[PATCH v1 0/3] driver core: sync state fixups

[PATCH v1 0/3] driver core: sync state fixups

[Saravana Kannan]

Patch 1/3 fixes a bug where sync_state() might not be called when it
should be. Patches 2/3 and 3/3 are just minor fix ups that I'm grouping
together. Not much to say here.

-Saravana

Saravana Kannan (3):
  driver core: Call sync_state() even if supplier has no consumers
  driver core: Add dev_has_sync_state()
  driver core: Skip unnecessary work when device doesn't have
    sync_state()

 drivers/base/core.c    | 27 ++++++++++++++++++++-------
 include/linux/device.h | 11 +++++++++++
 2 files changed, 31 insertions(+), 7 deletions(-)

-- 
2.25.0.265.gbab2e86ba0-goog

[PATCH v1 1/3] driver core: Call sync_state() even if supplier has no consumers

[Saravana Kannan]

The initial patch that added sync_state() support didn't handle the case
where a supplier has no consumers. This was because when a device is
successfully bound with a driver, only its suppliers were checked to see
if they are eligible to get a sync_state(). This is not sufficient for
devices that have no consumers but still need to do device state clean
up. So fix this.

Fixes: fc5a251d0fd7ca90 (driver core: Add sync_state driver/bus callback)
Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/base/core.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 42a672456432..3306d5ae92a6 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -745,25 +745,31 @@ static void __device_links_queue_sync_state(struct device *dev,
 /**
  * device_links_flush_sync_list - Call sync_state() on a list of devices
  * @list: List of devices to call sync_state() on
+ * @dont_lock_dev: Device for which lock is already held by the caller
  *
  * Calls sync_state() on all the devices that have been queued for it. This
- * function is used in conjunction with __device_links_queue_sync_state().
+ * function is used in conjunction with __device_links_queue_sync_state(). The
+ * @dont_lock_dev parameter is useful when this function is called from a
+ * context where a device lock is already held.
  */
-static void device_links_flush_sync_list(struct list_head *list)
+static void device_links_flush_sync_list(struct list_head *list,
+					 struct device *dont_lock_dev)
 {
 	struct device *dev, *tmp;
 
 	list_for_each_entry_safe(dev, tmp, list, links.defer_sync) {
 		list_del_init(&dev->links.defer_sync);
 
-		device_lock(dev);
+		if (dev != dont_lock_dev)
+			device_lock(dev);
 
 		if (dev->bus->sync_state)
 			dev->bus->sync_state(dev);
 		else if (dev->driver && dev->driver->sync_state)
 			dev->driver->sync_state(dev);
 
-		device_unlock(dev);
+		if (dev != dont_lock_dev)
+			device_unlock(dev);
 
 		put_device(dev);
 	}
@@ -801,7 +807,7 @@ void device_links_supplier_sync_state_resume(void)
 out:
 	device_links_write_unlock();
 
-	device_links_flush_sync_list(&sync_list);
+	device_links_flush_sync_list(&sync_list, NULL);
 }
 
 static int sync_state_resume_initcall(void)
@@ -865,6 +871,11 @@ void device_links_driver_bound(struct device *dev)
 			driver_deferred_probe_add(link->consumer);
 	}
 
+	if (defer_sync_state_count)
+		__device_links_supplier_defer_sync(dev);
+	else
+		__device_links_queue_sync_state(dev, &sync_list);
+
 	list_for_each_entry(link, &dev->links.suppliers, c_node) {
 		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
@@ -883,7 +894,7 @@ void device_links_driver_bound(struct device *dev)
 
 	device_links_write_unlock();
 
-	device_links_flush_sync_list(&sync_list);
+	device_links_flush_sync_list(&sync_list, dev);
 }
 
 static void device_link_drop_managed(struct device_link *link)
-- 
2.25.0.265.gbab2e86ba0-goog

[PATCH v1 2/3] driver core: Add dev_has_sync_state()

[Saravana Kannan]

Add an API to check if a device has sync_state support in its driver or
bus.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 include/linux/device.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/device.h b/include/linux/device.h
index 0cd7c647c16c..fa04dfd22bbc 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -798,6 +798,17 @@ static inline struct device_node *dev_of_node(struct device *dev)
 	return dev->of_node;
 }
 
+static inline bool dev_has_sync_state(struct device *dev)
+{
+	if (!dev)
+		return false;
+	if (dev->driver && dev->driver->sync_state)
+		return true;
+	if (dev->bus && dev->bus->sync_state)
+		return true;
+	return false;
+}
+
 /*
  * High level routines for use by the bus drivers
  */
-- 
2.25.0.265.gbab2e86ba0-goog

[PATCH v1 3/3] driver core: Skip unnecessary work when device doesn't have sync_state()

[Saravana Kannan]

A bunch of busy work is done for devices that don't have sync_state()
support. Stop doing the busy work.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/base/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 3306d5ae92a6..1ecd69d26837 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -718,6 +718,8 @@ static void __device_links_queue_sync_state(struct device *dev,
 {
 	struct device_link *link;
 
+	if (!dev_has_sync_state(dev))
+		return;
 	if (dev->state_synced)
 		return;
 
@@ -819,7 +821,7 @@ late_initcall(sync_state_resume_initcall);
 
 static void __device_links_supplier_defer_sync(struct device *sup)
 {
-	if (list_empty(&sup->links.defer_sync))
+	if (list_empty(&sup->links.defer_sync) && dev_has_sync_state(dev))
 		list_add_tail(&sup->links.defer_sync, &deferred_sync);
 }
 
-- 
2.25.0.265.gbab2e86ba0-goog