Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH net-next v4] ipv6: add IFLA_INET6_RA_MTU to expose mtu
 value in the RA message
To:     Rocco Yue <rocco.yue@mediatek.com>,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, rocco.yue@gmail.com,
        chao.song@mediatek.com, zhuoliang.zhang@mediatek.com
References: <20210817072609.2110-1-rocco.yue@mediatek.com>
From:   David Ahern <dsahern@gmail.com>
Message-ID: <ad32c931-3056-cdef-4b9b-aab654c61cb9@gmail.com>
Date:   Tue, 17 Aug 2021 09:05:36 -0600
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0)
 Gecko/20100101 Thunderbird/78.12.0
MIME-Version: 1.0
In-Reply-To: <20210817072609.2110-1-rocco.yue@mediatek.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 8/17/21 1:26 AM, Rocco Yue wrote:
> @@ -1496,6 +1490,11 @@ static void ndisc_router_discovery(struct sk_buff *skb)
>  		memcpy(&n, ((u8 *)(ndopts.nd_opts_mtu+1))+2, sizeof(mtu));
>  		mtu = ntohl(n);
>  
> +		if (in6_dev->ra_mtu != mtu) {
> +			in6_dev->ra_mtu = mtu;
> +			send_ifinfo_notify = true;
> +		}
> +
>  		if (mtu < IPV6_MIN_MTU || mtu > skb->dev->mtu) {
>  			ND_PRINTK(2, warn, "RA: invalid mtu: %d\n", mtu);
>  		} else if (in6_dev->cnf.mtu6 != mtu) {


If an RA no longer carries an MTU or if accept_ra_mtu is reset, then
in6_dev->ra_mtu should be reset to 0 right?

rest of the change looks good to me.