bonding: remove bond read lock for bond_mii_monitor()
Subsystems (3)
PATCH v2 1/5 bonding: remove bond read lock for bond_mii_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 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 <[email protected]>
--- drivers/net/bonding/bond_main.c | 44 +++++++++++------------------------------ 1 file changed, 12 insertions(+), 32 deletions(-)
drivers/net/bonding/bond_main.c +12 -32
@@ -2155,49 +2155,29 @@ void bond_mii_monitor(struct work_struct *work) struct bonding *bond = container_of(work, struct bonding, mii_work.work);bool should_notify_peers = false; -unsigned long delay; -read_lock (&bond->lock); - - delay =msecs_to_jiffies (bond->params.miimon); +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_miimon_inspect (bond)) { -read_unlock (&bond->lock); - -/* Race avoidance with bond_close cancel of workqueue */ -if (!rtnl_trylock ()) { -read_lock (&bond->lock); - delay =1 ; - should_notify_peers = false; - goto re_arm; - } - -read_lock (&bond->lock); - +if (bond_miimon_inspect (bond))bond_miimon_commit (bond); -read_unlock (&bond->lock); -rtnl_unlock ();/* might sleep, hold no other locks */ -read_lock (&bond->lock); - } +if (should_notify_peers) +call_netdevice_notifiers (NETDEV_NOTIFY_PEERS , bond->dev); + +rtnl_unlock (); re_arm:if (bond->params.miimon) -queue_delayed_work (bond->wq, &bond->mii_work, delay); - -read_unlock (&bond->lock); - -if (should_notify_peers) { -if (!rtnl_trylock ()) -return ; -call_netdevice_notifiers (NETDEV_NOTIFY_PEERS , bond->dev); -rtnl_unlock (); - } +queue_delayed_work (bond->wq, &bond->mii_work, +msecs_to_jiffies (bond->params.miimon)); }static bool bond_has_this_ip (struct bonding *bond,__be32 ip)
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1.8.2.1