[PATCH nf-next 1/1] net: tcp: Refine the __tcp_select_window

[PATCH nf-next 1/1] net: tcp: Refine the __tcp_select_window

[gfree.wind]

From: Gao Feng <fgao@ikuai8.com>

1. Move the "window = tp->rcv_wnd;" into the condition block without
tp->rx_opt.rcv_wscale.
Because it is unnecessary when enable wscale;

2. Use the macro ALIGN instead of two statements.
The two statements are used to make window align to 1<<wscale.
Use the ALIGN is more clearer.

3. Use the rounddown to make codes clearer.

Signed-off-by: Gao Feng <fgao@ikuai8.com>
---
 net/ipv4/tcp_output.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 22548b5..1397194 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2561,7 +2561,6 @@ u32 __tcp_select_window(struct sock *sk)
 	/* Don't do rounding if we are using window scaling, since the
 	 * scaled window will not line up with the MSS boundary anyway.
 	 */
-	window = tp->rcv_wnd;
 	if (tp->rx_opt.rcv_wscale) {
 		window = free_space;
 
@@ -2569,10 +2568,9 @@ u32 __tcp_select_window(struct sock *sk)
 		 * Import case: prevent zero window announcement if
 		 * 1<<rcv_wscale > mss.
 		 */
-		if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window)
-			window = (((window >> tp->rx_opt.rcv_wscale) + 1)
-				  << tp->rx_opt.rcv_wscale);
+		window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale));
 	} else {
+		window = tp->rcv_wnd;
 		/* Get the largest window that is a nice multiple of mss.
 		 * Window clamp already applied above.
 		 * If our current window offering is within 1 mss of the
@@ -2582,7 +2580,7 @@ u32 __tcp_select_window(struct sock *sk)
 		 * is too small.
 		 */
 		if (window <= free_space - mss || window > free_space)
-			window = (free_space / mss) * mss;
+			window = rounddown(free_space, mss);
 		else if (mss == full_space &&
 			 free_space > window + (full_space >> 1))
 			window = free_space;
-- 
1.9.1

Re: [PATCH nf-next 1/1] net: tcp: Refine the __tcp_select_window

[David Miller]

From: gfree.wind@foxmail.com
Date: Thu, 30 Mar 2017 06:49:19 +0800

> From: Gao Feng <fgao@ikuai8.com>
> 
> 1. Move the "window = tp->rcv_wnd;" into the condition block without
> tp->rx_opt.rcv_wscale.
> Because it is unnecessary when enable wscale;
> 
> 2. Use the macro ALIGN instead of two statements.
> The two statements are used to make window align to 1<<wscale.
> Use the ALIGN is more clearer.
> 
> 3. Use the rounddown to make codes clearer.
> 
> Signed-off-by: Gao Feng <fgao@ikuai8.com>

Applied, but please do not target non-netfilter patches using
"nf-next" in your Subject lines.

RE: [PATCH nf-next 1/1] net: tcp: Refine the __tcp_select_window

[Gao Feng]

> -----Original Message-----
> From: netdev-owner@vger.kernel.org [mailto:netdev-owner@vger.kernel.org]
> On Behalf Of David Miller
> Sent: Friday, March 31, 2017 6:42 AM
> To: gfree.wind@foxmail.com
> Cc: kuznet@ms2.inr.ac.ru; jmorris@namei.org; netdev@vger.kernel.org;
> fgao@ikuai8.com
> Subject: Re: [PATCH nf-next 1/1] net: tcp: Refine the __tcp_select_window
> 
> From: gfree.wind@foxmail.com
> Date: Thu, 30 Mar 2017 06:49:19 +0800
> 
> > From: Gao Feng <fgao@ikuai8.com>
> >
> > 1. Move the "window = tp->rcv_wnd;" into the condition block without
> > tp->rx_opt.rcv_wscale.
> > Because it is unnecessary when enable wscale;
> >
> > 2. Use the macro ALIGN instead of two statements.
> > The two statements are used to make window align to 1<<wscale.
> > Use the ALIGN is more clearer.
> >
> > 3. Use the rounddown to make codes clearer.
> >
> > Signed-off-by: Gao Feng <fgao@ikuai8.com>
> 
> Applied, but please do not target non-netfilter patches using "nf-next" in
your
> Subject lines.

Sorry, I misspelled the subject.
I would pay more attention on it.

Regards
Feng