[media] media-device: split media initialization and registration

The media device node is registered and so made visible to user-space
before entities are registered and links created which means that the
media graph obtained by user-space could be only partially enumerated
if that happens too early before all the graph has been created.

To avoid this race condition, split the media init and registration
in separate functions and only register the media device node when
all the pending subdevices have been registered, either explicitly
by the driver or asynchronously using v4l2_async_register_subdev().

The media_device_register() had a check for drivers not filling dev
and model fields but all drivers in mainline set them and not doing
it will be a driver bug so change the function return to void and
add a BUG_ON() for dev being NULL instead.

Also, add a media_device_cleanup() function that will destroy the
graph_mutex that is initialized in media_device_init().

[mchehab@osg.samsung.com: Fix compilation if !CONFIG_MEDIA_CONTROLLER
 and remove two warnings added by this changeset]
Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

6 files changed, 68 insertions, 57 deletions

diff --git a/drivers/media/usb/au0828/au0828-core.c b/drivers/media/usb/au0828/au0828-core.c
index 1b207fa16a55..fbdaeb206565 100644
--- a/drivers/media/usb/au0828/au0828-core.c
+++ b/drivers/media/usb/au0828/au0828-core.c
@@ -136,6 +136,7 @@ static void au0828_unregister_media_device(struct au0828_dev *dev)
 #ifdef CONFIG_MEDIA_CONTROLLER
 	if (dev->media_dev) {
 		media_device_unregister(dev->media_dev);
+		media_device_cleanup(dev->media_dev);
 		kfree(dev->media_dev);
 		dev->media_dev = NULL;
 	}
@@ -216,12 +217,11 @@ static void au0828_usb_disconnect(struct usb_interface *interface)
 	au0828_usb_release(dev);
 }
 
-static void au0828_media_device_register(struct au0828_dev *dev,
-					  struct usb_device *udev)
+static void au0828_media_device_init(struct au0828_dev *dev,
+				     struct usb_device *udev)
 {
 #ifdef CONFIG_MEDIA_CONTROLLER
 	struct media_device *mdev;
-	int ret;
 
 	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
 	if (!mdev)
@@ -239,14 +239,7 @@ static void au0828_media_device_register(struct au0828_dev *dev,
 	mdev->hw_revision = le16_to_cpu(udev->descriptor.bcdDevice);
 	mdev->driver_version = LINUX_VERSION_CODE;
 
-	ret = media_device_register(mdev);
-	if (ret) {
-		pr_err(
-			"Couldn't create a media device. Error: %d\n",
-			ret);
-		kfree(mdev);
-		return;
-	}
+	media_device_init(mdev);
 
 	dev->media_dev = mdev;
 #endif
@@ -374,8 +367,8 @@ static int au0828_usb_probe(struct usb_interface *interface,
 	dev->boardnr = id->driver_info;
 	dev->board = au0828_boards[dev->boardnr];
 
-	/* Register the media controller */
-	au0828_media_device_register(dev, usbdev);
+	/* Initialize the media controller */
+	au0828_media_device_init(dev, usbdev);
 
 #ifdef CONFIG_VIDEO_AU0828_V4L2
 	dev->v4l2_dev.release = au0828_usb_v4l2_release;
@@ -446,9 +439,17 @@ static int au0828_usb_probe(struct usb_interface *interface,
 	if (retval) {
 		pr_err("%s() au0282_dev_register failed to create graph\n",
 		       __func__);
-		au0828_usb_disconnect(interface);
+		goto done;
 	}
 
