linux-kernel - [PATCH 5/5] metag: cpu hotplug: route

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Date:	Mon, 1 Jul 2013 17:04:19 +0100
From:	James Hogan <james.hogan@...tec.com>
To:	<linux-kernel@...r.kernel.org>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	James Hogan <james.hogan@...tec.com>
Subject: [PATCH 5/5] metag: cpu hotplug: route_irq: preserve irq mask

The route_irq() function needs to preserve the irq mask by using the
_irqsave/irqrestore variants of raw spin lock functions instead of the
_irq variants. This is because it is called from __cpu_disable() (via
migrate_irqs()), which is called with IRQs disabled, so using the _irq
variants re-enables IRQs.

This appears to have been causing occasional hits of the
BUG_ON(!irqs_disabled()) in __irq_work_run() during CPU hotplug soak
testing:
  BUG: failure at kernel/irq_work.c:122/__irq_work_run()!

Signed-off-by: James Hogan <james.hogan@...tec.com>
---
 arch/metag/kernel/irq.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/metag/kernel/irq.c b/arch/metag/kernel/irq.c
index d91b1e9..2a2c9d5 100644
--- a/arch/metag/kernel/irq.c
+++ b/arch/metag/kernel/irq.c
@@ -279,11 +279,12 @@ static void route_irq(struct irq_data *data, unsigned int irq, unsigned int cpu)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
 	struct irq_chip *chip = irq_data_get_irq_chip(data);
+	unsigned long flags;
 
-	raw_spin_lock_irq(&desc->lock);
+	raw_spin_lock_irqsave(&desc->lock, flags);
 	if (chip->irq_set_affinity)
 		chip->irq_set_affinity(data, cpumask_of(cpu), false);
-	raw_spin_unlock_irq(&desc->lock);
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
 }
 
 /*
-- 
1.8.1.2


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