From: Sven Eckelmann <sven.eckelmann@gmx.de>
To: b.a.t.m.a.n@lists.open-mesh.net
Subject: [B.A.T.M.A.N.] [PATCH 1/4] batman-adv: Introduce if_list_lock to protect if_list
Date: Thu, 16 Sep 2010 22:18:34 +0200 [thread overview]
Message-ID: <1284668317-19890-2-git-send-email-sven.eckelmann@gmx.de> (raw)
In-Reply-To: <1284668317-19890-1-git-send-email-sven.eckelmann@gmx.de>
The update critical sections of if_list must be protected by a locking
primitive other than RCU. The iterator must also be protected by the
chosen locking mechanism.
The rtnl_lock in hardif_remove_interfaces must also be moved outside the
iterator primitive to ensure that we don't deadlock the kernel due to
differently nested locks in hardif_remove_interfaces and hard_if_event.
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
---
batman-adv/hard-interface.c | 17 +++++++++++++++--
1 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/batman-adv/hard-interface.c b/batman-adv/hard-interface.c
index edbfddf..3cd7cb1 100644
--- a/batman-adv/hard-interface.c
+++ b/batman-adv/hard-interface.c
@@ -35,6 +35,9 @@
#define MIN(x, y) ((x) < (y) ? (x) : (y))
+/* protect update critical side of if_list - but not the content */
+static DEFINE_SPINLOCK(if_list_lock);
+
struct batman_if *get_batman_if_by_netdev(struct net_device *net_dev)
{
struct batman_if *batman_if;
@@ -402,7 +405,11 @@ static struct batman_if *hardif_add_interface(struct net_device *net_dev)
INIT_LIST_HEAD(&batman_if->list);
check_known_mac_addr(batman_if->net_dev->dev_addr);
+
+ spin_lock(&if_list_lock);
list_add_tail_rcu(&batman_if->list, &if_list);
+ spin_unlock(&if_list_lock);
+
return batman_if;
free_if:
@@ -430,6 +437,8 @@ static void hardif_remove_interface(struct batman_if *batman_if)
return;
batman_if->if_status = IF_TO_BE_REMOVED;
+
+ /* caller must take if_list_lock */
list_del_rcu(&batman_if->list);
sysfs_del_hardif(&batman_if->hardif_obj);
dev_put(batman_if->net_dev);
@@ -440,11 +449,13 @@ void hardif_remove_interfaces(void)
{
struct batman_if *batman_if, *batman_if_tmp;
+ rtnl_lock();
+ spin_lock(&if_list_lock);
list_for_each_entry_safe(batman_if, batman_if_tmp, &if_list, list) {
- rtnl_lock();
hardif_remove_interface(batman_if);
- rtnl_unlock();
}
+ spin_unlock(&if_list_lock);
+ rtnl_unlock();
}
static int hard_if_event(struct notifier_block *this,
@@ -469,7 +480,9 @@ static int hard_if_event(struct notifier_block *this,
hardif_deactivate_interface(batman_if);
break;
case NETDEV_UNREGISTER:
+ spin_lock(&if_list_lock);
hardif_remove_interface(batman_if);
+ spin_unlock(&if_list_lock);
break;
case NETDEV_CHANGEMTU:
if (batman_if->soft_iface)
--
1.7.2.3
next prev parent reply other threads:[~2010-09-16 20:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-16 20:18 [B.A.T.M.A.N.] Initial rcu locking patchset Sven Eckelmann
2010-09-16 20:18 ` Sven Eckelmann [this message]
2010-09-16 20:18 ` [B.A.T.M.A.N.] [PATCH 2/4] batman-adv: Protect update side of gw_list Sven Eckelmann
2010-09-16 20:18 ` [B.A.T.M.A.N.] [PATCH 3/4] batman-adv: Always protect list_for_each_entry_rcu with RCU Sven Eckelmann
2010-09-16 20:18 ` [B.A.T.M.A.N.] [PATCH 4/4] batman-adv: Remove unneeded rcu_read_lock Sven Eckelmann
2010-09-16 21:22 ` [B.A.T.M.A.N.] Adding of basic gw_node/batman_if refcnt Sven Eckelmann
2010-09-17 1:17 ` Sven Eckelmann
2010-09-16 21:22 ` [B.A.T.M.A.N.] [PATCH 1/2] batman-adv: Use refcnt to track usage count of gw_node Sven Eckelmann
2010-09-16 21:22 ` [B.A.T.M.A.N.] [PATCH 2/2] batman-adv: Use refcnt to track usage count of batman_if Sven Eckelmann
2010-09-16 21:32 ` Sven Eckelmann
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