From mboxrd@z Thu Jan 1 00:00:00 1970 From: Veaceslav Falico Subject: Re: [PATCH net-next 2/4] bonding: use RCU protection for alb xmit path Date: Mon, 30 Sep 2013 12:52:33 +0200 Message-ID: <20130930105233.GA6096@redhat.com> References: <524812C1.6070407@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Cc: Jay Vosburgh , Andy Gospodarek , "David S. Miller" , Nikolay Aleksandrov , Netdev To: Ding Tianhong Return-path: Received: from mx1.redhat.com ([209.132.183.28]:37876 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753540Ab3I3Kyc (ORCPT ); Mon, 30 Sep 2013 06:54:32 -0400 Content-Disposition: inline In-Reply-To: <524812C1.6070407@huawei.com> Sender: netdev-owner@vger.kernel.org List-ID: On Sun, Sep 29, 2013 at 07:45:05PM +0800, 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. > >Signed-off-by: Ding Tianhong >Signed-off-by: Yang Yingliang >Cc: Nikolay Aleksandrov >Cc: Veaceslav Falico >--- > drivers/net/bonding/bond_alb.c | 23 +++++++++-------------- > drivers/net/bonding/bonding.h | 2 +- > 2 files changed, 10 insertions(+), 15 deletions(-) > >diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c >index e960418..a1444d5 100644 >--- a/drivers/net/bonding/bond_alb.c >+++ b/drivers/net/bonding/bond_alb.c >@@ -230,7 +230,7 @@ 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, iter) { >+ bond_for_each_slave_rcu(bond, slave, iter) { > if (SLAVE_IS_OK(slave)) { > long long gap = compute_gap(slave); > >@@ -387,7 +387,7 @@ static struct slave *rlb_next_rx_slave(struct bonding *bond) > struct list_head *iter; > bool found = false; > >- bond_for_each_slave(bond, slave, iter) { >+ bond_for_each_slave_rcu(bond, slave, iter) { > if (!SLAVE_IS_OK(slave)) > continue; > if (!found) { >@@ -628,12 +628,14 @@ 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; > > _lock_rx_hashtbl(bond); > >+ curr_active_slave = rcu_dereference(bond->curr_active_slave); >+ > hash_index = _simple_hash((u8 *)&arp->ip_dst, sizeof(arp->ip_dst)); > client_info = &(bond_info->rx_hashtbl[hash_index]); > >@@ -658,8 +660,8 @@ static struct slave *rlb_choose_channel(struct sk_buff *skb, struct bonding *bon > * 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; >+ client_info->slave != curr_active_slave) { >+ client_info->slave = curr_active_slave; > rlb_update_client(client_info); > } > } >@@ -1343,11 +1345,6 @@ int bond_alb_xmit(struct sk_buff *skb, struct net_device *bond_dev) > skb_reset_mac_header(skb); > eth_data = eth_hdr(skb); > >- /* 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: { > const struct iphdr *iph = ip_hdr(skb); >@@ -1429,12 +1426,12 @@ 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); >@@ -1449,8 +1446,6 @@ 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 713b6af..1c7d559 100644 >--- a/drivers/net/bonding/bonding.h >+++ b/drivers/net/bonding/bonding.h >@@ -459,7 +459,7 @@ static inline struct slave *bond_slave_has_mac(struct bonding *bond, > struct list_head *iter; > struct slave *tmp; > >- bond_for_each_slave(bond, tmp, iter) >+ bond_for_each_slave_rcu(bond, tmp, iter) This suggests that rcu_read_lock() is always held here, however it's not the case, as far as I can tell: bond_release()/bond_uninit() -> __bond_release_one() -> bond_alb_deinit_slave() -> alb_change_hw_addr_on_detach() -> bond_slave_has_mac() There is nobody that takes rcu_read_lock() there. And, for example, when doing: echo -$slave > /sys/class/net/$bond_int/bonding/slaves nobody is holding it. And, btw, in bond_for_each_slave_rcu(), which is actually a wrapper for netdev_for_each_lower_private_rcu(), which calls netdev_lower_get_next_private_rcu(), which has: 4543 void *netdev_lower_get_next_private_rcu(struct net_device *dev, 4544 struct list_head **iter) 4545 { 4546 struct netdev_adjacent *lower; 4547 4548 WARN_ON_ONCE(!rcu_read_lock_held()); so you should have seen that warning when trying to remove a slave in alb mode. > if (ether_addr_equal_64bits(mac, tmp->dev->dev_addr)) > return tmp; > >-- >1.8.2.1 > > >