From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ding Tianhong Subject: Re: [PATCH net-next 6/6] bonding: use RCU protection for alb xmit path Date: Wed, 4 Sep 2013 14:24:47 +0800 Message-ID: <5226D22F.2060706@huawei.com> References: <52206E54.4040001@huawei.com> <5225B855.6080101@redhat.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: Nikolay Aleksandrov Return-path: Received: from szxga02-in.huawei.com ([119.145.14.65]:25518 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755945Ab3IDGZZ (ORCPT ); Wed, 4 Sep 2013 02:25:25 -0400 In-Reply-To: <5225B855.6080101@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On 2013/9/3 18:22, Nikolay Aleksandrov wrote: > 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). > yes, I ignore it, fix it in next version. >> _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; >> >> > > > . >