[PATCH/RFC 1/7] dsbr100: implement proper locking

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Signed-off-by: David Ellingsworth <david@xxxxxxxxxxxxxxxxx>
---
 drivers/media/radio/dsbr100.c |   77 +++++++++++++++++-----------------------
 1 files changed, 33 insertions(+), 44 deletions(-)

diff --git a/drivers/media/radio/dsbr100.c b/drivers/media/radio/dsbr100.c
index ed9cd7a..673eda8 100644
--- a/drivers/media/radio/dsbr100.c
+++ b/drivers/media/radio/dsbr100.c
@@ -182,7 +182,7 @@ static int dsbr100_start(struct dsbr100_device *radio)
 	int retval;
 	int request;
 
-	mutex_lock(&radio->lock);
+	BUG_ON(!mutex_is_locked(&radio->lock));
 
 	retval = usb_control_msg(radio->usbdev,
 		usb_rcvctrlpipe(radio->usbdev, 0),
@@ -207,11 +207,9 @@ static int dsbr100_start(struct dsbr100_device *radio)
 	}
 
 	radio->status = STARTED;
-	mutex_unlock(&radio->lock);
 	return (radio->transfer_buffer)[0];
 
 usb_control_msg_failed:
-	mutex_unlock(&radio->lock);
 	dev_err(&radio->usbdev->dev,
 		"%s - usb_control_msg returned %i, request %i\n",
 			__func__, retval, request);
@@ -225,7 +223,7 @@ static int dsbr100_stop(struct dsbr100_device *radio)
 	int retval;
 	int request;
 
-	mutex_lock(&radio->lock);
+	BUG_ON(!mutex_is_locked(&radio->lock));
 
 	retval = usb_control_msg(radio->usbdev,
 		usb_rcvctrlpipe(radio->usbdev, 0),
@@ -250,11 +248,9 @@ static int dsbr100_stop(struct dsbr100_device *radio)
 	}
 
 	radio->status = STOPPED;
-	mutex_unlock(&radio->lock);
 	return (radio->transfer_buffer)[0];
 
 usb_control_msg_failed:
-	mutex_unlock(&radio->lock);
 	dev_err(&radio->usbdev->dev,
 		"%s - usb_control_msg returned %i, request %i\n",
 			__func__, retval, request);
@@ -269,7 +265,7 @@ static int dsbr100_setfreq(struct dsbr100_device *radio)
 	int request;
 	int freq = (radio->curfreq / 16 * 80) / 1000 + 856;
 
-	mutex_lock(&radio->lock);
+	BUG_ON(!mutex_is_locked(&radio->lock));
 
 	retval = usb_control_msg(radio->usbdev,
 		usb_rcvctrlpipe(radio->usbdev, 0),
@@ -306,12 +302,10 @@ static int dsbr100_setfreq(struct dsbr100_device *radio)
 	}
 
 	radio->stereo = !((radio->transfer_buffer)[0] & 0x01);
-	mutex_unlock(&radio->lock);
 	return (radio->transfer_buffer)[0];
 
 usb_control_msg_failed:
 	radio->stereo = -1;
-	mutex_unlock(&radio->lock);
 	dev_err(&radio->usbdev->dev,
 		"%s - usb_control_msg returned %i, request %i\n",
 			__func__, retval, request);
@@ -324,7 +318,7 @@ static void dsbr100_getstat(struct dsbr100_device *radio)
 {
 	int retval;
 
-	mutex_lock(&radio->lock);
+	BUG_ON(!mutex_is_locked(&radio->lock));
 
 	retval = usb_control_msg(radio->usbdev,
 		usb_rcvctrlpipe(radio->usbdev, 0),
@@ -340,8 +334,6 @@ static void dsbr100_getstat(struct dsbr100_device *radio)
 	} else {
 		radio->stereo = !(radio->transfer_buffer[0] & 0x01);
 	}
-
-	mutex_unlock(&radio->lock);
 }
 
 /* USB subsystem interface begins here */
@@ -385,10 +377,6 @@ 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;
 
