netdev - Re: [net-next v6 3/4] net: bonding: send peer notify when failure recovery

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Message-Id: <C46140E5-35E2-49A2-8E58-FB3AC49AA53E@bamaicloud.com>
Date: Wed, 18 Jun 2025 10:51:07 +0800
From: Tonghao Zhang <tonghao@...aicloud.com>
To: jv@...sburgh.net
Cc: netdev@...r.kernel.org,
 "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>,
 Steven Rostedt <rostedt@...dmis.org>,
 Masami Hiramatsu <mhiramat@...nel.org>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Nikolay Aleksandrov <razor@...ckwall.org>,
 Zengbing Tu <tuzengbing@...iglobal.com>
Subject: Re: [net-next v6 3/4] net: bonding: send peer notify when failure
 recovery



> 2025年6月17日 19:39，Tonghao Zhang <tonghao@...aicloud.com> 写道：
> 
>> 
>> 2025年6月17日 18:47，Tonghao Zhang <tonghao@...aicloud.com> 写道：
>> 
>> 
>> 
>>> 2025年6月17日 08:36，Jay Vosburgh <jv@...sburgh.net> 写道：
>>> 
>>> Tonghao Zhang <tonghao@...aicloud.com> 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.
>>> 
>>> I think the description above needs to mention that the
>>> gratuitous ARP/ND only happens if broadcast_neighbor is enabled.
>> Ok, thanks
>>> 
>>> I'll note that the documentation update does include this
>>> caveat.
>>> 
>>>> 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>
>>>> Cc: Steven Rostedt <rostedt@...dmis.org>
>>>> Cc: Masami Hiramatsu <mhiramat@...nel.org>
>>>> Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
>>>> Cc: Nikolay Aleksandrov <razor@...ckwall.org>
>>>> Signed-off-by: Tonghao Zhang <tonghao@...aicloud.com>
>>>> Signed-off-by: Zengbing Tu <tuzengbing@...iglobal.com>
>>>> Reviewed-by: Nikolay Aleksandrov <razor@...ckwall.org>
>>>> ---
>>>> 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 12046ef51569..0acece55d9cb 100644
>>>> --- a/drivers/net/bonding/bond_main.c
>>>> +++ b/drivers/net/bonding/bond_main.c
>>>> @@ -1237,17 +1237,28 @@ 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) ||
>>>> -     test_bit(__LINK_STATE_LINKWATCH_PENDING, &slave->dev->state))
>>>> +     !netif_carrier_ok(bond->dev))
>>>> return false;
>>>> 
>>>> + if (BOND_MODE(bond) == BOND_MODE_8023AD) {
>>>> + usable = rcu_dereference_rtnl(bond->usable_slaves);
>>>> + 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");
>>> 
>>> Is it actually correct that if slave == NULL, the notify peers
>>> logic will send to all ports?  I'm not sure why this changed.
>> when bond is lacp mode, and send_peer_notif > 0, usable_slaves > 0, then slave == NULL, the debug log will print info "bond_should_notify_peers: slave all”.
> In lacp mode, when broadcast_neighbor enabled, send_peer_notif will be set in ad_cond_set_peer_notif.
Hi Jay
This patch is ok? Or delete the debug info if you're confused. I think this is correct and useful to debug notify peers function.
>> 
>> In active-backup mode, slave is not NULL, that means "bond_should_notify_peers: slave xx".
>>> 
>>> -J
>>> 
>>>> 
>>>> return true;
>>>> }
>>>> -- 
>>>> 2.34.1
>>> 
>>> ---
>>> -Jay Vosburgh, jv@...sburgh.net