[PATCH v1] PM-runtime: Check supplier_preactivated before release supplier

[peter.wang]

From: Peter Wang <peter.wang@xxxxxxxxxxxx>

With divice link of DL_FLAG_PM_RUNTIME, if consumer call pm_runtime_get_suppliers
to prevent supplier enter suspend, pm_runtime_release_supplier should
check supplier_preactivated before let supplier enter suspend.

If the link is drop or release, bypass check supplier_preactivated.

Signed-off-by: Peter Wang <peter.wang@xxxxxxxxxxxx>
---
 drivers/base/core.c          |  2 +-
 drivers/base/power/runtime.c | 15 ++++++++++++---
 include/linux/pm_runtime.h   |  5 +++--
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 7cd789c4985d..3b9cc559928f 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -486,7 +486,7 @@ static void device_link_release_fn(struct work_struct *work)
 	/* Ensure that all references to the link object have been dropped. */
 	device_link_synchronize_removal();
 
-	pm_runtime_release_supplier(link, true);
+	pm_runtime_release_supplier(link, true, true);
 
 	put_device(link->consumer);
 	put_device(link->supplier);
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 676dc72d912d..3c4f425937a1 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -314,10 +314,19 @@ static int rpm_get_suppliers(struct device *dev)
  * and if @check_idle is set, check if that device is idle (and so it can be
  * suspended).
  */
-void pm_runtime_release_supplier(struct device_link *link, bool check_idle)
+void pm_runtime_release_supplier(struct device_link *link, bool check_idle,
+	bool drop)
 {
 	struct device *supplier = link->supplier;
 
+	/*
+	 * When consumer hold supplier, supplier cannot enter suspend.
+	 * Driect release supplier and let supplier enter suspend is not allow.
+	 * Unless the link is drop, direct relsease supplier should be okay.
+	 */
+	if (link->supplier_preactivated && !drop)
+		return;
+
 	/*
 	 * The additional power.usage_count check is a safety net in case
 	 * the rpm_active refcount becomes saturated, in which case
@@ -338,7 +347,7 @@ static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)
 
 	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 				device_links_read_lock_held())
-		pm_runtime_release_supplier(link, try_to_suspend);
+		pm_runtime_release_supplier(link, try_to_suspend, false);
 }
 
 static void rpm_put_suppliers(struct device *dev)
@@ -1838,7 +1847,7 @@ void pm_runtime_drop_link(struct device_link *link)
 		return;
 
 	pm_runtime_drop_link_count(link->consumer);
-	pm_runtime_release_supplier(link, true);
+	pm_runtime_release_supplier(link, true, true);
 }
 
 static bool pm_runtime_need_not_resume(struct device *dev)
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index 9e4d056967c6..354ffb1eaec0 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -88,7 +88,8 @@ 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_link *link);
-extern void pm_runtime_release_supplier(struct device_link *link, bool check_idle);
+extern void pm_runtime_release_supplier(struct device_link *link,
+	bool check_idle, bool drop);
 
 extern int devm_pm_runtime_enable(struct device *dev);
 
@@ -315,7 +316,7 @@ 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_link *link) {}
 static inline void pm_runtime_release_supplier(struct device_link *link,
-					       bool check_idle) {}
+					       bool check_idle, bool drop) {}
 
 #endif /* !CONFIG_PM */
 
-- 
2.18.0