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

[Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>]

>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")

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/sysdev/xive/common.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index 6595462..2708d42 100644
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -672,6 +672,10 @@ static int xive_irq_set_affinity(struct irq_data *d,
 	if (cpumask_any_and(cpumask, cpu_online_mask) >= nr_cpu_ids)
 		return -EINVAL;
 
+	/* Don't do anything if the interrupt isn't started */
+	if (!irqd_is_started(d))
+		return IRQ_SET_MASK_OK;
+
 	/*
 	 * If existing target is already in the new mask, and is
 	 * online then do nothing.
-- 
1.8.3.1