linux-kernel - [PATCH v6 12/23] PM: EM: Add helpers to read under RCU lock the EM table

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Message-Id: <20240104171553.2080674-13-lukasz.luba@arm.com>
Date: Thu,  4 Jan 2024 17:15:42 +0000
From: Lukasz Luba <lukasz.luba@....com>
To: linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	rafael@...nel.org
Cc: lukasz.luba@....com,
	dietmar.eggemann@....com,
	rui.zhang@...el.com,
	amit.kucheria@...durent.com,
	amit.kachhap@...il.com,
	daniel.lezcano@...aro.org,
	viresh.kumar@...aro.org,
	len.brown@...el.com,
	pavel@....cz,
	mhiramat@...nel.org,
	qyousef@...alina.io,
	wvw@...gle.com
Subject: [PATCH v6 12/23] PM: EM: Add helpers to read under RCU lock the EM table

To use the runtime modifiable EM table there is a need to use RCU
read locking properly. Add helper functions for the device drivers and
frameworks to make sure it's done properly.

Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 include/linux/energy_model.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index f33257ed83fd..cfaf5d8b1aad 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -338,6 +338,20 @@ static inline int em_pd_nr_perf_states(struct em_perf_domain *pd)
 	return pd->nr_perf_states;
 }
 
+static inline struct em_perf_state *em_get_table(struct em_perf_domain *pd)
+{
+	struct em_perf_table __rcu *table;
+
+	rcu_read_lock();
+	table = rcu_dereference(pd->em_table);
+	return table->state;
+}
+
+static inline void em_put_table(void)
+{
+	rcu_read_unlock();
+}
+
 #else
 struct em_data_callback {};
 #define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) { }
@@ -384,6 +398,11 @@ int em_dev_update_perf_domain(struct device *dev,
 {
 	return -EINVAL;
 }
+static inline struct em_perf_state *em_get_table(struct em_perf_domain *pd)
+{
+	return NULL;
+}
+static inline void em_put_table(void) {}
 #endif
 
 #endif
-- 
2.25.1