[PATCH 4/9] platform/x86: lenovo-wmi-{capdata,other}: Only allocate capdata list when necessary

[Rong Zhang]

When no capability data is available, there is no need to allocate
capability data list as it's basically unused except for the
priv->list->count == 0 placeholder.

Therefore, only allocate priv->list when necessary, otherwise its
absence implies the absence of capability data. In this manner,
lenovo-wmi-other can skip registering unavailable functionalities
accordingly. Meanwhile, skip creating the debugfs directory as it
provides nothing when there is no capability data.

Signed-off-by: Rong Zhang <i@xxxxxxxx>
---
 drivers/platform/x86/lenovo/wmi-capdata.c | 43 ++++++++++++++++++++++---------
 drivers/platform/x86/lenovo/wmi-other.c   | 11 +++++---
 2 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/drivers/platform/x86/lenovo/wmi-capdata.c b/drivers/platform/x86/lenovo/wmi-capdata.c
index 0123ec8f7b53..793b5103d533 100644
--- a/drivers/platform/x86/lenovo/wmi-capdata.c
+++ b/drivers/platform/x86/lenovo/wmi-capdata.c
@@ -313,8 +313,8 @@ static const struct component_ops lwmi_cd_component_ops = {
  * @dev: The sub-master capdata basic device.
  *
  * Call component_bind_all to bind the sub-component device to the sub-master
- * device. On success, collect the pointer to the sub-component list and try
- * to call the master callback.
+ * device. On success, collect the pointer (or ERR_PTR(-ENODEV) if it's stubbed)
+ * to the sub-component list and try to call the master callback.
  *
  * Return: 0 on success, or an error code.
  */
@@ -328,7 +328,7 @@ static int lwmi_cd_sub_master_bind(struct device *dev)
 	if (ret)
 		return ret;
 
-	priv->sub_master->sub_component_list = sub_component_list;
+	priv->sub_master->sub_component_list = sub_component_list ?: ERR_PTR(-ENODEV);
 	lwmi_cd_call_master_cb(priv);
 
 	return 0;
@@ -460,6 +460,9 @@ static const struct component_ops lwmi_cd_sub_component_ops = {
 	{											\
 		u8 idx;										\
 												\
+		if (WARN_ON(!list))								\
+			return -EINVAL;								\
+												\
 		guard(mutex)(&list->list_mutex);						\
 		for (idx = 0; idx < list->count; idx++) {					\
 			if (list->_cdxx[idx].id != attribute_id)				\
@@ -571,6 +574,9 @@ DEFINE_SHOW_ATTRIBUTE(lwmi_cd_debugfs);
  */
 static void lwmi_cd_debugfs_add(struct lwmi_cd_priv *priv)
 {
+	if (!priv->list)
+		return;
+
 	priv->debugfs_dir = lwmi_debugfs_create_dir(priv->wdev);
 
 	debugfs_create_file("capdata", 0444, priv->debugfs_dir, priv, &lwmi_cd_debugfs_fops);
@@ -582,6 +588,7 @@ static void lwmi_cd_debugfs_add(struct lwmi_cd_priv *priv)
  */
 static void lwmi_cd_debugfs_remove(struct lwmi_cd_priv *priv)
 {
+	/* Debugfs can handle NULL dir, no need to check. */
 	debugfs_remove_recursive(priv->debugfs_dir);
 	priv->debugfs_dir = NULL;
 }
@@ -645,6 +652,9 @@ static int __lwmi_cd_cache(struct lwmi_cd_priv *priv)
  */
 static int lwmi_cd_cache(struct lwmi_cd_priv *priv)
 {
+	if (!priv->list)
+		return 0;
+
 	if (!priv->initialized)
 		return __lwmi_cd_cache(priv);
 
@@ -707,6 +717,9 @@ static int lwmi_cd_fan_list_alloc_cache(struct lwmi_cd_priv *priv)
 		count = 0;
 	}
 
