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[Xen-devel] Re: IRQs, move_in_progress, -EBUSY &c

To: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy@xxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Subject: [Xen-devel] Re: IRQs, move_in_progress, -EBUSY &c
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Wed, 11 Aug 2010 16:04:40 +0100
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On 11/08/2010 15:56, "George Dunlap" <George.Dunlap@xxxxxxxxxxxxx> wrote:

> However, it seems that moving IRQs is not handled properly.  Either
> the pvops kernel should retry if it gets an -EBUSY, or the hypercall
> should not fail, but wait until it can return success.

Move_in_progress is a private hypervisor implementation detail. We shouldn't
make it visible to the guest via EBUSY. Worst case we should be turning the
retry into a hypercall continuation. Even better if we don't need to make
the IRQ bind request wait at all... Not sure why that needs to happen at

 -- Keir

> I discovered all this by adding debug statements to the IRQ path; the
> patch is attached, if anyone else wants to use it.
>  -George

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