xhci: refuse loading if nousb is used

commit 1eaf35e4 upstream.

The module should fail to load.
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
[ gregkh: xhci: fix placement of call to usb_disabled()
    In the backport of 1eaf35e4, the call to
    usb_disabled() was too late, after we had already done some allocation.
    Move that call to the top of the function instead, making the logic
    match what is intended and is in the original patch. ]
Reported-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/usb/host/xhci.c

@@ -4857,6 +4857,9 @@ static int __init xhci_hcd_init(void)
 {
 	int retval;
 
+	if (usb_disabled())
+		return -ENODEV;
+
 	retval = xhci_register_pci();
 	if (retval < 0) {
 		pr_debug("Problem registering PCI driver.\n");
@@ -4884,6 +4887,7 @@ static int __init xhci_hcd_init(void)
 	BUILD_BUG_ON(sizeof(struct xhci_intr_reg) != 8*32/8);
 	/* xhci_run_regs has eight fields and embeds 128 xhci_intr_regs */
 	BUILD_BUG_ON(sizeof(struct xhci_run_regs) != (8+8*128)*32/8);
+
 	return 0;
 unreg_pci:
 	xhci_unregister_pci();