[PATCH] xen: fix off-by-one error in find_unbound_irq

[Ian Campbell <ian.campbell@citrix.com>]

e459de95 "Find an unbound irq number in reverse order (high to low)" introduced
an off by one error which would cause repeated allocations of the nr_irq'th IRQ
if there are no spare interrupts (i.e. get_nr_hw_irqs() == nr_irqs).

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
 drivers/xen/events.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 99f2b2a..5c64e1d 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -377,7 +377,7 @@ static int find_unbound_irq(void)
 		if (irq_info[irq].type == IRQT_UNBOUND)
 			break;
 
-	if (irq == start || irq == nr_irqs)
+	if (irq == start || irq == nr_irqs - 1)
 		panic("No available IRQ to bind to: increase nr_irqs!\n");
 
 	desc = irq_to_desc_alloc_node(irq, 0);
-- 
1.5.6.5