V4L/DVB: s2255drv: removes kref tracking and videodev parent

kref replaced as suggested in code review
uses atomic variable to track when it is ok to delete device
removes setting of video device parent, which is now
handled in v4l2_device.c
Signed-off-by: Dean Anderson <linux-dev@sensoray.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/s2255drv.c

@@ -230,7 +230,7 @@ struct s2255_fmt; /*forward declaration */
 struct s2255_dev {
 	struct video_device	vdev[MAX_CHANNELS];
 	struct v4l2_device 	v4l2_dev;
-	int                     channels; /* number of channels registered */
+	atomic_t                channels; /* number of channels registered */
 	int			frames;
 	struct mutex		lock;
 	struct mutex		open_lock;
@@ -276,12 +276,8 @@ struct s2255_dev {
 	/* dsp firmware version (f2255usb.bin) */
 	int                     dsp_fw_ver;
 	u16                     pid; /* product id */
-	struct kref		kref;
 };
 
-/* kref will be removed soon */
-#define to_s2255_dev_from_kref(d) container_of(d, struct s2255_dev, kref)
-
 static inline struct s2255_dev *to_s2255_dev(struct v4l2_device *v4l2_dev)
 {
 	return container_of(v4l2_dev, struct s2255_dev, v4l2_dev);
@@ -372,7 +368,7 @@ static int s2255_set_mode(struct s2255_dev *dev, unsigned long chn,
 			  struct s2255_mode *mode);
 static int s2255_board_shutdown(struct s2255_dev *dev);
 static void s2255_fwload_start(struct s2255_dev *dev, int reset);
-static void s2255_destroy(struct kref *kref);
+static void s2255_destroy(struct s2255_dev *dev);
 static long s2255_vendor_req(struct s2255_dev *dev, unsigned char req,
 			     u16 index, u16 value, void *buf,
 			     s32 buf_len, int bOut);
@@ -1720,7 +1716,7 @@ static int s2255_open(struct file *file)
 	dprintk(1, "s2255: open called (dev=%s)\n",
 		video_device_node_name(vdev));
 
-	for (i = 0; i < dev->channels; i++)
+	for (i = 0; i < MAX_CHANNELS; i++)
 		if (&dev->vdev[i] == vdev) {
 			cur_channel = i;
 			break;
@@ -1834,9 +1830,8 @@ static unsigned int s2255_poll(struct file *file,
 	return rc;
 }
 
-static void s2255_destroy(struct kref *kref)
+static void s2255_destroy(struct s2255_dev *dev)
 {
-	struct s2255_dev *dev = to_s2255_dev_from_kref(kref);
 	/* board shutdown stops the read pipe if it is running */
 	s2255_board_shutdown(dev);
 	/* make sure firmware still not trying to load */
@@ -1936,7 +1931,9 @@ static const struct v4l2_ioctl_ops s2255_ioctl_ops = {
 static void s2255_video_device_release(struct video_device *vdev)
 {
 	struct s2255_dev *dev = video_get_drvdata(vdev);
-	kref_put(&dev->kref, s2255_destroy);
+	dprintk(4, "%s, chnls: %d \n", __func__, atomic_read(&dev->channels));
+	if (atomic_dec_and_test(&dev->channels))
+		s2255_destroy(dev);
 	return;
 }
 
@@ -1965,7 +1962,8 @@ static int s2255_probe_v4l(struct s2255_dev *dev)
 		dev->vidq[i].channel = i;
 		/* register 4 video devices */
 		memcpy(&dev->vdev[i], &template, sizeof(struct video_device));
-		dev->vdev[i].parent = &dev->interface->dev;
+		dev->vdev[i].v4l2_dev = &dev->v4l2_dev;
+		video_set_drvdata(&dev->vdev[i], dev);
 		if (video_nr == -1)
 			ret = video_register_device(&dev->vdev[i],
 						    VFL_TYPE_GRABBER,
@@ -1974,13 +1972,12 @@ static int s2255_probe_v4l(struct s2255_dev *dev)
 			ret = video_register_device(&dev->vdev[i],
 						    VFL_TYPE_GRABBER,
 						    cur_nr + i);
-		video_set_drvdata(&dev->vdev[i], dev);
 		if (ret) {
 			dev_err(&dev->udev->dev,
 				"failed to register video device!\n");
 			break;
 		}
-		dev->channels++;
+		atomic_inc(&dev->channels);
 		v4l2_info(&dev->v4l2_dev, "V4L2 device registered as %s\n",
 			  video_device_node_name(&dev->vdev[i]));
 
