configfs: switch ->default groups to a linked list

Replace the current NULL-terminated array of default groups with a linked
list.  This gets rid of lots of nasty code to size and/or dynamically
allocate the array.

While we're at it also provide a conveniant helper to remove the default
groups.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felipe Balbi <balbi@kernel.org>		[drivers/usb/gadget]
Acked-by: Joel Becker <jlbec@evilplan.org>
Acked-by: Nicholas Bellinger <nab@linux-iscsi.org>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>

4 files changed, 97 insertions, 148 deletions

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 590c449..2f8081f 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -49,7 +49,6 @@ struct gadget_info {
 	struct config_group configs_group;
 	struct config_group strings_group;
 	struct config_group os_desc_group;
-	struct config_group *default_groups[5];
 
 	struct mutex lock;
 	struct usb_gadget_strings *gstrings[MAX_USB_STRING_LANGS + 1];
@@ -71,7 +70,6 @@ static inline struct gadget_info *to_gadget_info(struct config_item *item)
 struct config_usb_cfg {
 	struct config_group group;
 	struct config_group strings_group;
-	struct config_group *default_groups[2];
 	struct list_head string_list;
 	struct usb_configuration c;
 	struct list_head func_list;
@@ -666,13 +664,12 @@ static struct config_group *config_desc_make(
 	INIT_LIST_HEAD(&cfg->string_list);
 	INIT_LIST_HEAD(&cfg->func_list);
 
-	cfg->group.default_groups = cfg->default_groups;
-	cfg->default_groups[0] = &cfg->strings_group;
-
 	config_group_init_type_name(&cfg->group, name,
 				&gadget_config_type);
+
 	config_group_init_type_name(&cfg->strings_group, "strings",
 			&gadget_config_name_strings_type);
+	configfs_add_default_group(&cfg->strings_group, &cfg->group);
 
 	ret = usb_add_config_only(&gi->cdev, &cfg->c);
 	if (ret)
@@ -1149,15 +1146,11 @@ int usb_os_desc_prepare_interf_dir(struct config_group *parent,
 				   char **names,
 				   struct module *owner)
 {
-	struct config_group **f_default_groups, *os_desc_group,
-				**interface_groups;
+	struct config_group *os_desc_group;
 	struct config_item_type *os_desc_type, *interface_type;
 
 	vla_group(data_chunk);
-	vla_item(data_chunk, struct config_group *, f_default_groups, 2);
 	vla_item(data_chunk, struct config_group, os_desc_group, 1);
-	vla_item(data_chunk, struct config_group *, interface_groups,
-		 n_interf + 1);
 	vla_item(data_chunk, struct config_item_type, os_desc_type, 1);
 	vla_item(data_chunk, struct config_item_type, interface_type, 1);
 
@@ -1165,18 +1158,14 @@ int usb_os_desc_prepare_interf_dir(struct config_group *parent,
 	if (!vlabuf)
 		return -ENOMEM;
 
-	f_default_groups = vla_ptr(vlabuf, data_chunk, f_default_groups);
 	os_desc_group = vla_ptr(vlabuf, data_chunk, os_desc_group);
 	os_desc_type = vla_ptr(vlabuf, data_chunk, os_desc_type);
-	interface_groups = vla_ptr(vlabuf, data_chunk, interface_groups);
 	interface_type = vla_ptr(vlabuf, data_chunk, interface_type);
 
-	parent->default_groups = f_default_groups;
 	os_desc_type->ct_owner = owner;
 	config_group_init_type_name(os_desc_group, "os_desc", os_desc_type);
-	f_default_groups[0] = os_desc_group;
+	configfs_add_default_group(os_desc_group, parent);
 
-	os_desc_group->default_groups = interface_groups;
 	interface_type->ct_group_ops = &interf_grp_ops;
 	interface_type->ct_attrs = interf_grp_attrs;
 	interface_type->ct_owner = owner;
@@ -1189,7 +1178,7 @@ int usb_os_desc_prepare_interf_dir(struct config_group *parent,
 		config_group_init_type_name(&d->group, "", interface_type);
 		config_item_set_name(&d->group.cg_item, "interface.%s",
 				     names[n_interf]);
-		interface_groups[n_interf] = &d->group;
+		configfs_add_default_group(&d->group, os_desc_group);
 	}
 
 	return 0;
@@ -1423,20 +1412,23 @@ static struct config_group *gadgets_make(
 	if (!gi)
 		return ERR_PTR(-ENOMEM);
 
