netdev - Re: [PATCH v3 net-next 08/10] net: dsa: microchip: add support for port mirror operations

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Date:   Sat, 31 Jul 2021 18:24:07 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Prasanna Vengateshan <prasanna.vengateshan@...rochip.com>
Cc:     andrew@...n.ch, netdev@...r.kernel.org, robh+dt@...nel.org,
        UNGLinuxDriver@...rochip.com, Woojung.Huh@...rochip.com,
        hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
        kuba@...nel.org, linux-kernel@...r.kernel.org,
        vivien.didelot@...il.com, f.fainelli@...il.com,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v3 net-next 08/10] net: dsa: microchip: add support for
 port mirror operations

On Fri, Jul 23, 2021 at 11:01:06PM +0530, Prasanna Vengateshan wrote:
> Added support for port_mirror_add() and port_mirror_del operations
> 
> Sniffing is limited to one port & alert the user if any new
> sniffing port is selected
> 
> Signed-off-by: Prasanna Vengateshan <prasanna.vengateshan@...rochip.com>
> ---
>  drivers/net/dsa/microchip/lan937x_main.c | 83 ++++++++++++++++++++++++
>  1 file changed, 83 insertions(+)
> 
> diff --git a/drivers/net/dsa/microchip/lan937x_main.c b/drivers/net/dsa/microchip/lan937x_main.c
> index 3380a4617725..171c46f37fa4 100644
> --- a/drivers/net/dsa/microchip/lan937x_main.c
> +++ b/drivers/net/dsa/microchip/lan937x_main.c
> @@ -129,6 +129,87 @@ static void lan937x_port_stp_state_set(struct dsa_switch *ds, int port,
>  	mutex_unlock(&dev->dev_mutex);
>  }
>  
> +static int lan937x_port_mirror_add(struct dsa_switch *ds, int port,
> +				   struct dsa_mall_mirror_tc_entry *mirror,
> +				   bool ingress)
> +{
> +	struct ksz_device *dev = ds->priv;
> +	int ret, p;
> +	u8 data;
> +
> +	/* Configure ingress/egress mirroring*/
> +	if (ingress)
> +		ret = lan937x_port_cfg(dev, port, P_MIRROR_CTRL, PORT_MIRROR_RX,
> +				       true);
> +	else
> +		ret = lan937x_port_cfg(dev, port, P_MIRROR_CTRL, PORT_MIRROR_TX,
> +				       true);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Configure sniffer port meanwhile limit to one sniffer port
> +	 * Check if any of the port is already set for sniffing
> +	 * If yes, instruct the user to remove the previous entry & exit
> +	 */
> +	for (p = 0; p < dev->port_cnt; p++) {
> +		/*Skip the current sniffing port*/
> +		if (p == mirror->to_local_port)
> +			continue;
> +
> +		ret = lan937x_pread8(dev, p, P_MIRROR_CTRL, &data);
> +		if (ret < 0)
> +			return ret;
> +
> +		if (data & PORT_MIRROR_SNIFFER) {
> +			dev_err(dev->dev,
> +				"Delete existing rules towards %s & try\n",
> +				dsa_to_port(ds, p)->name);
> +			return -EBUSY;
> +		}
> +	}

I think this check should be placed before you enable
PORT_MIRROR_RX/PORT_MIRROR_TX.

> +
> +	ret = lan937x_port_cfg(dev, mirror->to_local_port, P_MIRROR_CTRL,
> +			       PORT_MIRROR_SNIFFER, true);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = lan937x_cfg(dev, S_MIRROR_CTRL, SW_MIRROR_RX_TX, false);
> +
> +	return ret;

You can forgo an assignment to "ret" here and do "return lan937x_cfg(...)"