netdev - Re: [PATCH] net: usbnet: skip info->stop() callback if suspend

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Message-ID: <ttbjrqjhnwlwlhvsmmwdtzcvpfogxvyih2fovw7nl5bk7hfqkv@4cfkfuuj6vwr>
Date: Thu, 4 Sep 2025 15:26:03 +0800
From: Xu Yang <xu.yang_2@....com>
To: Oliver Neukum <oneukum@...e.com>
Cc: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com, 
	kuba@...nel.org, pabeni@...hat.com, linux-usb@...r.kernel.org, 
	netdev@...r.kernel.org
Subject: Re: [PATCH] net: usbnet: skip info->stop() callback if suspend_count
 is not 0

Hi Oliver,

Is this mail been missed?

On Thu, Aug 21, 2025 at 11:00:46AM +0800, Xu Yang wrote:
> On Mon, Aug 18, 2025 at 11:04:55AM +0200, Oliver Neukum wrote:
> > On 8/18/25 09:57, Xu Yang wrote:
> > 
> > > --- a/drivers/net/usb/usbnet.c
> > > +++ b/drivers/net/usb/usbnet.c
> > > @@ -839,7 +839,7 @@ int usbnet_stop (struct net_device *net)
> > >   	pm = usb_autopm_get_interface(dev->intf);
> > 
> > This needs to fail ...
> 
> It returns 0, so "pm = 0" here which means it succeed.
> 
> > 
> > >   	/* allow minidriver to stop correctly (wireless devices to turn off
> > >   	 * radio etc) */
> > > -	if (info->stop) {
> > > +	if (info->stop && !dev->suspend_count) {
> > 
> > ... for !dev->suspend_count to be false
> 
> The suspend_count won't go to 0 because there is no chance to call
> usbnet_resume() if the USB device is physically disconnected from the 
> USB port during system suspend.
> 
> > 
> > >   		retval = info->stop(dev);
> > >   		if (retval < 0)
> > >   			netif_info(dev, ifdown, dev->net,
> > 
> > In other words, this means that the driver has insufficient
> > error handling in this method. This needs to be fixed and it
> > needs to be fixed explicitly. We do not hide error handling.
> 
> Do you mean info->stop() should be called and return error code if something
> is wrong?

Do you mean this way? Or do you have any other suggestions?

Thanks,
Xu Yang

> 
> > 
> > Please use a literal "if (pm < 0)" to skip the parts we need to skip
> > if the resumption fails.
> 
> pm = 0 here.
> 
> Thanks,
> Xu Yang
> 
> > 
> > 	Regards
> > 		Oliver
> > 
> > NACKED-BY: Oliver Neukum <oneukum@...e.com>