linux-kernel - [PATCH v1 3/5] PM: sleep: Add helper functions to loop through superior/subordinate devs

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Message-Id: <20241114220921.2529905-4-saravanak@google.com>
Date: Thu, 14 Nov 2024 14:09:17 -0800
From: Saravana Kannan <saravanak@...gle.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>, Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Ingo Molnar <mingo@...hat.com>, 
	Peter Zijlstra <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>, 
	Vincent Guittot <vincent.guittot@...aro.org>, Dietmar Eggemann <dietmar.eggemann@....com>, 
	Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, 
	Valentin Schneider <vschneid@...hat.com>
Cc: Saravana Kannan <saravanak@...gle.com>, Geert Uytterhoeven <geert@...ux-m68k.org>, 
	Marek Vasut <marex@...x.de>, Bird@...gle.com, Tim <Tim.Bird@...y.com>, 
	kernel-team@...roid.com, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: [PATCH v1 3/5] PM: sleep: Add helper functions to loop through
 superior/subordinate devs

We have a lot of code that does or will loop through superior/subordinate
devices and take action on them. Refactor the code to pull out the common
"loop through" functionality into helper functions to avoid repeating the
logic.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/base/power/main.c | 70 ++++++++++++++++++++++-----------------
 1 file changed, 40 insertions(+), 30 deletions(-)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 9b9b6088e56a..aa1470ef6ac0 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -247,15 +247,22 @@ static int dpm_wait_fn(struct device *dev, void *async_ptr)
 	return 0;
 }
 
-static void dpm_wait_for_children(struct device *dev, bool async)
-{
-       device_for_each_child(dev, &async, dpm_wait_fn);
-}
-
-static void dpm_wait_for_suppliers(struct device *dev, bool async)
+static int dpm_for_each_superior(struct device *dev, void *data,
+				 int (*fn)(struct device *dev, void *data))
 {
+	struct device *parent;
+	int ret = 0, idx;
 	struct device_link *link;
-	int idx;
+
+	if (!dev)
+		return 0;
+
+	parent = get_device(dev->parent);
+	if (parent)
+		ret = fn(parent, data);
+	put_device(parent);
+	if (ret)
+		return ret;
 
 	idx = device_links_read_lock();
 
@@ -267,29 +274,20 @@ static void dpm_wait_for_suppliers(struct device *dev, bool async)
 	 * walking.
 	 */
 	list_for_each_entry_rcu_locked(link, &dev->links.suppliers, c_node)
-		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
-			dpm_wait(link->supplier, async);
+		if (READ_ONCE(link->status) != DL_STATE_DORMANT) {
+			ret = fn(link->supplier, data);
+			if (ret)
+				break;
+		}
 
 	device_links_read_unlock(idx);
+
+	return ret;
 }
 
 static bool dpm_wait_for_superior(struct device *dev, bool async)
 {
-	struct device *parent;
-
-	/*
-	 * If the device is resumed asynchronously and the parent's callback
-	 * deletes both the device and the parent itself, the parent object may
-	 * be freed while this function is running, so avoid that by reference
-	 * counting the parent once more unless the device has been deleted
-	 * already (in which case return right away).
-	 */
-	parent = get_device(dev->parent);
-	if (device_pm_initialized(dev))
-		dpm_wait(parent, async);
-	put_device(parent);
-
-	dpm_wait_for_suppliers(dev, async);
+	dpm_for_each_superior(dev, &async, dpm_wait_fn);
 
 	/*
 	 * If the parent's callback has deleted the device, attempting to resume
@@ -298,10 +296,18 @@ static bool dpm_wait_for_superior(struct device *dev, bool async)
 	return device_pm_initialized(dev);
 }
 
-static void dpm_wait_for_consumers(struct device *dev, bool async)
+static int dpm_for_each_subordinate(struct device *dev, void *data,
+				    int (*fn)(struct device *dev, void *data))
 {
+	int ret, idx;
 	struct device_link *link;
-	int idx;
+
+	if (!dev)
+		return 0;
+
+	ret = device_for_each_child(dev, data, fn);
+	if (ret)
+		return ret;
 
 	idx = device_links_read_lock();
 
@@ -315,16 +321,20 @@ static void dpm_wait_for_consumers(struct device *dev, bool async)
 	 * unregistration).
 	 */
 	list_for_each_entry_rcu_locked(link, &dev->links.consumers, s_node)
-		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
-			dpm_wait(link->consumer, async);
+		if (READ_ONCE(link->status) != DL_STATE_DORMANT) {
+			ret = fn(link->consumer, data);
+			if (ret)
+				break;
+		}
 
 	device_links_read_unlock(idx);
+
+	return ret;
 }
 
 static void dpm_wait_for_subordinate(struct device *dev, bool async)
 {
-	dpm_wait_for_children(dev, async);
-	dpm_wait_for_consumers(dev, async);
+	dpm_for_each_subordinate(dev, &async, dpm_wait_fn);
 }
 
 /**
-- 
2.47.0.338.g60cca15819-goog