linux-kernel - [PATCH 2/2] Revert "sched/core: Take the hotplug lock in sched_init

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Message-Id: <1545243796-23224-3-git-send-email-valentin.schneider@arm.com>
Date:   Wed, 19 Dec 2018 18:23:16 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org
Cc:     cai@....us, daniel.lezcano@...aro.org,
        linux-arm-kernel@...ts.infradead.org, longman@...hat.com,
        marc.zyngier@....com, mark.rutland@....com, mingo@...nel.org,
        peterz@...radead.org, tglx@...utronix.de, dietmar.eggemann@....com
Subject: [PATCH 2/2] Revert "sched/core: Take the hotplug lock in sched_init_smp()"

This reverts commit 40fa3780bac2b654edf23f6b13f4e2dd550aea10.

Now that we have a system-wide muting of hotplug lockdep during init,
this is no longer needed.

Signed-off-by: Valentin Schneider <valentin.schneider@....com>
---
 kernel/sched/core.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e4ca15d..144b778 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5854,14 +5854,11 @@ void __init sched_init_smp(void)
 	/*
 	 * There's no userspace yet to cause hotplug operations; hence all the
 	 * CPU masks are stable and all blatant races in the below code cannot
-	 * happen. The hotplug lock is nevertheless taken to satisfy lockdep,
-	 * but there won't be any contention on it.
+	 * happen.
 	 */
-	cpus_read_lock();
 	mutex_lock(&sched_domains_mutex);
 	sched_init_domains(cpu_active_mask);
 	mutex_unlock(&sched_domains_mutex);
-	cpus_read_unlock();
 
 	/* Move init over to a non-isolated CPU */
 	if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0)
--
2.7.4