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Subject: Re: [syzbot] [kernel?] WARNING: kobject bug in goku_remove
Author: chenglingfei@foxmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 3aa1dcaa4f6f5ae08936491e08bd456f331f2d40

diff --git a/drivers/usb/gadget/udc/goku_udc.c b/drivers/usb/gadget/udc/goku_udc.c
index ac2a984c2f87..827f698bf222 100644
--- a/drivers/usb/gadget/udc/goku_udc.c
+++ b/drivers/usb/gadget/udc/goku_udc.c
@@ -20,6 +20,7 @@
 // #define	VERBOSE		/* extra debug messages (success too) */
 // #define	USB_TRACE	/* packet-level success messages */
 
+#include <linux/container_of.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
@@ -1701,7 +1702,7 @@ static irqreturn_t goku_irq(int irq, void *_dev)
 
 static void gadget_release(struct device *_dev)
 {
-	struct goku_udc	*dev = dev_get_drvdata(_dev);
+	struct goku_udc *dev = container_of(_dev, struct goku_udc, gadget.dev);
 
 	kfree(dev);
 }
@@ -1714,12 +1715,14 @@ static void goku_remove(struct pci_dev *pdev)
 
 	DBG(dev, "%s\n", __func__);
 
-	usb_del_gadget_udc(&dev->gadget);
+	if (dev->added)
+		usb_del_gadget(&dev->gadget);
 
 	BUG_ON(dev->driver);
 
 #ifdef CONFIG_USB_GADGET_DEBUG_FILES
-	remove_proc_entry(proc_node_name, NULL);
+	if (dev->proc_created)
+		remove_proc_entry(proc_node_name, NULL);
 #endif
 	if (dev->regs)
 		udc_reset(dev);
@@ -1736,6 +1739,8 @@ static void goku_remove(struct pci_dev *pdev)
 	dev->regs = NULL;
 
 	INFO(dev, "unbind\n");
+
+	usb_put_gadget(&dev->gadget);
 }
 
 /* wrap this driver around the specified pci device, but
@@ -1751,16 +1756,13 @@ static int goku_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	if (!pdev->irq) {
 		printk(KERN_ERR "Check PCI %s IRQ setup!\n", pci_name(pdev));
-		retval = -ENODEV;
-		goto err;
+		return -ENODEV;
 	}
 
 	/* alloc, and start init */
 	dev = kzalloc_obj(*dev);
-	if (!dev) {
-		retval = -ENOMEM;
-		goto err;
-	}
+	if (!dev)
+		return -ENOMEM;
 
 	pci_set_drvdata(pdev, dev);
 	spin_lock_init(&dev->lock);
@@ -1771,6 +1773,8 @@ static int goku_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	/* the "gadget" abstracts/virtualizes the controller */
 	dev->gadget.name = driver_name;
 
+	usb_initialize_gadget(&pdev->dev, &dev->gadget, gadget_release);
+
 	/* now all the pci goodies ... */
 	retval = pci_enable_device(pdev);
 	if (retval < 0) {
@@ -1815,21 +1819,19 @@ static int goku_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 
 #ifdef CONFIG_USB_GADGET_DEBUG_FILES
-	proc_create_single_data(proc_node_name, 0, NULL, udc_proc_read, dev);
+	dev->proc_created = !!proc_create_single_data(proc_node_name, 0, NULL,
+						      udc_proc_read, dev);
 #endif
 
-	retval = usb_add_gadget_udc_release(&pdev->dev, &dev->gadget,
-			gadget_release);
+	retval = usb_add_gadget(&dev->gadget);
 	if (retval)
 		goto err;
+	dev->added = 1;
 
 	return 0;
 
 err:
-	if (dev)
-		goku_remove (pdev);
-	/* gadget_release is not registered yet, kfree explicitly */
-	kfree(dev);
+	goku_remove(pdev);
 	return retval;
 }
 
diff --git a/drivers/usb/gadget/udc/goku_udc.h b/drivers/usb/gadget/udc/goku_udc.h
index 70023d401079..f815f38304f6 100644
--- a/drivers/usb/gadget/udc/goku_udc.h
+++ b/drivers/usb/gadget/udc/goku_udc.h
@@ -247,7 +247,9 @@ struct goku_udc {
 					got_region:1,
 					req_config:1,
 					configured:1,
-					enabled:1;
+					enabled:1,
+					added:1,
+					proc_created:1;
 
 	/* pci state used to access those endpoints */
 	struct pci_dev			*pdev;
@@ -286,4 +288,3 @@ struct goku_udc {
 	xprintk(dev , KERN_WARNING , fmt , ## args)
 #define INFO(dev,fmt,args...) \
 	xprintk(dev , KERN_INFO , fmt , ## args)
-