Re: [PATCH net-next] tcp:elapsed variable calculated twice while keepalive working

[David Miller <davem@davemloft.net>]

From: Tingwei Liu <tingw.liu@gmail.com>
Date: Tue,  6 Aug 2013 20:38:58 +0800

> When tcp keepalive working elapsed calculated twice while the first time is not needed!
> 
> CC: Eric Dumazet <eric.dumazet@gmail.com>
> CC: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
> Signed-off-by: Tingwei Liu <tingw.liu@gmail.com>


Please put a space after "tcp:" in your Subject line prefixes, it looks
awful the way you've done it here.

> @@ -591,11 +591,11 @@ static void tcp_keepalive_timer (unsigned long data)
>  	if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE)
>  		goto out;
>  
> -	elapsed = keepalive_time_when(tp);
> -
>  	/* It is alive without keepalive 8) */
> -	if (tp->packets_out || tcp_send_head(sk))
> +	if (tp->packets_out || tcp_send_head(sk)) {
> +		elapsed = keepalive_time_when(tp);
>  		goto resched;
> +	}
>  
>  	elapsed = keepalive_time_elapsed(tp);

This is overkill, just delete the second assignment.  Your version makes
the code look less elegant and also makes it harder to audit.