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Date:   Tue, 27 Sep 2022 07:21:30 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Hangbin Liu <liuhangbin@gmail.com>
Cc:     netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Ido Schimmel <idosch@nvidia.com>,
        Petr Machata <petrm@nvidia.com>,
        Florent Fourcot <florent.fourcot@wifirst.fr>,
        Nikolay Aleksandrov <razor@blackwall.org>,
        Nicolas Dichtel <nicolas.dichtel@6wind.com>,
        Guillaume Nault <gnault@redhat.com>,
        David Ahern <dsahern@kernel.org>
Subject: Re: [PATCHv3 net-next] rtnetlink: Honour NLM_F_ECHO flag in
 rtnl_{new, set, del}link
Message-ID: <20220927072130.6d5204a3@kernel.org>
In-Reply-To: <20220927041303.152877-1-liuhangbin@gmail.com>
References: <20220927041303.152877-1-liuhangbin@gmail.com>
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On Tue, 27 Sep 2022 12:13:03 +0800 Hangbin Liu wrote:
> @@ -3382,6 +3401,12 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
>  		if (err)
>  			goto out_unregister;
>  	}
> +
> +	nskb = rtmsg_ifinfo_build_skb(RTM_NEWLINK, dev, 0, 0, GFP_KERNEL, NULL,
> +				      0, pid, nlh->nlmsg_seq);
> +	if (nskb)
> +		rtnl_notify(nskb, dev_net(dev), pid, RTNLGRP_LINK, nlh, GFP_KERNEL);
> +
>  out:
>  	if (link_net)
>  		put_net(link_net);

I'm surprised you're adding new notifications. Does the kernel not
already notify about new links? I thought rtnl_newlink_create() ->
rtnl_configure_link() -> __dev_notify_flags() sends a notification,
already.