From 1935299d9c946ac37eba3f820d2ce20885ec0739 Mon Sep 17 00:00:00 2001 From: Gao Feng Date: Thu, 30 Mar 2017 06:49:19 +0800 Subject: net: tcp: Refine the __tcp_select_window 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< Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 22548b5f05cb..13971942211b 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< 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; -- cgit v1.2.3 From 589c49cbf9674808fd4ac9b7c17155abc0686f86 Mon Sep 17 00:00:00 2001 From: Gao Feng Date: Tue, 4 Apr 2017 21:09:48 +0800 Subject: net: tcp: Define the TCP_MAX_WSCALE instead of literal number 14 Define one new macro TCP_MAX_WSCALE instead of literal number '14', and use U16_MAX instead of 65535 as the max value of TCP window. There is another minor change, use rounddown(space, mss) instead of (space / mss) * mss; Signed-off-by: Gao Feng Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 13971942211b..0e807a83c1bc 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -212,12 +212,12 @@ void tcp_select_initial_window(int __space, __u32 mss, /* If no clamp set the clamp to the max possible scaled window */ if (*window_clamp == 0) - (*window_clamp) = (65535 << 14); + (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); space = min(*window_clamp, space); /* Quantize space offering to a multiple of mss if possible. */ if (space > mss) - space = (space / mss) * mss; + space = rounddown(space, mss); /* NOTE: offering an initial window larger than 32767 * will break some buggy TCP stacks. If the admin tells us @@ -234,13 +234,11 @@ void tcp_select_initial_window(int __space, __u32 mss, (*rcv_wscale) = 0; if (wscale_ok) { - /* Set window scaling on max possible window - * See RFC1323 for an explanation of the limit to 14 - */ + /* Set window scaling on max possible window */ space = max_t(u32, space, sysctl_tcp_rmem[2]); space = max_t(u32, space, sysctl_rmem_max); space = min_t(u32, space, *window_clamp); - while (space > 65535 && (*rcv_wscale) < 14) { + while (space > U16_MAX && (*rcv_wscale) < TCP_MAX_WSCALE) { space >>= 1; (*rcv_wscale)++; } @@ -253,7 +251,7 @@ void tcp_select_initial_window(int __space, __u32 mss, } /* Set the clamp no higher than max representable value */ - (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); + (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); } EXPORT_SYMBOL(tcp_select_initial_window); -- cgit v1.2.3