[PATCH 2/3] cpufreq: Panic if policy is active in cpufreq_policy_free()

From: Viresh Kumar <viresh.kumar@linaro.org>
To: "Rafael J. Wysocki" <rafael@kernel.org>,
	Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org,
	Vincent Guittot <vincent.guittot@linaro.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] cpufreq: Panic if policy is active in cpufreq_policy_free()
Date: Thu, 26 May 2022 17:21:20 +0530	[thread overview]
Message-ID: <8c3d50faf8811e86136fb3f9c459e43fc3c50bc0.1653565641.git.viresh.kumar@linaro.org> (raw)
In-Reply-To: <cover.1653565641.git.viresh.kumar@linaro.org>

With the new design in place, show/store callbacks check if the policy
is active or not before proceeding further and cpufreq_policy_free()
must be called after emptying policy->cpus mask, i.e. inactive policy.

Lets make sure we don't get a bug around this later and catch this early
by putting a BUG_ON() within cpufreq_policy_free().

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index e24aa5d4bca5..53d163a84e06 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1284,6 +1284,12 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
 	unsigned long flags;
 	int cpu;
 
+	/*
+	 * The callers must ensure the policy is inactive by now, to avoid any
+	 * races with show()/store() callbacks.
+	 */
+	BUG_ON(!policy_is_inactive(policy));
+
 	/* Remove policy from list */
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 	list_del(&policy->policy_list);
-- 
2.31.1.272.g89b43f80a514

