netdev - Re: [PATCH net-next 1/3] ipv4: properly refresh rtable entries on pmtu/redirect events

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Date:	Tue, 28 May 2013 11:25:55 +0300 (EEST)
From:	Julian Anastasov <ja@....bg>
To:	Timo Teräs <timo.teras@....fi>
cc:	netdev@...r.kernel.org,
	Steffen Klassert <steffen.klassert@...unet.com>
Subject: Re: [PATCH net-next 1/3] ipv4: properly refresh rtable entries on
 pmtu/redirect events


	Hello,

On Tue, 28 May 2013, Timo Teräs wrote:

> This reverts commit 05ab86c5 (xfrm4: Invalidate all ipv4 routes on
> IPsec pmtu events). Flushing all cached entries is not needed.
> 
> Instead, invalidate only the related next hop dsts to recheck for
> the added next hop exception where needed. This also fixes a subtle
> race due to bumping generation id's before updating the pmtu.
> 
> Cc: Steffen Klassert <steffen.klassert@...unet.com>
> Signed-off-by: Timo Teräs <timo.teras@....fi>
> ---

> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index 550781a..561a378 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -594,11 +594,25 @@ static inline u32 fnhe_hashfun(__be32 daddr)
>  	return hval & (FNHE_HASH_SIZE - 1);
>  }
>  
> +static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
> +{
> +	rt->rt_pmtu = fnhe->fnhe_pmtu;
> +	rt->dst.expires = fnhe->fnhe_expires;

	The 'if (time_before' ... dst_set_expires() logic from
rt_bind_exception() is removed, may be it should be moved here,
i.e. fnhe_pmtu should be ignored if expired.

> @@ -627,8 +641,12 @@ static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
>  			fnhe->fnhe_gw = gw;
>  		if (pmtu) {
>  			fnhe->fnhe_pmtu = pmtu;
> -			fnhe->fnhe_expires = expires;
> +			fnhe->fnhe_expires = max(1UL, expires);
>  		}
> +		/* Update all cached dsts too */
> +		rt = rcu_dereference(fnhe->fnhe_rth);

	rt = rcu_dereference_protected(fnhe->fnhe_rth, 1);

Regards

--
Julian Anastasov <ja@....bg>