[PATCH v2 1/1] usb: gadget: Assign an unique name for each configfs driver

[Frank Li <Frank.Li@xxxxxxx>]

From: Rondreis <linhaoguo86@xxxxxxxxx>

When use configfs to attach more than one gadget.

Error: Driver 'configfs-gadget' is already registered, aborting...

	UDC core: g1: driver registration failed: -16

The problem is that when creating multiple gadgets with configfs and
binding them to different UDCs, the UDC drivers have the same name
"configfs-gadget". Because of the addition of the "gadget" bus, naming
conflicts will occur when more than one UDC drivers registered to the
bus.

It's not an isolated case, this patch refers to the commit f2d8c2606825
("usb: gadget: Fix non-unique driver names in raw-gadget driver").
Each configfs-gadget driver will be assigned a unique name
"configfs-gadget.N", with a different value of N for each driver
instance.

Fixes: fc274c1e9973 ("USB: gadget: Add a new bus for gadgets")

Signed-off-by: Rondreis <linhaoguo86@xxxxxxxxx>
Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
---

This patch is based on https://lore.kernel.org/lkml/20220907112210.11949-1-linhaoguo86@xxxxxxxxx/
fixed the all greg's comments.

I met the same issue.  Look likes Rodrieis have not continue to work this
patch since Sep, 2022.

I don't know full name of Rondreis.

 drivers/usb/gadget/configfs.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 3a6b4926193e..785be6aea720 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -4,12 +4,17 @@
 #include <linux/slab.h>
 #include <linux/device.h>
 #include <linux/nls.h>
+#include <linux/idr.h>
 #include <linux/usb/composite.h>
 #include <linux/usb/gadget_configfs.h>
 #include "configfs.h"
 #include "u_f.h"
 #include "u_os_desc.h"
 
+#define DRIVER_NAME "configfs-gadget"
+
+static DEFINE_IDA(driver_id_numbers);
+
 int check_user_usb_string(const char *name,
 		struct usb_gadget_strings *stringtab_dev)
 {
@@ -46,6 +51,7 @@ struct gadget_info {
 
 	struct usb_composite_driver composite;
 	struct usb_composite_dev cdev;
+	int driver_id_number;
 	bool use_os_desc;
 	char b_vendor_code;
 	char qw_sign[OS_STRING_QW_SIGN_LEN];
@@ -392,6 +398,8 @@ static void gadget_info_attr_release(struct config_item *item)
 	WARN_ON(!list_empty(&gi->string_list));
 	WARN_ON(!list_empty(&gi->available_func));
 	kfree(gi->composite.gadget_driver.function);
+	kfree(gi->composite.gadget_driver.driver.name);
+	ida_free(&driver_id_numbers, gi->driver_id_number);
 	kfree(gi);
 }
 
@@ -1571,7 +1579,6 @@ static const struct usb_gadget_driver configfs_driver_template = {
 	.max_speed	= USB_SPEED_SUPER_PLUS,
 	.driver = {
 		.owner          = THIS_MODULE,
-		.name		= "configfs-gadget",
 	},
 	.match_existing_only = 1,
 };
@@ -1581,6 +1588,7 @@ static struct config_group *gadgets_make(
 		const char *name)
 {
 	struct gadget_info *gi;
+	int ret = 0;
 
 	gi = kzalloc(sizeof(*gi), GFP_KERNEL);
 	if (!gi)
@@ -1622,16 +1630,30 @@ static struct config_group *gadgets_make(
 
 	gi->composite.gadget_driver = configfs_driver_template;
 
+	ret = ida_alloc(&driver_id_numbers, GFP_KERNEL);
+	if (ret < 0)
+		goto err;
+	gi->driver_id_number = ret;
+
+	gi->composite.gadget_driver.driver.name =
+		kasprintf(GFP_KERNEL, DRIVER_NAME ".%d", gi->driver_id_number);
+
 	gi->composite.gadget_driver.function = kstrdup(name, GFP_KERNEL);
 	gi->composite.name = gi->composite.gadget_driver.function;
 
-	if (!gi->composite.gadget_driver.function)
-		goto err;
+	if (!gi->composite.gadget_driver.function) {
+		ret = -ENOMEM;
+		goto err_func;
+	}
 
 	return &gi->group;
+
+err_func:
+	kfree(gi->composite.gadget_driver.driver.name);
+	ida_free(&driver_id_numbers, gi->driver_id_number);
 err:
 	kfree(gi);
-	return ERR_PTR(-ENOMEM);
+	return ERR_PTR(ret);
 }
 
 static void gadgets_drop(struct config_group *group, struct config_item *item)
-- 
2.34.1