Subject: Re: [PATCH] make _minimum_ TCP retransmission timeout configurable take 2

From: Rick Jones <[email-masked]>
Date: Fri, 31 Aug 2007 15:20:52 -0700

David Miller wrote:
> From: Rick Jones <[email-masked]>
> Date: Fri, 31 Aug 2007 13:59:50 -0700
> 
> 
>>ip is at tcp_rto_min+0x20/0x40
> 
> 
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 1ee7212..bbad2cd 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -560,7 +560,7 @@ static u32 tcp_rto_min(struct sock *sk)
>  	struct dst_entry *dst = __sk_dst_get(sk);
>  	u32 rto_min = TCP_RTO_MIN;
>  
> -	if (dst_metric_locked(dst, RTAX_RTO_MIN))
> +	if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
>  		rto_min = dst->metrics[RTAX_RTO_MIN-1];
>  	return rto_min;
>  }

Applied and beating on it with a while loop doing a bunch of ip route 
del add change stuff while netperf TCP_CRR tests are running.  Thusfar 
things seem OK wrt the system staying alive, but since I only saw the 
failure once I'm not sure how much that is really saying.

I'm going to go ahead and take a look at input vs output units and 
differences between those with rto_min vs rtt.

rick jones