+#ifdef CONFIG_MEDIA_CONTROLLER
+	retval = media_device_register(dev->media_dev);
+#endif
+
+done:
+	if (retval < 0)
+		au0828_usb_disconnect(interface);
+
 	return retval;
 }
 
diff --git a/drivers/media/usb/cx231xx/cx231xx-cards.c b/drivers/media/usb/cx231xx/cx231xx-cards.c
index 0e1efc59ff58..de0026b5265c 100644
--- a/drivers/media/usb/cx231xx/cx231xx-cards.c
+++ b/drivers/media/usb/cx231xx/cx231xx-cards.c
@@ -1172,6 +1172,7 @@ static void cx231xx_unregister_media_device(struct cx231xx *dev)
 #ifdef CONFIG_MEDIA_CONTROLLER
 	if (dev->media_dev) {
 		media_device_unregister(dev->media_dev);
+		media_device_cleanup(dev->media_dev);
 		kfree(dev->media_dev);
 		dev->media_dev = NULL;
 	}
@@ -1205,12 +1206,11 @@ void cx231xx_release_resources(struct cx231xx *dev)
 	clear_bit(dev->devno, &cx231xx_devused);
 }
 
-static void cx231xx_media_device_register(struct cx231xx *dev,
-					  struct usb_device *udev)
+static void cx231xx_media_device_init(struct cx231xx *dev,
+				      struct usb_device *udev)
 {
 #ifdef CONFIG_MEDIA_CONTROLLER
 	struct media_device *mdev;
-	int ret;
 
 	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
 	if (!mdev)
@@ -1224,14 +1224,7 @@ static void cx231xx_media_device_register(struct cx231xx *dev,
 	mdev->hw_revision = le16_to_cpu(udev->descriptor.bcdDevice);
 	mdev->driver_version = LINUX_VERSION_CODE;
 
-	ret = media_device_register(mdev);
-	if (ret) {
-		dev_err(dev->dev,
-			"Couldn't create a media device. Error: %d\n",
-			ret);
-		kfree(mdev);
-		return;
-	}
+	media_device_init(mdev);
 
 	dev->media_dev = mdev;
 #endif
@@ -1669,8 +1662,8 @@ static int cx231xx_usb_probe(struct usb_interface *interface,
 	/* save our data pointer in this interface device */
 	usb_set_intfdata(interface, dev);
 
-	/* Register the media controller */
-	cx231xx_media_device_register(dev, udev);
+	/* Initialize the media controller */
+	cx231xx_media_device_init(dev, udev);
 
 	/* Create v4l2 device */
 #ifdef CONFIG_MEDIA_CONTROLLER
@@ -1742,11 +1735,18 @@ static int cx231xx_usb_probe(struct usb_interface *interface,
 	request_modules(dev);
 
 	retval = cx231xx_create_media_graph(dev);
-	if (retval < 0) {
-		cx231xx_release_resources(dev);
-	}
+	if (retval < 0)
+		goto done;
+
+#ifdef CONFIG_MEDIA_CONTROLLER
+	retval = media_device_register(dev->media_dev);
+#endif
 
+done:
+	if (retval < 0)
+		cx231xx_release_resources(dev);
 	return retval;
+
 err_video_alt:
 	/* cx231xx_uninit_dev: */
 	cx231xx_close_extension(dev);
diff --git a/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c b/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c
index 6d3f61f6dc77..7f52bcbd8b0d 100644
--- a/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c
+++ b/drivers/media/usb/dvb-usb-v2/dvb_usb_core.c
@@ -400,13 +400,12 @@ skip_feed_stop:
 	return ret;
 }
 
-static void dvb_usbv2_media_device_register(struct dvb_usb_adapter *adap)
+static void dvb_usbv2_media_device_init(struct dvb_usb_adapter *adap)
 {
 #ifdef CONFIG_MEDIA_CONTROLLER_DVB
 	struct media_device *mdev;
 	struct dvb_usb_device *d = adap_to_d(adap);
 	struct usb_device *udev = d->udev;
-	int ret;
 
 	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
 	if (!mdev)
@@ -420,19 +419,18 @@ static void dvb_usbv2_media_device_register(struct dvb_usb_adapter *adap)
 	mdev->hw_revision = le16_to_cpu(udev->descriptor.bcdDevice);
 	mdev->driver_version = LINUX_VERSION_CODE;
 
