linux-kernel - [PATCH v2 1/4] thermal: cpufreq_cooling: Use private callback ops for each cooling device

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Message-Id: <20220613124327.30766-2-lukasz.luba@arm.com>
Date:   Mon, 13 Jun 2022 13:43:24 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Cc:     daniel.lezcano@...aro.org, amitk@...nel.org, rui.zhang@...el.com,
        lukasz.luba@....com, viresh.kumar@...aro.org, rafael@...nel.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, mingo@...hat.com
Subject: [PATCH v2 1/4] thermal: cpufreq_cooling: Use private callback ops for each cooling device

It is very unlikely that one CPU cluster would have the EM and some other
won't have it (because EM registration failed or DT lacks needed entry).
Although, we should avoid modifying global variable with callbacks anyway.
Redesign this and add safety for such situation.

Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 drivers/thermal/cpufreq_cooling.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/thermal/cpufreq_cooling.c b/drivers/thermal/cpufreq_cooling.c
index b8151d95a806..ad8b86f5281b 100644
--- a/drivers/thermal/cpufreq_cooling.c
+++ b/drivers/thermal/cpufreq_cooling.c
@@ -59,6 +59,7 @@ struct time_in_idle {
  * @cdev: thermal_cooling_device pointer to keep track of the
  *	registered cooling device.
  * @policy: cpufreq policy.
+ * @cooling_ops: cpufreq callbacks to thermal cooling device ops
  * @idle_time: idle time stats
  * @qos_req: PM QoS contraint to apply
  *
@@ -71,6 +72,7 @@ struct cpufreq_cooling_device {
 	unsigned int max_level;
 	struct em_perf_domain *em;
 	struct cpufreq_policy *policy;
+	struct thermal_cooling_device_ops cooling_ops;
 #ifndef CONFIG_SMP
 	struct time_in_idle *idle_time;
 #endif
@@ -485,14 +487,6 @@ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 	return ret;
 }
 
-/* Bind cpufreq callbacks to thermal cooling device ops */
-
-static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
-	.get_max_state		= cpufreq_get_max_state,
-	.get_cur_state		= cpufreq_get_cur_state,
-	.set_cur_state		= cpufreq_set_cur_state,
-};
-
 /**
  * __cpufreq_cooling_register - helper function to create cpufreq cooling device
  * @np: a valid struct device_node to the cooling device device tree node
@@ -554,7 +548,10 @@ __cpufreq_cooling_register(struct device_node *np,
 	/* max_level is an index, not a counter */
 	cpufreq_cdev->max_level = i - 1;
 
-	cooling_ops = &cpufreq_cooling_ops;
+	cooling_ops = &cpufreq_cdev->cooling_ops;
+	cooling_ops->get_max_state = cpufreq_get_max_state;
+	cooling_ops->get_cur_state = cpufreq_get_cur_state;
+	cooling_ops->set_cur_state = cpufreq_set_cur_state;
 
 #ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
 	if (em_is_sane(cpufreq_cdev, em)) {
-- 
2.17.1