netdev - Re: [PATCH] selftest: net: prevent use of uninitialized variable

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Message-ID: <aPjrPehLi14L9zuQ@horms.kernel.org>
Date: Wed, 22 Oct 2025 15:33:33 +0100
From: Simon Horman <horms@...nel.org>
To: Alessandro Zanni <alessandro.zanni87@...il.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, shuah@...nel.org, netdev@...r.kernel.org,
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftest: net: prevent use of uninitialized variable

On Tue, Oct 21, 2025 at 06:54:33PM +0200, Alessandro Zanni wrote:
> Fix to avoid the usage of the `ret` variable uninitialized in the
> following macro expansions.
> 
> It solves the following warning:
> 
> In file included from netlink-dumps.c:21:
> netlink-dumps.c: In function ‘dump_extack’:
> ../kselftest_harness.h:788:35: warning: ‘ret’ may be used uninitialized [-Wmaybe-uninitialized]
>   788 |                         intmax_t  __exp_print = (intmax_t)__exp; \
>       |                                   ^~~~~~~~~~~
> ../kselftest_harness.h:631:9: note: in expansion of macro ‘__EXPECT’
>   631 |         __EXPECT(expected, #expected, seen, #seen, ==, 0)
>       |         ^~~~~~~~
> netlink-dumps.c:169:9: note: in expansion of macro ‘EXPECT_EQ’
>   169 |         EXPECT_EQ(ret, FOUND_EXTACK);
>       |         ^~~~~~~~~
> 
> The issue can be reproduced, building the tests, with the command:
> make -C tools/testing/selftests TARGETS=net
> 
> Signed-off-by: Alessandro Zanni <alessandro.zanni87@...il.com>
> ---
>  tools/testing/selftests/net/netlink-dumps.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/net/netlink-dumps.c b/tools/testing/selftests/net/netlink-dumps.c
> index 7618ebe528a4..8ebb8b1b9c5c 100644
> --- a/tools/testing/selftests/net/netlink-dumps.c
> +++ b/tools/testing/selftests/net/netlink-dumps.c
> @@ -112,7 +112,7 @@ static const struct {
>  TEST(dump_extack)
>  {
>  	int netlink_sock;
> -	int i, cnt, ret;
> +	int i, cnt, ret = 0;

Hi Alessandro,

I suggest moving this line so that reverse xmas tree order - longest
line to shortest - is preserved.

>  	char buf[8192];
>  	int one = 1;
>  	ssize_t n;
> -- 
> 2.43.0
>