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Message-ID: <20131021070353.GA21849@redhat.com>
Date: Mon, 21 Oct 2013 09:03:53 +0200
From: Veaceslav Falico <vfalico@...hat.com>
To: Ding Tianhong <dingtianhong@...wei.com>
Cc: netdev@...r.kernel.org, jiri@...nulli.us,
Jay Vosburgh <fubar@...ibm.com>,
Andy Gospodarek <andy@...yhouse.net>
Subject: Re: [PATCH net-next] bonding: move bond-specific init after enslave
happens
On Mon, Oct 21, 2013 at 09:35:09AM +0800, Ding Tianhong wrote:
>On 2013/10/20 20:47, Veaceslav Falico wrote:
>> As Jiri noted, currently we first do all bonding-specific initialization
>> (specifically - bond_select_active_slave(bond)) before we actually attach
>> the slave (so that it becomes visible through bond_for_each_slave() and
>> friends). This might result in bond_select_active_slave() not seeing the
>> first/new slave and, thus, not actually selecting an active slave.
>>
>> Fix this by moving all the bond-related init part after we've actually
>> completely initialized and linked (via bond_master_upper_dev_link()) the
>> new slave.
>>
>> After this we have all the initialization of the new slave *before*
>> linking, and all the stuff that needs to be done on bonding *after* it. It
>> has also a bonus effect - we can remove the locking on the new slave init
>> completely, and only use it for bond_select_active_slave().
>>
>> Reported-by: Jiri Pirko <jiri@...nulli.us>
>> CC: Jay Vosburgh <fubar@...ibm.com>
>> CC: Andy Gospodarek <andy@...yhouse.net>
>> Signed-off-by: Veaceslav Falico <vfalico@...hat.com>
>> ---
>> drivers/net/bonding/bond_main.c | 29 ++++++++++-------------------
>> 1 file changed, 10 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index d90734f..047c0fb 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -1471,22 +1471,14 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>> goto err_close;
>> }
>>
>> - write_lock_bh(&bond->lock);
>> -
>> prev_slave = bond_last_slave(bond);
>> bond_attach_slave(bond, new_slave);
>>
>> new_slave->delay = 0;
>> new_slave->link_failure_count = 0;
>>
>> - write_unlock_bh(&bond->lock);
>> -
>> - bond_compute_features(bond);
>> -
>> bond_update_speed_duplex(new_slave);
>>
>> - read_lock(&bond->lock);
>> -
>> new_slave->last_arp_rx = jiffies -
>> (msecs_to_jiffies(bond->params.arp_interval) + 1);
>> for (i = 0; i < BOND_MAX_ARP_TARGETS; i++)
>> @@ -1547,12 +1539,9 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>> }
>> }
>>
>> - write_lock_bh(&bond->curr_slave_lock);
>> -
>> switch (bond->params.mode) {
>> case BOND_MODE_ACTIVEBACKUP:
>> bond_set_slave_inactive_flags(new_slave);
>> - bond_select_active_slave(bond);
>> break;
>> case BOND_MODE_8023AD:
>> /* in 802.3ad mode, the internal mechanism
>> @@ -1578,7 +1567,6 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>> case BOND_MODE_ALB:
>> bond_set_active_slave(new_slave);
>> bond_set_slave_inactive_flags(new_slave);
>> - bond_select_active_slave(bond);
>> break;
>> default:
>> pr_debug("This slave is always active in trunk mode\n");
>> @@ -1596,10 +1584,6 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>> break;
>> } /* switch(bond_mode) */
>>
>> - write_unlock_bh(&bond->curr_slave_lock);
>> -
>> - bond_set_carrier(bond);
>> -
>> #ifdef CONFIG_NET_POLL_CONTROLLER
>> slave_dev->npinfo = bond->dev->npinfo;
>> if (slave_dev->npinfo) {
>> @@ -1614,8 +1598,6 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>> }
>> #endif
>>
>> - read_unlock(&bond->lock);
>> -
>> res = netdev_rx_handler_register(slave_dev, bond_handle_frame,
>> new_slave);
>> if (res) {
>> @@ -1629,6 +1611,16 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>> goto err_unregister;
>> }
>>
>> + bond_compute_features(bond);
>> + bond_set_carrier(bond);
>> +
>> + if (USES_PRIMARY(bond->params.mode)) {
>> + read_lock(&bond->lock);
>> + write_lock_bh(&bond->curr_slave_lock);
>> + bond_select_active_slave(bond);
>> + write_unlock_bh(&bond->curr_slave_lock);
>> + read_unlock(&bond->lock);
>> + }
>>
>
>agree to move the lock, and I think bond_attach_slave() should add here,
>as it look more logical, the slave_cnt should not add before the slave truly
>add to the bond.
bond_(de)attach_slave() should be removed completely, actually. we don't
need special functions for ++/--.
OTOH, the whole slave_cnt is flawed a bit, whilst using RCU - we can never
guarantee that it's the actual value if we don't hold rtnl lock (we do in
ioctl, but we don't in the hash functions).
I'll take a closer look and send v2.
>
>Regards.
>Ding
>
>> pr_info("%s: enslaving %s as a%s interface with a%s link.\n",
>> bond_dev->name, slave_dev->name,
>> @@ -1686,7 +1678,6 @@ err_free:
>> kfree(new_slave);
>>
>> err_undo_flags:
>> - bond_compute_features(bond);
>> /* Enslave of first slave has failed and we need to fix master's mac */
>> if (!bond_has_slaves(bond) &&
>> ether_addr_equal(bond_dev->dev_addr, slave_dev->dev_addr))
>>
>
>
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