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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        syzbot+c0b807de416427ff3dd1@syzkaller.appspotmail.com,
        Sven Eckelmann <sven@narfation.org>,
        Simon Wunderlich <sw@simonwunderlich.de>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 012/146] batman-adv: Avoid WARN_ON timing related checks
Date:   Mon, 21 Jun 2021 18:14:02 +0200
Message-Id: <20210621154911.682289245@linuxfoundation.org>
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From: Sven Eckelmann <sven@narfation.org>

[ Upstream commit 9f460ae31c4435fd022c443a6029352217a16ac1 ]

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@i-love.sakura.ne.jp>
Reported-by: syzbot+c0b807de416427ff3dd1@syzkaller.appspotmail.com
Fixes: ef0a937f7a14 ("batman-adv: consider outgoing interface in OGM sending")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 206d0b424712..c0aa54d21c64 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -410,8 +410,10 @@ 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;
-- 
2.30.2