V4L/DVB (10054): dsbr100: fix unplug oops

This patch corrects unplug procedure. Patch adds
usb_dsbr100_video_device_release, new macros - videodev_to_radio, mutex
lock and a lot of safety checks.
Struct video_device videodev is embedded in dsbr100_device structure.
Signed-off-by: Alexey Klimov <klimov.linux@gmail.com>
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/radio/dsbr100.c

@@ -145,6 +145,7 @@ devices, that would be 76 and 91.  */
 #define FREQ_MAX 108.0
 #define FREQ_MUL 16000
 
+#define videodev_to_radio(d) container_of(d, struct dsbr100_device, videodev)
 
 static int usb_dsbr100_probe(struct usb_interface *intf,
 			     const struct usb_device_id *id);
@@ -161,8 +162,9 @@ module_param(radio_nr, int, 0);
 /* Data for one (physical) device */
 struct dsbr100_device {
 	struct usb_device *usbdev;
-	struct video_device *videodev;
+	struct video_device videodev;
 	u8 *transfer_buffer;
+	struct mutex lock;	/* buffer locking */
 	int curfreq;
 	int stereo;
 	int users;
@@ -195,6 +197,7 @@ static struct usb_driver usb_dsbr100_driver = {
 /* switch on radio */
 static int dsbr100_start(struct dsbr100_device *radio)
 {
+	mutex_lock(&radio->lock);
 	if (usb_control_msg(radio->usbdev, usb_rcvctrlpipe(radio->usbdev, 0),
 			USB_REQ_GET_STATUS,
 			USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
@@ -202,9 +205,13 @@ static int dsbr100_start(struct dsbr100_device *radio)
 	usb_control_msg(radio->usbdev, usb_rcvctrlpipe(radio->usbdev, 0),
 			DSB100_ONOFF,
 			USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
-			0x01, 0x00, radio->transfer_buffer, 8, 300) < 0)
+			0x01, 0x00, radio->transfer_buffer, 8, 300) < 0) {
+		mutex_unlock(&radio->lock);
 		return -1;
+	}
+
 	radio->muted=0;
+	mutex_unlock(&radio->lock);
 	return (radio->transfer_buffer)[0];
 }
 
@@ -212,6 +219,7 @@ static int dsbr100_start(struct dsbr100_device *radio)
 /* switch off radio */
 static int dsbr100_stop(struct dsbr100_device *radio)
 {
+	mutex_lock(&radio->lock);
 	if (usb_control_msg(radio->usbdev, usb_rcvctrlpipe(radio->usbdev, 0),
 			USB_REQ_GET_STATUS,
 			USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
@@ -219,9 +227,13 @@ static int dsbr100_stop(struct dsbr100_device *radio)
 	usb_control_msg(radio->usbdev, usb_rcvctrlpipe(radio->usbdev, 0),
 			DSB100_ONOFF,
 			USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
-			0x00, 0x00, radio->transfer_buffer, 8, 300) < 0)
+			0x00, 0x00, radio->transfer_buffer, 8, 300) < 0) {
+		mutex_unlock(&radio->lock);
 		return -1;
+	}
+
 	radio->muted=1;
+	mutex_unlock(&radio->lock);
 	return (radio->transfer_buffer)[0];
 }
 
@@ -229,6 +241,7 @@ static int dsbr100_stop(struct dsbr100_device *radio)
 static int dsbr100_setfreq(struct dsbr100_device *radio, int freq)
 {
 	freq = (freq / 16 * 80) / 1000 + 856;
+	mutex_lock(&radio->lock);
 	if (usb_control_msg(radio->usbdev, usb_rcvctrlpipe(radio->usbdev, 0),
 			DSB100_TUNE,
 			USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
@@ -243,9 +256,12 @@ static int dsbr100_setfreq(struct dsbr100_device *radio, int freq)
 			USB_TYPE_VENDOR | USB_RECIP_DEVICE |  USB_DIR_IN,
 			0x00, 0x24, radio->transfer_buffer, 8, 300) < 0) {
 		radio->stereo = -1;
+		mutex_unlock(&radio->lock);
 		return -1;
 	}
+
 	radio->stereo = !((radio->transfer_buffer)[0] & 0x01);
+	mutex_unlock(&radio->lock);
 	return (radio->transfer_buffer)[0];
 }
 
@@ -253,6 +269,7 @@ static int dsbr100_setfreq(struct dsbr100_device *radio, int freq)
 sees a stereo signal or not.  Pity. */
 static void dsbr100_getstat(struct dsbr100_device *radio)
 {
+	mutex_lock(&radio->lock);
 	if (usb_control_msg(radio->usbdev, usb_rcvctrlpipe(radio->usbdev, 0),
 		USB_REQ_GET_STATUS,
 		USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
@@ -260,6 +277,7 @@ static void dsbr100_getstat(struct dsbr100_device *radio)
 		radio->stereo = -1;
 	else
 		radio->stereo = !(radio->transfer_buffer[0] & 0x01);
+	mutex_unlock(&radio->lock);
 }
 
 
@@ -274,16 +292,12 @@ static void usb_dsbr100_disconnect(struct usb_interface *intf)
 	struct dsbr100_device *radio = usb_get_intfdata(intf);
 
 	usb_set_intfdata (intf, NULL);
-	if (radio) {
-		video_unregister_device(radio->videodev);
-		radio->videodev = NULL;
-		if (radio->users) {
-			kfree(radio->transfer_buffer);
-			kfree(radio);
-		} else {
+
+	mutex_lock(&radio->lock);
 	radio->removed = 1;
-		}
-	}
+	mutex_unlock(&radio->lock);
+
+	video_unregister_device(&radio->videodev);
 }
 
