Commit 589c49cb authored by Gao Feng's avatar Gao Feng Committed by David S. Miller
Browse files

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: default avatarGao Feng <fgao@ikuai8.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5e351410

include/net/tcp.h

+3 −0
Original line number Diff line number Diff line
@@ -78,6 +78,9 @@ void tcp_time_wait(struct sock *sk, int state, int timeo); 
/* Maximal number of ACKs sent quickly to accelerate slow-start. */

#define TCP_MAX_QUICKACKS	16U



/* Maximal number of window scale according to RFC1323 */

#define TCP_MAX_WSCALE		14U



/* urg_data states */

#define TCP_URG_VALID	0x0100

#define TCP_URG_NOTYET	0x0200

net/ipv4/tcp.c

+1 −1
Original line number Diff line number Diff line
@@ -2393,7 +2393,7 @@ static int tcp_repair_options_est(struct tcp_sock *tp, 
				u16 snd_wscale = opt.opt_val & 0xFFFF;

				u16 rcv_wscale = opt.opt_val >> 16;



				if (snd_wscale > 14 || rcv_wscale > 14)

				if (snd_wscale > TCP_MAX_WSCALE || rcv_wscale > TCP_MAX_WSCALE)

					return -EFBIG;



				tp->rx_opt.snd_wscale = snd_wscale;

net/ipv4/tcp_input.c

+5 −4
Original line number Diff line number Diff line
@@ -3759,11 +3759,12 @@ void tcp_parse_options(const struct sk_buff *skb, 
				    !estab && sysctl_tcp_window_scaling) {

					__u8 snd_wscale = *(__u8 *)ptr;

					opt_rx->wscale_ok = 1;

					if (snd_wscale > 14) {

						net_info_ratelimited("%s: Illegal window scaling value %d >14 received\n",

					if (snd_wscale > TCP_MAX_WSCALE) {

						net_info_ratelimited("%s: Illegal window scaling value %d > %u received\n",

								     __func__,

								     snd_wscale);

						snd_wscale = 14;

								     snd_wscale,

								     TCP_MAX_WSCALE);

						snd_wscale = TCP_MAX_WSCALE;

					}

					opt_rx->snd_wscale = snd_wscale;

				}

net/ipv4/tcp_output.c

+5 −7
Original line number Diff line number Diff line
@@ -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);

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