netdev - Re: [PATCH v3 1/4] Simplify usbnet_cdc_update

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Date:   Mon, 02 Jul 2018 10:25:44 +0200
From:   Oliver Neukum <oneukum@...e.com>
To:     Miguel Rodríguez Pérez 
        <miguel@....uvigo.gal>, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v3 1/4] Simplify usbnet_cdc_update_filter

On So, 2018-07-01 at 11:05 +0200, Miguel Rodríguez Pérez         wrote:
> Remove some unneded varibles to make the code easier to read
> and, replace the generic usb_control_msg function for the
> more specific usbnet_write_cmd.
> 
> Signed-off-by: Miguel Rodríguez Pérez <miguel@....uvigo.gal>

No,

sorry, but this is not good. The reason is a bit subtle.
Drivers need to reset the filters when handling post_reset()
[ and reset_resume() ] usbnet_write_cmd() falls back to
kmemdup() with GFP_KERNEL. Usbnet is a framework with class
drivers and some of the devices we drive have a storage
interface. Thence we are on the block error handling path here.

The simplest solution is to leave out this patch in the sequence.

	Regards
		Oliver


NACKED-BY: Oliver Neukum <oneukum@...e.com>


> ---
>  drivers/net/usb/cdc_ether.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
> index 178b956501a7..815ed0dc18fe 100644
> --- a/drivers/net/usb/cdc_ether.c
> +++ b/drivers/net/usb/cdc_ether.c
> @@ -77,9 +77,7 @@ static const u8 mbm_guid[16] = {
>  
>  static void usbnet_cdc_update_filter(struct usbnet *dev)
>  {
> -	struct cdc_state	*info = (void *) &dev->data;
> -	struct usb_interface	*intf = info->control;
> -	struct net_device	*net = dev->net;
> +	struct net_device *net = dev->net;
>  
>  	u16 cdc_filter = USB_CDC_PACKET_TYPE_DIRECTED
>  			| USB_CDC_PACKET_TYPE_BROADCAST;
> @@ -93,16 +91,13 @@ static void usbnet_cdc_update_filter(struct usbnet *dev)
>  	if (!netdev_mc_empty(net) || (net->flags & IFF_ALLMULTI))
>  		cdc_filter |= USB_CDC_PACKET_TYPE_ALL_MULTICAST;
>  
> -	usb_control_msg(dev->udev,
> -			usb_sndctrlpipe(dev->udev, 0),
> +	usbnet_write_cmd(dev,
>  			USB_CDC_SET_ETHERNET_PACKET_FILTER,
> -			USB_TYPE_CLASS | USB_RECIP_INTERFACE,
> +			USB_TYPE_CLASS | USB_DIR_OUT | USB_RECIP_INTERFACE,
>  			cdc_filter,
> -			intf->cur_altsetting->desc.bInterfaceNumber,
> +			dev->intf->cur_altsetting->desc.bInterfaceNumber,
>  			NULL,
> -			0,
> -			USB_CTRL_SET_TIMEOUT
> -		);
> +			0);
>  }
>  
>  /* probes control interface, claims data interface, collects the bulk