linux-kernel - Re: [PATCH] selftests/net: initialize char variable to null

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Message-ID: <willemdebruijn.kernel.6edcbeb29a45@gmail.com>
Date: Mon, 24 Nov 2025 12:46:52 -0500
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Ankit Khushwaha <ankitkhushwaha.linux@...il.com>, 
 Willem de Bruijn <willemdebruijn.kernel@...il.com>, 
 Jason Xing <kernelxing@...cent.com>, 
 "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>, 
 Shuah Khan <shuah@...nel.org>
Cc: netdev@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 Ankit Khushwaha <ankitkhushwaha.linux@...il.com>
Subject: Re: [PATCH] selftests/net: initialize char variable to null

Ankit Khushwaha wrote:
> char variable in 'so_txtime.c' & 'txtimestamp.c' left uninitilized
> by when switch default case taken. raises following warning.
> 
> 	txtimestamp.c:240:2: warning: variable 'tsname' is used uninitialized
> 	whenever switch default is taken [-Wsometimes-uninitialized]
> 
> 	so_txtime.c:210:3: warning: variable 'reason' is used uninitialized
> 	whenever switch default is taken [-Wsometimes-uninitialized]
> 
> initialize these variables to NULL to fix this.
> 
> Signed-off-by: Ankit Khushwaha <ankitkhushwaha.linux@...il.com>

These are false positives as the default branches in both cases exit
the program with error(..).

Since we do not observe these in normal kernel compilations: are you
enabling non-standard warnings?

> ---
>  tools/testing/selftests/net/so_txtime.c   | 2 +-
>  tools/testing/selftests/net/txtimestamp.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/so_txtime.c b/tools/testing/selftests/net/so_txtime.c
> index 8457b7ccbc09..b76df1efc2ef 100644
> --- a/tools/testing/selftests/net/so_txtime.c
> +++ b/tools/testing/selftests/net/so_txtime.c
> @@ -174,7 +174,7 @@ static int do_recv_errqueue_timeout(int fdt)
>  	msg.msg_controllen = sizeof(control);
> 
>  	while (1) {
> -		const char *reason;
> +		const char *reason = NULL;
> 
>  		ret = recvmsg(fdt, &msg, MSG_ERRQUEUE);
>  		if (ret == -1 && errno == EAGAIN)
> diff --git a/tools/testing/selftests/net/txtimestamp.c b/tools/testing/selftests/net/txtimestamp.c
> index dae91eb97d69..bcc14688661d 100644
> --- a/tools/testing/selftests/net/txtimestamp.c
> +++ b/tools/testing/selftests/net/txtimestamp.c
> @@ -217,7 +217,7 @@ static void print_timestamp_usr(void)
>  static void print_timestamp(struct scm_timestamping *tss, int tstype,
>  			    int tskey, int payload_len)
>  {
> -	const char *tsname;
> +	const char *tsname = NULL;
> 
>  	validate_key(tskey, tstype);
> 
> --
> 2.52.0
>