netdev - Re: [PATCH bpf v1] libbpf: fix build failure from uninitialized variable warning

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Message-ID: <CAPGftE9HxJG+3Lajk7x_+fTzjChNdu20R21H46dJVFq65pscDg@mail.gmail.com>
Date:   Wed, 2 Sep 2020 00:39:57 -0700
From:   Tony Ambardar <tony.ambardar@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andriin@...com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH bpf v1] libbpf: fix build failure from uninitialized
 variable warning

On Mon, 31 Aug 2020 at 07:59, Daniel Borkmann <daniel@...earbox.net> wrote:
>
> On 8/31/20 2:03 AM, Tony Ambardar wrote:
> > While compiling libbpf, some GCC versions (at least 8.4.0) have difficulty
> > determining control flow and a emit warning for potentially uninitialized
> > usage of 'map', which results in a build error if using "-Werror":
> >
> > In file included from libbpf.c:56:
> > libbpf.c: In function '__bpf_object__open':
> > libbpf_internal.h:59:2: warning: 'map' may be used uninitialized in this function [-Wmaybe-uninitialized]
> >    libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \
> >    ^~~~~~~~~~~~
> > libbpf.c:5032:18: note: 'map' was declared here
> >    struct bpf_map *map, *targ_map;
> >                    ^~~
> >
> > The warning/error is false based on code inspection, so silence it with a
> > NULL initialization.
> >
> > Fixes: 646f02ffdd49 ("libbpf: Add BTF-defined map-in-map support")
> > Ref: 063e68813391 ("libbpf: Fix false uninitialized variable warning")
> >
> > Signed-off-by: Tony Ambardar <Tony.Ambardar@...il.com>
>
> Applied, thanks!

Thanks, Daniel. I forgot to ask/confirm whether this will get applied
to the 5.8.x stable branch, since it was first encountered there.