netdev - [PATCH 1/1] batman-adv: Avoid WARN

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Message-Id: <20210608152947.30833-2-sw@simonwunderlich.de>
Date:   Tue,  8 Jun 2021 17:29:47 +0200
From:   Simon Wunderlich <sw@...onwunderlich.de>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     netdev@...r.kernel.org, b.a.t.m.a.n@...ts.open-mesh.org,
        Sven Eckelmann <sven@...fation.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        syzbot+c0b807de416427ff3dd1@...kaller.appspotmail.com,
        Simon Wunderlich <sw@...onwunderlich.de>
Subject: [PATCH 1/1] batman-adv: Avoid WARN_ON timing related checks

From: Sven Eckelmann <sven@...fation.org>

The soft/batadv interface for a queued OGM can be changed during the time
the OGM was queued for transmission and when the OGM is actually
transmitted by the worker.

But WARN_ON must be used to denote kernel bugs and not to print simple
warnings. A warning can simply be printed using pr_warn.

Reported-by: Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Reported-by: syzbot+c0b807de416427ff3dd1@...kaller.appspotmail.com
Fixes: ef0a937f7a14 ("batman-adv: consider outgoing interface in OGM sending")
Signed-off-by: Sven Eckelmann <sven@...fation.org>
Signed-off-by: Simon Wunderlich <sw@...onwunderlich.de>
---
 net/batman-adv/bat_iv_ogm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 789f257be24f..fc8be49010b9 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -409,8 +409,10 @@ static void batadv_iv_ogm_emit(struct batadv_forw_packet *forw_packet)
 	if (WARN_ON(!forw_packet->if_outgoing))
 		return;
 
-	if (WARN_ON(forw_packet->if_outgoing->soft_iface != soft_iface))
+	if (forw_packet->if_outgoing->soft_iface != soft_iface) {
+		pr_warn("%s: soft interface switch for queued OGM\n", __func__);
 		return;
+	}
 
 	if (forw_packet->if_incoming->if_status != BATADV_IF_ACTIVE)
 		return;
-- 
2.20.1