From 84adfb565b6243b9b377757390108c5692b82114 Mon Sep 17 00:00:00 2001
From: Scott Wood <swood@redhat.com>
Date: Sat, 27 Jul 2019 00:56:34 -0500
Subject: [PATCH 475/518] sched: migrate disable: Protect cpus_ptr with lock

[ Upstream commit 27ee52a891ed2c7e2e2c8332ccae0de7c2674b09 ]

Various places assume that cpus_ptr is protected by rq/pi locks,
so don't change it before grabbing those locks.

Signed-off-by: Scott Wood <swood@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
 kernel/sched/core.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f3f220e5b62c5..99bf52f77fcd5 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6925,9 +6925,8 @@ migrate_disable_update_cpus_allowed(struct task_struct *p)
 	struct rq *rq;
 	struct rq_flags rf;
 
-	p->cpus_ptr = cpumask_of(smp_processor_id());
-
 	rq = task_rq_lock(p, &rf);
+	p->cpus_ptr = cpumask_of(smp_processor_id());
 	update_nr_migratory(p, -1);
 	p->nr_cpus_allowed = 1;
 	task_rq_unlock(rq, p, &rf);
@@ -6939,9 +6938,8 @@ migrate_enable_update_cpus_allowed(struct task_struct *p)
 	struct rq *rq;
 	struct rq_flags rf;
 
-	p->cpus_ptr = &p->cpus_mask;
-
 	rq = task_rq_lock(p, &rf);
+	p->cpus_ptr = &p->cpus_mask;
 	p->nr_cpus_allowed = cpumask_weight(&p->cpus_mask);
 	update_nr_migratory(p, 1);
 	task_rq_unlock(rq, p, &rf);
-- 
2.41.0