@@ -1990,11 +1987,11 @@ static int s2255_probe_v4l(struct s2255_dev *dev)
 	       S2255_MAJOR_VERSION,
 	       S2255_MINOR_VERSION);
 	/* if no channels registered, return error and probe will fail*/
-	if (dev->channels == 0) {
+	if (atomic_read(&dev->channels) == 0) {
 		v4l2_device_unregister(&dev->v4l2_dev);
 		return ret;
 	}
-	if (dev->channels != MAX_CHANNELS)
+	if (atomic_read(&dev->channels) != MAX_CHANNELS)
 		printk(KERN_WARNING "s2255: Not all channels available.\n");
 	return 0;
 }
@@ -2567,7 +2564,7 @@ static int s2255_probe(struct usb_interface *interface,
 		s2255_dev_err(&interface->dev, "out of memory\n");
 		return -ENOMEM;
 	}
-	kref_init(&dev->kref);
+	atomic_set(&dev->channels, 0);
 	dev->pid = id->idProduct;
 	dev->fw_data = kzalloc(sizeof(struct s2255_fw), GFP_KERNEL);
 	if (!dev->fw_data)
@@ -2581,7 +2578,7 @@ static int s2255_probe(struct usb_interface *interface,
 		retval = -ENODEV;
 		goto errorUDEV;
 	}
-	dprintk(1, "dev: %p, kref: %p udev %p interface %p\n", dev, &dev->kref,
+	dprintk(1, "dev: %p, udev %p interface %p\n", dev,
 		dev->udev, interface);
 	dev->interface = interface;
 	/* set up the endpoint information  */
@@ -2652,9 +2649,6 @@ static int s2255_probe(struct usb_interface *interface,
 		goto errorBOARDINIT;
 	spin_lock_init(&dev->slock);
 	s2255_fwload_start(dev, 0);
-	/* kref for each vdev. Released on video_device_release callback */
-	for (i = 0; i < MAX_CHANNELS; i++)
-		kref_get(&dev->kref);
 	/* loads v4l specific */
 	retval = s2255_probe_v4l(dev);
 	if (retval)
@@ -2688,11 +2682,15 @@ static void s2255_disconnect(struct usb_interface *interface)
 {
 	struct s2255_dev *dev = to_s2255_dev(usb_get_intfdata(interface));
 	int i;
+	int channels = atomic_read(&dev->channels);
 	v4l2_device_unregister(&dev->v4l2_dev);
+	/*see comments in the uvc_driver.c usb disconnect function */
+	atomic_inc(&dev->channels);
 	/* unregister each video device. */
-	for (i = 0; i < MAX_CHANNELS; i++)
+	for (i = 0; i < channels; i++) {
 		if (video_is_registered(&dev->vdev[i]))
 			video_unregister_device(&dev->vdev[i]);
+	}
 	/* wake up any of our timers */
 	atomic_set(&dev->fw_data->fw_state, S2255_FW_DISCONNECTING);
 	wake_up(&dev->fw_data->wait_fw);
@@ -2702,7 +2700,8 @@ static void s2255_disconnect(struct usb_interface *interface)
 		dev->vidstatus_ready[i] = 1;
 		wake_up(&dev->wait_vidstatus[i]);
 	}
-	kref_put(&dev->kref, s2255_destroy);
+	if (atomic_dec_and_test(&dev->channels))
+		s2255_destroy(dev);
 	dev_info(&interface->dev, "%s\n", __func__);
 }