-	ret = media_device_register(mdev);
-	if (ret) {
-		dev_err(&d->udev->dev,
-			"Couldn't create a media device. Error: %d\n",
-			ret);
-		kfree(mdev);
-		return;
-	}
+	media_device_init(mdev);
 
 	dvb_register_media_controller(&adap->dvb_adap, mdev);
 
 	dev_info(&d->udev->dev, "media controller created\n");
+#endif
+}
 
+static void dvb_usbv2_media_device_register(struct dvb_usb_adapter *adap)
+{
+#ifdef CONFIG_MEDIA_CONTROLLER_DVB
+	media_device_register(adap->dvb_adap.mdev);
 #endif
 }
 
@@ -444,6 +442,7 @@ static void dvb_usbv2_media_device_unregister(struct dvb_usb_adapter *adap)
 		return;
 
 	media_device_unregister(adap->dvb_adap.mdev);
+	media_device_cleanup(adap->dvb_adap.mdev);
 	kfree(adap->dvb_adap.mdev);
 	adap->dvb_adap.mdev = NULL;
 
@@ -467,7 +466,7 @@ static int dvb_usbv2_adapter_dvb_init(struct dvb_usb_adapter *adap)
 
 	adap->dvb_adap.priv = adap;
 
-	dvb_usbv2_media_device_register(adap);
+	dvb_usbv2_media_device_init(adap);
 
 	if (d->props->read_mac_address) {
 		ret = d->props->read_mac_address(adap,
@@ -702,6 +701,8 @@ static int dvb_usbv2_adapter_frontend_init(struct dvb_usb_adapter *adap)
 	if (ret < 0)
 		goto err_dvb_unregister_frontend;
 
+	dvb_usbv2_media_device_register(adap);
+
 	return 0;
 
 err_dvb_unregister_frontend:
diff --git a/drivers/media/usb/dvb-usb/dvb-usb-dvb.c b/drivers/media/usb/dvb-usb/dvb-usb-dvb.c
index b51dbdf03f42..6a4bb2d86175 100644
--- a/drivers/media/usb/dvb-usb/dvb-usb-dvb.c
+++ b/drivers/media/usb/dvb-usb/dvb-usb-dvb.c
@@ -95,13 +95,12 @@ static int dvb_usb_stop_feed(struct dvb_demux_feed *dvbdmxfeed)
 	return dvb_usb_ctrl_feed(dvbdmxfeed, 0);
 }
 
-static void dvb_usb_media_device_register(struct dvb_usb_adapter *adap)
+static void dvb_usb_media_device_init(struct dvb_usb_adapter *adap)
 {
 #ifdef CONFIG_MEDIA_CONTROLLER_DVB
 	struct media_device *mdev;
 	struct dvb_usb_device *d = adap->dev;
 	struct usb_device *udev = d->udev;
-	int ret;
 
 	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
 	if (!mdev)
@@ -115,20 +114,21 @@ static void dvb_usb_media_device_register(struct dvb_usb_adapter *adap)
 	mdev->hw_revision = le16_to_cpu(udev->descriptor.bcdDevice);
 	mdev->driver_version = LINUX_VERSION_CODE;
 
-	ret = media_device_register(mdev);
-	if (ret) {
-		dev_err(&d->udev->dev,
-			"Couldn't create a media device. Error: %d\n",
-			ret);
-		kfree(mdev);
-		return;
-	}
+	media_device_init(mdev);
+
 	dvb_register_media_controller(&adap->dvb_adap, mdev);
 
 	dev_info(&d->udev->dev, "media controller created\n");
 #endif
 }
 
+static void dvb_usb_media_device_register(struct dvb_usb_adapter *adap)
+{
+#ifdef CONFIG_MEDIA_CONTROLLER_DVB
+	media_device_register(adap->dvb_adap.mdev);
+#endif
+}
+
 static void dvb_usb_media_device_unregister(struct dvb_usb_adapter *adap)
 {
 #ifdef CONFIG_MEDIA_CONTROLLER_DVB
@@ -136,6 +136,7 @@ static void dvb_usb_media_device_unregister(struct dvb_usb_adapter *adap)
 		return;
 
