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Staging: batman-adv: Introduce if_list_lock to protect if_list

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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>
This commit is contained in:
Sven Eckelmann
2010-09-18 21:01:15 +02:00
committed by Greg Kroah-Hartman
parent 67c3b70593
commit af2ac7bfec
1 changed files with 15 additions and 2 deletions
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17
drivers/staging/batman-adv/hard-interface.c
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@@ -33,6 +33,9 @@
#define MIN(x, y) ((x) < (y) ? (x) : (y)) #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 *get_batman_if_by_netdev(struct net_device *net_dev)
{ {
struct batman_if *batman_if; 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); INIT_LIST_HEAD(&batman_if->list);
check_known_mac_addr(batman_if->net_dev->dev_addr); check_known_mac_addr(batman_if->net_dev->dev_addr);
spin_lock(&if_list_lock);
list_add_tail_rcu(&batman_if->list, &if_list); list_add_tail_rcu(&batman_if->list, &if_list);
spin_unlock(&if_list_lock);
return batman_if; return batman_if;
free_if: free_if:
@@ -428,6 +435,8 @@ static void hardif_remove_interface(struct batman_if *batman_if)
return; return;
batman_if->if_status = IF_TO_BE_REMOVED; batman_if->if_status = IF_TO_BE_REMOVED;
/* caller must take if_list_lock */
list_del_rcu(&batman_if->list); list_del_rcu(&batman_if->list);
sysfs_del_hardif(&batman_if->hardif_obj); sysfs_del_hardif(&batman_if->hardif_obj);
dev_put(batman_if->net_dev); dev_put(batman_if->net_dev);
@@ -438,11 +447,13 @@ void hardif_remove_interfaces(void)
{ {
struct batman_if *batman_if, *batman_if_tmp; struct batman_if *batman_if, *batman_if_tmp;
list_for_each_entry_safe(batman_if, batman_if_tmp, &if_list, list) {
rtnl_lock(); rtnl_lock();
spin_lock(&if_list_lock);
list_for_each_entry_safe(batman_if, batman_if_tmp, &if_list, list) {
hardif_remove_interface(batman_if); hardif_remove_interface(batman_if);
rtnl_unlock();
} }
spin_unlock(&if_list_lock);
rtnl_unlock();
} }
static int hard_if_event(struct notifier_block *this, 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); hardif_deactivate_interface(batman_if);
break; break;
case NETDEV_UNREGISTER: case NETDEV_UNREGISTER:
spin_lock(&if_list_lock);
hardif_remove_interface(batman_if); hardif_remove_interface(batman_if);
spin_unlock(&if_list_lock);
break; break;
case NETDEV_CHANGEMTU: case NETDEV_CHANGEMTU:
if (batman_if->soft_iface) if (batman_if->soft_iface)