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Re: [PATCH] Re: [Xen-devel] Re: [PATCH 2/2] PV framebuffer

To: Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>, Markus Armbruster <armbru@xxxxxxxxxx>
Subject: Re: [PATCH] Re: [Xen-devel] Re: [PATCH 2/2] PV framebuffer
From: Keir Fraser <keir@xxxxxxxxxxxxx>
Date: Thu, 14 Dec 2006 11:30:13 +0000
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On 14/12/06 10:58, "Atsushi SAKAI" <sakaia@xxxxxxxxxxxxxx> wrote:

>  I searched the code and found
> the code in smp_call_function line337@linux/arch/ia64/kernel/smp.c
>    WARN_ON(irqs_disabled());
> The call trace problem caused by spin_lock_irqsave()
> in xenfb_update_screen@linux/drivers/xen/fbfront/xenfb.c
> Why you need to use spin_lock_irqsave in xenfb_update()?
> I understand the locking but why irqsave is required at this point?

The lock is used in fb_ops, vm_ops and kthread contexts. None of these are
executed in IRQ context so irqsave is not needed. I'll remove it. I'm not
sure whether you can call zap_page_range() even with a spinlock held

 -- Keir

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