From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikolay Aleksandrov Subject: Re: [PATCH net-next 6/6] bonding: use RCU protection for alb xmit path Date: Tue, 03 Sep 2013 12:22:13 +0200 Message-ID: <5225B855.6080101@redhat.com> References: <52206E54.4040001@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Jay Vosburgh , Andy Gospodarek , "David S. Miller" , Veaceslav Falico , Netdev , Hideaki YOSHIFUJI To: Ding Tianhong Return-path: Received: from mx1.redhat.com ([209.132.183.28]:8229 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759710Ab3ICKZz (ORCPT ); Tue, 3 Sep 2013 06:25:55 -0400 In-Reply-To: <52206E54.4040001@huawei.com> Sender: netdev-owner@vger.kernel.org List-ID: On 08/30/2013 12:05 PM, Ding Tianhong wrote: > The commit 278b20837511776dc9d5f6ee1c7fabd5479838bb > (bonding: initial RCU conversion) has convert the roundrobin, active-backup, > broadcast and xor xmit path to rcu protection, the performance will be better > for these mode, so this time, convert xmit path for alb mode. > > Suggested-by: Nikolay Aleksandrov > Signed-off-by: Ding Tianhong > Signed-off-by: Yang Yingliang > Cc: Nikolay Aleksandrov > Cc: Veaceslav Falico > --- > drivers/net/bonding/bond_alb.c | 20 +++++++++----------- > drivers/net/bonding/bonding.h | 2 +- > 2 files changed, 10 insertions(+), 12 deletions(-) > > diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c > index d266c56..e94a5d0 100644 > --- a/drivers/net/bonding/bond_alb.c > +++ b/drivers/net/bonding/bond_alb.c > @@ -229,7 +229,7 @@ static struct slave *tlb_get_least_loaded_slave(struct bonding *bond) > max_gap = LLONG_MIN; > > /* Find the slave with the largest gap */ > - bond_for_each_slave(bond, slave) { > + bond_for_each_slave_rcu(bond, slave) { > if (SLAVE_IS_OK(slave)) { > long long gap = compute_gap(slave); > > @@ -625,10 +625,12 @@ static struct slave *rlb_choose_channel(struct sk_buff *skb, struct bonding *bon > { > struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond)); > struct arp_pkt *arp = arp_pkt(skb); > - struct slave *assigned_slave; > + struct slave *assigned_slave, *curr_active_slave; > struct rlb_client_info *client_info; > u32 hash_index = 0; > > + curr_active_slave = rcu_dereference(bond->curr_active_slave); > + I think this code is prone to a race condition with the slave removal, because without the lock __bond_release_one() may think that it has done the LB release (bond_alb_deinit_slave) and cleared the slave while you may set it after locking. I guess you should move the dereference after the lock so to make sure that the LB release hasn't passed (or it has and it'll be different). > _lock_rx_hashtbl(bond); > > hash_index = _simple_hash((u8 *)&arp->ip_dst, sizeof(arp->ip_dst)); > @@ -654,9 +656,9 @@ static struct slave *rlb_choose_channel(struct sk_buff *skb, struct bonding *bon > * move the old client to primary (curr_active_slave) so > * that the new client can be assigned to this entry. > */ > - if (bond->curr_active_slave && > - client_info->slave != bond->curr_active_slave) { > - client_info->slave = bond->curr_active_slave; > + if (curr_active_slave && > + client_info->slave != curr_active_slave) { > + client_info->slave = curr_active_slave; > rlb_update_client(client_info); > } > } > @@ -1336,8 +1338,6 @@ int bond_alb_xmit(struct sk_buff *skb, struct net_device *bond_dev) > > /* make sure that the curr_active_slave do not change during tx > */ > - read_lock(&bond->lock); > - read_lock(&bond->curr_slave_lock); > > switch (ntohs(skb->protocol)) { > case ETH_P_IP: { > @@ -1420,12 +1420,12 @@ int bond_alb_xmit(struct sk_buff *skb, struct net_device *bond_dev) > > if (!tx_slave) { > /* unbalanced or unassigned, send through primary */ > - tx_slave = bond->curr_active_slave; > + tx_slave = rcu_dereference(bond->curr_active_slave); > bond_info->unbalanced_load += skb->len; > } > > if (tx_slave && SLAVE_IS_OK(tx_slave)) { > - if (tx_slave != bond->curr_active_slave) { > + if (tx_slave != rcu_dereference(bond->curr_active_slave)) { > memcpy(eth_data->h_source, > tx_slave->dev->dev_addr, > ETH_ALEN); > @@ -1440,8 +1440,6 @@ int bond_alb_xmit(struct sk_buff *skb, struct net_device *bond_dev) > } > } > > - read_unlock(&bond->curr_slave_lock); > - read_unlock(&bond->lock); > if (res) { > /* no suitable interface, frame not sent */ > kfree_skb(skb); > diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h > index a3ab47f..9bc3af0 100644 > --- a/drivers/net/bonding/bonding.h > +++ b/drivers/net/bonding/bonding.h > @@ -536,7 +536,7 @@ static inline struct slave *bond_slave_has_mac(struct bonding *bond, > { > struct slave *tmp; > > - bond_for_each_slave(bond, tmp) > + bond_for_each_slave_rcu(bond, tmp) > if (ether_addr_equal_64bits(mac, tmp->dev->dev_addr)) > return tmp; > >