From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ding Tianhong Subject: Re: [PATCH net-next 2/4] bonding: use RCU protection for alb xmit path Date: Mon, 30 Sep 2013 19:19:58 +0800 Message-ID: <52495E5E.5050502@huawei.com> References: <524812C1.6070407@huawei.com> <20130930105233.GA6096@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" , Nikolay Aleksandrov , Netdev To: Veaceslav Falico Return-path: Received: from szxga02-in.huawei.com ([119.145.14.65]:47329 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754531Ab3I3LVA (ORCPT ); Mon, 30 Sep 2013 07:21:00 -0400 In-Reply-To: <20130930105233.GA6096@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On 2013/9/30 18:52, Veaceslav Falico wrote: > 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 >> >> >> oh, yes, has to do little more,thanks. > > . >