irqchip/mips-gic: Use for_each_set_bit to iterate over IRQs

The MIPS GIC driver has previously iterated over bits set in a bitmap
representing pending IRQs by calling find_first_bit, clearing that bit
then calling find_first_bit again until all bits are clear. If multiple
interrupts are pending then this is wasteful, as find_first_bit will
have to loop over the whole bitmap from the start. Use the
for_each_set_bit macro which performs exactly what we need here instead.
It will use find_next_bit and thus only scan over the relevant part of
the bitmap, and it makes the intent of the code more clear.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Link: https://lkml.kernel.org/r/20160819171119.28121-1-paul.burton@imgtec.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index c5f33c3..a376fc6 100644 (file)
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -371,18 +371,13 @@ static void gic_handle_shared_int(bool chained)
        bitmap_and(pending, pending, intrmask, gic_shared_intrs);
        bitmap_and(pending, pending, pcpu_mask, gic_shared_intrs);
 
-       intr = find_first_bit(pending, gic_shared_intrs);
-       while (intr != gic_shared_intrs) {
+       for_each_set_bit(intr, pending, gic_shared_intrs) {
                virq = irq_linear_revmap(gic_irq_domain,
                                         GIC_SHARED_TO_HWIRQ(intr));
                if (chained)
                        generic_handle_irq(virq);
                else
                        do_IRQ(virq);
-
-               /* go to next pending bit */
-               bitmap_clear(pending, intr, 1);
-               intr = find_first_bit(pending, gic_shared_intrs);
        }
 }