sparseirq: make for_each_irq_desc() more robust

Raja reported for_each_irq_desc() has possibility unsafeness:

if anyone write folliwing code, for_each_irq_desc() doesn't work
as intended:

(right now this code does not exist at all)

 if (safe)
   for_each_irq_desc(irq, desc) {
      ...
   }
 else
   panic();

Reported-by: Raja R Harinath <harinath@hurrynot.org>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 2 deletions

diff --git a/include/linux/irqnr.h b/include/linux/irqnr.h
index 86af92e9e84c..52ebbb4b161d 100644
--- a/include/linux/irqnr.h
+++ b/include/linux/irqnr.h
@@ -28,13 +28,17 @@ extern struct irq_desc *irq_to_desc(unsigned int irq);
 # define for_each_irq_desc(irq, desc)                                   \
         for (irq = 0, desc = irq_to_desc(irq); irq < nr_irqs;           \
              irq++, desc = irq_to_desc(irq))                            \
-                if (desc)
+                if (!desc)                                              \
+                        ;                                               \
+                else
 
 
 # define for_each_irq_desc_reverse(irq, desc)                           \
         for (irq = nr_irqs - 1, desc = irq_to_desc(irq); irq >= 0;      \
              irq--, desc = irq_to_desc(irq))                            \
-                if (desc)
+                if (!desc)                                              \
+                        ;                                               \
+                else
 
 #endif /* CONFIG_GENERIC_HARDIRQS */