[PATCH net-next v3 1/2] bonding: Add independent control state machine

[Aahil Awatramani <aahila@google.com>]

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>
---
 Documentation/networking/bonding.rst | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/Documentation/networking/bonding.rst b/Documentation/networking/bonding.rst
index f7a73421eb76..e774b48de9f5 100644
--- a/Documentation/networking/bonding.rst
+++ b/Documentation/networking/bonding.rst
@@ -444,6 +444,18 @@ arp_missed_max
 
 	The default value is 2, and the allowable range is 1 - 255.
 
+coupled_control
+
+    Specifies whether the LACP state machine's MUX in the 802.3ad mode
+    should have separate Collecting and Distributing states.
+
+    This is by implementing the independent control state machine per
+    IEEE 802.1AX-2008 5.4.15 in addition to the existing coupled control
+    state machine.
+
+    The default value is 1. This setting does not separate the Collecting
+    and Distributing states, maintaining the bond in coupled control.
+
 downdelay
 
 	Specifies the time, in milliseconds, to wait before disabling
-- 
2.43.0.275.g3460e3d667-goog