1 files changed, 202 insertions, 25 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index dbb0f9130f42..0cad34f1eede 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -64,12 +64,12 @@ static inline void device_links_write_unlock(void)
 	mutex_unlock(&device_links_lock);
 }
 
-int device_links_read_lock(void)
+int device_links_read_lock(void) __acquires(&device_links_srcu)
 {
 	return srcu_read_lock(&device_links_srcu);
 }
 
-void device_links_read_unlock(int idx)
+void device_links_read_unlock(int idx) __releases(&device_links_srcu)
 {
 	srcu_read_unlock(&device_links_srcu, idx);
 }
@@ -365,6 +365,7 @@ struct device_link *device_link_add(struct device *consumer,
 				link->flags |= DL_FLAG_STATELESS;
 				goto reorder;
 			} else {
+				link->flags |= DL_FLAG_STATELESS;
 				goto out;
 			}
 		}
@@ -433,12 +434,16 @@ struct device_link *device_link_add(struct device *consumer,
 	    flags & DL_FLAG_PM_RUNTIME)
 		pm_runtime_resume(supplier);
 
+	list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
+	list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
+
 	if (flags & DL_FLAG_SYNC_STATE_ONLY) {
 		dev_dbg(consumer,
 			"Linked as a sync state only consumer to %s\n",
 			dev_name(supplier));
 		goto out;
 	}
+
 reorder:
 	/*
 	 * Move the consumer and all of the devices depending on it to the end
@@ -449,12 +454,9 @@ reorder:
 	 */
 	device_reorder_to_tail(consumer, NULL);
 
-	list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
-	list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
-
 	dev_dbg(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
 
- out:
+out:
 	device_pm_unlock();
 	device_links_write_unlock();
 
@@ -523,9 +525,13 @@ static void device_link_add_missing_supplier_links(void)
 
 	mutex_lock(&wfs_lock);
 	list_for_each_entry_safe(dev, tmp, &wait_for_suppliers,
-				 links.needs_suppliers)
-		if (!fwnode_call_int_op(dev->fwnode, add_links, dev))
+				 links.needs_suppliers) {
+		int ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
+		if (!ret)
 			list_del_init(&dev->links.needs_suppliers);
+		else if (ret != -ENODEV)
+			dev->links.need_for_probe = false;
+	}
 	mutex_unlock(&wfs_lock);
 }
 
@@ -825,6 +831,13 @@ static void __device_links_supplier_defer_sync(struct device *sup)
 		list_add_tail(&sup->links.defer_sync, &deferred_sync);
 }
 
+static void device_link_drop_managed(struct device_link *link)
+{
+	link->flags &= ~DL_FLAG_MANAGED;
+	WRITE_ONCE(link->status, DL_STATE_NONE);
+	kref_put(&link->kref, __device_link_del);
+}
+
 /**
  * device_links_driver_bound - Update device links after probing its driver.
  * @dev: Device to update the links for.
@@ -838,7 +851,7 @@ static void __device_links_supplier_defer_sync(struct device *sup)
  */
 void device_links_driver_bound(struct device *dev)
 {
-	struct device_link *link;
+	struct device_link *link, *ln;
 	LIST_HEAD(sync_list);
 
 	/*
@@ -878,18 +891,35 @@ void device_links_driver_bound(struct device *dev)
 	else
 		__device_links_queue_sync_state(dev, &sync_list);
 
-	list_for_each_entry(link, &dev->links.suppliers, c_node) {
+	list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
+		struct device *supplier;
+
 		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
-		WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
-		WRITE_ONCE(link->status, DL_STATE_ACTIVE);
+		supplier = link->supplier;
+		if (link->flags & DL_FLAG_SYNC_STATE_ONLY) {
+			/*
+			 * When DL_FLAG_SYNC_STATE_ONLY is set, it means no
+			 * other DL_MANAGED_LINK_FLAGS have been set. So, it's
+			 * save to drop the managed link completely.
+			 */
+			device_link_drop_managed(link);
+		} else {
+			WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
+			WRITE_ONCE(link->status, DL_STATE_ACTIVE);
+		}
 
+		/*
+		 * This needs to be done even for the deleted
+		 * DL_FLAG_SYNC_STATE_ONLY device link in case it was the last
+		 * device link that was preventing the supplier from getting a
+		 * sync_state() call.
+		 */
 		if (defer_sync_state_count)
-			__device_links_supplier_defer_sync(link->supplier);
+			__device_links_supplier_defer_sync(supplier);
 		else
-			__device_links_queue_sync_state(link->supplier,
-							&sync_list);
+			__device_links_queue_sync_state(supplier, &sync_list);
 	}
 
 	dev->links.status = DL_DEV_DRIVER_BOUND;
@@ -899,13 +929,6 @@ void device_links_driver_bound(struct device *dev)
 	device_links_flush_sync_list(&sync_list, dev);
 }
 
-static void device_link_drop_managed(struct device_link *link)
-{
-	link->flags &= ~DL_FLAG_MANAGED;
-	WRITE_ONCE(link->status, DL_STATE_NONE);
-	kref_put(&link->kref, __device_link_del);
-}
-
 /**
  * __device_links_no_driver - Update links of a device without a driver.
  * @dev: Device without a drvier.
@@ -2341,6 +2364,36 @@ static int device_private_init(struct device *dev)
 	return 0;
 }
 