 
@@ -303,6 +317,10 @@ static int vidioc_g_tuner(struct file *file, void *priv,
 {
 	struct dsbr100_device *radio = video_drvdata(file);
 
+	/* safety check */
+	if (radio->removed)
+		return -EIO;
+
 	if (v->index > 0)
 		return -EINVAL;
 
@@ -324,6 +342,12 @@ static int vidioc_g_tuner(struct file *file, void *priv,
 static int vidioc_s_tuner(struct file *file, void *priv,
 				struct v4l2_tuner *v)
 {
+	struct dsbr100_device *radio = video_drvdata(file);
+
+	/* safety check */
+	if (radio->removed)
+		return -EIO;
+
 	if (v->index > 0)
 		return -EINVAL;
 
@@ -335,6 +359,10 @@ static int vidioc_s_frequency(struct file *file, void *priv,
 {
 	struct dsbr100_device *radio = video_drvdata(file);
 
+	/* safety check */
+	if (radio->removed)
+		return -EIO;
+
 	radio->curfreq = f->frequency;
 	if (dsbr100_setfreq(radio, radio->curfreq) == -1)
 		dev_warn(&radio->usbdev->dev, "Set frequency failed\n");
@@ -346,6 +374,10 @@ static int vidioc_g_frequency(struct file *file, void *priv,
 {
 	struct dsbr100_device *radio = video_drvdata(file);
 
+	/* safety check */
+	if (radio->removed)
+		return -EIO;
+
 	f->type = V4L2_TUNER_RADIO;
 	f->frequency = radio->curfreq;
 	return 0;
@@ -370,6 +402,10 @@ static int vidioc_g_ctrl(struct file *file, void *priv,
 {
 	struct dsbr100_device *radio = video_drvdata(file);
 
+	/* safety check */
+	if (radio->removed)
+		return -EIO;
+
 	switch (ctrl->id) {
 	case V4L2_CID_AUDIO_MUTE:
 		ctrl->value = radio->muted;
@@ -383,6 +419,10 @@ static int vidioc_s_ctrl(struct file *file, void *priv,
 {
 	struct dsbr100_device *radio = video_drvdata(file);
 
+	/* safety check */
+	if (radio->removed)
+		return -EIO;
+
 	switch (ctrl->id) {
 	case V4L2_CID_AUDIO_MUTE:
 		if (ctrl->value) {
@@ -464,13 +504,19 @@ static int usb_dsbr100_open(struct inode *inode, struct file *file)
 static int usb_dsbr100_close(struct inode *inode, struct file *file)
 {
 	struct dsbr100_device *radio = video_drvdata(file);
+	int retval;
 
 	if (!radio)
 		return -ENODEV;
+
 	radio->users = 0;
-	if (radio->removed) {
-		kfree(radio->transfer_buffer);
-		kfree(radio);
+	if (!radio->removed) {
+		retval = dsbr100_stop(radio);
+		if (retval == -1) {
+			dev_warn(&radio->usbdev->dev,
+				"dsbr100_stop failed\n");
+		}
+
 	}
 	return 0;
 }
@@ -505,6 +551,14 @@ static int usb_dsbr100_resume(struct usb_interface *intf)
 	return 0;
 }
 
+static void usb_dsbr100_video_device_release(struct video_device *videodev)
+{
+	struct dsbr100_device *radio = videodev_to_radio(videodev);
+
+	kfree(radio->transfer_buffer);
+	kfree(radio);
+}
+
 /* File system interface */
 static const struct file_operations usb_dsbr100_fops = {
 	.owner		= THIS_MODULE,
@@ -533,11 +587,11 @@ static const struct v4l2_ioctl_ops usb_dsbr100_ioctl_ops = {
 };
 
 /* V4L2 interface */
-static struct video_device dsbr100_videodev_template = {
+static struct video_device dsbr100_videodev_data = {
 	.name		= "D-Link DSB-R 100",
 	.fops		= &usb_dsbr100_fops,
 	.ioctl_ops 	= &usb_dsbr100_ioctl_ops,
-	.release	= video_device_release,
+	.release	= usb_dsbr100_video_device_release,
 };
 
 /* check if the device is present and register with v4l and
@@ -558,23 +612,17 @@ static int usb_dsbr100_probe(struct usb_interface *intf,
 		kfree(radio);
 		return -ENOMEM;
 	}
-	radio->videodev = video_device_alloc();
 
-	if (!(radio->videodev)) {
-		kfree(radio->transfer_buffer);
-		kfree(radio);
-		return -ENOMEM;
-	}
-	memcpy(radio->videodev, &dsbr100_videodev_template,
-		sizeof(dsbr100_videodev_template));
+	mutex_init(&radio->lock);
+	radio->videodev = dsbr100_videodev_data;
+
 	radio->removed = 0;
 	radio->users = 0;
 	radio->usbdev = interface_to_usbdev(intf);
 	radio->curfreq = FREQ_MIN * FREQ_MUL;
-	video_set_drvdata(radio->videodev, radio);
-	if (video_register_device(radio->videodev, VFL_TYPE_RADIO, radio_nr) < 0) {
+	video_set_drvdata(&radio->videodev, radio);
+	if (video_register_device(&radio->videodev, VFL_TYPE_RADIO, radio_nr) < 0) {
 		dev_warn(&intf->dev, "Could not register video device\n");
-		video_device_release(radio->videodev);
 		kfree(radio->transfer_buffer);
 		kfree(radio);
 		return -EIO;