Merge tag 'driver-core-5.8-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core into master

Pull driver core fixes from Greg KH:
 "Here are 3 driver core fixes for 5.8-rc6.

  They resolve some issues found with the deferred probe code for some
  types of devices on some embedded systems. They have been tested a
  bunch and have been in linux-next for a while with no reported issues"

* tag 'driver-core-5.8-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  driver core: Avoid deferred probe due to fw_devlink_pause/resume()
  driver core: Rename dev_links_info.defer_sync to defer_hook
  driver core: Don't do deferred probe in parallel with kernel_init thread

Author: torvalds

drivers/base/base.h

@@ -153,7 +153,6 @@ extern char *make_class_name(const char *name, struct kobject *kobj);
 extern int devres_release_all(struct device *dev);
 extern void device_block_probing(void);
 extern void device_unblock_probing(void);
-extern void driver_deferred_probe_force_trigger(void);
 
 /* /sys/devices directory */
 extern struct kset *devices_kset;

drivers/base/core.c

@@ -50,6 +50,7 @@ static DEFINE_MUTEX(wfs_lock);
 static LIST_HEAD(deferred_sync);
 static unsigned int defer_sync_state_count = 1;
 static unsigned int defer_fw_devlink_count;
+static LIST_HEAD(deferred_fw_devlink);
 static DEFINE_MUTEX(defer_fw_devlink_lock);
 static bool fw_devlink_is_permissive(void);
 
@@ -754,11 +755,11 @@ static void __device_links_queue_sync_state(struct device *dev,
 	 */
 	dev->state_synced = true;
 
-	if (WARN_ON(!list_empty(&dev->links.defer_sync)))
+	if (WARN_ON(!list_empty(&dev->links.defer_hook)))
 		return;
 
 	get_device(dev);
-	list_add_tail(&dev->links.defer_sync, list);
+	list_add_tail(&dev->links.defer_hook, list);
 }
 
 /**
@@ -776,8 +777,8 @@ static void device_links_flush_sync_list(struct list_head *list,
 {
 	struct device *dev, *tmp;
 
-	list_for_each_entry_safe(dev, tmp, list, links.defer_sync) {
-		list_del_init(&dev->links.defer_sync);
+	list_for_each_entry_safe(dev, tmp, list, links.defer_hook) {
+		list_del_init(&dev->links.defer_hook);
 
 		if (dev != dont_lock_dev)
 			device_lock(dev);
@@ -815,12 +816,12 @@ void device_links_supplier_sync_state_resume(void)
 	if (defer_sync_state_count)
 		goto out;
 
-	list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_sync) {
+	list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_hook) {
 		/*
 		 * Delete from deferred_sync list before queuing it to
-		 * sync_list because defer_sync is used for both lists.
+		 * sync_list because defer_hook is used for both lists.
 		 */
-		list_del_init(&dev->links.defer_sync);
+		list_del_init(&dev->links.defer_hook);
 		__device_links_queue_sync_state(dev, &sync_list);
 	}
 out:
@@ -838,8 +839,8 @@ late_initcall(sync_state_resume_initcall);
 
 static void __device_links_supplier_defer_sync(struct device *sup)
 {
-	if (list_empty(&sup->links.defer_sync) && dev_has_sync_state(sup))
-		list_add_tail(&sup->links.defer_sync, &deferred_sync);
+	if (list_empty(&sup->links.defer_hook) && dev_has_sync_state(sup))
+		list_add_tail(&sup->links.defer_hook, &deferred_sync);
 }
 
 static void device_link_drop_managed(struct device_link *link)
@@ -1052,7 +1053,7 @@ void device_links_driver_cleanup(struct device *dev)
 		WRITE_ONCE(link->status, DL_STATE_DORMANT);
 	}
 
-	list_del_init(&dev->links.defer_sync);
+	list_del_init(&dev->links.defer_hook);
 	__device_links_no_driver(dev);
 
 	device_links_write_unlock();
@@ -1244,6 +1245,12 @@ static void fw_devlink_link_device(struct device *dev)
 			fw_ret = -EAGAIN;
 	} else {
 		fw_ret = -ENODEV;
+		/*
+		 * defer_hook is not used to add device to deferred_sync list
+		 * until device is bound. Since deferred fw devlink also blocks
+		 * probing, same list hook can be used for deferred_fw_devlink.
+		 */
+		list_add_tail(&dev->links.defer_hook, &deferred_fw_devlink);
 	}
 
 	if (fw_ret == -ENODEV)
@@ -1312,6 +1319,9 @@ void fw_devlink_pause(void)
  */
 void fw_devlink_resume(void)
 {
+	struct device *dev, *tmp;
+	LIST_HEAD(probe_list);
+
 	mutex_lock(&defer_fw_devlink_lock);
 	if (!defer_fw_devlink_count) {
 		WARN(true, "Unmatched fw_devlink pause/resume!");
@@ -1323,9 +1333,19 @@ void fw_devlink_resume(void)
 		goto out;
 
 	device_link_add_missing_supplier_links();
-	driver_deferred_probe_force_trigger();
+	list_splice_tail_init(&deferred_fw_devlink, &probe_list);
 out:
 	mutex_unlock(&defer_fw_devlink_lock);
+
+	/*
+	 * bus_probe_device() can cause new devices to get added and they'll
+	 * try to grab defer_fw_devlink_lock. So, this needs to be done outside
+	 * the defer_fw_devlink_lock.
+	 */
+	list_for_each_entry_safe(dev, tmp, &probe_list, links.defer_hook) {
+		list_del_init(&dev->links.defer_hook);
+		bus_probe_device(dev);
+	}
 }
 /* Device links support end. */
 
@@ -2172,7 +2192,7 @@ void device_initialize(struct device *dev)
 	INIT_LIST_HEAD(&dev->links.consumers);
 	INIT_LIST_HEAD(&dev->links.suppliers);
 	INIT_LIST_HEAD(&dev->links.needs_suppliers);
-	INIT_LIST_HEAD(&dev->links.defer_sync);
+	INIT_LIST_HEAD(&dev->links.defer_hook);
 	dev->links.status = DL_DEV_NO_DRIVER;
 }
 EXPORT_SYMBOL_GPL(device_initialize);

drivers/base/dd.c

@@ -164,11 +164,6 @@ static void driver_deferred_probe_trigger(void)
 	if (!driver_deferred_probe_enable)
 		return;
 
-	driver_deferred_probe_force_trigger();
-}
-
-void driver_deferred_probe_force_trigger(void)
-{
 	/*
 	 * A successful probe means that all the devices in the pending list
 	 * should be triggered to be reprobed.  Move all the deferred devices

include/linux/device.h

@@ -433,7 +433,8 @@ enum dl_dev_state {
  * @suppliers: List of links to supplier devices.
  * @consumers: List of links to consumer devices.
  * @needs_suppliers: Hook to global list of devices waiting for suppliers.
- * @defer_sync: Hook to global list of devices that have deferred sync_state.
+ * @defer_hook: Hook to global list of devices that have deferred sync_state or
+ *		deferred fw_devlink.
  * @need_for_probe: If needs_suppliers is on a list, this indicates if the
  *		    suppliers are needed for probe or not.
  * @status: Driver status information.
@@ -442,7 +443,7 @@ struct dev_links_info {
 	struct list_head suppliers;
 	struct list_head consumers;
 	struct list_head needs_suppliers;
-	struct list_head defer_sync;
+	struct list_head defer_hook;
 	bool need_for_probe;
 	enum dl_dev_state status;
 };