From ca07fb07c9a362149ea72f0de8f7eefd00489ecc Mon Sep 17 00:00:00 2001 From: Ying Xue Date: Mon, 21 Apr 2014 10:55:43 +0800 Subject: [PATCH] tipc: adjust locking policy of protecting tipc_ptr pointer of net_device Currently the 'tipc_ptr' pointer is protected by tipc_net_lock write lock on write side, and RCU read lock is applied to read side. In addition, there have two paths on write side where we may change variables pointed by the 'tipc_ptr' pointer: one is to configure bearer by tipc-config tool and another one is that bearer status is changed by notification events of its attached interface. But on the latter path, we improperly deem that accessing 'tipc_ptr' pointer happens on read side with rcu_read_lock() although some variables pointed by the 'tipc_ptr' pointer are changed possibly. Moreover, as now the both paths are guarded by RTNL lock, it's better to adjust the locking policy of 'tipc_ptr' pointer protection, allowing RTNL instead of tipc_net_lock write lock to protect it on write side, which will help us purge tipc_net_lock in the future. Signed-off-by: Ying Xue Reviewed-by: Jon Maloy Reviewed-by: Erik Hugne Tested-by: Erik Hugne Signed-off-by: David S. Miller --- net/tipc/bearer.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c index 3fef7eb776dc..dfb4c7fe4865 100644 --- a/net/tipc/bearer.c +++ b/net/tipc/bearer.c @@ -535,7 +535,7 @@ static int tipc_l2_rcv_msg(struct sk_buff *buf, struct net_device *dev, } rcu_read_lock(); - b_ptr = rcu_dereference(dev->tipc_ptr); + b_ptr = rcu_dereference_rtnl(dev->tipc_ptr); if (likely(b_ptr)) { if (likely(buf->pkt_type <= PACKET_BROADCAST)) { buf->next = NULL; @@ -568,12 +568,9 @@ static int tipc_l2_device_event(struct notifier_block *nb, unsigned long evt, if (!net_eq(dev_net(dev), &init_net)) return NOTIFY_DONE; - rcu_read_lock(); - b_ptr = rcu_dereference(dev->tipc_ptr); - if (!b_ptr) { - rcu_read_unlock(); + b_ptr = rtnl_dereference(dev->tipc_ptr); + if (!b_ptr) return NOTIFY_DONE; - } b_ptr->mtu = dev->mtu; @@ -595,8 +592,6 @@ static int tipc_l2_device_event(struct notifier_block *nb, unsigned long evt, tipc_disable_bearer(b_ptr->name); break; } - rcu_read_unlock(); - return NOTIFY_OK; }