netdev - Re: [PATCH net-next v2 3/4] net: bonding: send peer notify when failure recovery

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Message-Id: <A07A9C4B-E8E2-402A-AD41-DDB0DA114DF4@bamaicloud.com>
Date: Wed, 14 May 2025 14:07:55 +0800
From: Tonghao Zhang <tonghao@...aicloud.com>
To: Nikolay Aleksandrov <razor@...ckwall.org>
Cc: netdev@...r.kernel.org,
 Jay Vosburgh <jv@...sburgh.net>,
 "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>,
 Simon Horman <horms@...nel.org>,
 Jonathan Corbet <corbet@....net>,
 Andrew Lunn <andrew+netdev@...n.ch>,
 Zengbing Tu <tuzengbing@...iglobal.com>
Subject: Re: [PATCH net-next v2 3/4] net: bonding: send peer notify when
 failure recovery



> 2025年5月13日 18:37，Nikolay Aleksandrov <razor@...ckwall.org> 写道：
> 
> On 5/13/25 12:47, Tonghao Zhang wrote:
>> After LACP protocol recovery, the port can transmit packets.
>> However, if the bond port doesn't send gratuitous ARP/ND
>> packets to the switch, the switch won't return packets through
>> the current interface. This causes traffic imbalance. To resolve
>> this issue, when LACP protocol recovers, send ARP/ND packets.
>> 
>> Cc: Jay Vosburgh <jv@...sburgh.net>
>> Cc: "David S. Miller" <davem@...emloft.net>
>> Cc: Eric Dumazet <edumazet@...gle.com>
>> Cc: Jakub Kicinski <kuba@...nel.org>
>> Cc: Paolo Abeni <pabeni@...hat.com>
>> Cc: Simon Horman <horms@...nel.org>
>> Cc: Jonathan Corbet <corbet@....net>
>> Cc: Andrew Lunn <andrew+netdev@...n.ch>
>> Signed-off-by: Tonghao Zhang <tonghao@...aicloud.com>
>> Signed-off-by: Zengbing Tu <tuzengbing@...iglobal.com>
>> ---
>> Documentation/networking/bonding.rst |  5 +++--
>> drivers/net/bonding/bond_3ad.c       | 13 +++++++++++++
>> drivers/net/bonding/bond_main.c      | 21 ++++++++++++++++-----
>> 3 files changed, 32 insertions(+), 7 deletions(-)
>> 
>> diff --git a/Documentation/networking/bonding.rst b/Documentation/networking/bonding.rst
>> index 14f7593d888d..f8f5766703d4 100644
>> --- a/Documentation/networking/bonding.rst
>> +++ b/Documentation/networking/bonding.rst
>> @@ -773,8 +773,9 @@ num_unsol_na
>> greater than 1.
>> 
>> The valid range is 0 - 255; the default value is 1.  These options
>> - affect only the active-backup mode.  These options were added for
>> - bonding versions 3.3.0 and 3.4.0 respectively.
>> + affect the active-backup or 802.3ad (broadcast_neighbor enabled) mode.
>> + These options were added for bonding versions 3.3.0 and 3.4.0
>> + respectively.
>> 
>> From Linux 3.0 and bonding version 3.7.1, these notifications
>> are generated by the ipv4 and ipv6 code and the numbers of
>> diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
>> index c6807e473ab7..d1c2d416ac87 100644
>> --- a/drivers/net/bonding/bond_3ad.c
>> +++ b/drivers/net/bonding/bond_3ad.c
>> @@ -982,6 +982,17 @@ static int ad_marker_send(struct port *port, struct bond_marker *marker)
>> return 0;
>> }
>> 
>> +static void ad_cond_set_peer_notif(struct port *port)
>> +{
>> + struct bonding *bond = port->slave->bond;
>> +
>> + if (bond->params.broadcast_neighbor && rtnl_trylock()) {
>> + bond->send_peer_notif = bond->params.num_peer_notif *
>> + max(1, bond->params.peer_notif_delay);
>> + rtnl_unlock();
>> + }> +}
>> +
>> /**
>>  * ad_mux_machine - handle a port's mux state machine
>>  * @port: the port we're looking at
>> @@ -2061,6 +2072,8 @@ static void ad_enable_collecting_distributing(struct port *port,
>> __enable_port(port);
>> /* Slave array needs update */
>> *update_slave_arr = true;
>> + /* Should notify peers if possible */
>> + ad_cond_set_peer_notif(port);
>> }
>> }
>> 
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 8ee26ddddbc8..70bb1e33cee2 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -1243,17 +1243,28 @@ static struct slave *bond_find_best_slave(struct bonding *bond)
>> /* must be called in RCU critical section or with RTNL held */
>> static bool bond_should_notify_peers(struct bonding *bond)
>> {
>> - struct slave *slave = rcu_dereference_rtnl(bond->curr_active_slave);
>> + struct bond_up_slave *usable;
>> + struct slave *slave = NULL;
>> 
>> - if (!slave || !bond->send_peer_notif ||
>> + if (!bond->send_peer_notif ||
>>     bond->send_peer_notif %
>>     max(1, bond->params.peer_notif_delay) != 0 ||
>> -     !netif_carrier_ok(bond->dev) ||
>> +     !netif_carrier_ok(bond->dev))>   return false;
>> 
>> + if (BOND_MODE(bond) == BOND_MODE_8023AD) {
>> + usable = rtnl_dereference(bond->usable_slaves);
> 
> If mii monitor is enabled in 802.3ad bond mode then this will be 
> dereferenced in bond_mii_monitor() with rcu, so you'd have to use
> rcu_dereference_rtnl() instead.
Ok, thanks for your review.
> 
>> + if (!usable || !READ_ONCE(usable->count))
>> + return false;
>> + } else {
>> + slave = rcu_dereference_rtnl(bond->curr_active_slave);
>> + if (!slave || test_bit(__LINK_STATE_LINKWATCH_PENDING,
>> +        &slave->dev->state))
>> + return false;
>> + }
>> +
>> netdev_dbg(bond->dev, "bond_should_notify_peers: slave %s\n",
>> -    slave ? slave->dev->name : "NULL");
>> +    slave ? slave->dev->name : "all");
>> 
>> return true;
>> }