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Subject: Re: [RFC PATCH kernel] powerpc/xive: Drop deregistered irqs
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alexey Kardashevskiy <aik@ozlabs.ru>, linuxppc-dev@lists.ozlabs.org
Date: Sun, 14 Jul 2019 11:31:43 +1000
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Cc: Greg Kurz <groug@kaod.org>, Nicholas Piggin <npiggin@gmail.com>,
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On Sat, 2019-07-13 at 18:53 +1000, Alexey Kardashevskiy wrote:
> 
> On 13/07/2019 09:47, Benjamin Herrenschmidt wrote:
> > On Fri, 2019-07-12 at 19:37 +1000, Alexey Kardashevskiy wrote:
> > > 
> > 
> > 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/kernel/irq.c#n614
> > > 
> > > If so, then in order to do EOI, I'll need the desc which is gone,
> > > or
> > > I am missing the point?
> > 
> > All you need is drop the local CPU priority.
> 
> I know that, the question was how. I cannot use irq_chip in
> arch/powerpc/kernel/irq.c and I do not want to add
> ppc_md.enable_irqs().

Well, best is probably to do just that though, but call it something
like ppc_md.orphan_irq() or something like that instead. Another option
as you mention is to try to scrub queues, but that's trickier to do due
to the lockless nature of the queue handling.

Cheers,
Ben.