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Date: Wed, 23 Mar 2011 10:07:10 +0800
From: Weiping Pan <panweiping3@...il.com>
To: Jiri Pirko <jpirko@...hat.com>
CC: netdev@...r.kernel.org, davem@...emloft.net,
nicolas.2p.debian@...il.com, andy@...yhouse.net, fubar@...ibm.com
Subject: Re: [patch net-2.6] bonding: fix rx_handler locking
On 03/22/2011 08:38 PM, Jiri Pirko wrote:
> This prevents possible race between bond_enslave and bond_handle_frame
> as reported by Nicolas by moving rx_handler register/unregister.
> slave->bond is added to hold pointer to master bonding sructure. That
> way dev->master is no longer used in bond_handler_frame.
> Also, this removes "BUG: scheduling while atomic" message
>
> Reported-by: Nicolas de Pesloüan<nicolas.2p.debian@...il.com>
> Signed-off-by: Jiri Pirko<jpirko@...hat.com>
> ---
> drivers/net/bonding/bond_main.c | 56 +++++++++++++++++++++-----------------
> drivers/net/bonding/bonding.h | 1 +
> 2 files changed, 32 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 338bea1..16d6fe9 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1482,21 +1482,16 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
> {
> struct sk_buff *skb = *pskb;
> struct slave *slave;
> - struct net_device *bond_dev;
> struct bonding *bond;
>
> - slave = bond_slave_get_rcu(skb->dev);
> - bond_dev = ACCESS_ONCE(slave->dev->master);
> - if (unlikely(!bond_dev))
> - return RX_HANDLER_PASS;
> -
> skb = skb_share_check(skb, GFP_ATOMIC);
> if (unlikely(!skb))
> return RX_HANDLER_CONSUMED;
>
> *pskb = skb;
>
> - bond = netdev_priv(bond_dev);
> + slave = bond_slave_get_rcu(skb->dev);
> + bond = slave->bond;
>
> if (bond->params.arp_interval)
> slave->dev->last_rx = jiffies;
> @@ -1505,10 +1500,10 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
> return RX_HANDLER_EXACT;
> }
>
> - skb->dev = bond_dev;
> + skb->dev = bond->dev;
>
> if (bond->params.mode == BOND_MODE_ALB&&
> - bond_dev->priv_flags& IFF_BRIDGE_PORT&&
> + bond->dev->priv_flags& IFF_BRIDGE_PORT&&
> skb->pkt_type == PACKET_HOST) {
>
> if (unlikely(skb_cow_head(skb,
> @@ -1516,7 +1511,7 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
> kfree_skb(skb);
> return RX_HANDLER_CONSUMED;
> }
> - memcpy(eth_hdr(skb)->h_dest, bond_dev->dev_addr, ETH_ALEN);
> + memcpy(eth_hdr(skb)->h_dest, bond->dev->dev_addr, ETH_ALEN);
> }
>
> return RX_HANDLER_ANOTHER;
> @@ -1698,20 +1693,15 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
> pr_debug("Error %d calling netdev_set_bond_master\n", res);
> goto err_restore_mac;
> }
> - res = netdev_rx_handler_register(slave_dev, bond_handle_frame,
> - new_slave);
> - if (res) {
> - pr_debug("Error %d calling netdev_rx_handler_register\n", res);
> - goto err_unset_master;
> - }
>
> /* open the slave since the application closed it */
> res = dev_open(slave_dev);
> if (res) {
> pr_debug("Opening slave %s failed\n", slave_dev->name);
> - goto err_unreg_rxhandler;
> + goto err_unset_master;
> }
>
> + new_slave->bond = bond;
> new_slave->dev = slave_dev;
> slave_dev->priv_flags |= IFF_BONDING;
>
> @@ -1907,6 +1897,13 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
> if (res)
> goto err_close;
>
> + res = netdev_rx_handler_register(slave_dev, bond_handle_frame,
> + new_slave);
> + if (res) {
> + pr_debug("Error %d calling netdev_rx_handler_register\n", res);
> + goto err_dest_symlinks;
> + }
> +
> pr_info("%s: enslaving %s as a%s interface with a%s link.\n",
> bond_dev->name, slave_dev->name,
> bond_is_active_slave(new_slave) ? "n active" : " backup",
> @@ -1916,13 +1913,12 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
> return 0;
>
> /* Undo stages on error */
> +err_dest_symlinks:
> + bond_destroy_slave_symlinks(bond_dev, slave_dev);
> +
> err_close:
> dev_close(slave_dev);
>
> -err_unreg_rxhandler:
> - netdev_rx_handler_unregister(slave_dev);
> - synchronize_net();
> -
> err_unset_master:
> netdev_set_bond_master(slave_dev, NULL);
>
> @@ -1988,6 +1984,14 @@ int bond_release(struct net_device *bond_dev, struct net_device *slave_dev)
> return -EINVAL;
> }
>
> + /* unregister rx_handler early so bond_handle_frame wouldn't be called
> + * for this slave anymore.
