From 71bc3b2dc5d02566afe1b23a7b72bfc8acdd04e1 Mon Sep 17 00:00:00 2001 From: "nikolay@redhat.com" Date: Thu, 1 Aug 2013 16:54:48 +0200 Subject: [PATCH] bonding: remove unnecessary read_locks of curr_slave_lock In all the cases we already hold bond->lock for reading, so the slave can't get away and the check != NULL is sufficient. curr_active_slave can still change after the read_lock is unlocked prior to use of the dereferenced value, so there's no need for it. It either contains a valid slave which we use (and can't get away), or it is NULL which is checked. In some places the read_lock of curr_slave_lock was left because we need it not to change while performing some action (e.g. syncing current active slave's addresses, sending ARP requests through the active slave) such cases will be dealt with individually while converting to RCU. Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller --- drivers/net/bonding/bond_main.c | 33 ++++++++------------------------- 1 file changed, 8 insertions(+), 25 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 2e8ec8b..ac60b69 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2092,23 +2092,19 @@ static int bond_ioctl_change_active(struct net_device *bond_dev, struct net_devi read_lock(&bond->lock); - read_lock(&bond->curr_slave_lock); old_active = bond->curr_active_slave; - read_unlock(&bond->curr_slave_lock); - new_active = bond_get_slave_by_dev(bond, slave_dev); - /* * Changing to the current active: do nothing; return success. */ - if (new_active && (new_active == old_active)) { + if (new_active && new_active == old_active) { read_unlock(&bond->lock); return 0; } - if ((new_active) && - (old_active) && - (new_active->link == BOND_LINK_UP) && + if (new_active && + old_active && + new_active->link == BOND_LINK_UP && IS_UP(new_active->dev)) { block_netpoll_tx(); write_lock_bh(&bond->curr_slave_lock); @@ -2660,10 +2656,7 @@ void bond_loadbalance_arp_mon(struct work_struct *work) if (list_empty(&bond->slave_list)) goto re_arm; - read_lock(&bond->curr_slave_lock); oldcurrent = bond->curr_active_slave; - read_unlock(&bond->curr_slave_lock); - /* 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 @@ -3818,11 +3811,7 @@ static int bond_xmit_roundrobin(struct sk_buff *skb, struct net_device *bond_dev */ if ((iph->protocol == IPPROTO_IGMP) && (skb->protocol == htons(ETH_P_IP))) { - - read_lock(&bond->curr_slave_lock); slave = bond->curr_active_slave; - read_unlock(&bond->curr_slave_lock); - if (!slave) goto out; } else { @@ -3867,15 +3856,12 @@ out: static int bond_xmit_activebackup(struct sk_buff *skb, struct net_device *bond_dev) { struct bonding *bond = netdev_priv(bond_dev); + struct slave *slave; int res = 1; - read_lock(&bond->curr_slave_lock); - - if (bond->curr_active_slave) - res = bond_dev_queue_xmit(bond, skb, - bond->curr_active_slave->dev); - - read_unlock(&bond->curr_slave_lock); + slave = bond->curr_active_slave; + if (slave) + res = bond_dev_queue_xmit(bond, skb, slave->dev); if (res) /* no suitable interface, frame not sent */ @@ -3935,10 +3921,7 @@ static int bond_xmit_broadcast(struct sk_buff *skb, struct net_device *bond_dev) int i; int res = 1; - read_lock(&bond->curr_slave_lock); start_at = bond->curr_active_slave; - read_unlock(&bond->curr_slave_lock); - if (!start_at) goto out; -- 2.7.4