Re: ehci_hcd related S3 lockup on ASUS laptops, again

[Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>]

On Fri, 13 Apr 2012, Steven Rostedt wrote:

> > Second, if you do
> > 
> > 	echo 0 >/sys/bus/usb/devices/usb1/bConfigurationValue
> 
> This never returned. I did the echo, and the command locked up.
> 
> (process 3077)
> 
> cat /proc/3077/wchan 
> usb_disconnect

I found the reason for the deadlock.  The patch below will work around
the problem for now, although it's not a correct fix.  You'll still get
some complaints from lockdep.

Alan Stern



Index: usb-3.4/drivers/usb/core/hub.c
===================================================================
--- usb-3.4.orig/drivers/usb/core/hub.c
+++ usb-3.4/drivers/usb/core/hub.c
@@ -1667,7 +1667,7 @@ void usb_disconnect(struct usb_device **
 {
 	struct usb_device	*udev = *pdev;
 	int			i;
-	struct usb_hcd		*hcd = bus_to_hcd(udev->bus);
+//	struct usb_hcd		*hcd = bus_to_hcd(udev->bus);
 
 	/* mark the device as inactive, so any further urb submissions for
 	 * this device (and any of its children) will fail immediately.
@@ -1690,9 +1690,9 @@ void usb_disconnect(struct usb_device **
 	 * so that the hardware is now fully quiesced.
 	 */
 	dev_dbg (&udev->dev, "unregistering device\n");
-	mutex_lock(hcd->bandwidth_mutex);
+//	mutex_lock(hcd->bandwidth_mutex);
 	usb_disable_device(udev, 0);
-	mutex_unlock(hcd->bandwidth_mutex);
+//	mutex_unlock(hcd->bandwidth_mutex);
 	usb_hcd_synchronize_unlinks(udev);
 
 	usb_remove_ep_devs(&udev->ep0);

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