intel_th: fix device leak on output open()

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

Note that a recent commit fixed the leak in a couple of open() error
paths but not all of them, and the reference is still leaking on
successful open().

Fixes: 39f4034693b7 ("intel_th: Add driver infrastructure for Intel(R) Trace Hub devices")
Fixes: 6d5925b667e4 ("intel_th: Fix error handling in intel_th_output_open")
Cc: stable@vger.kernel.org	# 4.4: 6d5925b667e4
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ma Ke <make24@iscas.ac.cn>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251208153524.68637-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/intel_th/core.c b/drivers/hwtracing/intel_th/core.c
index 591b7c12aae5e45d3cf36c8094b1021b6ee438b4..d9c17214d3dc595e7011cf181d59e8656a3fd43b 100644 (file)
--- a/drivers/hwtracing/intel_th/core.c
+++ b/drivers/hwtracing/intel_th/core.c
@@ -810,9 +810,12 @@ 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 out_no_device;
+               goto out_put_device;
        }
 
        thdrv = to_intel_th_driver(dev->driver);
@@ -836,12 +839,22 @@ static int intel_th_output_open(struct inode *inode, struct file *file)
 
 out_put_device:
        put_device(dev);
-out_no_device:
+
        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,
 };