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

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Date:   Mon, 2 Jul 2018 13:19:20 +0200
From:   Miguel Rodríguez Pérez <miguel@....uvigo.gal>
To:     Oliver Neukum <oneukum@...e.com>, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v3 1/4] Simplify usbnet_cdc_update_filter

I get a panic if I remove this patch, because intf comes NULL for
cdc_ncm devices. I'll send an updated patch that solves this issue while
still using usb_control_msg.

On 02/07/18 10:25, Oliver Neukum wrote:
> 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
> 

-- 
Miguel Rodríguez Pérez
Laboratorio de Redes
EE Telecomunicación – Universidade de Vigo