linux-kernel - Re: [PATCH] net: dsa: microchip: fix bridging with more than two member ports

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Date:   Fri, 18 Feb 2022 14:07:48 +0100
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Svenning Sørensen <sss@...omea.com>
Cc:     Woojung Huh <woojung.huh@...rochip.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Oleksij Rempel <linux@...pel-privat.de>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: dsa: microchip: fix bridging with more than two
 member ports

On Fri, Feb 18, 2022 at 11:27:01AM +0000, Svenning Sørensen wrote:
> Commit b3612ccdf284 ("net: dsa: microchip: implement multi-bridge support")
> plugged a packet leak between ports that were members of different bridges.
> Unfortunately, this broke another use case, namely that of more than two
> ports that are members of the same bridge.
> 
> After that commit, when a port is added to a bridge, hardware bridging
> between other member ports of that bridge will be cleared, preventing
> packet exchange between them.
> 
> Fix by ensuring that the Port VLAN Membership bitmap includes any existing
> ports in the bridge, not just the port being added.
> 
> Fixes: b3612ccdf284 ("net: dsa: microchip: implement multi-bridge support")
> Signed-off-by: Svenning Sørensen <sss@...omea.com>

Thank you for your patch. You are right. I'm able to reproduce this issue on
ksz9477.

Tested-by: Oleksij Rempel <o.rempel@...gutronix.de>

> ---
>  drivers/net/dsa/microchip/ksz_common.c | 26 +++++++++++++++++++++++---
>  1 file changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
> index 55dbda04ea62..243f8ad6d06e 100644
> --- a/drivers/net/dsa/microchip/ksz_common.c
> +++ b/drivers/net/dsa/microchip/ksz_common.c
> @@ -26,7 +26,7 @@ void ksz_update_port_member(struct ksz_device *dev, int port)
>  	struct dsa_switch *ds = dev->ds;
>  	u8 port_member = 0, cpu_port;
>  	const struct dsa_port *dp;
> -	int i;
> +	int i, j;
>  
>  	if (!dsa_is_user_port(ds, port))
>  		return;
> @@ -45,13 +45,33 @@ void ksz_update_port_member(struct ksz_device *dev, int port)
>  			continue;
>  		if (!dsa_port_bridge_same(dp, other_dp))
>  			continue;
> +		if (other_p->stp_state != BR_STATE_FORWARDING)
> +			continue;
>  
> -		if (other_p->stp_state == BR_STATE_FORWARDING &&
> -		    p->stp_state == BR_STATE_FORWARDING) {
> +		if (p->stp_state == BR_STATE_FORWARDING) {
>  			val |= BIT(port);
>  			port_member |= BIT(i);
>  		}
>  
> +		/* Retain port [i]'s relationship to other ports than [port] */
> +		for (j = 0; j < ds->num_ports; j++) {
> +			const struct dsa_port *third_dp;
> +			struct ksz_port *third_p;
> +
> +			if (j == i)
> +				continue;
> +			if (j == port)
> +				continue;
> +			if (!dsa_is_user_port(ds, j))
> +				continue;
> +			third_p = &dev->ports[j];
> +			if (third_p->stp_state != BR_STATE_FORWARDING)
> +				continue;
> +			third_dp = dsa_to_port(ds, j);
> +			if (dsa_port_bridge_same(other_dp, third_dp))
> +				val |= BIT(j);
> +		}
> +
>  		dev->dev_ops->cfg_port_member(dev, i, val | cpu_port);
>  	}
>  
> -- 
> 2.20.1
> 
> 

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