-	gi->group.default_groups = gi->default_groups;
-	gi->group.default_groups[0] = &gi->functions_group;
-	gi->group.default_groups[1] = &gi->configs_group;
-	gi->group.default_groups[2] = &gi->strings_group;
-	gi->group.default_groups[3] = &gi->os_desc_group;
+	config_group_init_type_name(&gi->group, name, &gadget_root_type);
 
 	config_group_init_type_name(&gi->functions_group, "functions",
 			&functions_type);
+	configfs_add_default_group(&gi->functions_group, &gi->group);
+
 	config_group_init_type_name(&gi->configs_group, "configs",
 			&config_desc_type);
+	configfs_add_default_group(&gi->configs_group, &gi->group);
+
 	config_group_init_type_name(&gi->strings_group, "strings",
 			&gadget_strings_strings_type);
+	configfs_add_default_group(&gi->strings_group, &gi->group);
+
 	config_group_init_type_name(&gi->os_desc_group, "os_desc",
 			&os_desc_type);
+	configfs_add_default_group(&gi->os_desc_group, &gi->group);
 
 	gi->composite.bind = configfs_do_nothing;
 	gi->composite.unbind = configfs_do_nothing;
@@ -1461,8 +1453,6 @@ static struct config_group *gadgets_make(
 	if (!gi->composite.gadget_driver.function)
 		goto err;
 
-	config_group_init_type_name(&gi->group, name,
-				&gadget_root_type);
 	return &gi->group;
 err:
 	kfree(gi);
diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c
index 223ccf8..142bb77 100644
--- a/drivers/usb/gadget/function/f_mass_storage.c
+++ b/drivers/usb/gadget/function/f_mass_storage.c
@@ -3484,12 +3484,12 @@ static struct usb_function_instance *fsg_alloc_inst(void)
 
 	opts->lun0.lun = opts->common->luns[0];
 	opts->lun0.lun_id = 0;
-	config_group_init_type_name(&opts->lun0.group, "lun.0", &fsg_lun_type);
-	opts->default_groups[0] = &opts->lun0.group;
-	opts->func_inst.group.default_groups = opts->default_groups;
 
 	config_group_init_type_name(&opts->func_inst.group, "", &fsg_func_type);
 
+	config_group_init_type_name(&opts->lun0.group, "lun.0", &fsg_lun_type);
+	configfs_add_default_group(&opts->lun0.group, &opts->func_inst.group);
+
 	return &opts->func_inst;
 
 release_buffers:
diff --git a/drivers/usb/gadget/function/f_rndis.c b/drivers/usb/gadget/function/f_rndis.c
index e587767..f577eec 100644
--- a/drivers/usb/gadget/function/f_rndis.c
+++ b/drivers/usb/gadget/function/f_rndis.c
@@ -889,7 +889,6 @@ static void rndis_free_inst(struct usb_function_instance *f)
 			free_netdev(opts->net);
 	}
 
-	kfree(opts->rndis_os_desc.group.default_groups); /* single VLA chunk */
 	kfree(opts);
 }
 
@@ -916,10 +915,10 @@ static struct usb_function_instance *rndis_alloc_inst(void)
 
 	descs[0] = &opts->rndis_os_desc;
 	names[0] = "rndis";
-	usb_os_desc_prepare_interf_dir(&opts->func_inst.group, 1, descs,
-				       names, THIS_MODULE);
 	config_group_init_type_name(&opts->func_inst.group, "",
 				    &rndis_func_type);
+	usb_os_desc_prepare_interf_dir(&opts->func_inst.group, 1, descs,
+				       names, THIS_MODULE);
 
 	return &opts->func_inst;
 }
diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
index ad8c9b0..66753ba 100644
--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -272,11 +272,6 @@ static struct config_item_type uvcg_default_processing_type = {
 
