linux-kernel - Re: [PATCH] bonding: Switch periodic LACPDU state machine from counter to jiffies

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Message-ID: <20250716090945.GL721198@horms.kernel.org>
Date: Wed, 16 Jul 2025 10:09:45 +0100
From: Simon Horman <horms@...nel.org>
To: carlos.bilbao@...nel.org
Cc: jv@...sburgh.net, andrew+netdev@...n.ch, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	sforshee@...nel.org, bilbao@...edu
Subject: Re: [PATCH] bonding: Switch periodic LACPDU state machine from
 counter to jiffies

On Tue, Jul 15, 2025 at 03:57:33PM -0500, carlos.bilbao@...nel.org wrote:
> From: Carlos Bilbao <carlos.bilbao@...nel.org>
> 
> Replace the bonding periodic state machine for LACPDU transmission of
> function ad_periodic_machine() with a jiffies-based mechanism, which is
> more accurate and can help reduce drift under contention.
> 
> Signed-off-by: Carlos Bilbao (DigitalOcean) <carlos.bilbao@...nel.org>
> ---
>  drivers/net/bonding/bond_3ad.c | 79 +++++++++++++---------------------
>  include/net/bond_3ad.h         |  2 +-
>  2 files changed, 32 insertions(+), 49 deletions(-)
> 

Hi Carlos,

Some minor feedback from my side.

> diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c

...

> @@ -1471,21 +1451,24 @@ static void ad_periodic_machine(struct port *port, struct bond_params *bond_para
>  			  "Periodic Machine: Port=%d, Last State=%d, Curr State=%d\n",
>  			  port->actor_port_number, last_state,
>  			  port->sm_periodic_state);
> +
>  		switch (port->sm_periodic_state) {
> -		case AD_NO_PERIODIC:
> -			port->sm_periodic_timer_counter = 0;
> -			break;
> -		case AD_FAST_PERIODIC:
> -			/* decrement 1 tick we lost in the PERIODIC_TX cycle */
> -			port->sm_periodic_timer_counter = __ad_timer_to_ticks(AD_PERIODIC_TIMER, (u16)(AD_FAST_PERIODIC_TIME))-1;
> -			break;
> -		case AD_SLOW_PERIODIC:
> -			/* decrement 1 tick we lost in the PERIODIC_TX cycle */
> -			port->sm_periodic_timer_counter = __ad_timer_to_ticks(AD_PERIODIC_TIMER, (u16)(AD_SLOW_PERIODIC_TIME))-1;
> -			break;
>  		case AD_PERIODIC_TX:
>  			port->ntt = true;
> -			break;
> +			if (!(port->partner_oper.port_state &
> +						LACP_STATE_LACP_TIMEOUT))
> +				port->sm_periodic_state = AD_SLOW_PERIODIC;
> +			else
> +				port->sm_periodic_state = AD_FAST_PERIODIC;
> +		fallthrough;

super-nit: maybe one more tab of indentation for the line above.

> +		case AD_SLOW_PERIODIC:
> +		case AD_FAST_PERIODIC:
> +			if (port->sm_periodic_state == AD_SLOW_PERIODIC)
> +				port->sm_periodic_next_jiffies = jiffies
> +					+ HZ * AD_SLOW_PERIODIC_TIME;
> +			else /* AD_FAST_PERIODIC */
> +				port->sm_periodic_next_jiffies = jiffies
> +					+ HZ * AD_FAST_PERIODIC_TIME;

Clang 20.1.8 complains that either a break; or fallthrough; should go here.
For consistency with the code above I'd suggest the latter.


>  		default:
>  			break;
>  		}

...