From af2ac7bfec4176cad5e04402d116b5242d759bf8 Mon Sep 17 00:00:00 2001
From: Sven Eckelmann <sven.eckelmann@gmx.de>
Date: Sat, 18 Sep 2010 21:01:15 +0200
Subject: [PATCH] Staging: batman-adv: Introduce if_list_lock to protect
if_list
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/staging/batman-adv/hard-interface.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/batman-adv/hard-interface.c b/drivers/staging/batman-adv/hard-interface.c
index a587da9c827e0..35b198c6bad5c 100644
--- a/drivers/staging/batman-adv/hard-interface.c
+++ b/drivers/staging/batman-adv/hard-interface.c
@@ -33,6 +33,9 @@
#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;
@@ -400,7 +403,11 @@ 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:
@@ -428,6 +435,8 @@ 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);
@@ -438,11 +447,13 @@ 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,
@@ -467,7 +478,9 @@ 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)
--
2.30.2