USB HCD: avoid duplicate local_irq_disable()

Arnd Bergmann wrote:

usb_hcd_flush_endpoint() has a retry loop that starts with a spin_lock_irq(),
but only gives up the spinlock, not the irq_disable before jumping to the
rescan label.

Alan Stern:

I agree with your sentiment, but it would be better to solve this
problem without using local_irq_disable().
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/hcd.c

@@ -1311,8 +1311,8 @@ void usb_hcd_flush_endpoint(struct usb_device *udev,
 	hcd = bus_to_hcd(udev->bus);
 
 	/* No more submits can occur */
-rescan:
 	spin_lock_irq(&hcd_urb_list_lock);
+rescan:
 	list_for_each_entry (urb, &ep->urb_list, urb_list) {
 		int	is_in;
 
@@ -1345,6 +1345,7 @@ void usb_hcd_flush_endpoint(struct usb_device *udev,
 		usb_put_urb (urb);
 
 		/* list contents may have changed */
+		spin_lock(&hcd_urb_list_lock);
 		goto rescan;
 	}
 	spin_unlock_irq(&hcd_urb_list_lock);