Re: [PATCH] ipvs: Fix reuse connection if real server is dead

[Julian Anastasov <ja@xxxxxx>]

        Hello,

On Tue, 7 May 2013, Grzegorz Lyczba wrote:

> Expire cached connection for new TCP connection if real server is down
> 
> Signed-off-by: Grzegorz Lyczba <grzegorz.lyczba@xxxxxxxxx>
> ---
>  net/netfilter/ipvs/ip_vs_core.c |   20 ++++++++++++++++++++
>  1 files changed, 20 insertions(+), 0 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index 47edf5a..7c5f083 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -1002,6 +1002,17 @@ static inline int is_tcp_reset(const struct sk_buff 
> *skb, int nh_len)
>       return th->rst;
>  }
>  
> +static inline int is_tcp_syn(const struct sk_buff *skb, int nh_len)
> +{
> +    struct tcphdr _tcph, *th;
> +
> +    th = skb_header_pointer(skb, nh_len, sizeof(_tcph), &_tcph);

        As Hans notes, it is a good idea to support SCTP by
using the iph address as second argument. May be the func can
be named is_new_conn:

static inline bool is_new_conn(const struct sk_buff *skb,
                               struct ip_vs_iphdr *iph)
...

> +    if (th == NULL)
> +        return 0;
> +    return th->syn;
> +}
> +
> +
>  /* Handle response packets: rewrite addresses and send away...
>   */
>  static unsigned int
> @@ -1627,6 +1638,15 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb, 
> int af)
>        * Check if the packet belongs to an existing connection entry
>        */
>       cp = pp->conn_in_get(af, skb, &iph, 0);
> +
> +     if (likely(cp) && likely(cp->dest) &&

        I hope it is appropriate to use the expire_nodest_conn flag:

        if (unlikely(sysctl_expire_nodest_conn(ipvs) && cp && cp->dest &&
...

> +         unlikely(!atomic_read(&cp->dest->weight)) &&

        We should add '!iph.fragoffs &&' here.

> +         iph.protocol == IPPROTO_TCP && is_tcp_syn(skb, iph.len)) {
> +             ip_vs_conn_expire_now(cp);
> +             __ip_vs_conn_put(cp);
> +             cp = NULL;
> +     }
> +
>       if (unlikely(!cp) && !iph.fragoffs) {
>               /* No (second) fragments need to enter here, as nf_defrag_ipv6
>                * replayed fragment zero will already have created the cp

Regards

--
Julian Anastasov <ja@xxxxxx>
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