V4L/DVB (5678): Zr364xx: fix return values

This patch fixes several return value related problems in zr364xx.

- return -ENOMEM instead of -ENODEV on out of memory

- zr364xx checks video_register_device() error only when
  its return value is -1. But video_register_device() doesn't
  always return -1 on error.

- If usb_register() returns error, module_init() wrongly returns 1:
	retval = usb_register(&zr364xx_driver) < 0;
	...
	return retval;

  And it allows the module to be loaded. Because sys_init_module() doesn't
  see positive return value as error.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Antoine Jacquet <royale@zerezo.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/zr364xx.c

@@ -792,6 +792,7 @@ static int zr364xx_probe(struct usb_interface *intf,
 {
 	struct usb_device *udev = interface_to_usbdev(intf);
 	struct zr364xx_camera *cam = NULL;
+	int err;
 
 	DBG("probing...");
 
@@ -799,12 +800,11 @@ static int zr364xx_probe(struct usb_interface *intf,
 	info("model %04x:%04x detected", udev->descriptor.idVendor,
 	     udev->descriptor.idProduct);
 
-	if ((cam =
-	     kmalloc(sizeof(struct zr364xx_camera), GFP_KERNEL)) == NULL) {
+	cam = kzalloc(sizeof(struct zr364xx_camera), GFP_KERNEL);
+	if (cam == NULL) {
 		info("cam: out of memory !");
-		return -ENODEV;
+		return -ENOMEM;
 	}
-	memset(cam, 0x00, sizeof(struct zr364xx_camera));
 	/* save the init method used by this camera */
 	cam->method = id->driver_info;
 
@@ -812,7 +812,7 @@ static int zr364xx_probe(struct usb_interface *intf,
 	if (cam->vdev == NULL) {
 		info("cam->vdev: out of memory !");
 		kfree(cam);
-		return -ENODEV;
+		return -ENOMEM;
 	}
 	memcpy(cam->vdev, &zr364xx_template, sizeof(zr364xx_template));
 	video_set_drvdata(cam->vdev, cam);
@@ -858,12 +858,13 @@ static int zr364xx_probe(struct usb_interface *intf,
 	cam->brightness = 64;
 	mutex_init(&cam->lock);
 
-	if (video_register_device(cam->vdev, VFL_TYPE_GRABBER, -1) == -1) {
+	err = video_register_device(cam->vdev, VFL_TYPE_GRABBER, -1);
+	if (err) {
 		info("video_register_device failed");
 		video_device_release(cam->vdev);
 		kfree(cam->buffer);
 		kfree(cam);
-		return -ENODEV;
+		return err;
 	}
 
 	usb_set_intfdata(intf, cam);
@@ -905,7 +906,7 @@ static struct usb_driver zr364xx_driver = {
 static int __init zr364xx_init(void)
 {
 	int retval;
-	retval = usb_register(&zr364xx_driver) < 0;
+	retval = usb_register(&zr364xx_driver);
 	if (retval)
 		info("usb_register failed!");
 	else