[PATCH v6 RESEND] media: pci: intel: ivsc: improve device reference counting in mei_ace driver

[PATCH v6 RESEND] media: pci: intel: ivsc: improve device reference counting in mei_ace driver

[Ma Ke]

Put the reference to csi_dev acquired during driver probe in
mei_ace_setup_dev_link() inside the same function, instead of during
driver unbind in mei_ace_remove(). This can be done as
device_link_add() already takes a reference to csi_dev.

Found by code review.

Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
Changes in v6:
- modified the commit message as suggestions;
Changes in v5:
- jumped to err instead of err_put to avoid calling put_device() again in err_put as reviewer's instructions;
Changes in v4:
- updated the subject as suggestions;
Changes in v3:
- deleted the tag of Fixes and CC, and moved put_device() to immediately after device_link_add() as suggestions;
Changes in v2:
- modified the put_device() operations and the patch title as suggestions.
---
 drivers/media/pci/intel/ivsc/mei_ace.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/pci/intel/ivsc/mei_ace.c b/drivers/media/pci/intel/ivsc/mei_ace.c
index 98310b8511b1..b306a320b70f 100644
--- a/drivers/media/pci/intel/ivsc/mei_ace.c
+++ b/drivers/media/pci/intel/ivsc/mei_ace.c
@@ -414,10 +414,11 @@ static int mei_ace_setup_dev_link(struct mei_ace *ace)
 	/* setup link between mei_ace and mei_csi */
 	ace->csi_link = device_link_add(csi_dev, dev, DL_FLAG_PM_RUNTIME |
 					DL_FLAG_RPM_ACTIVE | DL_FLAG_STATELESS);
+	put_device(csi_dev);
 	if (!ace->csi_link) {
 		ret = -EINVAL;
 		dev_err(dev, "failed to link to %s\n", dev_name(csi_dev));
-		goto err_put;
+		goto err;
 	}
 
 	ace->csi_dev = csi_dev;
@@ -522,7 +523,6 @@ static void mei_ace_remove(struct mei_cl_device *cldev)
 	cancel_work_sync(&ace->work);
 
 	device_link_del(ace->csi_link);
-	put_device(ace->csi_dev);
 
 	pm_runtime_disable(&cldev->dev);
 	pm_runtime_set_suspended(&cldev->dev);
-- 
2.17.1

Re: [PATCH v6 RESEND] media: pci: intel: ivsc: improve device reference counting in mei_ace driver

[Sakari Ailus]

Hi Ma,

On Wed, Oct 22, 2025 at 05:25:45PM +0800, Ma Ke wrote:
> Put the reference to csi_dev acquired during driver probe in
> mei_ace_setup_dev_link() inside the same function, instead of during
> driver unbind in mei_ace_remove(). This can be done as
> device_link_add() already takes a reference to csi_dev.
> 
> Found by code review.
> 
> Signed-off-by: Ma Ke <make24@iscas.ac.cn>
> ---
> Changes in v6:
> - modified the commit message as suggestions;
> Changes in v5:
> - jumped to err instead of err_put to avoid calling put_device() again in err_put as reviewer's instructions;
> Changes in v4:
> - updated the subject as suggestions;
> Changes in v3:
> - deleted the tag of Fixes and CC, and moved put_device() to immediately after device_link_add() as suggestions;
> Changes in v2:
> - modified the put_device() operations and the patch title as suggestions.

v5 of this patch has been already merged with a modified commit message;
there's no need to resend this anymore.

-- 
Kind regards,

Sakari Ailus