Make sure to drop the reference taken when looking up the th device
during output device open() on errors and on close().

Fixes: 39f4034693b7 ("intel_th: Add driver infrastructure for Intel(R) Trace Hub devices")
Cc: stable@vger.kernel.org	# 4.4
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/hwtracing/intel_th/core.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/intel_th/core.c b/drivers/hwtracing/intel_th/core.c
index 47d9e6c3bac0..ddc51de2d775 100644
--- a/drivers/hwtracing/intel_th/core.c
+++ b/drivers/hwtracing/intel_th/core.c
@@ -810,13 +810,20 @@ static int intel_th_output_open(struct inode *inode, struct file *file)
 	int err;
 
 	dev = bus_find_device_by_devt(&intel_th_bus, inode->i_rdev);
-	if (!dev || !dev->driver)
+	if (!dev)
 		return -ENODEV;
 
+	if (!dev->driver) {
+		err = -ENODEV;
+		goto err_put_dev;
+	}
+
 	thdrv = to_intel_th_driver(dev->driver);
 	fops = fops_get(thdrv->fops);
-	if (!fops)
-		return -ENODEV;
+	if (!fops) {
+		err = -ENODEV;
+		goto err_put_dev;
+	}
 
 	replace_fops(file, fops);
 
@@ -827,11 +834,26 @@ static int intel_th_output_open(struct inode *inode, struct file *file)
 		return err;
 	}
 
+	return 0;
+
+err_put_dev:
+	put_device(dev);
+
+	return err;
+}
+
+static int intel_th_output_release(struct inode *inode, struct file *file)
+{
+	struct intel_th_device *thdev = file->private_data;
+
+	put_device(&thdev->dev);
+
 	return 0;
 }
 
 static const struct file_operations intel_th_output_fops = {
 	.open	= intel_th_output_open,
+	.release = intel_th_output_release,
 	.llseek	= noop_llseek,
 };
 
-- 
2.51.2