Re: [PATCH] ipv6: Fix problem with expired dst cache

[Eric Dumazet <eric.dumazet@gmail.com>]

Le vendredi 24 février 2012 à 14:20 +0800, Gao feng a écrit :
> if the ipv6 dst cache copy from the dst witch generated by ICMPV6 RA packet.
> this dst cache will not be checked expire because it has no RTF_EXPIRES flag
> So this dst cache always be used until the dst gc run.
> 
> add a pointer in struct rt6_info,point to where the dst cache copy from.
> in func rt6_check_expired check if rt6->info->rt6i_copy is expired.
> 

Sorry, I really dont understand what you are saying.

Also, adding a pointer to a structure without holding a reference on it
is suspicious.

> Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
> ---
>  include/net/ip6_fib.h |    1 +
>  net/ipv6/route.c      |   16 ++++++++++++++--
>  2 files changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
> index b26bb81..3da4d58c 100644
> --- a/include/net/ip6_fib.h
> +++ b/include/net/ip6_fib.h
> @@ -106,6 +106,7 @@ struct rt6_info {
>  	u32				rt6i_metric;
>  	u32				rt6i_peer_genid;
>  
> +	struct rt6_info			*rt6i_copy;
>  	struct inet6_dev		*rt6i_idev;
>  	struct inet_peer		*rt6i_peer;
>  
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 8c2e3ab..939d06a 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -316,8 +316,15 @@ static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
>  
>  static __inline__ int rt6_check_expired(const struct rt6_info *rt)
>  {
> -	return (rt->rt6i_flags & RTF_EXPIRES) &&
> -		time_after(jiffies, rt->dst.expires);
> +	if ((rt->rt6i_flags & RTF_EXPIRES) &&
> +		time_after(jiffies, rt->dst.expires))
> +		return 1;
> +
> +	if (rt->rt6i_copy && (rt->rt6i_copy->rt6i_flags & RTF_EXPIRES) &&
> +		time_after(jiffies, rt->rt6i_copy->dst.expires))
> +		return 1;
> +
> +	return 0;
>  }
>  
>  static inline int rt6_need_strict(const struct in6_addr *daddr)
> @@ -1804,6 +1811,11 @@ static struct rt6_info *ip6_rt_copy(const struct rt6_info *ort,
>  		rt->rt6i_gateway = ort->rt6i_gateway;
>  		rt->rt6i_flags = ort->rt6i_flags & ~RTF_EXPIRES;
>  		rt->rt6i_metric = 0;
> +
> +		if (ort->rt6i_copy)
> +			rt->rt6i_copy = ort->rt6i_copy;
> +		else
> +			rt->rt6i_copy = ort;
>  
>  #ifdef CONFIG_IPV6_SUBTREES
>  		memcpy(&rt->rt6i_src, &ort->rt6i_src, sizeof(struct rt6key));