Re: [PATCH] powerpc: xive: ensure active irqd when setting affinity

Michael Ellerman [mpe@ellerman.id.au] wrote:

Sukadev Bhattiprolu [off-list ref] writes:

quoted

From fd0abf5c61b6041fdb75296e8580b86dc91d08d6 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 1 Aug 2017 20:54:41 -0500
Subject: [PATCH] powerpc: xive: ensure active irqd when setting affinity

Ensure irqd is active before attempting to set affinity. This should
make the set affinity code more robust. For instance, this prevents
these messages seen on a 4.12 based kernel when taking cpus offline:

   [  123.053037264,3] XIVE[ IC 00  ] ISN 2 lead to invalid IVE !
   [   77.885859] xive: Error -6 reconfiguring irq 17
   [   77.885862] IRQ17: set affinity failed(-6).

The underlying problem with taking cpus offline was fixed in 4.13-rc1 by:

   commit 91f26cb4cd3c ("genirq/cpuhotplug: Do not migrated shutdown irqs")

So do we still need this? Or is the above only a partial fix?

It would be good to have this fix.

Commit 91f26cb4cd3c fixes the problem, so we wont see the errors with
that commit applied. But if such a problem were to show up again, xive
will handle them earlier before hitting those errors.

Sukadev

I'm a bit confused.

cheers