From: Ding Tianhong <dingtianhong@huawei•com>
To: Jay Vosburgh <fubar@us•ibm.com>,
Andy Gospodarek <andy@greyhouse•net>,
"David S. Miller" <davem@davemloft•net>,
Nikolay Aleksandrov <nikolay@redhat•com>,
Veaceslav Falico <vfalico@redhat•com>,
Netdev <netdev@vger•kernel.org>
Subject: [PATCH net-next v2 4/5] bonding: remove bond read lock for bond_activebackup_arp_mon()
Date: Thu, 24 Oct 2013 11:09:25 +0800 [thread overview]
Message-ID: <52688F65.3080507@huawei.com> (raw)
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 has 3 way 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 exist 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>
---
drivers/net/bonding/bond_main.c | 46 ++++++++++++-----------------------------
1 file changed, 13 insertions(+), 33 deletions(-)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 149f4b9..f3df532 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -2763,51 +2763,31 @@ void bond_activebackup_arp_mon(struct work_struct *work)
struct bonding *bond = container_of(work, struct bonding,
arp_work.work);
bool should_notify_peers = false;
- int delta_in_ticks;
- read_lock(&bond->lock);
-
- delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);
+ if (!rtnl_trylock())
+ goto re_arm;
- if (!bond_has_slaves(bond))
+ if (!bond_has_slaves(bond)) {
+ rtnl_unlock();
goto re_arm;
+ }
should_notify_peers = bond_should_notify_peers(bond);
- if (bond_ab_arp_inspect(bond)) {
- read_unlock(&bond->lock);
-
- /* Race avoidance with bond_close flush of workqueue */
- if (!rtnl_trylock()) {
- read_lock(&bond->lock);
- delta_in_ticks = 1;
- should_notify_peers = false;
- goto re_arm;
- }
-
- read_lock(&bond->lock);
-
+ if (bond_ab_arp_inspect(bond))
bond_ab_arp_commit(bond);
- read_unlock(&bond->lock);
- rtnl_unlock();
- read_lock(&bond->lock);
- }
-
bond_ab_arp_probe(bond);
-re_arm:
- if (bond->params.arp_interval)
- queue_delayed_work(bond->wq, &bond->arp_work, delta_in_ticks);
+ if (should_notify_peers)
+ call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, bond->dev);
- read_unlock(&bond->lock);
+ rtnl_unlock();
- if (should_notify_peers) {
- if (!rtnl_trylock())
- return;
- call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, bond->dev);
- rtnl_unlock();
- }
+re_arm:
+ if (bond->params.arp_interval)
+ queue_delayed_work(bond->wq, &bond->arp_work,
+ msecs_to_jiffies(bond->params.arp_interval));
}
/*-------------------------- netdev event handling --------------------------*/
--
1.8.2.1
reply other threads:[~2013-10-24 3:11 UTC|newest]
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