[PATCH AUTOSEL 5.2 190/249] cpufreq: Avoid calling cpufreq_verify_current_freq() from handle_update()

From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Sasha Levin <sashal@kernel.org>,
	linux-pm@vger.kernel.org
Subject: [PATCH AUTOSEL 5.2 190/249] cpufreq: Avoid calling cpufreq_verify_current_freq() from handle_update()
Date: Mon, 15 Jul 2019 09:45:55 -0400	[thread overview]
Message-ID: <20190715134655.4076-190-sashal@kernel.org> (raw)
In-Reply-To: <20190715134655.4076-1-sashal@kernel.org>

From: Viresh Kumar <viresh.kumar@linaro.org>

[ Upstream commit 70a59fde6e69d1d8579f84bf4555bfffb3ce452d ]

On some occasions cpufreq_verify_current_freq() schedules a work whose
callback is handle_update(), which further calls cpufreq_update_policy()
which may end up calling cpufreq_verify_current_freq() again.

On the other hand, when cpufreq_update_policy() is called from
handle_update(), the pointer to the cpufreq policy is already
available, but cpufreq_cpu_acquire() is still called to get it in
cpufreq_update_policy(), which should be avoided as well.

To fix these issues, create a new helper, refresh_frequency_limits(),
and make both handle_update() call it cpufreq_update_policy().

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
[ rjw: Rename reeval_frequency_limits() as refresh_frequency_limits() ]
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/cpufreq/cpufreq.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index e84bf0eb7239..876a4cb09de3 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1114,13 +1114,25 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
 	return ret;
 }
 
+static void refresh_frequency_limits(struct cpufreq_policy *policy)
+{
+	struct cpufreq_policy new_policy = *policy;
+
+	pr_debug("updating policy for CPU %u\n", policy->cpu);
+
+	new_policy.min = policy->user_policy.min;
+	new_policy.max = policy->user_policy.max;
+
+	cpufreq_set_policy(policy, &new_policy);
+}
+
 static void handle_update(struct work_struct *work)
 {
 	struct cpufreq_policy *policy =
 		container_of(work, struct cpufreq_policy, update);
-	unsigned int cpu = policy->cpu;
-	pr_debug("handle_update for cpu %u called\n", cpu);
-	cpufreq_update_policy(cpu);
+
+	pr_debug("handle_update for cpu %u called\n", policy->cpu);
+	refresh_frequency_limits(policy);
 }
 
 static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
@@ -2392,7 +2404,6 @@ int cpufreq_set_policy(struct cpufreq_policy *policy,
 void cpufreq_update_policy(unsigned int cpu)
 {
 	struct cpufreq_policy *policy = cpufreq_cpu_acquire(cpu);
-	struct cpufreq_policy new_policy;
 
 	if (!policy)
 		return;
@@ -2405,12 +2416,7 @@ void cpufreq_update_policy(unsigned int cpu)
 	    (cpufreq_suspended || WARN_ON(!cpufreq_update_current_freq(policy))))
 		goto unlock;
 
-	pr_debug("updating policy for CPU %u\n", cpu);
-	memcpy(&new_policy, policy, sizeof(*policy));
-	new_policy.min = policy->user_policy.min;
-	new_policy.max = policy->user_policy.max;
-
-	cpufreq_set_policy(policy, &new_policy);
+	refresh_frequency_limits(policy);
 
 unlock:
 	cpufreq_cpu_release(policy);
-- 
2.20.1

