[ARM] Fix ARM IRQ probe code

- Add semaphore to prevent simultaneous probe_irq_on() callers.
- Add probe_irq_mask() for yenta.c

arch/arm/kernel/armksyms.c

@@ -127,6 +127,7 @@ EXPORT_SYMBOL(__bad_xchg);
 EXPORT_SYMBOL(__readwrite_bug);
 EXPORT_SYMBOL(enable_irq);
 EXPORT_SYMBOL(disable_irq);
+EXPORT_SYMBOL(probe_irq_mask);
 EXPORT_SYMBOL(set_irq_type);
 EXPORT_SYMBOL(pm_idle);
 EXPORT_SYMBOL(pm_power_off);

arch/arm/kernel/irq.c

@@ -606,6 +606,8 @@ void free_irq(unsigned int irq, void *dev_id)
 	}
 }
 
+static DECLARE_MUTEX(probe_sem);
+
 /* Start the interrupt probing.  Unlike other architectures,
  * we don't return a mask of interrupts from probe_irq_on,
  * but return the number of interrupts enabled for the probe.
@@ -617,6 +619,8 @@ unsigned long probe_irq_on(void)
 	unsigned int i, irqs = 0;
 	unsigned long delay;
 
+	down(&probe_sem);
+
 	/*
 	 * first snaffle up any unassigned but
 	 * probe-able interrupts
@@ -656,6 +660,21 @@ unsigned long probe_irq_on(void)
 	return irqs;
 }
 
+unsigned int probe_irq_mask(unsigned long irqs)
+{
+	unsigned int mask = 0, i;
+
+	spin_lock_irq(&irq_controller_lock);
+	for(i = 0; i < 16 && i < NR_IRQS; i++)
+		if (irq_desc[i].probing && irq_desc[i].triggered)
+			mask |= 1 << i;
+	spin_unlock_irq(&irq_controller_lock);
+
+	up(&probe_sem);
+
+	return mask;
+}
+
 /*
  * Possible return values:
  *  >= 0 - interrupt number
@@ -687,6 +706,8 @@ int probe_irq_off(unsigned long irqs)
 out:
 	spin_unlock_irq(&irq_controller_lock);
 
+	up(&probe_sem);
+
 	return irq_found;
 }