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authorDavid S. Miller <davem@sunset.davemloft.net>2007-08-24 22:21:50 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2007-08-26 18:35:36 -0700
commit26722873a460703e319462afa7ebb8ed3a036c07 (patch)
treed621eb098a252a8e91d74d635d33eb30ee05aa21
parenta96fb49be3dd2031f722bf32af6ed7db965b60f7 (diff)
downloadlinux-stericsson-26722873a460703e319462afa7ebb8ed3a036c07.tar.gz
[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>
-rw-r--r--net/ipv4/tcp_input.c10
1 files changed, 9 insertions, 1 deletions
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);