From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Date: Wed, 21 Oct 2020 19:12:15 +0000 (+0200)
Subject: PM: runtime: Drop runtime PM references to supplier on link removal
X-Git-Tag: v5.9.7~6
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4163d25d6e9852806c9c86776d2db7fb0c3ee8ca;p=thirdparty%2Fkernel%2Fstable.git

PM: runtime: Drop runtime PM references to supplier on link removal

commit e0e398e204634db8fb71bd89cf2f6e3e5bd09b51 upstream.

While removing a device link, drop the supplier device's runtime PM
usage counter as many times as needed to drop all of the runtime PM
references to it from the consumer in addition to dropping the
consumer's link count.

Fixes: baa8809f6097 ("PM / runtime: Optimize the use of device links")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: 5.1+ <stable@vger.kernel.org> # 5.1+
Tested-by: Xiang Chen <chenxiang66@hisilicon.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 792b92439b77d..91980be5543d3 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -763,8 +763,7 @@ static void __device_link_del(struct kref *kref)
 	dev_dbg(link->consumer, "Dropping the link to %s\n",
 		dev_name(link->supplier));
 
-	if (link->flags & DL_FLAG_PM_RUNTIME)
-		pm_runtime_drop_link(link->consumer);
+	pm_runtime_drop_link(link);
 
 	list_del_rcu(&link->s_node);
 	list_del_rcu(&link->c_node);
@@ -778,8 +777,7 @@ static void __device_link_del(struct kref *kref)
 	dev_info(link->consumer, "Dropping the link to %s\n",
 		 dev_name(link->supplier));
 
-	if (link->flags & DL_FLAG_PM_RUNTIME)
-		pm_runtime_drop_link(link->consumer);
+	pm_runtime_drop_link(link);
 
 	list_del(&link->s_node);
 	list_del(&link->c_node);
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 6f605f7820bb5..6919f7fc226bb 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1729,7 +1729,7 @@ void pm_runtime_new_link(struct device *dev)
 	spin_unlock_irq(&dev->power.lock);
 }
 
-void pm_runtime_drop_link(struct device *dev)
+static void pm_runtime_drop_link_count(struct device *dev)
 {
 	spin_lock_irq(&dev->power.lock);
 	WARN_ON(dev->power.links_count == 0);
@@ -1737,6 +1737,25 @@ void pm_runtime_drop_link(struct device *dev)
 	spin_unlock_irq(&dev->power.lock);
 }
 
+/**
+ * pm_runtime_drop_link - Prepare for device link removal.
+ * @link: Device link going away.
+ *
+ * Drop the link count of the consumer end of @link and decrement the supplier
+ * device's runtime PM usage counter as many times as needed to drop all of the
+ * PM runtime reference to it from the consumer.
+ */
+void pm_runtime_drop_link(struct device_link *link)
+{
+	if (!(link->flags & DL_FLAG_PM_RUNTIME))
+		return;
+
+	pm_runtime_drop_link_count(link->consumer);
+
+	while (refcount_dec_not_one(&link->rpm_active))
+		pm_runtime_put(link->supplier);
+}
+
 static bool pm_runtime_need_not_resume(struct device *dev)
 {
 	return atomic_read(&dev->power.usage_count) <= 1 &&
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index 6245caa18034c..07f2eea1df0aa 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -58,7 +58,7 @@ extern void pm_runtime_clean_up_links(struct device *dev);
 extern void pm_runtime_get_suppliers(struct device *dev);
 extern void pm_runtime_put_suppliers(struct device *dev);
 extern void pm_runtime_new_link(struct device *dev);
-extern void pm_runtime_drop_link(struct device *dev);
+extern void pm_runtime_drop_link(struct device_link *link);
 
 /**
  * pm_runtime_get_if_in_use - Conditionally bump up runtime PM usage counter.
@@ -280,7 +280,7 @@ static inline void pm_runtime_clean_up_links(struct device *dev) {}
 static inline void pm_runtime_get_suppliers(struct device *dev) {}
 static inline void pm_runtime_put_suppliers(struct device *dev) {}
 static inline void pm_runtime_new_link(struct device *dev) {}
-static inline void pm_runtime_drop_link(struct device *dev) {}
+static inline void pm_runtime_drop_link(struct device_link *link) {}
 
 #endif /* !CONFIG_PM */