netdev - [PATCH next 2/2] batman-adv: fix global protection fault during soft

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Date:	Fri, 19 Apr 2013 11:04:52 +0200
From:	Antonio Quartulli <ordex@...istici.org>
To:	davem@...emloft.net
Cc:	b.a.t.m.a.n@...ts.open-mesh.org, netdev@...r.kernel.org,
	Antonio Quartulli <ordex@...istici.org>,
	Marek Lindner <lindner_marek@...oo.de>
Subject: [PATCH next 2/2] batman-adv: fix global protection fault during soft_iface destruction

batadv_mesh_free() schedules some RCU callbacks which need the bat_priv struct
to do their jobs, while free_netdev(), which is called immediately after, is
destroying the private data.

Put an rcu_barrier() in the middle so that free_netdev() is invoked only after
all the callbacks returned.

This bug has been introduced by ab8f433dd39be94e8617cff2dfe9f7eca162eb15
("batman-adv: Move deinitialization of soft-interface to destructor")

Signed-off-by: Antonio Quartulli <ordex@...istici.org>
Signed-off-by: Marek Lindner <lindner_marek@...oo.de>
---
 net/batman-adv/soft-interface.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 403b8c4..6f20d33 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -582,6 +582,13 @@ static void batadv_softif_free(struct net_device *dev)
 {
 	batadv_debugfs_del_meshif(dev);
 	batadv_mesh_free(dev);
+
+	/* some scheduled RCU callbacks need the bat_priv struct to accomplish
+	 * their tasks. Wait for them all to be finished before freeing the
+	 * netdev and its private data (bat_priv)
+	 */
+	rcu_barrier();
+
 	free_netdev(dev);
 }
 
-- 
1.8.1.5

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