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

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Date:	Tue, 02 Jul 2013 11:46:36 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	James Hogan <james.hogan@...tec.com>
CC:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 5/5] metag: cpu hotplug: route_irq: preserve irq mask

On 07/01/2013 09:34 PM, James Hogan wrote:
> 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>
> ---

Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>

Regards,
Srivatsa S. Bhat

>  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);
>  }
> 
>  /*
> 

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