netdev - Re: [PATCH net-next v2] selftests: mptcp: Mark xerror _

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Message-ID: <632d57cf-becd-4d09-bb21-0e3db6776c49@kernel.org>
Date: Sat, 29 Nov 2025 19:13:08 +0100
From: Matthieu Baerts <matttbe@...nel.org>
To: Ankit Khushwaha <ankitkhushwaha.linux@...il.com>,
 Mat Martineau <martineau@...nel.org>, Geliang Tang <geliang@...nel.org>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Simon Horman <horms@...nel.org>
Cc: Shuah Khan <shuah@...nel.org>, netdev@...r.kernel.org,
 mptcp@...ts.linux.dev, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2] selftests: mptcp: Mark xerror __noreturn

Hi Ankit,

On 29/11/2025 05:38, Ankit Khushwaha wrote:
> Compiler reports potential uses of uninitialized variables in
> mptcp_connect.c when xerror() is called from failure paths.
> 
> mptcp_connect.c:1262:11: warning: variable 'raw_addr' is used
>       uninitialized whenever 'if' condition is false
>       [-Wsometimes-uninitialized]
> 
> xerror() terminates execution by calling exit(), but it is not visible
> to the compiler & assumes control flow may continue past the call.
> 
> Annotate xerror() with __noreturn so the compiler can correctly reason
> about control flow and avoid false-positive uninitialized variable
> warnings.
> 
> Signed-off-by: Ankit Khushwaha <ankitkhushwaha.linux@...il.com>
> ---
> changelog:
> v2: 
> - annotate 'xerror()' with __noreturn
> - remove defining 'raw_addr' to NULL

Thank you for the new version!

Note: this patch can target 'net' instead of 'net-next'.

> ---
>  tools/testing/selftests/net/mptcp/Makefile        | 4 ++++
>  tools/testing/selftests/net/mptcp/mptcp_connect.c | 3 ++-
>  tools/testing/selftests/net/mptcp/mptcp_inq.c     | 3 ++-
>  tools/testing/selftests/net/mptcp/mptcp_sockopt.c | 3 ++-

Good idea to fix the other tools too!

>  4 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/mptcp/Makefile b/tools/testing/selftests/net/mptcp/Makefile
> index 15d144a25d82..4c94c01b893a 100644
> --- a/tools/testing/selftests/net/mptcp/Makefile
> +++ b/tools/testing/selftests/net/mptcp/Makefile
> @@ -35,3 +35,7 @@ TEST_INCLUDES := ../lib.sh $(wildcard ../lib/sh/*.sh)
>  EXTRA_CLEAN := *.pcap
> 
>  include ../../lib.mk
> +
> +$(OUTPUT)/mptcp_connect: CFLAGS += -I$(top_srcdir)/tools/include
> +$(OUTPUT)/mptcp_sockopt: CFLAGS += -I$(top_srcdir)/tools/include
> +$(OUTPUT)/mptcp_inq: CFLAGS += -I$(top_srcdir)/tools/include

Small detail: I think you can simply append the "main" CFLAGS at the top
of the file instead of adding specific rules per tool.

Note: because the CFLAGS variable is already long, please split it like
it is done in tools/testing/selftests/net/Makefile.

While at it, do you mind adding __noreturn to die_perror() in
mptcp_diag.c mptcp_inq.c mptcp_sockopt.c as well please?

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.