bonding: remove bond read lock for bond_activebackup_arp_mon()
authordingtianhong <dingtianhong@huawei.com>
Thu, 24 Oct 2013 03:09:25 +0000 (11:09 +0800)
committerDavid S. Miller <davem@davemloft.net>
Sun, 27 Oct 2013 20:36:29 +0000 (16:36 -0400)
commit80b9d236ec56ecc18da4a43bd79e8ec9ac5036ff
tree8bcd60a4486a458bad82b39f65ad4e251af7fba9
parent7f1bb571b753ac75b6548f0b7c932dfc0bb1f970
bonding: remove bond read lock for bond_activebackup_arp_mon()

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>
drivers/net/bonding/bond_main.c