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bonding: remove bond read lock for bond_3ad_state_machine_handler()

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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 <dingtianhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
dingtianhong 2013-10-24 11:09:31 +08:00 committed by David S. Miller
parent 80b9d236ec
commit 5cc172c6de
1 changed files with 5 additions and 4 deletions
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9
drivers/net/bonding/bond_3ad.c
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@ -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);
}
/**