Re: [PATCH] Invalidate expired persistance templates

[Roberto Nibali <ratz@xxxxxx>]

> 2.4 version as advertised.
>
>     [IPVS, 2.4] Ignore expired templates and cleanup expiry
>     
>     * Backport 2.6's behaviour to delete timers rather than
>     seting their expriy to 0 in ip_vs_conn_expire_now().
>     
>     * Give expired connections a nice short timeout.
>     3*HZ is arbitary, though it matches the timeout
>     that connections are given when they are created.
>     
>     * Mark expired connections with a new flag, IP_VS_CONN_F_EXPIRED.
This is simply brilliant! Atomic change without breaking anything as 
mentioned by Julian's concerns.
> diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> index ba304fa..ab16dbc 100644
> --- a/include/net/ip_vs.h
> +++ b/include/net/ip_vs.h
> @@ -83,6 +83,10 @@
>  #define IP_VS_CONN_F_SEQ_MASK         0x0600    /* in/out sequence mask */
>  #define IP_VS_CONN_F_NO_CPORT         0x0800    /* no client port set yet */
>  #define IP_VS_CONN_F_TEMPLATE         0x1000    /* template, not connection */
> +#define IP_VS_CONN_F_EXPIRED          0x2000    /* expired, currently used to
> +                                                  mark old templates whose
> +                                                  controlled connections are
> +                                                  yet to expire */
>  
>  /* Move it to better place one day, for now keep it unique */
>  #define NFC_IPVS_PROPERTY      0x10000
> diff --git a/net/ipv4/ipvs/ip_vs_conn.c b/net/ipv4/ipvs/ip_vs_conn.c
> index 015c819..ea3f778 100644
> --- a/net/ipv4/ipvs/ip_vs_conn.c
> +++ b/net/ipv4/ipvs/ip_vs_conn.c
> @@ -257,6 +257,7 @@ struct ip_vs_conn *ip_vs_ct_in_get
>                 if (s_addr==cp->caddr && s_port==cp->cport &&
>                     d_port==cp->vport && d_addr==cp->vaddr &&
>                     cp->flags & IP_VS_CONN_F_TEMPLATE &&
> +                   ! cp->flags & IP_VS_CONN_F_EXPIRED &&
>                     protocol==cp->protocol) {
>                         /* HIT */
>                         atomic_inc(&cp->refcnt);
> @@ -1221,10 +1222,9 @@ static void ip_vs_conn_expire(unsigned l
>  {
>         struct ip_vs_conn *cp = (struct ip_vs_conn *)data;
>  
> -	if (cp->timeout_table)
> -               cp->timeout = cp->timeout_table->timeout[IP_VS_S_TIME_WAIT];
> -       else
> -               cp->timeout = vs_timeout_table.timeout[IP_VS_S_TIME_WAIT];
> +       cp->timeout = 3*HZ;
> +       /* Only effects templates, but harmless for others */
> +       cp->flags |= IP_VS_CONN_F_EXPIRED;
Well, using this we can also leave the 60*HZ. Flagging the template as 
expired is a really great idea and should not break anything.
>  
>  	/*
>          *      hey, I'm using it
> @@ -1280,8 +1280,8 @@ static void ip_vs_conn_expire(unsigned l
>  
>  void ip_vs_conn_expire_now(struct ip_vs_conn *cp)
>  {
> -       cp->timeout = 0;
> -       mod_timer(&cp->timer, jiffies);
> +       if (del_timer(&cp->timer))
> +               mod_timer(&cp->timer, jiffies);
>  }
Similar to 2.6, right?

I'll include your patch as a hotfix to my local tree which needs to be 
released today.
Best regards and thanks for putting so much thinking into it,
Roberto Nibali, ratz
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