netdev - [PATCH 11/17] batman-adv: Use kref_get for batadv_gw

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Message-Id: <1462908605-27412-12-git-send-email-a@unstable.cc>
Date:	Wed, 11 May 2016 03:29:59 +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,
	Sven Eckelmann <sven@...fation.org>,
	Marek Lindner <mareklindner@...mailbox.ch>,
	Antonio Quartulli <a@...table.cc>
Subject: [PATCH 11/17] batman-adv: Use kref_get for batadv_gw_select

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

batadv_gw_select requires that the caller already has a valid reference for
new_gw_node. It is therefore not possible that it has an reference counter
of 0 and was still given to this function

The kref_get function instead WARNs (with debug information) when the
reference counter would still be 0. This makes a bug in batman-adv better
visible because kref_get_unless_zero would have ignored this problem.

Signed-off-by: Sven Eckelmann <sven@...fation.org>
Signed-off-by: Marek Lindner <mareklindner@...mailbox.ch>
Signed-off-by: Antonio Quartulli <a@...table.cc>
---
 net/batman-adv/gateway_client.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index c59aff5ccac8..bb1c4f37716e 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -135,8 +135,8 @@ static void batadv_gw_select(struct batadv_priv *bat_priv,
 
 	spin_lock_bh(&bat_priv->gw.list_lock);
 
-	if (new_gw_node && !kref_get_unless_zero(&new_gw_node->refcount))
-		new_gw_node = NULL;
+	if (new_gw_node)
+		kref_get(&new_gw_node->refcount);
 
 	curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
 	rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
-- 
2.8.2