[PATCH] drm/loongson: clean up KMS polling on probe failure

[Myeonghun Pak <mhun512@gmail.com>]

lsdc_pci_probe() initializes KMS polling before setting up vblank support,
requesting the IRQ and registering the DRM device. If any of those later
steps fails, probe returns without finalizing polling. The remove path has
the same lifetime gap when tearing down a successfully registered device.

Route those probe failures through a poll cleanup label. Also finalize
polling from remove before unregistering the DRM device.

This issue was identified during our ongoing static-analysis research while
reviewing kernel code.

Fixes: f39db26c5428 ("drm: Add kms driver for loongson display controller")
Cc: stable@vger.kernel.org
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
---
 drivers/gpu/drm/loongson/lsdc_drv.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/loongson/lsdc_drv.c b/drivers/gpu/drm/loongson/lsdc_drv.c
index abf5bf68ee..3db1f8690a 100644
--- a/drivers/gpu/drm/loongson/lsdc_drv.c
+++ b/drivers/gpu/drm/loongson/lsdc_drv.c
@@ -297,7 +297,7 @@ static int lsdc_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (loongson_vblank) {
 		ret = drm_vblank_init(ddev, descp->num_of_crtc);
 		if (ret)
-			return ret;
+			goto err_poll_fini;
 
 		ret = devm_request_irq(&pdev->dev, pdev->irq,
 				       descp->funcs->irq_handler,
@@ -305,7 +305,7 @@ static int lsdc_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 				       dev_name(&pdev->dev), ddev);
 		if (ret) {
 			drm_err(ddev, "Failed to register interrupt: %d\n", ret);
-			return ret;
+			goto err_poll_fini;
 		}
 
 		drm_info(ddev, "registered irq: %u\n", pdev->irq);
@@ -313,17 +313,22 @@ static int lsdc_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	ret = drm_dev_register(ddev, 0);
 	if (ret)
-		return ret;
+		goto err_poll_fini;
 
 	drm_client_setup(ddev, NULL);
 
 	return 0;
+
+err_poll_fini:
+	drm_kms_helper_poll_fini(ddev);
+	return ret;
 }
 
 static void lsdc_pci_remove(struct pci_dev *pdev)
 {
 	struct drm_device *ddev = pci_get_drvdata(pdev);
 
+	drm_kms_helper_poll_fini(ddev);
 	drm_dev_unregister(ddev);
 	drm_atomic_helper_shutdown(ddev);
 }
-- 
2.47.1