linux-kernel - [PATCH v1 2/2] PM: core: Add two macros for walking device links

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Message-ID: <1944671.tdWV9SEqCh@rafael.j.wysocki>
Date: Tue, 02 Sep 2025 15:45:14 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 LKML <linux-kernel@...r.kernel.org>, Danilo Krummrich <dakr@...nel.org>,
 Ulf Hansson <ulf.hansson@...aro.org>, Saravana Kannan <saravanak@...gle.com>,
 Johannes Berg <johannes@...solutions.net>
Subject: [PATCH v1 2/2] PM: core: Add two macros for walking device links

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Add separate macros for walking links to suppliers and consumers of a
device to help device links users to avoid exposing the internals of
struct dev_links_info in their code and possible coding mistakes related
to that.

Accordingly, use the new macros to replace open-coded device links list
walks in the core power management code.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/base/base.h          |    8 ++++++++
 drivers/base/power/main.c    |   18 +++++++-----------
 drivers/base/power/runtime.c |    3 +--
 3 files changed, 16 insertions(+), 13 deletions(-)

--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -251,6 +251,14 @@
 void fw_devlink_drivers_done(void);
 void fw_devlink_probing_done(void);
 
+#define dev_for_each_link_to_supplier(__link, __dev)	\
+	list_for_each_entry_srcu(__link, &(__dev)->links.suppliers, c_node, \
+				 device_links_read_lock_held())
+
+#define dev_for_each_link_to_consumer(__link, __dev)	\
+	list_for_each_entry_srcu(__link, &(__dev)->links.consumers, s_node, \
+				 device_links_read_lock_held())
+
 /* device pm support */
 void device_pm_move_to_tail(struct device *dev);
 
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -40,10 +40,6 @@
 
 typedef int (*pm_callback_t)(struct device *);
 
-#define list_for_each_entry_srcu_locked(pos, head, member) \
-	list_for_each_entry_srcu(pos, head, member, \
-			device_links_read_lock_held())
-
 /*
  * The entries in the dpm_list list are in a depth first order, simply
  * because children are guaranteed to be discovered after parents, and
@@ -281,7 +277,7 @@
 	 * callbacks freeing the link objects for the links in the list we're
 	 * walking.
 	 */
-	list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node)
+	dev_for_each_link_to_supplier(link, dev)
 		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
 			dpm_wait(link->supplier, async);
 
@@ -338,7 +334,7 @@
 	 * continue instead of trying to continue in parallel with its
 	 * unregistration).
 	 */
-	list_for_each_entry_srcu_locked(link, &dev->links.consumers, s_node)
+	dev_for_each_link_to_consumer(link, dev)
 		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
 			dpm_wait(link->consumer, async);
 
@@ -675,7 +671,7 @@
 	idx = device_links_read_lock();
 
 	/* Start processing the device's "async" consumers. */
-	list_for_each_entry_srcu_locked(link, &dev->links.consumers, s_node)
+	dev_for_each_link_to_consumer(link, dev)
 		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
 			dpm_async_with_cleanup(link->consumer, func);
 
@@ -1330,7 +1326,7 @@
 	idx = device_links_read_lock();
 
 	/* Start processing the device's "async" suppliers. */
-	list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node)
+	dev_for_each_link_to_supplier(link, dev)
 		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
 			dpm_async_with_cleanup(link->supplier, func);
 
@@ -1384,7 +1380,7 @@
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node)
+	dev_for_each_link_to_supplier(link, dev)
 		link->supplier->power.must_resume = true;
 
 	device_links_read_unlock(idx);
@@ -1813,7 +1809,7 @@
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node) {
+	dev_for_each_link_to_supplier(link, dev) {
 		spin_lock_irq(&link->supplier->power.lock);
 		link->supplier->power.direct_complete = false;
 		spin_unlock_irq(&link->supplier->power.lock);
@@ -2065,7 +2061,7 @@
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node) {
+	dev_for_each_link_to_supplier(link, dev) {
 		if (!device_link_test(link, DL_FLAG_PM_RUNTIME))
 			continue;
 
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1903,8 +1903,7 @@
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_srcu(link, &dev->links.suppliers, c_node,
-				 device_links_read_lock_held())
+	dev_for_each_link_to_supplier(link, dev)
 		if (device_link_test(link, DL_FLAG_PM_RUNTIME)) {
 			link->supplier_preactivated = true;
 			pm_runtime_get_sync(link->supplier);