+static u32 fw_devlink_flags;
+static int __init fw_devlink_setup(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+
+	if (strcmp(arg, "off") == 0) {
+		fw_devlink_flags = 0;
+	} else if (strcmp(arg, "permissive") == 0) {
+		fw_devlink_flags = DL_FLAG_SYNC_STATE_ONLY;
+	} else if (strcmp(arg, "on") == 0) {
+		fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER;
+	} else if (strcmp(arg, "rpm") == 0) {
+		fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER |
+				   DL_FLAG_PM_RUNTIME;
+	}
+	return 0;
+}
+early_param("fw_devlink", fw_devlink_setup);
+
+u32 fw_devlink_get_flags(void)
+{
+	return fw_devlink_flags;
+}
+
+static bool fw_devlink_is_permissive(void)
+{
+	return fw_devlink_flags == DL_FLAG_SYNC_STATE_ONLY;
+}
+
 /**
  * device_add - add device to device hierarchy.
  * @dev: device.
@@ -2375,6 +2428,7 @@ int device_add(struct device *dev)
 	struct class_interface *class_intf;
 	int error = -EINVAL, fw_ret;
 	struct kobject *glue_dir = NULL;
+	bool is_fwnode_dev = false;
 
 	dev = get_device(dev);
 	if (!dev)
@@ -2472,8 +2526,10 @@ int device_add(struct device *dev)
 
 	kobject_uevent(&dev->kobj, KOBJ_ADD);
 
-	if (dev->fwnode && !dev->fwnode->dev)
+	if (dev->fwnode && !dev->fwnode->dev) {
 		dev->fwnode->dev = dev;
+		is_fwnode_dev = true;
+	}
 
 	/*
 	 * Check if any of the other devices (consumers) have been waiting for
@@ -2489,9 +2545,10 @@ int device_add(struct device *dev)
 	 */
 	device_link_add_missing_supplier_links();
 
-	if (fwnode_has_op(dev->fwnode, add_links)) {
+	if (fw_devlink_flags && is_fwnode_dev &&
+	    fwnode_has_op(dev->fwnode, add_links)) {
 		fw_ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
-		if (fw_ret == -ENODEV)
+		if (fw_ret == -ENODEV && !fw_devlink_is_permissive())
 			device_link_wait_for_mandatory_supplier(dev);
 		else if (fw_ret)
 			device_link_wait_for_optional_supplier(dev);
@@ -3471,6 +3528,126 @@ out:
 }
 EXPORT_SYMBOL_GPL(device_move);
 
+static int device_attrs_change_owner(struct device *dev, kuid_t kuid,
+				     kgid_t kgid)
+{
+	struct kobject *kobj = &dev->kobj;
+	struct class *class = dev->class;
+	const struct device_type *type = dev->type;
+	int error;
+
+	if (class) {
+		/*
+		 * Change the device groups of the device class for @dev to
+		 * @kuid/@kgid.
+		 */
+		error = sysfs_groups_change_owner(kobj, class->dev_groups, kuid,
+						  kgid);
+		if (error)
+			return error;
+	}
+
+	if (type) {
+		/*
+		 * Change the device groups of the device type for @dev to
+		 * @kuid/@kgid.
+		 */
+		error = sysfs_groups_change_owner(kobj, type->groups, kuid,
+						  kgid);
+		if (error)
+			return error;
+	}
+
+	/* Change the device groups of @dev to @kuid/@kgid. */
+	error = sysfs_groups_change_owner(kobj, dev->groups, kuid, kgid);
+	if (error)
+		return error;
+
+	if (device_supports_offline(dev) && !dev->offline_disabled) {
+		/* Change online device attributes of @dev to @kuid/@kgid. */
+		error = sysfs_file_change_owner(kobj, dev_attr_online.attr.name,
+						kuid, kgid);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+/**
+ * device_change_owner - change the owner of an existing device.
+ * @dev: device.
+ * @kuid: new owner's kuid
+ * @kgid: new owner's kgid
+ *
+ * This changes the owner of @dev and its corresponding sysfs entries to
+ * @kuid/@kgid. This function closely mirrors how @dev was added via driver
+ * core.
+ *
+ * Returns 0 on success or error code on failure.
+ */
+int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
+{
+	int error;
+	struct kobject *kobj = &dev->kobj;
+
+	dev = get_device(dev);
+	if (!dev)
+		return -EINVAL;
+
+	/*
+	 * Change the kobject and the default attributes and groups of the
+	 * ktype associated with it to @kuid/@kgid.
+	 */
+	error = sysfs_change_owner(kobj, kuid, kgid);
+	if (error)
+		goto out;
+
+	/*
+	 * Change the uevent file for @dev to the new owner. The uevent file
+	 * was created in a separate step when @dev got added and we mirror
+	 * that step here.
+	 */
+	error = sysfs_file_change_owner(kobj, dev_attr_uevent.attr.name, kuid,
+					kgid);
+	if (error)
+		goto out;
+
+	/*
+	 * Change the device groups, the device groups associated with the
+	 * device class, and the groups associated with the device type of @dev
+	 * to @kuid/@kgid.
+	 */
+	error = device_attrs_change_owner(dev, kuid, kgid);
+	if (error)
+		goto out;
+
+	error = dpm_sysfs_change_owner(dev, kuid, kgid);
+	if (error)
+		goto out;
+
+#ifdef CONFIG_BLOCK
+	if (sysfs_deprecated && dev->class == &block_class)
+		goto out;
+#endif
+
+	/*
+	 * Change the owner of the symlink located in the class directory of
+	 * the device class associated with @dev which points to the actual
+	 * directory entry for @dev to @kuid/@kgid. This ensures that the
+	 * symlink shows the same permissions as its target.
+	 */
+	error = sysfs_link_change_owner(&dev->class->p->subsys.kobj, &dev->kobj,
+					dev_name(dev), kuid, kgid);
+	if (error)
+		goto out;
+
+out:
+	put_device(dev);
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_change_owner);
+
 /**
  * device_shutdown - call ->shutdown() on each device to shutdown.
  */