linux-kernel - [PATCH] cpufreq: Make cpufreq_online() call driver->offline() on errors

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Date:   Mon, 21 Jun 2021 19:26:12 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM <linux-pm@...r.kernel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] cpufreq: Make cpufreq_online() call driver->offline() on errors

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

In the CPU removal path the ->offline() callback provided by the
driver is always invoked before ->exit(), but in the cpufreq_online()
error path it is not, so ->exit() is somehow expected to know the
context in which it has been called and act accordingly.

That is less than straightforward, so make cpufreq_online() invoke
the driver's ->offline() callback before ->exit() too.

This only potentially affects intel_pstate at this point.

Fixes: 91a12e91dc39 ("cpufreq: Allow light-weight tear down and bring up of CPUs")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/cpufreq.c |    3 +++
 1 file changed, 3 insertions(+)

Index: linux-pm/drivers/cpufreq/cpufreq.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq.c
+++ linux-pm/drivers/cpufreq/cpufreq.c
@@ -1516,6 +1516,9 @@ out_destroy_policy:
 	up_write(&policy->rwsem);

 out_exit_policy:
+	if (cpufreq_driver->offline)
+		cpufreq_driver->offline(policy);
+
 	if (cpufreq_driver->exit)
 		cpufreq_driver->exit(policy);