 /* struct uvcg_processing {}; */
 
-static struct config_group *uvcg_processing_default_groups[] = {
-	&uvcg_default_processing.group,
-	NULL,
-};
-
 /* control/processing */
 static struct uvcg_processing_grp {
 	struct config_group	group;
@@ -394,11 +389,6 @@ static struct config_item_type uvcg_default_camera_type = {
 
 /* struct uvcg_camera {}; */
 
-static struct config_group *uvcg_camera_default_groups[] = {
-	&uvcg_default_camera.group,
-	NULL,
-};
-
 /* control/terminal/camera */
 static struct uvcg_camera_grp {
 	struct config_group	group;
@@ -477,11 +467,6 @@ static struct config_item_type uvcg_default_output_type = {
 
 /* struct uvcg_output {}; */
 
-static struct config_group *uvcg_output_default_groups[] = {
-	&uvcg_default_output.group,
-	NULL,
-};
-
 /* control/terminal/output */
 static struct uvcg_output_grp {
 	struct config_group	group;
@@ -491,12 +476,6 @@ static struct config_item_type uvcg_output_grp_type = {
 	.ct_owner = THIS_MODULE,
 };
 
-static struct config_group *uvcg_terminal_default_groups[] = {
-	&uvcg_camera_grp.group,
-	&uvcg_output_grp.group,
-	NULL,
-};
-
 /* control/terminal */
 static struct uvcg_terminal_grp {
 	struct config_group	group;
@@ -619,12 +598,6 @@ static struct config_item_type uvcg_control_class_type = {
 	.ct_owner	= THIS_MODULE,
 };
 
-static struct config_group *uvcg_control_class_default_groups[] = {
-	&uvcg_control_class_fs.group,
-	&uvcg_control_class_ss.group,
-	NULL,
-};
-
 /* control/class */
 static struct uvcg_control_class_grp {
 	struct config_group	group;
@@ -634,14 +607,6 @@ static struct config_item_type uvcg_control_class_grp_type = {
 	.ct_owner = THIS_MODULE,
 };
 
-static struct config_group *uvcg_control_default_groups[] = {
-	&uvcg_control_header_grp.group,
-	&uvcg_processing_grp.group,
-	&uvcg_terminal_grp.group,
-	&uvcg_control_class_grp.group,
-	NULL,
-};
-
 /* control */
 static struct uvcg_control_grp {
 	struct config_group	group;
@@ -1780,11 +1745,6 @@ static struct config_item_type uvcg_default_color_matching_type = {
 
 /* struct uvcg_color_matching {}; */
 
-static struct config_group *uvcg_color_matching_default_groups[] = {
-	&uvcg_default_color_matching.group,
-	NULL,
-};
-
 /* streaming/color_matching */
 static struct uvcg_color_matching_grp {
 	struct config_group	group;
@@ -2145,13 +2105,6 @@ static struct config_item_type uvcg_streaming_class_type = {
 	.ct_owner	= THIS_MODULE,
 };
 
-static struct config_group *uvcg_streaming_class_default_groups[] = {
-	&uvcg_streaming_class_fs.group,
-	&uvcg_streaming_class_hs.group,
-	&uvcg_streaming_class_ss.group,
-	NULL,
-};
-
 /* streaming/class */
 static struct uvcg_streaming_class_grp {
 	struct config_group	group;
@@ -2161,15 +2114,6 @@ static struct config_item_type uvcg_streaming_class_grp_type = {
 	.ct_owner = THIS_MODULE,
 };
 
-static struct config_group *uvcg_streaming_default_groups[] = {
-	&uvcg_streaming_header_grp.group,
-	&uvcg_uncompressed_grp.group,
-	&uvcg_mjpeg_grp.group,
-	&uvcg_color_matching_grp.group,
-	&uvcg_streaming_class_grp.group,
-	NULL,
-};
-
 /* streaming */
 static struct uvcg_streaming_grp {
 	struct config_group	group;
@@ -2179,12 +2123,6 @@ static struct config_item_type uvcg_streaming_grp_type = {
 	.ct_owner = THIS_MODULE,
 };
 
