/config to compile kernel, i will use this helpful
feature.
I don't think other BPF selftests check for missing kernel config if
they are specified in the 'config' file, but even if it is the case, I
think it would be better to skip all the MPTCP tests, and not try to
have them checking something that doesn't exist: no need to validate
these tests if the expected kernel config has not been enabled.
If i use the kernel not support MPTCP, the compile error still exists,
and i can not build the bpf test successfully. Maybe skill the test case
seems better when kernel not support. Now that bpf_core_field_exists
check already used in the code, i think it is better to use new
definition mode.
I understand it would be better, but it means more code to maintain to
handle that (and remembering that in future test cases). If that's not
necessary, then no need to do the effort.
@BPF maintainers: do we need to support kernels not respecting the
tools/testing/selftests/bpf/config file? Should we detect when a
required kernel config is not set and skip some tests?
I guess it depends on the CONFIG_. Otherwise, it takes out the goodies of using
<vmlinux.h> when writing bpf selftests.
If fixing the config is an option and sounds like it is for Tao, then it is
always good to run everything in test_progs.
There are some "___local" definitions in the selftests. If mptcp test wants to
go this path, then Matt's request to at least test__skip() makes sense to me.
pw-bot: cr
But again, please correct me if I'm wrong, but I don't think there is
anything to change here to fix your compilation issue: simply make sure
to use this tools/testing/selftests/bpf/config file to generate your
kernel config, no?
Cheers,
Matt
