Subject: Re: [PATCH] bridge: control carrier based on ports online

From: Nicolas de Pesloüan<[email-masked]>
Date: Mon, 07 Mar 2011 21:48:16 +0100

Le 07/03/2011 19:34, Stephen Hemminger a écrit :
> This makes the bridge device behave like a physical device.
> In earlier releases the bridge always asserted carrier. This
> changes the behavior so that bridge device carrier is on only
> if one or more ports are in the forwarding state. This
> should help IPv6 autoconfiguration, DHCP, and routing daemons.
>
> I did brief testing with Network and Virt manager and they
> seem fine, but since this changes behavior of bridge, it should
> wait until net-next (2.6.39).
>
> Signed-off-by: Stephen Hemminger<[email-masked]>
>
> ---
>   net/bridge/br_device.c    |    4 ++++
>   net/bridge/br_stp.c       |   35 ++++++++++++++++++++++-------------
>   net/bridge/br_stp_timer.c |    1 +
>   3 files changed, 27 insertions(+), 13 deletions(-)
>
> --- a/net/bridge/br_device.c	2011-03-07 08:40:08.913599513 -0800
> +++ b/net/bridge/br_device.c	2011-03-07 08:40:48.382377389 -0800
> @@ -78,6 +78,8 @@ static int br_dev_open(struct net_device
>   {
>   	struct net_bridge *br = netdev_priv(dev);
>
> +	netif_carrier_off(dev);
> +
>   	br_features_recompute(br);
>   	netif_start_queue(dev);
>   	br_stp_enable_bridge(br);
> @@ -94,6 +96,8 @@ static int br_dev_stop(struct net_device
>   {
>   	struct net_bridge *br = netdev_priv(dev);
>
> +	netif_carrier_off(dev);
> +
>   	br_stp_disable_bridge(br);
>   	br_multicast_stop(br);
>
> --- a/net/bridge/br_stp.c	2011-03-07 08:41:58.619783678 -0800
> +++ b/net/bridge/br_stp.c	2011-03-07 08:53:58.953558810 -0800
> @@ -397,28 +397,37 @@ static void br_make_forwarding(struct ne
>   void br_port_state_selection(struct net_bridge *br)
>   {
>   	struct net_bridge_port *p;
> +	unsigned int liveports = 0;
>
>   	/* Don't change port states if userspace is handling STP */
>   	if (br->stp_enabled == BR_USER_STP)
>   		return;
>
>   	list_for_each_entry(p,&br->port_list, list) {
> -		if (p->state != BR_STATE_DISABLED) {
> -			if (p->port_no == br->root_port) {
> -				p->config_pending = 0;
> -				p->topology_change_ack = 0;
> -				br_make_forwarding(p);
> -			} else if (br_is_designated_port(p)) {
> -				del_timer(&p->message_age_timer);
> -				br_make_forwarding(p);
> -			} else {
> -				p->config_pending = 0;
> -				p->topology_change_ack = 0;
> -				br_make_blocking(p);
> -			}
> +		if (p->state == BR_STATE_DISABLED)
> +			continue;
> +
> +		if (p->port_no == br->root_port) {
> +			p->config_pending = 0;
> +			p->topology_change_ack = 0;
> +			br_make_forwarding(p);
> +		} else if (br_is_designated_port(p)) {
> +			del_timer(&p->message_age_timer);
> +			br_make_forwarding(p);
> +		} else {
> +			p->config_pending = 0;
> +			p->topology_change_ack = 0;
> +			br_make_blocking(p);

Is the above part really related to the purpose of this patch? It looks like (good) cleanup, but 
should be in a different patch.

Except from this comment,

Reviewed-by: Nicolas de Pesloüan <[email-masked]>

>   		}
>
> +		if (p->state == BR_STATE_FORWARDING)
> +			++liveports;
>   	}
> +
> +	if (liveports == 0)
> +		netif_carrier_off(br->dev);
> +	else
> +		netif_carrier_on(br->dev);
>   }
>
>   /* called under bridge lock */
> --- a/net/bridge/br_stp_timer.c	2011-03-07 08:53:25.728770710 -0800
> +++ b/net/bridge/br_stp_timer.c	2011-03-07 08:53:40.273116636 -0800
> @@ -94,6 +94,7 @@ static void br_forward_delay_timer_expir
>   		p->state = BR_STATE_FORWARDING;
>   		if (br_is_designated_for_some_port(br))
>   			br_topology_change_detection(br);
> +		netif_carrier_on(br->dev);
>   	}
>   	br_log_state(p);
>   	spin_unlock(&br->lock);
>