Re: [PATCH net 1/2] bonding: send LACPDUs periodically in passive mode after receiving partner's LACPDU

On 7/25/25 09:28, Hangbin Liu wrote:

When `lacp_active` is set to `off`, the bond operates in passive mode, meaning it only "speaks when spoken to." However, the current kernel implementation only sends an LACPDU in response when the partner's state changes.

As a result, once LACP negotiation succeeds, the actor stops sending LACPDUs until the partner times out and sends an "expired" LACPDU. This causes continuous LACP state flapping.

According to IEEE 802.1AX-2014, 6.4.13 Periodic Transmission machine. The values of Partner_Oper_Port_State.LACP_Activity and Actor_Oper_Port_State.LACP_Activity determine whether periodic transmissions take place. If either or both parameters are set to Active LACP, then periodic transmissions occur; if both are set to Passive LACP, then periodic transmissions do not occur.

To comply with this, we remove the `!bond->params.lacp_active` check in `ad_periodic_machine()`. Instead, we initialize the actor's port's `LACP_STATE_LACP_ACTIVITY` state based on `lacp_active` setting.

Additionally, we avoid setting the partner's state to `LACP_STATE_LACP_ACTIVITY` in the EXPIRED state, since we should not assume the partner is active by default.

This ensures that in passive mode, the bond starts sending periodic LACPDUs after receiving one from the partner, and avoids flapping due to inactivity.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")

Shouldn't the fixes tag be lacp_active commit id? E.g. 3a755cd8b7c6 ("bonding: add new option lacp_active")

Signed-off-by: Hangbin Liu liuhangbin@gmail.com

drivers/net/bonding/bond_3ad.c | 72 ++++++++++++++++++++++-------- drivers/net/bonding/bond_options.c | 1 + include/net/bond_3ad.h | 1 + 3 files changed, 56 insertions(+), 18 deletions(-)

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c index 2fca8e84ab10..aa64b397bb19 100644 --- a/drivers/net/bonding/bond_3ad.c +++ b/drivers/net/bonding/bond_3ad.c @@ -95,13 +95,13 @@ static int ad_marker_send(struct port *port, struct bond_marker *marker); static void ad_mux_machine(struct port *port, bool *update_slave_arr); static void ad_rx_machine(struct lacpdu *lacpdu, struct port *port); static void ad_tx_machine(struct port *port); -static void ad_periodic_machine(struct port *port, struct bond_params *bond_params); +static void ad_periodic_machine(struct port *port); static void ad_port_selection_logic(struct port *port, bool *update_slave_arr); static void ad_agg_selection_logic(struct aggregator *aggregator, bool *update_slave_arr); static void ad_clear_agg(struct aggregator *aggregator); static void ad_initialize_agg(struct aggregator *aggregator); -static void ad_initialize_port(struct port *port, int lacp_fast); +static void ad_initialize_port(struct port *port, struct bond_params *bond_params); static void ad_enable_collecting(struct port *port); static void ad_disable_distributing(struct port *port, bool *update_slave_arr); @@ -1307,10 +1307,16 @@ static void ad_rx_machine(struct lacpdu *lacpdu, struct port *port) * case of EXPIRED even if LINK_DOWN didn't arrive for * the port. */

• 	port->partner_oper.port_state &= ~LACP_STATE_SYNCHRONIZATION;
  port->sm_vars &= ~AD_PORT_MATCHED;
  

• 	/* Based on IEEE 8021AX-2014, Figure 6-18 - Receive
  

• 	 * machine state diagram, the statue should be
  

• 	 * Partner_Oper_Port_State.Synchronization = FALSE;
  

• 	 * Partner_Oper_Port_State.LACP_Timeout = Short Timeout;
  

• 	 * start current_while_timer(Short Timeout);
  

• 	 * Actor_Oper_Port_State.Expired = TRUE;
  

• 	 */
  

• 	port->partner_oper.port_state &= ~LACP_STATE_SYNCHRONIZATION;
  port->partner_oper.port_state |= LACP_STATE_LACP_TIMEOUT;
  

• 	port->partner_oper.port_state |= LACP_STATE_LACP_ACTIVITY;
  port->sm_rx_timer_counter = __ad_timer_to_ticks(AD_CURRENT_WHILE_TIMER, (u16)(AD_SHORT_TIMEOUT));
  port->actor_oper_port_state |= LACP_STATE_EXPIRED;
  port->sm_vars |= AD_PORT_CHURNED;
  

@@ -1417,11 +1423,10 @@ static void ad_tx_machine(struct port *port) /**

• ad_periodic_machine - handle a port's periodic state machine
• @port: the port we're looking at

• • @bond_params: bond parameters we will use
  • Turn ntt flag on priodically to perform periodic transmission of lacpdu's.
  */

-static void ad_periodic_machine(struct port *port, struct bond_params *bond_params) +static void ad_periodic_machine(struct port *port) { periodic_states_t last_state; @@ -1430,8 +1435,7 @@ static void ad_periodic_machine(struct port *port, struct bond_params *bond_para /* check if port was reinitialized */ if (((port->sm_vars & AD_PORT_BEGIN) || !(port->sm_vars & AD_PORT_LACP_ENABLED) || !port->is_enabled) ||

•    (!(port->actor_oper_port_state & LACP_STATE_LACP_ACTIVITY) && !(port->partner_oper.port_state & LACP_STATE_LACP_ACTIVITY)) ||
  

•    !bond_params->lacp_active) {
  

•    (!(port->actor_oper_port_state & LACP_STATE_LACP_ACTIVITY) && !(port->partner_oper.port_state & LACP_STATE_LACP_ACTIVITY))) {
  

  port->sm_periodic_state = AD_NO_PERIODIC; } /* check if state machine should change state */

@@ -1955,16 +1959,16 @@ static void ad_initialize_agg(struct aggregator *aggregator) /**

• ad_initialize_port - initialize a given port's parameters
• @port: the port we're looking at

• • @lacp_fast: boolean. whether fast periodic should be used

• • @bond_params: bond parameters we will use
  */

-static void ad_initialize_port(struct port *port, int lacp_fast) +static void ad_initialize_port(struct port *port, struct bond_params *bond_params) { static const struct port_params tmpl = { .system_priority = 0xffff, .key = 1, .port_number = 1, .port_priority = 0xff,

• .port_state      = 1,
  

• .port_state      = 0,
  

1 == LACP_STATE_ACTIVITY :) Just noting that this lets LACP_STATE_ACTIVITY to be set based on lacp_active.