@@ -410,12 +398,6 @@ 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;
 
@@ -428,17 +410,12 @@ static int vidioc_s_frequency(struct file *file, void *priv,
 	struct dsbr100_device *radio = video_drvdata(file);
 	int retval;
 
-	/* safety check */
-	if (radio->removed)
-		return -EIO;
-
-	mutex_lock(&radio->lock);
 	radio->curfreq = f->frequency;
-	mutex_unlock(&radio->lock);
 
 	retval = dsbr100_setfreq(radio);
 	if (retval < 0)
 		dev_warn(&radio->usbdev->dev, "Set frequency failed\n");
+
 	return 0;
 }
 
@@ -447,10 +424,6 @@ 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;
@@ -472,10 +445,6 @@ 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->status;
@@ -490,10 +459,6 @@ static int vidioc_s_ctrl(struct file *file, void *priv,
 	struct dsbr100_device *radio = video_drvdata(file);
 	int retval;
 
-	/* safety check */
-	if (radio->removed)
-		return -EIO;
-
 	switch (ctrl->id) {
 	case V4L2_CID_AUDIO_MUTE:
 		if (ctrl->value) {
@@ -513,6 +478,7 @@ static int vidioc_s_ctrl(struct file *file, void *priv,
 		}
 		return 0;
 	}
+
 	return -EINVAL;
 }
 
@@ -548,12 +514,34 @@ static int vidioc_s_audio(struct file *file, void *priv,
 	return 0;
 }
 
+static long usb_dsbr100_ioctl(struct file *file, unsigned int cmd,
+				unsigned long arg)
+{
+	struct dsbr100_device *radio = video_drvdata(file);
+	long retval = 0;
+
+	mutex_lock(&radio->lock);
+
+	if (radio->removed) {
+		retval = -EIO;
+		goto unlock;
+	}
+
+	retval = video_ioctl2(file, cmd, arg);
+
+unlock:
+	mutex_unlock(&radio->lock);
+	return retval;
+}
+
 /* Suspend device - stop device. */
 static int usb_dsbr100_suspend(struct usb_interface *intf, pm_message_t message)
 {
 	struct dsbr100_device *radio = usb_get_intfdata(intf);
 	int retval;
 
+	mutex_lock(&radio->lock);
+
 	if (radio->status == STARTED) {
 		retval = dsbr100_stop(radio);
 		if (retval < 0)
@@ -564,12 +552,10 @@ static int usb_dsbr100_suspend(struct usb_interface *intf, pm_message_t message)
 		 * we set status equal to STARTED.
 		 * On resume we will check status and run radio if needed.
 		 */
-
-		mutex_lock(&radio->lock);
 		radio->status = STARTED;
-		mutex_unlock(&radio->lock);
 	}
 
+	mutex_unlock(&radio->lock);
 	dev_info(&intf->dev, "going into suspend..\n");
 
 	return 0;
@@ -581,12 +567,15 @@ static int usb_dsbr100_resume(struct usb_interface *intf)
 	struct dsbr100_device *radio = usb_get_intfdata(intf);
 	int retval;
 
+	mutex_lock(&radio->lock);
+
 	if (radio->status == STARTED) {
 		retval = dsbr100_start(radio);
 		if (retval < 0)
 			dev_warn(&intf->dev, "dsbr100_start failed\n");
 	}
 
+	mutex_unlock(&radio->lock);
 	dev_info(&intf->dev, "coming out of suspend..\n");
 
 	return 0;
@@ -605,7 +594,7 @@ static void usb_dsbr100_video_device_release(struct video_device *videodev)
 /* File system interface */
 static const struct v4l2_file_operations usb_dsbr100_fops = {
 	.owner		= THIS_MODULE,
-	.ioctl		= video_ioctl2,
+	.unlocked_ioctl	= usb_dsbr100_ioctl,
 };
 
 static const struct v4l2_ioctl_ops usb_dsbr100_ioctl_ops = {
-- 
1.7.1

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