genirq: Do not poll disabled, percpu and timer interrupts

There is no point in polling disabled lines.

percpu does not make sense at all because we only poll on the cpu
we're currently running on. Also polling per_cpu interrupts is racy as
hell. The handler runs without locking so we might get a huge
surprise.

If the timer interrupt needs polling, then we wont get there anyway.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/irq/spurious.c

@@ -25,30 +25,42 @@ static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs, 0, 0);
 /*
  * Recovery handler for misrouted interrupts.
  */
-static int try_one_irq(int irq, struct irq_desc *desc)
+static int try_one_irq(int irq, struct irq_desc *desc, bool force)
 {
 	struct irqaction *action;
 	int ok = 0, work = 0;
 
 	raw_spin_lock(&desc->lock);
+
+	/* PER_CPU and nested thread interrupts are never polled */
+	if (desc->status & (IRQ_PER_CPU | IRQ_NESTED_THREAD))
+		goto out;
+
+	/*
+	 * Do not poll disabled interrupts unless the spurious
+	 * disabled poller asks explicitely.
+	 */
+	if ((desc->status & IRQ_DISABLED) && !force)
+		goto out;
+
+	/*
+	 * All handlers must agree on IRQF_SHARED, so we test just the
+	 * first. Check for action->next as well.
+	 */
+	action = desc->action;
+	if (!action || !(action->flags & IRQF_SHARED) ||
+	    (action->flags & __IRQF_TIMER) || !action->next)
+		goto out;
+
 	/* Already running on another processor */
 	if (desc->status & IRQ_INPROGRESS) {
 		/*
 		 * Already running: If it is shared get the other
 		 * CPU to go looking for our mystery interrupt too
 		 */
-		if (desc->action && (desc->action->flags & IRQF_SHARED))
-			desc->status |= IRQ_PENDING;
-		raw_spin_unlock(&desc->lock);
-		return ok;
-	}
-	/*
-	 * All handlers must agree on IRQF_SHARED, so we test just the
-	 * first. Check for action->next as well.
-	 */
-	action = desc->action;
-	if (!action || !(action->flags & IRQF_SHARED) || !action->next)
+		desc->status |= IRQ_PENDING;
 		goto out;
+	}
 
 	/* Honour the normal IRQ locking */
 	desc->status |= IRQ_INPROGRESS;
@@ -87,7 +99,7 @@ static int misrouted_irq(int irq)
 		if (i == irq)	/* Already tried */
 			continue;
 
-		if (try_one_irq(i, desc))
+		if (try_one_irq(i, desc, false))
 			ok = 1;
 	}
 	/* So the caller can adjust the irq error counts */
@@ -112,7 +124,7 @@ static void poll_spurious_irqs(unsigned long dummy)
 			continue;
 
 		local_irq_disable();
-		try_one_irq(i, desc);
+		try_one_irq(i, desc, true);
 		local_irq_enable();
 	}