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Date: Fri,  5 Jan 2024 00:06:31 +0000
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Message-ID: <20240105000632.2484182-1-aahila@google.com>
Subject: [PATCH 1/2 net-next v2] bonding: Extending LACP MUX State Machine to
 include a Collecting State.
From: Aahil Awatramani <aahila@google.com>
To: Aahil Awatramani <aahila@google.com>, David Dillow <dave@thedillows.org>, 
	Mahesh Bandewar <maheshb@google.com>, Jay Vosburgh <j.vosburgh@gmail.com>, 
	Andy Gospodarek <andy@greyhouse.net>, "David S . Miller" <davem@davemloft.net>, 
	Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>, 
	Martin KaFai Lau <martin.lau@kernel.org>, Herbert Xu <herbert@gondor.apana.org.au>, 
	Daniel Borkmann <daniel@iogearbox.net>, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
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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.
Additionally this also brings the 802.3ad bonding driver's implementation
closer to the LACP specification which already predefined this behaviour,
that is currently the implementation only supports coupled control.

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 | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/networking/bonding.rst b/Documentation/networking/bonding.rst
index f7a73421eb76..cb3e6013605d 100644
--- a/Documentation/networking/bonding.rst
+++ b/Documentation/networking/bonding.rst
@@ -444,6 +444,14 @@ 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.
+
+    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
-- 
2.43.0.472.g3155946c3a-goog