diff options
| -rw-r--r-- | include/linux/netdevice.h | 3 | ||||
| -rw-r--r-- | net/core/dev.c | 2 | ||||
| -rw-r--r-- | net/core/rtnetlink.c | 33 |
3 files changed, 36 insertions, 2 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 59e27a2b7bf0..b6a1e7f643da 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3894,7 +3894,8 @@ void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev); extern int netdev_budget; extern unsigned int netdev_budget_usecs; -/* Called by rtnetlink.c:rtnl_unlock() */ +/* Used by rtnetlink.c:__rtnl_unlock()/rtnl_unlock() */ +extern struct list_head net_todo_list; void netdev_run_todo(void); static inline void __dev_put(struct net_device *dev) diff --git a/net/core/dev.c b/net/core/dev.c index 8c6c08446556..2ec17358d7b4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -9431,7 +9431,7 @@ static int dev_new_index(struct net *net) } /* Delayed registration/unregisteration */ -static LIST_HEAD(net_todo_list); +LIST_HEAD(net_todo_list); DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq); static void net_set_todo(struct net_device *dev) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 159c9c61e6af..0e4502d641eb 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -95,6 +95,39 @@ void __rtnl_unlock(void) defer_kfree_skb_list = NULL; + /* Ensure that we didn't actually add any TODO item when __rtnl_unlock() + * is used. In some places, e.g. in cfg80211, we have code that will do + * something like + * rtnl_lock() + * wiphy_lock() + * ... + * rtnl_unlock() + * + * and because netdev_run_todo() acquires the RTNL for items on the list + * we could cause a situation such as this: + * Thread 1 Thread 2 + * rtnl_lock() + * unregister_netdevice() + * __rtnl_unlock() + * rtnl_lock() + * wiphy_lock() + * rtnl_unlock() + * netdev_run_todo() + * __rtnl_unlock() + * + * // list not empty now + * // because of thread 2 + * rtnl_lock() + * while (!list_empty(...)) + * rtnl_lock() + * wiphy_lock() + * **** DEADLOCK **** + * + * However, usage of __rtnl_unlock() is rare, and so we can ensure that + * it's not used in cases where something is added to do the list. + */ + WARN_ON(!list_empty(&net_todo_list)); + mutex_unlock(&rtnl_mutex); while (head) { |