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bonding: remove bond read lock for bond_alb_monitor() 

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 11:09:12 +08:00 committed by David S. Miller
parent 6b6c526147
commit 2d0dafb015
1 changed files with 4 additions and 16 deletions
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20
drivers/net/bonding/bond_alb.c
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@ -1495,11 +1495,13 @@ void bond_alb_monitor(struct work_struct *work)
struct list_head *iter;
struct slave *slave;
read_lock(&bond->lock);
if (!rtnl_trylock())
goto re_arm;
if (!bond_has_slaves(bond)) {
bond_info->tx_rebalance_counter = 0;
bond_info->lp_counter = 0;
rtnl_unlock();
goto re_arm;
}
@ -1548,16 +1550,6 @@ void bond_alb_monitor(struct work_struct *work)
if (bond_info->primary_is_promisc &&
(++bond_info->rlb_promisc_timeout_counter >= RLB_PROMISC_TIMEOUT)) {
/*
* dev_set_promiscuity requires rtnl and
* nothing else. Avoid race with bond_close.
*/
read_unlock(&bond->lock);
if (!rtnl_trylock()) {
read_lock(&bond->lock);
goto re_arm;
}
bond_info->rlb_promisc_timeout_counter = 0;
/* If the primary was set to promiscuous mode
@ -1566,9 +1558,6 @@ void bond_alb_monitor(struct work_struct *work)
*/
dev_set_promiscuity(bond->curr_active_slave->dev, -1);
bond_info->primary_is_promisc = 0;
rtnl_unlock();
read_lock(&bond->lock);
}
if (bond_info->rlb_rebalance) {
@ -1591,10 +1580,9 @@ void bond_alb_monitor(struct work_struct *work)
}
}
rtnl_unlock();
re_arm:
queue_delayed_work(bond->wq, &bond->alb_work, alb_delta_in_ticks);
read_unlock(&bond->lock);
}
/* assumption: called before the slave is attached to the bond