netdev - [PATCH 1/2] batman-adv: fix lockdep splat when doing mcast

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Message-Id: <1452707514-5091-2-git-send-email-a@unstable.cc>
Date:	Thu, 14 Jan 2016 01:51:53 +0800
From:	Antonio Quartulli <a@...table.cc>
To:	davem@...emloft.net
Cc:	netdev@...r.kernel.org, b.a.t.m.a.n@...ts.open-mesh.org,
	Simon Wunderlich <simon@...n-mesh.com>,
	Marek Lindner <mareklindner@...mailbox.ch>,
	Antonio Quartulli <a@...table.cc>
Subject: [PATCH 1/2] batman-adv: fix lockdep splat when doing mcast_free

From: Simon Wunderlich <simon@...n-mesh.com>

While testing, we got something like this:

WARNING: CPU: 0 PID: 238 at net/batman-adv/multicast.c:142 batadv_mcast_mla_tt_retract+0x94/0x205 [batman_adv]()
[...]
Call Trace:
[<ffffffff815fc597>] dump_stack+0x4b/0x64
[<ffffffff810b34dc>] warn_slowpath_common+0xbc/0x120
[<ffffffffa0024ec5>] ? batadv_mcast_mla_tt_retract+0x94/0x205 [batman_adv]
[<ffffffff810b3705>] warn_slowpath_null+0x15/0x20
[<ffffffffa0024ec5>] batadv_mcast_mla_tt_retract+0x94/0x205 [batman_adv]
[<ffffffffa00273fe>] batadv_mcast_free+0x36/0x39 [batman_adv]
[<ffffffffa0020c77>] batadv_mesh_free+0x7d/0x13f [batman_adv]
[<ffffffffa0036a6b>] batadv_softif_free+0x15/0x25 [batman_adv]
[...]

Signed-off-by: Simon Wunderlich <simon@...n-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@...mailbox.ch>
Signed-off-by: Antonio Quartulli <a@...table.cc>
---
 net/batman-adv/multicast.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index eb76386f8d4b..75fa5013af72 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -802,7 +802,9 @@ void batadv_mcast_free(struct batadv_priv *bat_priv)
 	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_MCAST, 1);
 	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_MCAST, 1);

+	spin_lock_bh(&bat_priv->tt.commit_lock);
 	batadv_mcast_mla_tt_retract(bat_priv, NULL);
+	spin_unlock_bh(&bat_priv->tt.commit_lock);
 }

 /**
-- 
2.7.0