> + */
> + netdev_rx_handler_unregister(slave_dev);
> + write_unlock_bh(&bond->lock);
> + synchronize_net();
> + write_lock_bh(&bond->lock);
> +
> if (!bond->params.fail_over_mac) {
> if (!compare_ether_addr(bond_dev->dev_addr, slave->perm_hwaddr)&&
> bond->slave_cnt> 1)
> @@ -2104,8 +2108,6 @@ int bond_release(struct net_device *bond_dev, struct net_device *slave_dev)
> netif_addr_unlock_bh(bond_dev);
> }
>
> - netdev_rx_handler_unregister(slave_dev);
> - synchronize_net();
> netdev_set_bond_master(slave_dev, NULL);
>
> slave_disable_netpoll(slave);
> @@ -2186,6 +2188,12 @@ static int bond_release_all(struct net_device *bond_dev)
> */
> write_unlock_bh(&bond->lock);
>
> + /* unregister rx_handler early so bond_handle_frame wouldn't
> + * be called for this slave anymore.
> + */
> + netdev_rx_handler_unregister(slave_dev);
> + synchronize_net();
> +
> if (bond_is_lb(bond)) {
> /* must be called only after the slave
> * has been detached from the list
> @@ -2217,8 +2225,6 @@ static int bond_release_all(struct net_device *bond_dev)
> netif_addr_unlock_bh(bond_dev);
> }
>
> - netdev_rx_handler_unregister(slave_dev);
> - synchronize_net();
> netdev_set_bond_master(slave_dev, NULL);
>
> slave_disable_netpoll(slave);
> diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
> index 6b26962..90736cb 100644
> --- a/drivers/net/bonding/bonding.h
> +++ b/drivers/net/bonding/bonding.h
> @@ -187,6 +187,7 @@ struct slave {
> struct net_device *dev; /* first - useful for panic debug */
> struct slave *next;
> struct slave *prev;
> + struct bonding *bond; /* our master */
> int delay;
> unsigned long jiffies;
> unsigned long last_arp_rx;
Hi,
I test this patch with VirtualBox, no kernel panic occurs.
git log 08351fc6a75731226e1112fc7254542bd3a2912e
[root@...alhost ~]# vboxmanage showvminfo server |grep ^NIC
NIC 1: MAC: 0800273A4DBD, Attachment: Bridged Interface
'eth0', Cable connected: on, Trace: off (file: none), Type: 82540EM,
Reported speed: 0 Mbps, Boot priority: 0
NIC 2: MAC: 080027B5FCD1, Attachment: Bridged Interface
'eth0', Cable connected: on, Trace: off (file: none), Type: 82540EM,
Reported speed: 0 Mbps, Boot priority: 0
NIC 3: MAC: 080027C77BFC, Attachment: Bridged Interface
'eth0', Cable connected: on, Trace: off (file: none), Type: 82540EM,
Reported speed: 0 Mbps, Boot priority: 0
NIC 4: MAC: 080027261BDB, Attachment: Bridged Interface
'eth0', Cable connected: on, Trace: off (file: none), Type: 82540EM,
Reported speed: 0 Mbps, Boot priority: 0
NIC 5: disabled
NIC 6: disabled
NIC 7: disabled
NIC 8: disabled
Here is my test case.
#! /bin/sh
ifconfig eth9 down
NUM=0
for i in {1..100}
do
modprobe -r bonding
modprobe bonding max_bonds=0
echo +bond0 > /sys/class/net/bonding_masters
echo +bond1 > /sys/class/net/bonding_masters
echo +eth9 > /sys/class/net/bond1/bonding/slaves
echo $i " PASS"
(( NUM += 1))
done
echo $NUM " PASS"
Hope it will be useful for you.
thanks
Weiping Pan
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