}; static const struct lacpdu lacpdu = { .subtype = 0x01, @@ -1982,12 +1986,14 @@ static void ad_initialize_port(struct port *port, int lacp_fast) port->actor_port_priority = 0xff; port->actor_port_aggregator_identifier = 0; port->ntt = false;

• port->actor_admin_port_state = LACP_STATE_AGGREGATION |
  

• 			       LACP_STATE_LACP_ACTIVITY;
  

• port->actor_oper_port_state  = LACP_STATE_AGGREGATION |
  

• 			       LACP_STATE_LACP_ACTIVITY;
  

• port->actor_admin_port_state = LACP_STATE_AGGREGATION;
  

• port->actor_oper_port_state  = LACP_STATE_AGGREGATION;
  

• if (bond_params->lacp_active) {
  

• 	port->actor_admin_port_state |= LACP_STATE_LACP_ACTIVITY;
  

• 	port->actor_oper_port_state  |= LACP_STATE_LACP_ACTIVITY;
  

• }
  

• if (lacp_fast)
  

• if (bond_params->lacp_fast)
  port->actor_oper_port_state |= LACP_STATE_LACP_TIMEOUT;
  

memcpy(&port->partner_admin, &tmpl, sizeof(tmpl)); @@ -2201,7 +2207,7 @@ void bond_3ad_bind_slave(struct slave *slave) /* port initialization */ port = &(SLAVE_AD_INFO(slave)->port);

• ad_initialize_port(port, bond->params.lacp_fast);
  

• ad_initialize_port(port, &bond->params);
  

port->slave = slave; port->actor_port_number = SLAVE_AD_INFO(slave)->id; @@ -2513,7 +2519,7 @@ void bond_3ad_state_machine_handler(struct work_struct *work) } ad_rx_machine(NULL, port);

• ad_periodic_machine(port, &bond->params);
  

• ad_periodic_machine(port);
  

  ad_port_selection_logic(port, &update_slave_arr); ad_mux_machine(port, &update_slave_arr); ad_tx_machine(port);

@@ -2883,6 +2889,36 @@ void bond_3ad_update_lacp_rate(struct bonding *bond) spin_unlock_bh(&bond->mode_lock); } +/**

• • bond_3ad_update_lacp_active - change the lacp active
• • @bond: bonding struct
• • When modify lacp_active parameter via sysfs,
• • update actor_oper_port_state of each port.

It could also be netlink, right? I'd just say something like: Update actor_oper_port_state when lacp_active is modified.

• • Hold bond->mode_lock,
• • so we can modify port->actor_oper_port_state,
• • no matter bond is up or down.

nit: this last part about bond up/down is unnecessary

• */

+void bond_3ad_update_lacp_active(struct bonding *bond) +{

• struct port *port = NULL;
• struct list_head *iter;
• struct slave *slave;
• int lacp_active;
• lacp_active = bond->params.lacp_active;
• spin_lock_bh(&bond->mode_lock);
• bond_for_each_slave(bond, slave, iter) {

• port = &(SLAVE_AD_INFO(slave)->port);
  

• if (lacp_active)
  

• 	port->actor_oper_port_state |= LACP_STATE_LACP_ACTIVITY;
  

• else
  

• 	port->actor_oper_port_state &= ~LACP_STATE_LACP_ACTIVITY;
  

• }
• spin_unlock_bh(&bond->mode_lock);

+}

size_t bond_3ad_stats_size(void) { return nla_total_size_64bit(sizeof(u64)) + /* BOND_3AD_STAT_LACPDU_RX */ diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c index 1d639a3be6ba..3b6f815c55ff 100644 --- a/drivers/net/bonding/bond_options.c +++ b/drivers/net/bonding/bond_options.c @@ -1660,6 +1660,7 @@ static int bond_option_lacp_active_set(struct bonding *bond, netdev_dbg(bond->dev, "Setting LACP active to %s (%llu)\n", newval->string, newval->value); bond->params.lacp_active = newval->value;

• bond_3ad_update_lacp_active(bond);

To me it looks like this fix needs to be in a separate patch.

return 0; } diff --git a/include/net/bond_3ad.h b/include/net/bond_3ad.h index 2053cd8e788a..dba369a2cf27 100644 --- a/include/net/bond_3ad.h +++ b/include/net/bond_3ad.h @@ -307,6 +307,7 @@ int bond_3ad_lacpdu_recv(const struct sk_buff *skb, struct bonding *bond, struct slave *slave); int bond_3ad_set_carrier(struct bonding *bond); void bond_3ad_update_lacp_rate(struct bonding *bond); +void bond_3ad_update_lacp_active(struct bonding *bond); void bond_3ad_update_ad_actor_settings(struct bonding *bond); int bond_3ad_stats_fill(struct sk_buff *skb, struct bond_3ad_stats *stats); size_t bond_3ad_stats_size(void);