linux-kernel - Re: [PATCH] libbpf: Initialize err in probe_map

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Date:   Mon, 1 Aug 2022 18:25:07 +0200
From:   Jiri Olsa <olsajiri@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     bpf@...r.kernel.org, Andrii Nakryiko <andrii@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>,
        Dave Marchevsky <davemarchevsky@...com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] libbpf: Initialize err in probe_map_create

On Sun, Jul 31, 2022 at 07:51:09PM -0700, Florian Fainelli wrote:
> GCC-11 warns about the possibly unitialized err variable in
> probe_map_create:
> 
> libbpf_probes.c: In function 'probe_map_create':
> libbpf_probes.c:361:38: error: 'err' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>   361 |                 return fd < 0 && err == exp_err ? 1 : 0;
>       |                                  ~~~~^~~~~~~~~~
> 
> Fixes: 878d8def0603 ("libbpf: Rework feature-probing APIs")
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>

Acked-by: Jiri Olsa <jolsa@...nel.org>

jirka

> ---
>  tools/lib/bpf/libbpf_probes.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
> index 97b06cede56f..6cf44e61815d 100644
> --- a/tools/lib/bpf/libbpf_probes.c
> +++ b/tools/lib/bpf/libbpf_probes.c
> @@ -247,7 +247,7 @@ static int probe_map_create(enum bpf_map_type map_type, __u32 ifindex)
>  	LIBBPF_OPTS(bpf_map_create_opts, opts);
>  	int key_size, value_size, max_entries;
>  	__u32 btf_key_type_id = 0, btf_value_type_id = 0;
> -	int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err;
> +	int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0;
>  
>  	opts.map_ifindex = ifindex;
>  
> -- 
> 2.25.1
>