linux-kernel - Re: [PATCH] genirq: don't use flush_scheduled

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Date:	Fri, 17 Jun 2011 00:28:06 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] genirq: don't use flush_scheduled_work() in IRQ
 affinity notifiers

On Wed, 2011-06-15 at 16:29 +0200, Tejun Heo wrote:
> cd7eab44e9 (genirq: Add IRQ affinity notifiers) added use of
> flush_scheduled_work() which is being deprecated.  Add a dedicated
> workqueue and flush it instead of flushing system-wide workqueue.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ben Hutchings <bhutchings@...arflare.com>
> ---
> I'm planning on marking flush_scheduled_work() deprecated in
> linux-next soonish.  It would be great if this patch (or something
> else which removes flush_scheduled_work() call somehow) can be
> included in linux-next.
[...]
> --- work.orig/kernel/irq/manage.c
> +++ work/kernel/irq/manage.c
> @@ -74,6 +74,16 @@ EXPORT_SYMBOL(synchronize_irq);
>  
>  #ifdef CONFIG_SMP
>  cpumask_var_t irq_default_affinity;
> +static struct workqueue_struct *irq_affinity_notify_wq;
> +
> +static int __init irq_affinity_init(void)
> +{
> +	irq_affinity_notify_wq = alloc_workqueue("irq_affinity_notify", 0, 0);
> +	if (!irq_affinity_notify_wq)
> +		return -ENOMEM;
> +	return 0;
> +}
> +subsys_initcall(irq_affinity_init);
[...]

This facility is enabled on all configurations with NET && SMP &&
GENERIC_HARDIRQS, but at the moment is only useful for some net drivers
(currently only one).  So I don't think it should be creating a task at
boot time.  Does alloc_workqueue() still create any tasks immediately?

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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