From 22b71c8f4f3db8df92f5e7b081c265bc56c0bd2f Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 29 Aug 2010 19:23:12 +0000 Subject: tcp/dccp: Consolidate common code for RFC 3390 conversion This patch consolidates initial-window code common to TCP and CCID-2: * TCP uses RFC 3390 in a packet-oriented manner (tcp_input.c) and * CCID-2 uses RFC 3390 in packet-oriented manner (RFC 4341). Signed-off-by: Gerrit Renker Signed-off-by: David S. Miller --- include/net/tcp.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/net/tcp.h') diff --git a/include/net/tcp.h b/include/net/tcp.h index df6a2eb2019..a64022199b6 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -779,6 +779,21 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk) /* Use define here intentionally to get WARN_ON location shown at the caller */ #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) +/* + * Convert RFC 3390 larger initial window into an equivalent number of packets. + * + * John Heffner states: + * + * The RFC specifies a window of no more than 4380 bytes + * unless 2*MSS > 4380. Reading the pseudocode in the RFC + * is a bit misleading because they use a clamp at 4380 bytes + * rather than a multiplier in the relevant range. + */ +static inline u32 rfc3390_bytes_to_packets(const u32 smss) +{ + return smss <= 1095 ? 4 : (smss > 1460 ? 2 : 3); +} + extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh); extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst); -- cgit v1.2.3