3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sarah Sharp <redacted>

commit d01f87c0ffa96cb44faa78710711eb6e974b891c upstream.

Before a driver is probed, we want to disable USB 3.0 Link Power
Management (LPM), in case the driver needs hub-initiated LPM disabled.
After the probe finishes, we want to attempt to re-enable LPM, order to
balance the LPM ref count.

When a probe fails (such as when libusual doesn't want to bind to a USB
3.0 mass storage device), make sure to balance the LPM ref counts by
re-enabling LPM.

This patch should be backported to kernels as old as 3.5, that contain
the commit 8306095fd2c1100e8244c09bf560f97aca5a311d "USB: Disable USB
3.0 LPM in critical sections."

Signed-off-by: Sarah Sharp <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/core/driver.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c

@@ -372,6 +372,10 @@ static int usb_probe_interface(struct de
 	intf->condition = USB_INTERFACE_UNBOUND;
 	usb_cancel_queued_reset(intf);
 
+	/* If the LPM disable succeeded, balance the ref counts. */
+	if (!lpm_disable_error)
+		usb_unlocked_enable_lpm(udev);
+
 	/* Unbound interfaces are always runtime-PM-disabled and -suspended */
 	if (driver->supports_autosuspend)
 		pm_runtime_disable(dev);