linux-kernel - [PATCH] cpufreq: Rebuild sched-domains when removing cpufreq driver

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Date:   Mon, 18 Sep 2023 13:29:35 +0200
From:   Pierre Gondois <pierre.gondois@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Shrikanth Hegde <sshegde@...ux.vnet.ibm.com>, vschneid@...hat.com,
        Pierre Gondois <pierre.gondois@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        linux-pm@...r.kernel.org
Subject: [PATCH] cpufreq: Rebuild sched-domains when removing cpufreq driver

The Energy Aware Scheduler (EAS) relies on the schedutil governor.
When moving to/from the schedutil governor, sched domains must be
rebuilt to allow re-evaluating the enablement conditions of EAS.
This is done through sched_cpufreq_governor_change().

Having a cpufreq governor assumes having a cpufreq driver running.
Inserting/removing a cpufreq driver should trigger a re-evaluation
of EAS enablement conditions, avoiding to see EAS enabled when
removing a running cpufreq driver.

Add a sched_cpufreq_governor_change() call in cpufreq driver removal
path.

Signed-off-by: Pierre Gondois <pierre.gondois@....com>
---
 drivers/cpufreq/cpufreq.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 60ed89000e82..0a4979c34fd1 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1673,6 +1673,8 @@ static void __cpufreq_offline(unsigned int cpu, struct cpufreq_policy *policy)
 		cpufreq_driver->exit(policy);
 		policy->freq_table = NULL;
 	}
+
+	sched_cpufreq_governor_change(policy, policy->governor);
 }

 static int cpufreq_offline(unsigned int cpu)
-- 
2.25.1