netdev - Re: [PATCH net-next 1/6] ipv4: route: Ignore output interface in FIB lookup for PMTU route

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Message-ID: <26681884-43fa-65b7-4832-ef9d757e8c0b@gmail.com>
Date:   Mon, 3 Aug 2020 17:30:46 -0600
From:   David Ahern <dsahern@...il.com>
To:     Stefano Brivio <sbrivio@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Florian Westphal <fw@...len.de>, Aaron Conole <aconole@...hat.com>,
        Numan Siddique <nusiddiq@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Pravin B Shelar <pshelar@....org>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        Lourdes Pedrajas <lu@...o.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next 1/6] ipv4: route: Ignore output interface in FIB
 lookup for PMTU route

On 8/3/20 2:52 PM, Stefano Brivio wrote:
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index a01efa062f6b..c14fd8124f57 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -1050,6 +1050,7 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
>  	struct flowi4 fl4;
>  
>  	ip_rt_build_flow_key(&fl4, sk, skb);
> +	fl4.flowi4_oif = 0;	/* Don't make lookup fail for encapsulations */
>  	__ip_rt_update_pmtu(rt, &fl4, mtu);
>  }
>  
> 

Can this be limited to:
	if (skb &&
	    netif_is_bridge_port(skb->dev) || netif_is_ovs_port(skb->dev))
		fl4.flowi4_oif = 0;

I'm not sure we want to reset oif for all MTU updates.