From 5cc172c6de80cd9bf2a1228cb928b1fb42e30deb Mon Sep 17 00:00:00 2001 From: dingtianhong Date: Thu, 24 Oct 2013 11:09:31 +0800 Subject: [PATCH] bonding: remove bond read lock for bond_3ad_state_machine_handler() The bond slave list may change when the monitor is running, the slave list is no longer protected by bond->lock, only protected by rtnl lock(), so we have 3 ways to modify it: 1.add bond_master_upper_dev_link() and bond_upper_dev_unlink() in bond->lock, but it is unsafe to call call_netdevice_notifiers() in write lock. 2.remove unused bond->lock for monitor function, only use the existing rtnl lock(). 3.use rcu_read_lock() to protect it, of course, it will transform bond_for_each_slave to bond_for_each_slave_rcu() and performance is better, but in slow path, it is ignored. so I remove the bond->lock and move the rtnl lock to protect the whole monitor function. Signed-off-by: Ding Tianhong Signed-off-by: David S. Miller --- drivers/net/bonding/bond_3ad.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c index 187b1b7..d6fe00b 100644 --- a/drivers/net/bonding/bond_3ad.c +++ b/drivers/net/bonding/bond_3ad.c @@ -2068,8 +2068,10 @@ void bond_3ad_state_machine_handler(struct work_struct *work) struct slave *slave; struct port *port; - read_lock(&bond->lock); - + if (!rtnl_trylock()) { + queue_delayed_work(bond->wq, &bond->ad_work, ad_delta_in_ticks); + return; + } //check if there are any slaves if (!bond_has_slaves(bond)) goto re_arm; @@ -2122,9 +2124,8 @@ void bond_3ad_state_machine_handler(struct work_struct *work) } re_arm: + rtnl_unlock(); queue_delayed_work(bond->wq, &bond->ad_work, ad_delta_in_ticks); - - read_unlock(&bond->lock); } /** -- 2.7.4