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

To: Julian Anastasov <ja@xxxxxx>
Subject: Re: [PATCH] ipvs: Fix reuse connection if real server is dead
Cc: Grzegorz Łyczba <grzegorz.lyczba@xxxxxxxxx>, lvs-devel@xxxxxxxxxxxxxxx
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Mon, 13 May 2013 10:38:52 +0900
On Sat, May 11, 2013 at 04:23:33PM +0300, Julian Anastasov wrote:
> 
>       Hello,
> 
> On Sat, 11 May 2013, Grzegorz Łyczba wrote:
> 
> > From: Grzegorz Lyczba <grzegorz.lyczba@xxxxxxxxx>
> > 
> > Expire cached connection for new TCP/SCTP connection if real server is down
> > 
> > Signed-off-by: Grzegorz Lyczba <grzegorz.lyczba@xxxxxxxxx>
> 
>       The change looks correct but you have to fix some
> coding style issues. Otherwise, patch will be rejected.
> You can also check Documentation/CodingStyle
> 
> # scripts/checkpatch.pl /tmp/patch.diff
> WARNING: braces {} are not necessary for single statement blocks
> #25: FILE: net/netfilter/ipvs/ip_vs_core.c:1012:
> +               if (th == NULL) {
> +                       return false;
> +               }
> 
> WARNING: braces {} are not necessary for single statement blocks
> #34: FILE: net/netfilter/ipvs/ip_vs_core.c:1021:
> +               if (sch == NULL) {
> +                       return false;
> +               }
> 
> total: 0 errors, 2 warnings, 48 lines checked
> 
> > ---
> >  net/netfilter/ipvs/ip_vs_core.c |   36 ++++++++++++++++++++++++++++++++++++
> >  1 files changed, 36 insertions(+), 0 deletions(-)
> > 
> > diff --git a/net/netfilter/ipvs/ip_vs_core.c 
> > b/net/netfilter/ipvs/ip_vs_core.c
> > index 47edf5a..9ee8b70 100644
> > --- a/net/netfilter/ipvs/ip_vs_core.c
> > +++ b/net/netfilter/ipvs/ip_vs_core.c
> > @@ -1002,6 +1002,33 @@ static inline int is_tcp_reset(const struct sk_buff 
> > *skb, int nh_len)
> >     return th->rst;
> >  }
> >  
> > +static inline bool is_new_conn(const struct sk_buff *skb,
> > +       struct ip_vs_iphdr *iph)
> 
>       Above "struct" should be at the same column as "const"
> in first argument, like this:
> 
> static inline bool is_new_conn(const struct sk_buff *skb,
>                              struct ip_vs_iphdr *iph)
> 
> > +{
> > +   switch (iph->protocol) {
> 
>       I'm still not sure if this construct is allowed:
> 
>       case ...: {
>       }

I see some evidence of the above style in net/core/
so personally I am fine with it.

> 
>       May be it should be:
> 
>       case ...:
>               {
>               }
>       case ...
> 
>       but CodingStyle does not include rules about it.
> If in doubt, you can use 'if' instead of 'switch' without
> adding new indentation.
> 
> > +   case IPPROTO_TCP: {
> > +           struct tcphdr _tcph, *th;
> 
>       empty line is needed here
> 
> > +           th = skb_header_pointer(skb, iph->len, sizeof(_tcph), &_tcph);
> > +           if (th == NULL) {
> > +                   return false;
> 
>       extra braces
> 
> > +           }
> > +           return th->syn;
> > +   }
> > +   case IPPROTO_SCTP: {
> > +           sctp_chunkhdr_t *sch, schunk;
> 
>       empty line is needed here
> 
> > +           sch = skb_header_pointer(skb, iph->len + sizeof(sctp_sctphdr_t),
> > +                           sizeof(schunk), &schunk);
> > +           if (sch == NULL) {
> > +                   return false;
> 
>       extra braces
> 
> > +           }
> > +           return (sch->type == SCTP_CID_INIT);
> > +   }
> > +   default:
> > +           return false;
> > +   }
> > +}
> > +
> > +
> >  /* Handle response packets: rewrite addresses and send away...
> >   */
> >  static unsigned int
> > @@ -1627,6 +1654,15 @@ 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 (unlikely(sysctl_expire_nodest_conn(ipvs)) && cp && cp->dest &&
> > +       !iph.fragoffs && unlikely(!atomic_read(&cp->dest->weight)) &&
> 
>       Lets move '!iph.fragoffs' after the
> 'unlikely(!atomic_read(&cp->dest->weight))' because fragoffs
> is usually 0. Only IPv6 can see fragments at that point.
> 
> > +       is_new_conn(skb, &iph)) {
> > +           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
> > -- 
> > 1.7.5.4
> 
> Regards
> 
> --
> Julian Anastasov <ja@xxxxxx>

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