netdev - Re: [PATCH net-next] tcp: increase size at which tcp_bound_to_half_wnd bounds to > TCP_MSS

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Date:	Wed, 29 Jun 2016 00:35:42 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	"Seymour, Shane M" <shane.seymour@....com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] tcp: increase size at which
 tcp_bound_to_half_wnd bounds to > TCP_MSS_DEFAULT

On Tue, 2016-06-28 at 21:54 +0000, Seymour, Shane M wrote:
> > From: Eric Dumazet [mailto:eric.dumazet@...il.com]
> > Trying to cope with ridiculous windows these days is really a waste of
> > time, as we perform this check for all tcp sendmsg() calls :(
> 
> I don't disagree with you but unfortunately there are still devices
> out there like this and probably will be for a long time.
> 
> > Anyway, your patch is reversed.
> 
> I'm not sure what you mean by reversed, I didn't change the direction
> of the test in the code just what it's being compared against and so
> it's greater than not greater than or equal to.
> 
> Unless auto-correction changed reviewed to reversed?

Your diff is reversed. You sent :

--- b/include/net/tcp.h 2016-06-23 20:59:14.521686048 -0500
+++ a/include/net/tcp.h 2016-06-15 17:19:21.964821477 -0500
@@ -589,7 +589,7 @@ static inline int tcp_bound_to_half_wnd(
         * On the other hand, for extremely large MSS devices, handling
         * smaller than MSS windows in this way does make sense.
         */
-       if (tp->max_window > TCP_MSS_DEFAULT)
+       if (tp->max_window >= 512)
                cutoff = (tp->max_window >> 1);
        else
                cutoff = tp->max_window;



You meant instead :

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 0bcc70f4e1fb..8dafd2c31b1d 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -589,7 +589,7 @@ static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
 	 * On the other hand, for extremely large MSS devices, handling
 	 * smaller than MSS windows in this way does make sense.
 	 */
-	if (tp->max_window >= 512)
+	if (tp->max_window > TCP_MSS_DEFAULT)
 		cutoff = (tp->max_window >> 1);
 	else
 		cutoff = tp->max_window;