Subject: Re: [PATCH net-next 1/2] net: usb: qmi_wwan: add qmap id sysfs file for qmimux interfaces

From: Greg KH <[email-masked]>
Date: Wed, 27 Jan 2021 08:58:50 +0100

On Mon, Jan 25, 2021 at 04:22:34PM +0100, Daniele Palmas wrote:
> Add qmimux interface sysfs file qmap/mux_id to show qmap id set
> during the interface creation, in order to provide a method for
> userspace to associate QMI control channels to network interfaces.
> 
> Signed-off-by: Daniele Palmas <[email-masked]>
> ---
>  drivers/net/usb/qmi_wwan.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
> index 7ea113f51074..9b85e2ed4760 100644
> --- a/drivers/net/usb/qmi_wwan.c
> +++ b/drivers/net/usb/qmi_wwan.c
> @@ -218,6 +218,31 @@ static int qmimux_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
>  	return 1;
>  }
>  
> +static ssize_t mux_id_show(struct device *d, struct device_attribute *attr, char *buf)
> +{
> +	struct net_device *dev = to_net_dev(d);
> +	struct qmimux_priv *priv;
> +	ssize_t count = 0;
> +
> +	priv = netdev_priv(dev);
> +	count += scnprintf(&buf[count], PAGE_SIZE - count,
> +			   "0x%02x\n", priv->mux_id);

Odd way to do this, please just use sysfs_emit().  It looks like you
cut/pasted this from some other more complex logic.

thanks,

greg k-h