[TCP]: Comment fastpath_cnt_hint off-by-one trap

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/tcp.h

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index f8cf090..9ff456e 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -343,7 +343,8 @@
 	struct sk_buff *forward_skb_hint;
 	struct sk_buff *fastpath_skb_hint;
 
-	int     fastpath_cnt_hint;
+	int     fastpath_cnt_hint;	/* Lags behind by current skb's pcount
+					 * compared to respective fackets_out */
 	int     lost_cnt_hint;
 	int     retransmit_cnt_hint;