linux/debian/patches-rt/0313-sched-core-migrate_enable-must-access-takedown_cpu_t.patch

From b36ee36f5d6230ea331f5999401df432180eb114 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 29 Nov 2019 17:24:55 +0100
Subject: [PATCH 313/325] sched/core: migrate_enable() must access
 takedown_cpu_task on !HOTPLUG_CPU
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.115-rt48.tar.xz

[ Upstream commit a61d1977f692e46bad99a100f264981ba08cb4bd ]

The variable takedown_cpu_task is never declared/used on !HOTPLUG_CPU
except for migrate_enable(). This leads to a link error.

Don't use takedown_cpu_task in !HOTPLUG_CPU.

Reported-by: Dick Hollenbeck <dick@softplc.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/cpu.c        | 2 ++
 kernel/sched/core.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 2834eed32b55..d28254597f59 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -845,7 +845,9 @@ static int take_cpu_down(void *_param)
 	return 0;
 }
 
+#ifdef CONFIG_PREEMPT_RT_BASE
 struct task_struct *takedown_cpu_task;
+#endif
 
 static int takedown_cpu(unsigned int cpu)
 {
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e465381b464d..cbd76324babd 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7314,9 +7314,11 @@ void migrate_enable(void)
 
 	p->migrate_disable = 0;
 	rq->nr_pinned--;
+#ifdef CONFIG_HOTPLUG_CPU
 	if (rq->nr_pinned == 0 && unlikely(!cpu_active(cpu)) &&
 	    takedown_cpu_task)
 		wake_up_process(takedown_cpu_task);
+#endif
 
 	if (!p->migrate_disable_scheduled)
 		goto out;
-- 
2.25.1