1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 1f12fa0b67d7..f8cf090e8f49 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -332,7 +332,8 @@ struct tcp_sock {
 
         struct tcp_sack_block_wire recv_sack_cache[4];
 
-        u32     highest_sack;   /* Start seq of globally highest revd SACK (valid only in slowpath) */
+        u32     highest_sack;   /* Start seq of globally highest revd SACK
+                                 * (validity guaranteed only if sacked_out > 0) */
 
         /* from STCP, retrans queue hinting */
         struct sk_buff* lost_skb_hint;