irq: fix irqpoll && sparseirq

Steven Noonan reported a boot hang when using irqpoll and
CONFIG_HAVE_SPARSE_IRQ=y.

The irqpoll loop needs to be updated to not iterate from 1 to nr_irqs
but to iterate via for_each_irq_desc(). (in the former case desc can
be NULL which crashes the box)

Reported-by: Steven Noonan <steven@uplinklabs.net>
Tested-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 6 deletions

diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c
index b5d906002e1d..ec5a4bef3054 100644
--- a/kernel/irq/spurious.c
+++ b/kernel/irq/spurious.c
@@ -90,14 +90,15 @@ static int misrouted_irq(int irq)
 {
         int i;
         int ok = 0;
+        struct irq_desc *desc;
 
-        for (i = 1; i < nr_irqs; i++) {
-                struct irq_desc *desc;
+        for_each_irq_desc(i, desc) {
+                if (!i)
+                         continue;
 
                 if (i == irq)   /* Already tried */
                         continue;
 
-                desc = irq_to_desc(i);
                 if (try_one_irq(i, desc))
                         ok = 1;
         }
@@ -108,10 +109,14 @@ static int misrouted_irq(int irq)
 static void poll_spurious_irqs(unsigned long dummy)
 {
         int i;
-        for (i = 1; i < nr_irqs; i++) {
-                struct irq_desc *desc = irq_to_desc(i);
+        struct irq_desc *desc;
+
+        for_each_irq_desc(i, desc) {
                 unsigned int status;
 
+                if (!i)
+                         continue;
+
                 /* Racy but it doesn't matter */
                 status = desc->status;
                 barrier();
@@ -278,7 +283,7 @@ static int __init irqfixup_setup(char *str)
 
 __setup("irqfixup", irqfixup_setup);
 module_param(irqfixup, int, 0644);
-MODULE_PARM_DESC("irqfixup", "0: No fixup, 1: irqfixup mode 2: irqpoll mode");
+MODULE_PARM_DESC("irqfixup", "0: No fixup, 1: irqfixup mode, 2: irqpoll mode");
 
 static int __init irqpoll_setup(char *str)
 {