usb: gadget: Fix binding to UDC via configfs interface

By default user could store only valid UDC name in configfs UDC attr by doing: echo $UDC_NAME > UDC Commit (855ed04 "usb: gadget: udc-core: independent registration of gadgets and gadget drivers") broke this behavior and allowed to store any arbitrary string in UDC file and udc core was waiting for such controller to appear. echo "any arbitrary string here" > UDC This commit fix this by adding a flag which prevents configfs gadget from being added to list of pending drivers if UDC with given name has not been found. Signed-off-by: Krzysztof Opasiak <[email protected]> Signed-off-by: Felipe Balbi <[email protected]>
kyagi · May 31, 2016 · f1bddbb · f1bddbb
1 parent 1a695a9
commit f1bddbb
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Showing 3 changed files with 12 additions and 4 deletions.
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
@@ -1401,6 +1401,7 @@ static const struct usb_gadget_driver configfs_driver_template = {
 		.owner          = THIS_MODULE,
 		.name		= "configfs-gadget",
 	},
+	.match_existing_only = 1,
 };
 
 static struct config_group *gadgets_make(

diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
@@ -603,11 +603,15 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
 		}
 	}
 
-	list_add_tail(&driver->pending, &gadget_driver_pending_list);
-	pr_info("udc-core: couldn't find an available UDC - added [%s] to list of pending drivers\n",
-		driver->function);
+	if (!driver->match_existing_only) {
+		list_add_tail(&driver->pending, &gadget_driver_pending_list);
+		pr_info("udc-core: couldn't find an available UDC - added [%s] to list of pending drivers\n",
+			driver->function);
+		ret = 0;
+	}
+
 	mutex_unlock(&udc_lock);
-	return 0;
+	return ret;
 found:
 	ret = udc_bind_to_driver(udc, driver);
 	mutex_unlock(&udc_lock);

diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
@@ -1034,6 +1034,8 @@ static inline int usb_gadget_activate(struct usb_gadget *gadget)
  * @udc_name: A name of UDC this driver should be bound to. If udc_name is NULL,
  *	this driver will be bound to any available UDC.
  * @pending: UDC core private data used for deferred probe of this driver.
+ * @match_existing_only: If udc is not found, return an error and don't add this
+ *      gadget driver to list of pending driver
  *
  * Devices are disabled till a gadget driver successfully bind()s, which
  * means the driver will handle setup() requests needed to enumerate (and
@@ -1097,6 +1099,7 @@ struct usb_gadget_driver {
 
 	char			*udc_name;
 	struct list_head	pending;
+	unsigned                match_existing_only:1;
 };