From ed75ccbe26f4a672a41556120390e67c80a2c441 Mon Sep 17 00:00:00 2001 From: Marek Lindner Date: Thu, 10 Feb 2011 14:33:51 +0000 Subject: batman-adv: Correct rcu refcounting for batman_if It might be possible that 2 threads access the same data in the same rcu grace period. The first thread calls call_rcu() to decrement the refcount and free the data while the second thread increases the refcount to use the data. To avoid this race condition all refcount operations have to be atomic. Reported-by: Sven Eckelmann Signed-off-by: Marek Lindner --- net/batman-adv/hard-interface.h | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'net/batman-adv/hard-interface.h') diff --git a/net/batman-adv/hard-interface.h b/net/batman-adv/hard-interface.h index ad19543..e488b90 100644 --- a/net/batman-adv/hard-interface.h +++ b/net/batman-adv/hard-interface.h @@ -37,13 +37,12 @@ void hardif_disable_interface(struct batman_if *batman_if); void hardif_remove_interfaces(void); int hardif_min_mtu(struct net_device *soft_iface); void update_min_mtu(struct net_device *soft_iface); +void hardif_free_rcu(struct rcu_head *rcu); -static inline void hardif_free_ref(struct kref *refcount) +static inline void hardif_free_ref(struct batman_if *batman_if) { - struct batman_if *batman_if; - - batman_if = container_of(refcount, struct batman_if, refcount); - kfree(batman_if); + if (atomic_dec_and_test(&batman_if->refcount)) + call_rcu(&batman_if->rcu, hardif_free_rcu); } #endif /* _NET_BATMAN_ADV_HARD_INTERFACE_H_ */ -- cgit v1.1