netdev - [PATCH 1/3] batman-adv: Modify neigh_list only with rcu-list functions

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Message-Id: <20161026155515.18075-2-sw@simonwunderlich.de>
Date:   Wed, 26 Oct 2016 17:55:13 +0200
From:   Simon Wunderlich <sw@...onwunderlich.de>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, b.a.t.m.a.n@...ts.open-mesh.org,
        Sven Eckelmann <sven.eckelmann@...n-mesh.com>,
        Simon Wunderlich <sw@...onwunderlich.de>
Subject: [PATCH 1/3] batman-adv: Modify neigh_list only with rcu-list functions

From: Sven Eckelmann <sven.eckelmann@...n-mesh.com>

The batadv_hard_iface::neigh_list is accessed via rcu based primitives.
Thus all operations done on it have to fulfill the requirements by RCU. So
using non-RCU mechanisms like hlist_add_head is not allowed because it
misses the barriers required to protect concurrent readers when accessing
the data behind the pointer.

Fixes: cef63419f7db ("batman-adv: add list of unique single hop neighbors per hard-interface")
Signed-off-by: Sven Eckelmann <sven.eckelmann@...n-mesh.com>
Acked-by: Linus Lüssing <linus.luessing@...3.blue>
Signed-off-by: Simon Wunderlich <sw@...onwunderlich.de>
---
 net/batman-adv/originator.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/batman-adv/originator.c b/net/batman-adv/originator.c
index 5f3bfc4..7c8d160 100644
--- a/net/batman-adv/originator.c
+++ b/net/batman-adv/originator.c
@@ -544,7 +544,7 @@ batadv_hardif_neigh_create(struct batadv_hard_iface *hard_iface,
 	if (bat_priv->algo_ops->neigh.hardif_init)
 		bat_priv->algo_ops->neigh.hardif_init(hardif_neigh);
 
-	hlist_add_head(&hardif_neigh->list, &hard_iface->neigh_list);
+	hlist_add_head_rcu(&hardif_neigh->list, &hard_iface->neigh_list);
 
 out:
 	spin_unlock_bh(&hard_iface->neigh_list_lock);
-- 
2.10.1