bonding: Add independent control state machine

Add support for the independent control state machine per IEEE
802.1AX-2008 5.4.15 in addition to the existing implementation of the
coupled control state machine.

Introduces two new states, AD_MUX_COLLECTING and AD_MUX_DISTRIBUTING in
the LACP MUX state machine for separated handling of an initial
Collecting state before the Collecting and Distributing state. This
enables a port to be in a state where it can receive incoming packets
while not still distributing. This is useful for reducing packet loss when
a port begins distributing before its partner is able to collect.

Added new functions such as bond_set_slave_tx_disabled_flags and
bond_set_slave_rx_enabled_flags to precisely manage the port's collecting
and distributing states. Previously, there was no dedicated method to
disable TX while keeping RX enabled, which this patch addresses.

Note that the regular flow process in the kernel's bonding driver remains
unaffected by this patch. The extension requires explicit opt-in by the
user (in order to ensure no disruptions for existing setups) via netlink
support using the new bonding parameter coupled_control. The default value
for coupled_control is set to 1 so as to preserve existing behaviour.

Signed-off-by: Aahil Awatramani <aahila@google.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20240202175858.1573852-1-aahila@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/net/bonding.h b/include/net/bonding.h
index 5b8b1b644a2d..b61fb1aa3a56 100644
--- a/include/net/bonding.h
+++ b/include/net/bonding.h
@@ -148,6 +148,7 @@ struct bond_params {
 #if IS_ENABLED(CONFIG_IPV6)
 	struct in6_addr ns_targets[BOND_MAX_NS_TARGETS];
 #endif
+	int coupled_control;
 
 	/* 2 bytes of padding : see ether_addr_equal_64bits() */
 	u8 ad_actor_system[ETH_ALEN + 2];
@@ -167,6 +168,7 @@ struct slave {
 	u8     backup:1,   /* indicates backup slave. Value corresponds with
 			      BOND_STATE_ACTIVE and BOND_STATE_BACKUP */
 	       inactive:1, /* indicates inactive slave */
+	       rx_disabled:1, /* indicates whether slave's Rx is disabled */
 	       should_notify:1, /* indicates whether the state changed */
 	       should_notify_link:1; /* indicates whether the link changed */
 	u8     duplex;
@@ -568,6 +570,14 @@ static inline void bond_set_slave_inactive_flags(struct slave *slave,
 		bond_set_slave_state(slave, BOND_STATE_BACKUP, notify);
 	if (!slave->bond->params.all_slaves_active)
 		slave->inactive = 1;
+	if (BOND_MODE(slave->bond) == BOND_MODE_8023AD)
+		slave->rx_disabled = 1;
+}
+
+static inline void bond_set_slave_tx_disabled_flags(struct slave *slave,
+						 bool notify)
+{
+	bond_set_slave_state(slave, BOND_STATE_BACKUP, notify);
 }
 
 static inline void bond_set_slave_active_flags(struct slave *slave,
@@ -575,6 +585,14 @@ static inline void bond_set_slave_active_flags(struct slave *slave,
 {
 	bond_set_slave_state(slave, BOND_STATE_ACTIVE, notify);
 	slave->inactive = 0;
+	if (BOND_MODE(slave->bond) == BOND_MODE_8023AD)
+		slave->rx_disabled = 0;
+}
+
+static inline void bond_set_slave_rx_enabled_flags(struct slave *slave,
+					       bool notify)
+{
+	slave->rx_disabled = 0;
 }
 
 static inline bool bond_is_slave_inactive(struct slave *slave)
@@ -582,6 +600,11 @@ static inline bool bond_is_slave_inactive(struct slave *slave)
 	return slave->inactive;
 }
 
+static inline bool bond_is_slave_rx_disabled(struct slave *slave)
+{
+	return slave->rx_disabled;
+}
+
 static inline void bond_propose_link_state(struct slave *slave, int state)
 {
 	slave->link_new_state = state;