netdev - Re: [PATCH net-next v2 3/4] ipv6: use net->rt

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Date:	Mon, 10 Sep 2012 16:44:57 +0200
From:	Nicolas Dichtel <nicolas.dichtel@...nd.com>
To:	Vlad Yasevich <vyasevich@...il.com>
CC:	davem@...emloft.net, eric.dumazet@...il.com, sri@...ibm.com,
	linux-sctp@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2 3/4] ipv6: use net->rt_genid to check dst
 validity

Le 10/09/2012 16:43, Vlad Yasevich a écrit :
> On 09/10/2012 10:34 AM, Nicolas Dichtel wrote:
>> Le 10/09/2012 16:29, Vlad Yasevich a écrit :
>>> On 09/10/2012 09:22 AM, Nicolas Dichtel wrote:
>>>> IPv6 dst should take care of rt_genid too. When a xfrm policy is
>>>> inserted or
>>>> deleted, all dst should be invalidated.
>>>> To force the validation, dst entries should be created with
>>>> ->obsolete set to
>>>> DST_OBSOLETE_FORCE_CHK. This was already the case for all functions
>>>> calling
>>>> ip6_dst_alloc(), except for ip6_rt_copy().
>>>>
>>>> As a consequence, we can remove the specific code in
>>>> inet6_connection_sock.
>>>>
>>>> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
>>>> ---
>>>>   include/net/ip6_fib.h            |  2 +-
>>>>   net/ipv6/inet6_connection_sock.c | 23 +----------------------
>>>>   net/ipv6/route.c                 | 17 +++++++++++++----
>>>>   3 files changed, 15 insertions(+), 27 deletions(-)
>>>>
>>>> diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
>>>> index cd64cf3..5eb93f4 100644
>>>> --- a/include/net/ip6_fib.h
>>>> +++ b/include/net/ip6_fib.h
>>>> @@ -113,7 +113,7 @@ struct rt6_info {
>>>>       unsigned long            _rt6i_peer;
>>>>
>>>>   #ifdef CONFIG_XFRM
>>>> -    u32                rt6i_flow_cache_genid;
>>>> +    u32                rt6i_genid;
>>>>   #endif
>>>>       /* more non-fragment space at head required */
>>>>       unsigned short            rt6i_nfheader_len;
>>>> diff --git a/net/ipv6/inet6_connection_sock.c
>>>> b/net/ipv6/inet6_connection_sock.c
>>>> index 0251a60..c4f9341 100644
>>>> --- a/net/ipv6/inet6_connection_sock.c
>>>> +++ b/net/ipv6/inet6_connection_sock.c
>>>> @@ -175,33 +175,12 @@ void __inet6_csk_dst_store(struct sock *sk, struct
>>>> dst_entry *dst,
>>>>                  const struct in6_addr *saddr)
>>>>   {
>>>>       __ip6_dst_store(sk, dst, daddr, saddr);
>>>> -
>>>> -#ifdef CONFIG_XFRM
>>>> -    {
>>>> -        struct rt6_info *rt = (struct rt6_info  *)dst;
>>>> -        rt->rt6i_flow_cache_genid = atomic_read(&flow_cache_genid);
>>>> -    }
>>>> -#endif
>>>>   }
>>>>
>>>>   static inline
>>>>   struct dst_entry *__inet6_csk_dst_check(struct sock *sk, u32 cookie)
>>>>   {
>>>> -    struct dst_entry *dst;
>>>> -
>>>> -    dst = __sk_dst_check(sk, cookie);
>>>> -
>>>> -#ifdef CONFIG_XFRM
>>>> -    if (dst) {
>>>> -        struct rt6_info *rt = (struct rt6_info *)dst;
>>>> -        if (rt->rt6i_flow_cache_genid !=
>>>> atomic_read(&flow_cache_genid)) {
>>>> -            __sk_dst_reset(sk);
>>>> -            dst = NULL;
>>>> -        }
>>>> -    }
>>>> -#endif
>>>> -
>>>> -    return dst;
>>>> +    return __sk_dst_check(sk, cookie);
>>>>   }
>>>>
>>>>   static struct dst_entry *inet6_csk_route_socket(struct sock *sk,
>>>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>>>> index 339d921..db7b78f 100644
>>>> --- a/net/ipv6/route.c
>>>> +++ b/net/ipv6/route.c
>>>> @@ -281,13 +281,16 @@ static inline struct rt6_info
>>>> *ip6_dst_alloc(struct net
>>>> *net,
>>>>                            struct fib6_table *table)
>>>>   {
>>>>       struct rt6_info *rt = dst_alloc(&net->ipv6.ip6_dst_ops, dev,
>>>> -                    0, DST_OBSOLETE_NONE, flags);
>>>> +                    0, DST_OBSOLETE_FORCE_CHK, flags);
>>>>
>>>>       if (rt) {
>>>>           struct dst_entry *dst = &rt->dst;
>>>>
>>>>           memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst));
>>>>           rt6_init_peer(rt, table ? &table->tb6_peers :
>>>> net->ipv6.peers);
>>>> +#ifdef CONFIG_XFRM
>>>> +        rt->rt6i_genid = rt_genid(net);
>>>> +#endif
>>>
>>> This isn't XFRM dependent any more, is it?
>> Not dependent, but for IPv6, it's only usefull when xfrm is set. Goal of
>> this ifdef was to avoid the test if xfrm is not used.
>
> It's not the usage,  it's enable at build time and that's almost always on.  Now
> the cache behavior is different when XFRM is excluded from the kernel build.
>
> Before the ifdef was needed since you were actually looking at xfrm variable.
> Not anymore.   The ifdef doesn't make sense.
Ok, I will remove it.
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