linux-kernel - [RFC 2/3] rt: Update nr_cpus_allowed if the affinity of a task changes while its migration is disabled

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Date:   Fri, 16 Jun 2017 12:39:47 +0200
From:   Daniel Bristot de Oliveira <bristot@...hat.com>
To:     linux-rt-users@...r.kernel.org
Cc:     "Luis Claudio R . Goncalves" <lgoncalv@...hat.com>,
        Clark Williams <williams@...hat.com>,
        Luiz Capitulino <lcapitulino@...hat.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [RFC 2/3] rt: Update nr_cpus_allowed if the affinity of a task changes while its migration is disabled

Currently, if the affinity of a task changes when it is with migration
disabled, the nr_cpus_allowed is not being updated, creating an
inconsistency between nr_cpus_allowed and cpumask_weight(cpus_allowed)

This patch fixes this problem by calling set_cpus_allowed_common()
if the cpumask of a task changes while it is with migration disable.

Signed-off-by: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Luis Claudio R. Goncalves <lgoncalv@...hat.com>
Cc: Clark Williams <williams@...hat.com>
Cc: Luiz Capitulino <lcapitulino@...hat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: LKML <linux-kernel@...r.kernel.org>
Cc: linux-rt-users <linux-rt-users@...r.kernel.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 aeb3e12..0396bf2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1146,7 +1146,7 @@ void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
 	lockdep_assert_held(&p->pi_lock);
 
 	if (__migrate_disabled(p)) {
-		cpumask_copy(&p->cpus_allowed, new_mask);
+		set_cpus_allowed_common(p, new_mask);
 		return;
 	}
 
-- 
2.9.4