[PATCH net-next v2 4/10] bonding: rebuild the lock use for bond_loadbalance_arp_mon()
From: Ding Tianhong <hidden>
Date: 2013-11-08 02:08:27
Subsystem:
bonding driver, networking drivers, the rest · Maintainers:
Jay Vosburgh, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The bond_loadbalance_arp_mon() use the bond lock to protect the bond slave list, it is no effect, so I could use RTNL or RCU to replace it, considering the performance impact, the RCU is more better here, so the bond lock replace with the RCU. The bond_select_active_slave() need RTNL and curr_slave_lock together, but there is no RTNL lock here, so add a rtnl_rtylock. Suggested-by: Jay Vosburgh <redacted> Suggested-by: Veaceslav Falico <redacted> Signed-off-by: Ding Tianhong <redacted> --- drivers/net/bonding/bond_main.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index def489d..759dcd0 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c@@ -2407,12 +2407,14 @@ void bond_loadbalance_arp_mon(struct work_struct *work) struct list_head *iter; int do_failover = 0; - read_lock(&bond->lock); + rcu_read_lock(); - if (!bond_has_slaves(bond)) + if (!bond_has_slaves_rcu(bond)) { + rcu_read_unlock(); goto re_arm; + } - oldcurrent = bond->curr_active_slave; + oldcurrent = ACCESS_ONCE(bond->curr_active_slave); /* see if any of the previous devices are up now (i.e. they have * xmt and rcv traffic). the curr_active_slave does not come into * the picture unless it is null. also, slave->jiffies is not needed
@@ -2421,7 +2423,7 @@ void bond_loadbalance_arp_mon(struct work_struct *work) * TODO: what about up/down delay in arp mode? it wasn't here before * so it can wait */ - bond_for_each_slave(bond, slave, iter) { + bond_for_each_slave_rcu(bond, slave, iter) { unsigned long trans_start = dev_trans_start(slave->dev); if (slave->link != BOND_LINK_UP) {
@@ -2483,7 +2485,14 @@ void bond_loadbalance_arp_mon(struct work_struct *work) bond_arp_send_all(bond, slave); } + rcu_read_unlock(); + if (do_failover) { + /* the bond_select_active_slave must hold RTNL + * and curr_slave_lock for write. + */ + if (!rtnl_trylock()) + goto re_arm; block_netpoll_tx(); write_lock_bh(&bond->curr_slave_lock);
@@ -2491,14 +2500,13 @@ void bond_loadbalance_arp_mon(struct work_struct *work) write_unlock_bh(&bond->curr_slave_lock); unblock_netpoll_tx(); + rtnl_unlock(); } re_arm: if (bond->params.arp_interval) queue_delayed_work(bond->wq, &bond->arp_work, msecs_to_jiffies(bond->params.arp_interval)); - - read_unlock(&bond->lock); } /*
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1.8.2.1