From: Lorenz Bauer <lmb@cloudflare.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Martin KaFai Lau <kafai@fb.com>, Shuah Khan <shuah@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
kernel-team <kernel-team@cloudflare.com>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next v2 2/4] selftests: bpf: Add helper to compare socket cookies
Date: Fri, 2 Oct 2020 11:08:04 +0100 [thread overview]
Message-ID: <CACAyw99ji02q3XngQS=KbRtebRipNU4P3kUbV1ULeVy64MA3mg@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQJQeiyrN2JzOwV+zHDU5xg4TtpT0w9MgG6nujCK5z+GNQ@mail.gmail.com>
On Thu, 1 Oct 2020 at 18:11, Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
> >
> > I think this might be the same problem I fixed for libbpf with [0].
> > Turns out, GCC explicitly calls out (somewhere in their docs) that
> > uninitialized variable warnings work only when compiled in optimized
> > mode, because some internal data structures used to detect this are
> > only maintained in optimized mode build.
> >
> > Laurenz, can you try compiling your example with -O2?
>
> All of my experiments I did with -O2.
If anybody wants to play with this more: https://godbolt.org/z/77P6P9
Seems like red hat GCC has some special sauce that fixes this behaviour?
--
Lorenz Bauer | Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK
www.cloudflare.com
next prev parent reply other threads:[~2020-10-02 10:08 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-28 9:08 [PATCH bpf-next v2 0/4] Sockmap copying Lorenz Bauer
2020-09-28 9:08 ` [PATCH bpf-next v2 1/4] bpf: sockmap: enable map_update_elem from bpf_iter Lorenz Bauer
2020-09-29 5:35 ` Martin KaFai Lau
2020-09-28 9:08 ` [PATCH bpf-next v2 2/4] selftests: bpf: Add helper to compare socket cookies Lorenz Bauer
2020-09-29 5:59 ` Martin KaFai Lau
2020-09-29 15:48 ` Alexei Starovoitov
2020-09-30 9:28 ` Lorenz Bauer
2020-10-01 7:23 ` Alexei Starovoitov
2020-10-01 17:09 ` Andrii Nakryiko
2020-10-01 17:11 ` Alexei Starovoitov
2020-10-02 10:08 ` Lorenz Bauer [this message]
2020-09-28 9:08 ` [PATCH bpf-next v2 3/4] selftests: bpf: remove shared header from sockmap iter test Lorenz Bauer
2020-09-28 9:08 ` [PATCH bpf-next v2 4/4] selftest: bpf: Test copying a sockmap and sockhash Lorenz Bauer
2020-09-29 6:06 ` Martin KaFai Lau
2020-09-29 9:21 ` Lorenz Bauer
2020-09-29 17:23 ` Martin KaFai Lau
2020-09-30 9:37 ` Lorenz Bauer
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