linux-kernel - [PATCH v5 05/10] PM: EM: Add an iterator and accessor for the performance domain

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Message-ID: <20251014001055.772422-6-changwoo@igalia.com>
Date: Tue, 14 Oct 2025 09:10:50 +0900
From: Changwoo Min <changwoo@...lia.com>
To: lukasz.luba@....com,
	rafael@...nel.org,
	len.brown@...el.com,
	pavel@...nel.org
Cc: christian.loehle@....com,
	tj@...nel.org,
	kernel-dev@...lia.com,
	linux-pm@...r.kernel.org,
	sched-ext@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Changwoo Min <changwoo@...lia.com>
Subject: [PATCH v5 05/10] PM: EM: Add an iterator and accessor for the performance domain

Add an iterator function (for_each_em_perf_domain) that iterates all the
performance domains in the global list. A passed callback function (cb) is
called for each performance domain.

Additionally, add a lookup function (em_perf_domain_get_by_id) that
searches for a performance domain by matching the ID in the global list.

Signed-off-by: Changwoo Min <changwoo@...lia.com>
---
 kernel/power/em_netlink.h   | 14 ++++++++++++++
 kernel/power/energy_model.c | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/kernel/power/em_netlink.h b/kernel/power/em_netlink.h
index acd186c92d6b..8114b018c73b 100644
--- a/kernel/power/em_netlink.h
+++ b/kernel/power/em_netlink.h
@@ -10,7 +10,21 @@
 #define _EM_NETLINK_H
 
 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_NET)
+int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
+			    void *data);
+struct em_perf_domain *em_perf_domain_get_by_id(int id);
 #else
+static inline
+int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
+			    void *data)
+{
+	return -EINVAL;
+}
+static inline
+struct em_perf_domain *em_perf_domain_get_by_id(int id)
+{
+	return NULL;
+}
 #endif
 
 #endif /* _EM_NETLINK_H */
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 756debf5406a..43a243f9cfa2 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -17,6 +17,8 @@
 #include <linux/sched/topology.h>
 #include <linux/slab.h>
 
+#include "em_netlink.h"
+
 /*
  * Mutex serializing the registrations of performance domains and letting
  * callbacks defined by drivers sleep.
@@ -998,3 +1000,37 @@ void em_rebuild_sched_domains(void)
 	 */
 	schedule_work(&rebuild_sd_work);
 }
+
+int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
+			    void *data)
+{
+	struct em_perf_domain *pd;
+
+	lockdep_assert_not_held(&em_pd_mutex);
+	guard(mutex)(&em_pd_list_mutex);
+
+	list_for_each_entry(pd, &em_pd_list, node) {
+		int ret;
+
+		ret = cb(pd, data);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+struct em_perf_domain *em_perf_domain_get_by_id(int id)
+{
+	struct em_perf_domain *pd;
+
+	lockdep_assert_not_held(&em_pd_mutex);
+	guard(mutex)(&em_pd_list_mutex);
+
+	list_for_each_entry(pd, &em_pd_list, node) {
+		if (pd->id == id)
+			return pd;
+	}
+
+	return NULL;
+}
-- 
2.51.0