netdev - Re: [net-next PATCH 3/3] net: dsa: qca8k: limit user ports access to the first CPU port on setup

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Message-ID: <20230727211658.3gkjql5jww44hr4c@skbuf>
Date: Fri, 28 Jul 2023 00:16:58 +0300
From: Vladimir Oltean <olteanv@...il.com>
To: Christian Marangi <ansuelsmth@...il.com>
Cc: Andrew Lunn <andrew@...n.ch>, Florian Fainelli <f.fainelli@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Atin Bainada <hi@...nb.me>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [net-next PATCH 3/3] net: dsa: qca8k: limit user ports access to
 the first CPU port on setup

On Mon, Jul 24, 2023 at 05:30:58AM +0200, Christian Marangi wrote:
> In preparation for multi-CPU support, set CPU port LOOKUP MEMBER outside
> the port loop and setup the LOOKUP MEMBER mask for user ports only to
> the first CPU port.
> 
> This is to handle flooding condition where every CPU port is set as
> target and prevent packet duplication for unknown frames from user ports.
> 
> Secondary CPU port LOOKUP MEMBER mask will be setup later when
> port_change_master will be implemented.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
> ---

Reviewed-by: Vladimir Oltean <olteanv@...il.com>

>  drivers/net/dsa/qca/qca8k-8xxx.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/dsa/qca/qca8k-8xxx.c b/drivers/net/dsa/qca/qca8k-8xxx.c
> index 31552853fdd4..6286a64a2fe3 100644
> --- a/drivers/net/dsa/qca/qca8k-8xxx.c
> +++ b/drivers/net/dsa/qca/qca8k-8xxx.c
> @@ -1850,18 +1850,16 @@ qca8k_setup(struct dsa_switch *ds)
>  	if (ret)
>  		return ret;
>  
> +	/* CPU port gets connected to all user ports of the switch */
> +	ret = qca8k_rmw(priv, QCA8K_PORT_LOOKUP_CTRL(cpu_port),
> +			QCA8K_PORT_LOOKUP_MEMBER, dsa_user_ports(ds));
> +	if (ret)
> +		return ret;
> +
>  	/* Setup connection between CPU port & user ports
>  	 * Configure specific switch configuration for ports
>  	 */
>  	for (i = 0; i < QCA8K_NUM_PORTS; i++) {
> -		/* CPU port gets connected to all user ports of the switch */
> -		if (dsa_is_cpu_port(ds, i)) {
> -			ret = qca8k_rmw(priv, QCA8K_PORT_LOOKUP_CTRL(i),
> -					QCA8K_PORT_LOOKUP_MEMBER, dsa_user_ports(ds));
> -			if (ret)
> -				return ret;
> -		}
> -
>  		/* Individual user ports get connected to CPU port only */
>  		if (dsa_is_user_port(ds, i)) {
>  			ret = qca8k_rmw(priv, QCA8K_PORT_LOOKUP_CTRL(i),

FWIW, the remaining loop can be rewritten (in a separate patch) using
dsa_switch_for_each_user_port(), which is actually an operation of lower
complexity compared to "for" + "dsa_is_user_port".

> -- 
> 2.40.1
>