Subject: Re: [PATCH] selftest: net: fix socklen_t type mismatch in sctp_collision test

From: Simon Horman <[email-masked]>
Date: Tue, 28 Oct 2025 16:40:58 +0000

On Sun, Oct 26, 2025 at 11:16:49PM +0530, Ankit Khushwaha wrote:
> Socket APIs like recvfrom(), accept(), and getsockname() expect socklen_t*
> arg, but tests were using int variables. This causes -Wpointer-sign 
> warnings on platforms where socklen_t is unsigned.
> 
> Change the variable type from int to socklen_t to resolve the warning and
> ensure type safety across platforms.
> 
> warning fixed:
> 
> sctp_collision.c:62:70: warning: passing 'int *' to parameter of 
> type 'socklen_t *' (aka 'unsigned int *') converts between pointers to 
> integer types with different sign [-Wpointer-sign]
>    62 |                 ret = recvfrom(sd, buf, sizeof(buf), 
> 									0, (struct sockaddr *)&daddr, &len);
>       |                                                           ^~~~
> /usr/include/sys/socket.h:165:27: note: passing argument to 
> parameter '__addr_len' here
>   165 |                          socklen_t *__restrict __addr_len);
>       |                                                ^
> 
> Signed-off-by: Ankit Khushwaha <[email-masked]>
> ---
>  tools/testing/selftests/net/netfilter/sctp_collision.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/net/netfilter/sctp_collision.c b/tools/testing/selftests/net/netfilter/sctp_collision.c
> index 21bb1cfd8a85..91df996367e9 100644
> --- a/tools/testing/selftests/net/netfilter/sctp_collision.c
> +++ b/tools/testing/selftests/net/netfilter/sctp_collision.c
> @@ -9,7 +9,8 @@
>  int main(int argc, char *argv[])
>  {
>  	struct sockaddr_in saddr = {}, daddr = {};
> -	int sd, ret, len = sizeof(daddr);
> +	int sd, ret;
> +	socklen_t len = sizeof(daddr);
>  	struct timeval tv = {25, 0};
>  	char buf[] = "hello";

Hi Ankit,

Please preserve reverse xmas tree order - longest line to shortest - for
local variable declarations in Networking code.

In this case, I think that would be as follows (completely untested).

	struct sockaddr_in saddr = {}, daddr = {};
	socklen_t len = sizeof(daddr);
	struct timeval tv = {25, 0};
	char buf[] = "hello";
	int sd, ret;

...

-- 
pw-bot: changes-requested