usb/hcd: remove unnecessary local_irq_save

Remove the use of local_irq_save() and IRQF_DISABLED, no longer needed since
interrupt handlers are always run with interrupts disabled on the
current CPU.

Tested successfully with 3.12.0-rc4 on my PC. Didn't find
any issue because of this change.

Signed-off-by: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/hcd.c

@@ -2331,15 +2331,8 @@ EXPORT_SYMBOL_GPL(usb_bus_start_enum);
 irqreturn_t usb_hcd_irq (int irq, void *__hcd)
 {
 	struct usb_hcd		*hcd = __hcd;
-	unsigned long		flags;
 	irqreturn_t		rc;
 
-	/* IRQF_DISABLED doesn't work correctly with shared IRQs
-	 * when the first handler doesn't use it.  So let's just
-	 * assume it's never used.
-	 */
-	local_irq_save(flags);
-
 	if (unlikely(HCD_DEAD(hcd) || !HCD_HW_ACCESSIBLE(hcd)))
 		rc = IRQ_NONE;
 	else if (hcd->driver->irq(hcd) == IRQ_NONE)
@@ -2347,7 +2340,6 @@ irqreturn_t usb_hcd_irq (int irq, void *__hcd)
 	else
 		rc = IRQ_HANDLED;
 
-	local_irq_restore(flags);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(usb_hcd_irq);
@@ -2554,13 +2546,6 @@ static int usb_hcd_request_irqs(struct usb_hcd *hcd,
 
 	if (hcd->driver->irq) {
 
-		/* IRQF_DISABLED doesn't work as advertised when used together
-		 * with IRQF_SHARED. As usb_hcd_irq() will always disable
-		 * interrupts we can remove it here.
-		 */
-		if (irqflags & IRQF_SHARED)
-			irqflags &= ~IRQF_DISABLED;
-
 		snprintf(hcd->irq_descr, sizeof(hcd->irq_descr), "%s:usb%d",
 				hcd->driver->description, hcd->self.busnum);
 		retval = request_irq(irqnum, &usb_hcd_irq, irqflags,