From 26722873a460703e319462afa7ebb8ed3a036c07 Mon Sep 17 00:00:00 2001
From: "David S. Miller" <davem@sunset.davemloft.net>
Date: Fri, 24 Aug 2007 22:21:50 -0700
Subject: [PATCH] [TCP]: Describe tcp_init_cwnd() thoroughly in a comment.
People often get tripped up by this function and think that
it does not implemented the prescribed algorithms from
RFC2414 and RFC3390, even though it does.
So add a comment to head off such misunderstandings in the
future.
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/tcp_input.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f030435e0eb4..9785df37a65f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -755,7 +755,15 @@ void tcp_update_metrics(struct sock *sk)
}
}
-/* Numbers are taken from RFC2414. */
+/* Numbers are taken from RFC3390.
+ *
+ * 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 use a multiplier in the relevant range.
+ */
__u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst)
{
__u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0);