Re: [PATCH net v4] ipv4: bump rt_genid when a relevant devconf value changes through netlink

[David Ahern <dsahern@kernel.org>]

On 3/13/26 8:45 AM, Fernando Fernandez Mancera wrote:
> diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
> index 537bb6c315d2..6dd8fd0a1323 100644
> --- a/net/ipv4/devinet.c
> +++ b/net/ipv4/devinet.c
> @@ -2107,8 +2109,33 @@ static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla,
>  		return -EINVAL;
>  
>  	if (tb[IFLA_INET_CONF]) {
> -		nla_for_each_nested(a, tb[IFLA_INET_CONF], rem)
> -			ipv4_devconf_set(in_dev, nla_type(a), nla_get_u32(a));
> +		nla_for_each_nested(a, tb[IFLA_INET_CONF], rem) {
> +			int new_value = (int)nla_get_u32(a);
> +
> +			if (ipv4_devconf_get(in_dev, nla_type(a)) == new_value)
> +				continue;
> +
> +			ipv4_devconf_set(in_dev, nla_type(a), new_value);
> +			switch (nla_type(a)) {
> +			case IPV4_DEVCONF_FORWARDING:
> +				if (new_value)
> +					netif_disable_lro(dev);
> +				fallthrough;
> +			case IPV4_DEVCONF_NOXFRM:
> +			case IPV4_DEVCONF_NOPOLICY:
> +			case IPV4_DEVCONF_PROMOTE_SECONDARIES:
> +			case IPV4_DEVCONF_ROUTE_LOCALNET:
> +			case IPV4_DEVCONF_DROP_UNICAST_IN_L2_MULTICAST:
> +			case IPV4_DEVCONF_BC_FORWARDING:
> +			case IPV4_DEVCONF_ACCEPT_LOCAL:
> +				flush_cache = true;
> +				break;
> +			default:
> +				break;
> +			}
> +		}
> +		if (flush_cache)
> +			rt_cache_flush(net);
>  	}
>  
>  	return 0;

This replicates logic in devinet_conf_proc for example. Why not refactor
devinet.c to handle changes to values in 1 place only.

Also, you are flushing the cache for more values than sysfs does.