Re: [PATCH net-next v2] ipv6: make IPV6_FREEBIND and IPV6_TRANSPARENT setsockopt lockless

[Hangbin Liu <hangbin.liu@linux.dev>]

On Sat, Sep 12, 2026 at 09:40:40PM +0800, Xuanqiang Luo wrote:
> From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
> 
> IPV6_FREEBIND and IPV6_TRANSPARENT still take the socket lock despite
> using inet_assign_bit() to update the flags shared with IP_FREEBIND
> and IP_TRANSPARENT. IPv6 TCP and UDP sockets can already update these
> flags without the lock through the corresponding SOL_IP options.
> 
> Move both options to the lockless setsockopt path.
> 
> Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
> ---
> Changes:
> v2:
>   - Squash the two patches into one and drop the cover letter.
>     (Eric Dumazet.)
> 
> v1: https://lore.kernel.org/all/20260911102418.157071-1-xuanqiang.luo@linux.dev/
> 
>  net/ipv6/ipv6_sockglue.c | 36 +++++++++++++++---------------------
>  1 file changed, 15 insertions(+), 21 deletions(-)
> 
> diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
> index 1f68fb64a43ef..4b3536571c980 100644
> --- a/net/ipv6/ipv6_sockglue.c
> +++ b/net/ipv6/ipv6_sockglue.c
> @@ -398,6 +398,21 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
>  
>  	/* Handle options that can be set without locking the socket. */
>  	switch (optname) {
> +	case IPV6_FREEBIND:
> +		if (optlen < sizeof(int))
> +			return -EINVAL;
> +		/* Shared with IP_FREEBIND. */
> +		inet_assign_bit(FREEBIND, sk, valbool);
> +		return 0;
> +	case IPV6_TRANSPARENT:
> +		if (valbool && !sockopt_ns_capable(net->user_ns, CAP_NET_RAW) &&
> +		    !sockopt_ns_capable(net->user_ns, CAP_NET_ADMIN))
> +			return -EPERM;
> +		if (optlen < sizeof(int))
> +			return -EINVAL;
> +		/* Shared with IP_TRANSPARENT. */
> +		inet_assign_bit(TRANSPARENT, sk, valbool);
> +		return 0;
>  	case IPV6_UNICAST_HOPS:
>  		if (optlen < sizeof(int))
>  			return -EINVAL;
> @@ -666,27 +681,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
>  		retv = 0;
>  		break;
>  
> -	case IPV6_TRANSPARENT:
> -		if (valbool && !sockopt_ns_capable(net->user_ns, CAP_NET_RAW) &&
> -		    !sockopt_ns_capable(net->user_ns, CAP_NET_ADMIN)) {
> -			retv = -EPERM;
> -			break;
> -		}
> -		if (optlen < sizeof(int))
> -			goto e_inval;
> -		/* we don't have a separate transparent bit for IPV6 we use the one in the IPv4 socket */
> -		inet_assign_bit(TRANSPARENT, sk, valbool);
> -		retv = 0;
> -		break;
> -
> -	case IPV6_FREEBIND:
> -		if (optlen < sizeof(int))
> -			goto e_inval;
> -		/* we also don't have a separate freebind bit for IPV6 */
> -		inet_assign_bit(FREEBIND, sk, valbool);
> -		retv = 0;
> -		break;
> -
>  	case IPV6_RECVORIGDSTADDR:
>  		if (optlen < sizeof(int))
>  			goto e_inval;
> 
> base-commit: 348ea4642f56ab3dc93621c8e3ab0ccd0e5f1782
> -- 
> 2.43.0
> 

Reviewed-by: Hangbin Liu <liuhangbin@kylinos.cn>