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Re: [Xen-devel] hvm_set_callback_irq_level() deadlock?

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] hvm_set_callback_irq_level() deadlock?
From: Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>
Date: Wed, 07 Jan 2009 21:58:58 +0900
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Keir Fraser wrote:
On 07/01/2009 10:22, "Akio Takebe" <takebe_akio@xxxxxxxxxxxxxx> wrote:

Doesn't vioapic_irq_positive_edge() clearly expect to be called with that
lock held?
I concern about that vioapic_deliver() calls vcpu_kick(). If vcpu0 has the
lock and
vcpu1 cannot get lock and spin then vcpu0 sleep in another function,
it may cause deadlock because vioapic_irq_positive_edge() may call
vcpu_kick().
For example, the following function is OK?

I still don't see the problem. You'll have to spell out a concrete example,
explaining where the two CPUs would be spinning and what state they're in
(i.e, why they are depending on each other, and why no progress can be
made).

I thought more. Sorry, I was wrong.

Best Regards,

Akio Takebe

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