From: Sven Eckelmann Date: Mon, 1 Jun 2026 09:00:23 +0000 (+0200) Subject: batman-adv: tp_meter: fix fast recovery precondition X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2b0d08f08ed3b2174f05c43089ec65f3543a025b;p=thirdparty%2Flinux.git batman-adv: tp_meter: fix fast recovery precondition The fast recovery precondition checks if the recover (initialized to BATADV_TP_FIRST_SEQ) is bigger than the received ack. But since recover is only updated when this check is successful, it will never enter the fast recovery mode. According to RFC6582 Section 3.2 step 2, the check should actually be different: > When the third duplicate ACK is received, the TCP sender first > checks the value of recover to see if the Cumulative > Acknowledgment field covers more than recover The precondition must therefore check if recover is smaller than the received ack - basically swapping the operands of the current check. Cc: stable@kernel.org Fixes: 33a3bb4a3345 ("batman-adv: throughput meter implementation") Signed-off-by: Sven Eckelmann --- diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c index 1655f181c9293..ae6acbc60c8ed 100644 --- a/net/batman-adv/tp_meter.c +++ b/net/batman-adv/tp_meter.c @@ -733,7 +733,7 @@ static void batadv_tp_recv_ack(struct batadv_priv *bat_priv, if (atomic_read(&tp_vars->dup_acks) != 3) goto out; - if (recv_ack >= tp_vars->recover) + if (tp_vars->recover >= recv_ack) goto out; /* if this is the third duplicate ACK do Fast Retransmit */