Re: [PATCH v4 bpf-next 0/7] Fix, clean up, and revamp selftests/bpf Makefile

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Jakub Sitnicki <jakub@cloudflare.com>
Cc: Andrii Nakryiko <andriin@fb.com>, bpf <bpf@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	Alexei Starovoitov <ast@fb.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v4 bpf-next 0/7] Fix, clean up, and revamp selftests/bpf Makefile
Date: Wed, 16 Oct 2019 23:52:31 -0700	[thread overview]
Message-ID: <CAEf4BzZaSznrp0xLZ6Skpt3yuompUJU6XV863zSOPQfq4VL-UA@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQJKESit7tDy0atn0-Q7Se=kLhkCWGAmRPJSVPdNAS8BVg@mail.gmail.com>

On Wed, Oct 16, 2019 at 9:28 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Wed, Oct 16, 2019 at 4:49 AM Andrii Nakryiko <andriin@fb.com> wrote:
> >
> > This patch set extensively revamps selftests/bpf's Makefile to generalize test
> > runner concept and apply it uniformly to test_maps and test_progs test
> > runners, along with test_progs' few build "flavors", exercising various ways
> > to build BPF programs.
> >
> > As we do that, we fix dependencies between various phases of test runners, and
> > simplify some one-off rules and dependencies currently present in Makefile.
> > test_progs' flavors are now built into root $(OUTPUT) directory and can be run
> > without any extra steps right from there. E.g., test_progs-alu32 is built and
> > is supposed to be run from $(OUTPUT). It will cd into alu32/ subdirectory to
> > load correct set of BPF object files (which are different from the ones built
> > for test_progs).
> >
> > Outline:
> > - patch #1 teaches test_progs about flavor sub-directories;
> > - patch #2 fixes one of CO-RE tests to not depend strictly on process name;
> > - patch #3 changes test_maps's usage of map_tests/tests.h to be the same as
> >   test_progs' one;
> > - patch #4 adds convenient short `make test_progs`-like targets to build only
> >   individual tests, if necessary;
> > - patch #5 is a main patch in the series; it uses a bunch of make magic
> >   (mainly $(call) and $(eval)) to define test runner "skeleton" and apply it
> >   to 4 different test runners, lots more details in corresponding commit
> >   description;
> > - patch #6 does a bit of post-clean up for test_queue_map and test_stack_map
> >   BPF programs;
> > - patch #7 cleans up test_libbpf.sh/test_libbpf_open superseded by test_progs.
> >
> > v3->v4:
> > - remove accidentally checked in binaries;
>
> something really odd here.
> Before the patchset ./test_progs -n 27 passes
> after the patch it simply hangs.
> Though strace -f ./test_progs -n 27 passes.
> Any idea?

Interesting. For me test_progs -n27 passes by itself, whether with or
without Makefile changes. But when run together with #8
flow_dissector_reattach, it fails with
"(prog_tests/sockopt_inherit.c:28: errno: Network is unreachable) Fail
to connect to server", even without Makefile changes. It doesn't hang,
but the test has server and client threads being coordinated, so I
wouldn't be surprised that under some specific timing and error
conditions it can hang.

I bisected this failure to f97eea1756f3 ("selftests/bpf: Check that
flow dissector can be re-attached"), that's when
flow_dissector_reattach test was added. So apparently there is some
bad interaction there.

So I suspect my Makefile changes have nothing to do with this, it
would be really bizarre...

Jakub, do you mind checking as well?