From b5d9c9c281395f0967c8d93f42e8b0b8175b5180 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sat, 22 Oct 2011 01:25:23 -0400
Subject: [PATCH] inet: add rfc 3168 extract in front of INET_ECN_encapsulate()

INET_ECN_encapsulate() is better understood if we can read the official
statement.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/net/inet_ecn.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/net/inet_ecn.h b/include/net/inet_ecn.h
index 2fa8d1341a0a..2fa14691869c 100644
--- a/include/net/inet_ecn.h
+++ b/include/net/inet_ecn.h
@@ -30,6 +30,14 @@ static inline int INET_ECN_is_capable(__u8 dsfield)
 	return dsfield & INET_ECN_ECT_0;
 }
 
+/*
+ * RFC 3168 9.1.1
+ *  The full-functionality option for ECN encapsulation is to copy the
+ *  ECN codepoint of the inside header to the outside header on
+ *  encapsulation if the inside header is not-ECT or ECT, and to set the
+ *  ECN codepoint of the outside header to ECT(0) if the ECN codepoint of
+ *  the inside header is CE.
+ */
 static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner)
 {
 	outer &= ~INET_ECN_MASK;
-- 
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