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Subject[PATCH RT 08/23] sched: migrate disable: Protect cpus_ptr with lock
Date
From: Scott Wood <swood@redhat.com>

v4.14.170-rt75-rc2 stable review patch.
If anyone has any objections, please let me know.

-----------


[ 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 4708129e8df1..189e6f08575e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6923,9 +6923,8 @@ 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);
@@ -6937,9 +6936,8 @@ 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);
--
2.14.1
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