-static struct config_group *uvcg_default_groups[] = {
-	&uvcg_control_grp.group,
-	&uvcg_streaming_grp.group,
-	NULL,
-};
-
 static inline struct f_uvc_opts *to_f_uvc_opts(struct config_item *item)
 {
 	return container_of(to_config_group(item), struct f_uvc_opts,
@@ -2273,59 +2211,64 @@ static struct config_item_type uvc_func_type = {
 	.ct_owner	= THIS_MODULE,
 };
 
-static inline void uvcg_init_group(struct config_group *g,
-				   struct config_group **default_groups,
-				   const char *name,
-				   struct config_item_type *type)
-{
-	g->default_groups = default_groups;
-	config_group_init_type_name(g, name, type);
-}
-
 int uvcg_attach_configfs(struct f_uvc_opts *opts)
 {
 	config_group_init_type_name(&uvcg_control_header_grp.group,
 				    "header",
 				    &uvcg_control_header_grp_type);
+
 	config_group_init_type_name(&uvcg_default_processing.group,
-				    "default",
-				    &uvcg_default_processing_type);
-	uvcg_init_group(&uvcg_processing_grp.group,
-			uvcg_processing_default_groups,
-			"processing",
-			&uvcg_processing_grp_type);
+			"default", &uvcg_default_processing_type);
+	config_group_init_type_name(&uvcg_processing_grp.group,
+			"processing", &uvcg_processing_grp_type);
+	configfs_add_default_group(&uvcg_default_processing.group,
+			&uvcg_processing_grp.group);
+
 	config_group_init_type_name(&uvcg_default_camera.group,
-				    "default",
-				    &uvcg_default_camera_type);
-	uvcg_init_group(&uvcg_camera_grp.group,
-			uvcg_camera_default_groups,
-			"camera",
-			&uvcg_camera_grp_type);
+			"default", &uvcg_default_camera_type);
+	config_group_init_type_name(&uvcg_camera_grp.group,
+			"camera", &uvcg_camera_grp_type);
+	configfs_add_default_group(&uvcg_default_camera.group,
+			&uvcg_camera_grp.group);
+
 	config_group_init_type_name(&uvcg_default_output.group,
-				    "default",
-				    &uvcg_default_output_type);
-	uvcg_init_group(&uvcg_output_grp.group,
-			uvcg_output_default_groups,
-			"output",
-			&uvcg_output_grp_type);
-	uvcg_init_group(&uvcg_terminal_grp.group,
-			uvcg_terminal_default_groups,
-			"terminal",
-			&uvcg_terminal_grp_type);
+			"default", &uvcg_default_output_type);
+	config_group_init_type_name(&uvcg_output_grp.group,
+			"output", &uvcg_output_grp_type);
+	configfs_add_default_group(&uvcg_default_output.group,
+			&uvcg_output_grp.group);
+
+	config_group_init_type_name(&uvcg_terminal_grp.group,
+			"terminal", &uvcg_terminal_grp_type);
+	configfs_add_default_group(&uvcg_camera_grp.group,
+			&uvcg_terminal_grp.group);
+	configfs_add_default_group(&uvcg_output_grp.group,
+			&uvcg_terminal_grp.group);
+
 	config_group_init_type_name(&uvcg_control_class_fs.group,
-				    "fs",
-				    &uvcg_control_class_type);
+			"fs", &uvcg_control_class_type);
 	config_group_init_type_name(&uvcg_control_class_ss.group,
-				    "ss",
-				    &uvcg_control_class_type);
-	uvcg_init_group(&uvcg_control_class_grp.group,
-			uvcg_control_class_default_groups,
+			"ss", &uvcg_control_class_type);
+	config_group_init_type_name(&uvcg_control_class_grp.group,
 			"class",
 			&uvcg_control_class_grp_type);
-	uvcg_init_group(&uvcg_control_grp.group,
-			uvcg_control_default_groups,
+	configfs_add_default_group(&uvcg_control_class_fs.group,
