USB: make the autosuspend workqueue thread freezable

This patch (as881b) makes the ksuspend_usb_wq workqueue freezable.  We
don't want a rogue workqueue thread running around, unexpectedly
suspending or resuming USB devices in the middle of a system sleep
transition.

This fixes Bugzilla #8498.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/usb.c

@@ -205,7 +205,11 @@ struct device_type usb_device_type = {
 
 static int ksuspend_usb_init(void)
 {
-	ksuspend_usb_wq = create_singlethread_workqueue("ksuspend_usbd");
+	/* This workqueue is supposed to be both freezable and
+	 * singlethreaded.  Its job doesn't justify running on more
+	 * than one CPU.
+	 */
+	ksuspend_usb_wq = create_freezeable_workqueue("ksuspend_usbd");
 	if (!ksuspend_usb_wq)
 		return -ENOMEM;
 	return 0;