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

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Message-ID: <5e77a6d0-3841-0de6-fd6d-6e6763f575bf@iogearbox.net>
Date:   Mon, 31 Aug 2020 16:59:28 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Tony Ambardar <tony.ambardar@...il.com>,
        Alexei Starovoitov <ast@...nel.org>
Cc:     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 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!