On 7/18/25 1:22 AM, Ma Ke wrote:

Using device_find_child() to locate a probed virtual-device-port node causes a device refcount imbalance, as device_find_child() internally calls get_device() to increment the device’s reference count before returning its pointer. vdc_port_mpgroup_check() directly returns true upon finding a matching device without releasing the reference via put_device(). We should call put_device() to decrement refcount.

As comment of device_find_child() says, 'NOTE: you will need to drop the reference with put_device() after use'.

Found by code review.

Cc: stable@vger.kernel.org Fixes: 3ee70591d6c4 ("sunvdc: prevent sunvdc panic when mpgroup disk added to guest domain") Signed-off-by: Ma Ke make24@iscas.ac.cn

---

drivers/block/sunvdc.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/block/sunvdc.c b/drivers/block/sunvdc.c index b5727dea15bd..b6dbd5dd2723 100644 --- a/drivers/block/sunvdc.c +++ b/drivers/block/sunvdc.c @@ -950,6 +950,7 @@ static bool vdc_port_mpgroup_check(struct vio_dev *vdev) { struct vdc_check_port_data port_data; struct device *dev;

• bool found = false;

port_data.dev_no = vdev->dev_no; port_data.type = (char *)&vdev->type; @@ -957,10 +958,12 @@ static bool vdc_port_mpgroup_check(struct vio_dev *vdev) dev = device_find_child(vdev->dev.parent, &port_data, vdc_device_probed);

• if (dev)

• return true;
  

• if (dev) {

• found = true;
  

• put_device(dev);
  

• }

• return false;

• return found;

Don't bother with adding the extra bits just to get a single point of exit: keep with the existing style and keep the change simple.

if (dev) {     put_device(dev);     return true; }

(and why am I getting copied on a block device change?)

sln

} static int vdc_port_probe(struct vio_dev *vdev, const struct vio_device_id *id)