Re: [PATCH 2/2 net-next] ipv4: ipv4: handle devconf post-set actions on netlink updates

[Fernando Fernandez Mancera <fmancera@suse.de>]

On 3/25/26 5:10 PM, Fernando Fernandez Mancera wrote:
> When IPv4 device configuration parameters are updated via netlink, the
> kernel currently only updates the value. This bypasses several
> post-modification actions that occur when these same parameters are
> updated via sysctl, such as flushing the routing cache or emitting
> RTM_NEWNETCONF notifications.
> 
> This patch addresses the inconsistency by calling the
> devinet_conf_post_set() helper inside inet_set_link_af(). If a flush is
> required, we defer it until the netlink attribute parsing loop
> completes.
> 
> This ensures consistent behavior and side-effects for devconf changes,
> regardless of whether they are initiated via sysctl or netlink.
> 
> Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
> ---
>   net/ipv4/devinet.c | 22 ++++++++++++++++++++--
>   1 file changed, 20 insertions(+), 2 deletions(-)
> 
[...]
> @@ -2507,6 +2521,10 @@ static bool devinet_conf_post_set(struct net *net, struct ipv4_devconf *cnf,
>   		return false;
>   
>   	switch (attr) {
> +	case IPV4_DEVCONF_FORWARDING:
> +		if (new == 1)
> +			return true;
> +		break;

This is missing disabling LRO and also the proper netlink notification.

I will fix that on a V2. *facepalm* it does not matter how much I 
reviewed this, I missed that detail, sorry.

>   	case IPV4_DEVCONF_ROUTE_LOCALNET:
>   	case IPV4_DEVCONF_ACCEPT_LOCAL:
>   		if (new == 0)