USB: xhci: Don't wait for a disable slot cmd when HC dies.

When the host controller dies or is removed while a device is plugged in,
the USB core will attempt to deallocate the struct usb_device.  That will
call into xhci_free_dev().  This function used to attempt to submit a
disable slot command to the host controller and clean up the device
structures when that command returned.  Change xhci_free_dev() to skip the
command submission and just free the memory if the host controller died.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/xhci-hcd.c

@@ -1428,11 +1428,20 @@ void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 {
 	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
 	unsigned long flags;
+	u32 state;
 
 	if (udev->slot_id == 0)
 		return;
 
 	spin_lock_irqsave(&xhci->lock, flags);
+	/* Don't disable the slot if the host controller is dead. */
+	state = xhci_readl(xhci, &xhci->op_regs->status);
+	if (state == 0xffffffff) {
+		xhci_free_virt_device(xhci, udev->slot_id);
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		return;
+	}
+
 	if (xhci_queue_slot_control(xhci, TRB_DISABLE_SLOT, udev->slot_id)) {
 		spin_unlock_irqrestore(&xhci->lock, flags);
 		xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");