linux-kernel - [PATCH RT 14/30] sched: __set_cpus_allowed_ptr: Check cpus_mask, not cpus

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Date:   Thu, 23 Jan 2020 15:39:44 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org,
        linux-rt-users <linux-rt-users@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        John Kacur <jkacur@...hat.com>,
        Julia Cartwright <julia@...com>,
        Daniel Wagner <wagi@...om.org>,
        Tom Zanussi <zanussi@...nel.org>, Scott Wood <swood@...hat.com>
Subject: [PATCH RT 14/30] sched: __set_cpus_allowed_ptr: Check cpus_mask, not cpus_ptr

4.19.94-rt39-rc2 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Scott Wood <swood@...hat.com>

[ Upstream commit e5606fb7b042db634ed62b4dd733d62e050e468f ]

This function is concerned with the long-term cpu mask, not the
transitory mask the task might have while migrate disabled.  Before
this patch, if a task was migrate disabled at the time
__set_cpus_allowed_ptr() was called, and the new mask happened to be
equal to the cpu that the task was running on, then the mask update
would be lost.

Signed-off-by: Scott Wood <swood@...hat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3413b9ebef1f..d6bd8129a390 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1157,7 +1157,7 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
 		goto out;
 	}
 
-	if (cpumask_equal(p->cpus_ptr, new_mask))
+	if (cpumask_equal(&p->cpus_mask, new_mask))
 		goto out;
 
 	dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask);
-- 
2.24.1