+			&uvcg_control_class_grp.group);
+	configfs_add_default_group(&uvcg_control_class_ss.group,
+			&uvcg_control_class_grp.group);
+
+	config_group_init_type_name(&uvcg_control_grp.group,
 			"control",
 			&uvcg_control_grp_type);
+	configfs_add_default_group(&uvcg_control_header_grp.group,
+			&uvcg_control_grp.group);
+	configfs_add_default_group(&uvcg_processing_grp.group,
+			&uvcg_control_grp.group);
+	configfs_add_default_group(&uvcg_terminal_grp.group,
+			&uvcg_control_grp.group);
+	configfs_add_default_group(&uvcg_control_class_grp.group,
+			&uvcg_control_grp.group);
+
 	config_group_init_type_name(&uvcg_streaming_header_grp.group,
 				    "header",
 				    &uvcg_streaming_header_grp_type);
@@ -2338,30 +2281,47 @@ int uvcg_attach_configfs(struct f_uvc_opts *opts)
 	config_group_init_type_name(&uvcg_default_color_matching.group,
 				    "default",
 				    &uvcg_default_color_matching_type);
-	uvcg_init_group(&uvcg_color_matching_grp.group,
-			uvcg_color_matching_default_groups,
+	config_group_init_type_name(&uvcg_color_matching_grp.group,
 			"color_matching",
 			&uvcg_color_matching_grp_type);
+	configfs_add_default_group(&uvcg_default_color_matching.group,
+			&uvcg_color_matching_grp.group);
+
 	config_group_init_type_name(&uvcg_streaming_class_fs.group,
-				    "fs",
-				    &uvcg_streaming_class_type);
+			"fs", &uvcg_streaming_class_type);
 	config_group_init_type_name(&uvcg_streaming_class_hs.group,
-				    "hs",
-				    &uvcg_streaming_class_type);
+			"hs", &uvcg_streaming_class_type);
 	config_group_init_type_name(&uvcg_streaming_class_ss.group,
-				    "ss",
-				    &uvcg_streaming_class_type);
-	uvcg_init_group(&uvcg_streaming_class_grp.group,
-			uvcg_streaming_class_default_groups,
-			"class",
-			&uvcg_streaming_class_grp_type);
-	uvcg_init_group(&uvcg_streaming_grp.group,
-			uvcg_streaming_default_groups,
-			"streaming",
-			&uvcg_streaming_grp_type);
-	uvcg_init_group(&opts->func_inst.group,
-			uvcg_default_groups,
+			"ss", &uvcg_streaming_class_type);
+	config_group_init_type_name(&uvcg_streaming_class_grp.group,
+			"class", &uvcg_streaming_class_grp_type);
+	configfs_add_default_group(&uvcg_streaming_class_fs.group,
+			&uvcg_streaming_class_grp.group);
+	configfs_add_default_group(&uvcg_streaming_class_hs.group,
+			&uvcg_streaming_class_grp.group);
+	configfs_add_default_group(&uvcg_streaming_class_ss.group,
+			&uvcg_streaming_class_grp.group);
+
+	config_group_init_type_name(&uvcg_streaming_grp.group,
+			"streaming", &uvcg_streaming_grp_type);
+	configfs_add_default_group(&uvcg_streaming_header_grp.group,
+			&uvcg_streaming_grp.group);
+	configfs_add_default_group(&uvcg_uncompressed_grp.group,
+			&uvcg_streaming_grp.group);
+	configfs_add_default_group(&uvcg_mjpeg_grp.group,
+			&uvcg_streaming_grp.group);
+	configfs_add_default_group(&uvcg_color_matching_grp.group,
+			&uvcg_streaming_grp.group);
+	configfs_add_default_group(&uvcg_streaming_class_grp.group,
+			&uvcg_streaming_grp.group);
+
+	config_group_init_type_name(&opts->func_inst.group,
 			"",
 			&uvc_func_type);
+	configfs_add_default_group(&uvcg_control_grp.group,
+			&opts->func_inst.group);
+	configfs_add_default_group(&uvcg_streaming_grp.group,
+			&opts->func_inst.group);
+
 	return 0;
 }