netdev - Re: [PATCH 2/2] cdc_ncm: Admit multicast traffic

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Date:   Sat, 30 Jun 2018 14:17:31 +0200
From:   Bjørn Mork <bjorn@...k.no>
To:     Miguel Rodríguez Pérez 
        <miguel@....uvigo.gal>
Cc:     linux-usb@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 2/2] cdc_ncm: Admit multicast traffic

Miguel Rodríguez Pérez <miguel@....uvigo.gal> writes:

> +static void cdc_ncm_update_filter(struct usbnet *dev)
> +{
> +       struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
> +	u8 iface_no = ctx->control->cur_altsetting->desc.bInterfaceNumber;
> +	struct net_device *net = dev->net;

Why not change usbnet_cdc_update_filter to get the interface number from
dev->intf instead? Then you can export it and reuse it here instead of
creating a copy.  And it will also work for any other usbnet minidriver.

I.e. change this:

static void usbnet_cdc_update_filter(struct usbnet *dev)
{
	struct cdc_state	*info = (void *) &dev->data;
	struct usb_interface	*intf = info->control;

into:

static void usbnet_cdc_update_filter(struct usbnet *dev)
{
	struct usb_interface	*intf = dev->intf;


or simply use dev->intf to deref directly into an interface number, like
you do in your version.  The local 'intf' variable doesn't do much
good here.



> +
> +	u16 cdc_filter = USB_CDC_PACKET_TYPE_DIRECTED
> +			| USB_CDC_PACKET_TYPE_BROADCAST;
> +
> +	/* filtering on the device is an optional feature and not worth
> +	 * the hassle so we just roughly care about snooping and if any
> +	 * multicast is requested, we take every multicast
> +	 */
> +	if (net->flags & IFF_PROMISC)
> +		cdc_filter |= USB_CDC_PACKET_TYPE_PROMISCUOUS;
> +	if (!netdev_mc_empty(net) || (net->flags & IFF_ALLMULTI))
> +		cdc_filter |= USB_CDC_PACKET_TYPE_ALL_MULTICAST;
> +
> +	usbnet_write_cmd(dev,

This is a nice change. It should be probably done in
usbnet_cdc_update_filter in any case.  Unless there is some reason it
doesn't alreay use usbnet_write_cmd?

> +			USB_CDC_SET_ETHERNET_PACKET_FILTER,
> +			USB_TYPE_CLASS | USB_DIR_OUT | USB_RECIP_INTERFACE,
> +			cdc_filter,
> +			iface_no,
> +			NULL,
> +			0);
> +}
> +
>  static const struct ethtool_ops cdc_ncm_ethtool_ops = {
>  	.get_link          = usbnet_get_link,
>  	.nway_reset        = usbnet_nway_reset,
> @@ -1652,6 +1679,7 @@ static const struct driver_info cdc_ncm_info = {
>  	.status = cdc_ncm_status,
>  	.rx_fixup = cdc_ncm_rx_fixup,
>  	.tx_fixup = cdc_ncm_tx_fixup,
> +	.set_rx_mode = cdc_ncm_update_filter,
>  };
>
>  /* Same as cdc_ncm_info, but with FLAG_WWAN */


As the comment indicates:  There are more 'struct driver_info' variants
here.  Please add .set_rx_mode to all of them, unless you have a reason
not to?


Bjørn