netdev - Re: [PATCH net-next, v2] netlink: add IGMP/MLD join/leave notifications

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Message-ID: <ZzxAqq-TqLts1o4V@fedora>
Date: Tue, 19 Nov 2024 07:39:22 +0000
From: Hangbin Liu <liuhangbin@...il.com>
To: Yuyang Huang <yuyanghuang@...gle.com>
Cc: "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>, David Ahern <dsahern@...nel.org>,
	roopa@...ulusnetworks.com, jiri@...nulli.us,
	stephen@...workplumber.org, jimictw@...gle.com, prohr@...gle.com,
	nicolas.dichtel@...nd.com, andrew@...n.ch, netdev@...r.kernel.org,
	Maciej Żenczykowski <maze@...gle.com>,
	Lorenzo Colitti <lorenzo@...gle.com>,
	Patrick Ruddy <pruddy@...tta.att-mail.com>
Subject: Re: [PATCH net-next, v2] netlink: add IGMP/MLD join/leave
 notifications

Hi Yuyang,
On Sun, Nov 17, 2024 at 11:11:37PM +0900, Yuyang Huang wrote:
> +static int inet_fill_ifmcaddr(struct sk_buff *skb, struct net_device *dev,
> +			      __be32 addr, int event)
> +{
> +	struct ifaddrmsg *ifm;
> +	struct nlmsghdr *nlh;
> +
> +	nlh = nlmsg_put(skb, 0, 0, event, sizeof(struct ifaddrmsg), 0);
> +	if (!nlh)
> +		return -EMSGSIZE;
> +
> +	ifm = nlmsg_data(nlh);
> +	ifm->ifa_family = AF_INET;
> +	ifm->ifa_prefixlen = 32;
> +	ifm->ifa_flags = IFA_F_PERMANENT;
> +	ifm->ifa_scope = RT_SCOPE_LINK;

Why the IPv4 scope use RT_SCOPE_LINK,

> +static int inet6_fill_ifmcaddr(struct sk_buff *skb, struct net_device *dev,
> +			       const struct in6_addr *addr, int event)
> +{
> +	struct ifaddrmsg *ifm;
> +	struct nlmsghdr *nlh;
> +	u8 scope;
> +
> +	scope = RT_SCOPE_UNIVERSE;
> +	if (ipv6_addr_scope(addr) & IFA_SITE)
> +		scope = RT_SCOPE_SITE;

And IPv6 use RT_SCOPE_UNIVERSE by default?

> +
> +	nlh = nlmsg_put(skb, 0, 0, event, sizeof(struct ifaddrmsg), 0);
> +	if (!nlh)
> +		return -EMSGSIZE;
> +
> +	ifm = nlmsg_data(nlh);
> +	ifm->ifa_family = AF_INET6;
> +	ifm->ifa_prefixlen = 128;
> +	ifm->ifa_flags = IFA_F_PERMANENT;
> +	ifm->ifa_scope = scope;
> +	ifm->ifa_index = dev->ifindex;
> +
> +static void inet6_ifmcaddr_notify(struct net_device *dev,
> +				  const struct in6_addr *addr, int event)
> +{
> +	struct net *net = dev_net(dev);
> +	struct sk_buff *skb;
> +	int err = -ENOBUFS;
> +
> +	skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg))
> +			+ nla_total_size(16), GFP_ATOMIC);
> +	if (!skb)
> +		goto error;
> +
> +	err = inet6_fill_ifmcaddr(skb, dev, addr, event);
> +	if (err < 0) {
> +		WARN_ON(err == -EMSGSIZE);

Not sure if we really need this WARN_ON. Wait for others comments.

Thanks
Hangbin