 	media_device_unregister(adap->dvb_adap.mdev);
+	media_device_cleanup(adap->dvb_adap.mdev);
 	kfree(adap->dvb_adap.mdev);
 	adap->dvb_adap.mdev = NULL;
 #endif
@@ -154,7 +155,7 @@ int dvb_usb_adapter_dvb_init(struct dvb_usb_adapter *adap, short *adapter_nums)
 	}
 	adap->dvb_adap.priv = adap;
 
-	dvb_usb_media_device_register(adap);
+	dvb_usb_media_device_init(adap);
 
 	if (adap->dev->props.read_mac_address) {
 		if (adap->dev->props.read_mac_address(adap->dev, adap->dvb_adap.proposed_mac) == 0)
@@ -323,6 +324,8 @@ int dvb_usb_adapter_frontend_init(struct dvb_usb_adapter *adap)
 
 	ret = dvb_create_media_graph(&adap->dvb_adap);
 
+	dvb_usb_media_device_register(adap);
+
 	return ret;
 }
 
diff --git a/drivers/media/usb/siano/smsusb.c b/drivers/media/usb/siano/smsusb.c
index c945e4c2fbd4..8abbd3cc8eba 100644
--- a/drivers/media/usb/siano/smsusb.c
+++ b/drivers/media/usb/siano/smsusb.c
@@ -361,10 +361,11 @@ static void *siano_media_device_register(struct smsusb_device_t *dev,
 	mdev->hw_revision = le16_to_cpu(udev->descriptor.bcdDevice);
 	mdev->driver_version = LINUX_VERSION_CODE;
 
+	media_device_init(mdev);
+
 	ret = media_device_register(mdev);
 	if (ret) {
-		pr_err("Couldn't create a media device. Error: %d\n",
-			ret);
+		media_device_cleanup(mdev);
 		kfree(mdev);
 		return NULL;
 	}
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 39abbafad796..4e7148815a78 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1656,6 +1656,7 @@ static void uvc_delete(struct uvc_device *dev)
 #ifdef CONFIG_MEDIA_CONTROLLER
 	if (media_devnode_is_registered(&dev->mdev.devnode))
 		media_device_unregister(&dev->mdev);
+	media_device_cleanup(&dev->mdev);
 #endif
 
 	list_for_each_safe(p, n, &dev->chains) {
@@ -1906,7 +1907,7 @@ static int uvc_probe(struct usb_interface *intf,
 			"linux-uvc-devel mailing list.\n");
 	}
 
-	/* Register the media and V4L2 devices. */
+	/* Initialize the media device and register the V4L2 device. */
 #ifdef CONFIG_MEDIA_CONTROLLER
 	dev->mdev.dev = &intf->dev;
 	strlcpy(dev->mdev.model, dev->name, sizeof(dev->mdev.model));
@@ -1916,8 +1917,7 @@ static int uvc_probe(struct usb_interface *intf,
 	strcpy(dev->mdev.bus_info, udev->devpath);
 	dev->mdev.hw_revision = le16_to_cpu(udev->descriptor.bcdDevice);
 	dev->mdev.driver_version = LINUX_VERSION_CODE;
-	if (media_device_register(&dev->mdev) < 0)
-		goto error;
+	media_device_init(&dev->mdev);
 
 	dev->vdev.mdev = &dev->mdev;
 #endif
@@ -1936,6 +1936,11 @@ static int uvc_probe(struct usb_interface *intf,
 	if (uvc_register_chains(dev) < 0)
 		goto error;
 
+#ifdef CONFIG_MEDIA_CONTROLLER
+	/* Register the media device node */
+	if (media_device_register(&dev->mdev) < 0)
+		goto error;
+#endif
 	/* Save our data pointer in the interface data. */
 	usb_set_intfdata(intf, dev);