Driver core / debugfs fixes for 5.6-rc5

Here are 4 small driver core / debugfs patches for 5.6-rc3
 
 They are:
 	- debugfs api cleanup now that all callers for
 	  debugfs_create_regset32() have been fixed up.  This was
 	  waiting until after the -rc1 merge as these fixes came in
 	  through different trees
 	- driver core sync state fixes based on reports of minor issues
 	  found in the feature
 
 All of these have been in linux-next with no reported issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-5.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core and debugfs fixes from Greg KH:
 "Here are four small driver core / debugfs patches for 5.6-rc3:

   - debugfs api cleanup now that all debugfs_create_regset32() callers
     have been fixed up. This was waiting until after the -rc1 merge as
     these fixes came in through different trees

   - driver core sync state fixes based on reports of minor issues found
     in the feature

  All of these have been in linux-next with no reported issues"

* tag 'driver-core-5.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  driver core: Skip unnecessary work when device doesn't have sync_state()
  driver core: Add dev_has_sync_state()
  driver core: Call sync_state() even if supplier has no consumers
  debugfs: remove return value of debugfs_create_regset32()

Documentation/filesystems/debugfs.txt

@@ -164,9 +164,9 @@ file.
 	void __iomem *base;
     };
 
-    struct dentry *debugfs_create_regset32(const char *name, umode_t mode,
-				     struct dentry *parent,
-				     struct debugfs_regset32 *regset);
+    debugfs_create_regset32(const char *name, umode_t mode,
+			    struct dentry *parent,
+			    struct debugfs_regset32 *regset);
 
     void debugfs_print_regs32(struct seq_file *s, struct debugfs_reg32 *regs,
 			 int nregs, void __iomem *base, char *prefix);

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;
 
@@ -745,25 +747,31 @@ 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 +809,7 @@ 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)
@@ -813,7 +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(sup))
 		list_add_tail(&sup->links.defer_sync, &deferred_sync);
 }
 
@@ -865,6 +873,11 @@ 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 +896,7 @@ 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)

fs/debugfs/file.c

@@ -1090,21 +1090,12 @@ static const struct file_operations fops_regset32 = {
  * This function creates a file in debugfs with the given name that reports
  * the names and values of a set of 32-bit registers. If the @mode variable
  * is so set it can be read from. Writing is not supported.
- *
- * This function will return a pointer to a dentry if it succeeds.  This
- * pointer must be passed to the debugfs_remove() function when the file is
- * to be removed (no automatic cleanup happens if your module is unloaded,
- * you are responsible here.)  If an error occurs, ERR_PTR(-ERROR) will be
- * returned.
- *
- * If debugfs is not enabled in the kernel, the value ERR_PTR(-ENODEV) will
- * be returned.
  */
-struct dentry *debugfs_create_regset32(const char *name, umode_t mode,
-				       struct dentry *parent,
-				       struct debugfs_regset32 *regset)
+void debugfs_create_regset32(const char *name, umode_t mode,
+			     struct dentry *parent,
+			     struct debugfs_regset32 *regset)
 {
-	return debugfs_create_file(name, mode, parent, regset, &fops_regset32);
+	debugfs_create_file(name, mode, parent, regset, &fops_regset32);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_regset32);
 

include/linux/debugfs.h

@@ -127,9 +127,9 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode,
 				  struct dentry *parent,
 				  struct debugfs_blob_wrapper *blob);
 
-struct dentry *debugfs_create_regset32(const char *name, umode_t mode,
-				     struct dentry *parent,
-				     struct debugfs_regset32 *regset);
+void debugfs_create_regset32(const char *name, umode_t mode,
+			     struct dentry *parent,
+			     struct debugfs_regset32 *regset);
 
 void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
 			  int nregs, void __iomem *base, char *prefix);
@@ -304,11 +304,10 @@ static inline struct dentry *debugfs_create_blob(const char *name, umode_t mode,
 	return ERR_PTR(-ENODEV);
 }
 
-static inline struct dentry *debugfs_create_regset32(const char *name,
-				   umode_t mode, struct dentry *parent,
-				   struct debugfs_regset32 *regset)
+static inline void debugfs_create_regset32(const char *name, umode_t mode,
+					   struct dentry *parent,
+					   struct debugfs_regset32 *regset)
 {
-	return ERR_PTR(-ENODEV);
 }
 
 static inline void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,

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
  */