Re: Regression 3.0-rc6+ : khubd blocked (usbnet_cdc_unbind)

[Arkadiusz Miskiewicz <a.miskiewicz@gmail.com>]

On Wednesday 06 of July 2011, Alan Stern wrote:
> On Wed, 6 Jul 2011, Éric Piel wrote:
> > Hello,
> > It seems I'm very unlucky this week and I've come across to what looks
> > like a second regression in the kernel. I'm running a version few
> > commits after 3.0-rc6, which includes commit e534c5b831c8 "fix
> > regression occurring during device removal".
> > 
> > When I plug/unplug/plug a mobile phone, after waiting a few minutes I
> > get a "task khubd:621 blocked for more than 120 seconds." Note that it's
> > directly connected to my laptop, not via an external hub (although the
> > bug also happens with an external hub).
> > 
> > Below is the whole dmesg log (with usb debug messages on)
> > 
> > Let me know if you need me to investigate more, or maybe there is
> > already a fix for that bug?
> 
> Ah -- this stack dump points out the reason for the hang.  It looks
> like that "fix regression..." commit didn't go far enough; I neglected
> the fact that interfaces can be unbound out of order when a driver
> claims multiple interfaces.
> 
> Adding this patch on top of that commit should fix this.  Let me
> know what you both get.

This one makes usb working after resume from ram (current Linus git + this 
patch).

> 
> Alan Stern
> 
> 
> 
>  drivers/usb/core/message.c |    9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> Index: usb-3.0/drivers/usb/core/message.c
> ===================================================================
> --- usb-3.0.orig/drivers/usb/core/message.c
> +++ usb-3.0/drivers/usb/core/message.c
> @@ -1147,6 +1147,14 @@ void usb_disable_device(struct usb_devic
>  	 * any drivers bound to them (a key side effect)
>  	 */
>  	if (dev->actconfig) {
> +		/*
> +		 * FIXME: In order to avoid self-deadlock involving the
> +		 * bandwidth_mutex, we have to mark all the interfaces
> +		 * before unregistering any of them.
> +		 */
> +		for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++)
> +			dev->actconfig->interface[i]->unregistering = 1;
> +
>  		for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
>  			struct usb_interface	*interface;
> 
> @@ -1156,7 +1164,6 @@ void usb_disable_device(struct usb_devic
>  				continue;
>  			dev_dbg(&dev->dev, "unregistering interface %s\n",
>  				dev_name(&interface->dev));
> -			interface->unregistering = 1;
>  			remove_intf_ep_devs(interface);
>  			device_del(&interface->dev);
>  		}


-- 
Arkadiusz Miśkiewicz        PLD/Linux Team
arekm / maven.pl            http://ftp.pld-linux.org/