1 files changed, 6 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 9d206c282cf..8b9a4747417 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -1026,6 +1026,12 @@ void xfrm_state_delete_tunnel(struct xfrm_state *x)
 }
 EXPORT_SYMBOL(xfrm_state_delete_tunnel);
 
+/*
+ * This function is NOT optimal.  For example, with ESP it will give an
+ * MTU that's usually two bytes short of being optimal.  However, it will
+ * usually give an answer that's a multiple of 4 provided the input is
+ * also a multiple of 4.
+ */
 int xfrm_state_mtu(struct xfrm_state *x, int mtu)
 {
         int res = mtu;