+	if (!count)
+		return 0;
+
 	list = devm_kzalloc(&priv->wdev->dev, struct_size(list, cd_fan, count), GFP_KERNEL);
 	if (!list)
 		return -ENOMEM;
@@ -742,6 +755,8 @@ static int lwmi_cd_alloc(struct lwmi_cd_priv *priv)
 	int count;
 
 	count = wmidev_instance_count(priv->wdev);
+	if (!count)
+		return 0;
 
 	switch (priv->info->type) {
 	case LENOVO_CAPABILITY_DATA_00:
@@ -884,7 +899,9 @@ static int lwmi_cd_probe(struct wmi_device *wdev, const void *context)
 		enum lwmi_cd_type sub_component_type = LENOVO_FAN_TEST_DATA;
 		struct capdata00 capdata00;
 
-		ret = lwmi_cd00_get_data(priv->list, LWMI_ATTR_ID_FAN_TEST, &capdata00);
+		ret = priv->list
+			? lwmi_cd00_get_data(priv->list, LWMI_ATTR_ID_FAN_TEST, &capdata00)
+			: -ENODATA;
 		if (ret || !(capdata00.supported & LWMI_SUPP_VALID)) {
 			dev_dbg(&wdev->dev, "capdata00 declares no fan test support\n");
 			sub_component_type = CD_TYPE_NONE;
@@ -905,14 +922,16 @@ static int lwmi_cd_probe(struct wmi_device *wdev, const void *context)
 	case LENOVO_CAPABILITY_DATA_01:
 		priv->acpi_nb.notifier_call = lwmi_cd01_notifier_call;
 
-		ret = register_acpi_notifier(&priv->acpi_nb);
-		if (ret)
-			goto out;
+		if (priv->list) {
+			ret = register_acpi_notifier(&priv->acpi_nb);
+			if (ret)
+				goto out;
 
-		ret = devm_add_action_or_reset(&wdev->dev, lwmi_cd01_unregister,
-					       &priv->acpi_nb);
-		if (ret)
-			goto out;
+			ret = devm_add_action_or_reset(&wdev->dev, lwmi_cd01_unregister,
+						       &priv->acpi_nb);
+			if (ret)
+				goto out;
+		}
 
 		ret = component_add(&wdev->dev, &lwmi_cd_component_ops);
 		goto out;
@@ -930,7 +949,7 @@ static int lwmi_cd_probe(struct wmi_device *wdev, const void *context)
 		lwmi_cd_debugfs_add(priv);
 
 		dev_dbg(&wdev->dev, "registered %s with %u items\n",
-			info->name, priv->list->count);
+			info->name, priv->list ? priv->list->count : 0);
 	}
 	return ret;
 }
diff --git a/drivers/platform/x86/lenovo/wmi-other.c b/drivers/platform/x86/lenovo/wmi-other.c
index fbb32bf404f2..e6c8f6bcf050 100644
--- a/drivers/platform/x86/lenovo/wmi-other.c
+++ b/drivers/platform/x86/lenovo/wmi-other.c
@@ -1643,16 +1643,19 @@ static int lwmi_om_master_bind(struct device *dev)
 
 	priv->cd00_list = binder.cd00_list;
 	priv->cd01_list = binder.cd01_list;
-	if (!priv->cd00_list || !priv->cd01_list) {
+	if (!priv->cd00_list && !priv->cd01_list) {
 		component_unbind_all(dev, NULL);
 
 		return -ENODEV;
 	}
 
-	lwmi_om_fan_info_collect_cd00(priv);
-	lwmi_om_psy_ext_init(priv);
+	if (priv->cd00_list) {
+		lwmi_om_fan_info_collect_cd00(priv);
+		lwmi_om_psy_ext_init(priv);
+	}
 
-	lwmi_om_fw_attr_add(priv);
+	if (priv->cd01_list)
+		lwmi_om_fw_attr_add(priv);
 
 	return 0;
 }

-- 
2.55.0