netdev - Re: [PATCH bpf-next] selftests/bpf: Fix uninitialized duration warning

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Message-ID: <20181112235132.ipml6ixhv6bswixw@kafai-mbp.dhcp.thefacebook.com>
Date:   Mon, 12 Nov 2018 23:51:34 +0000
From:   Martin Lau <kafai@...com>
To:     Joe Stringer <joe@...d.net.nz>
CC:     "daniel@...earbox.net" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next] selftests/bpf: Fix uninitialized duration
 warning

On Fri, Nov 09, 2018 at 10:18:16AM -0800, Joe Stringer wrote:
> Daniel Borkmann reports:
> 
> test_progs.c: In function ‘main’:
> test_progs.c:81:3: warning: ‘duration’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>    printf("%s:PASS:%s %d nsec\n", __func__, tag, duration);\
>    ^~~~~~
> test_progs.c:1706:8: note: ‘duration’ was declared here
>   __u32 duration;
>         ^~~~~~~~
> 
> Signed-off-by: Joe Stringer <joe@...d.net.nz>
I can repro with my locally compiled gcc 7.3.  It fixed the warning.

Acked-by: Martin KaFai Lau <kafai@...com>

> ---
> 
> I'm actually not able to reproduce this with GCC 7.3 or 8.2, so I'll
> rely on review to establish that this patch works as intended.
> ---
>  tools/testing/selftests/bpf/test_progs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
> index 2d3c04f45530..c1e688f61061 100644
> --- a/tools/testing/selftests/bpf/test_progs.c
> +++ b/tools/testing/selftests/bpf/test_progs.c
> @@ -1703,7 +1703,7 @@ static void test_reference_tracking()
>  	const char *file = "./test_sk_lookup_kern.o";
>  	struct bpf_object *obj;
>  	struct bpf_program *prog;
> -	__u32 duration;
> +	__u32 duration = 0;
>  	int err = 0;
>  
>  	obj = bpf_object__open(file);
> -- 
> 2.17.1
>