Commit 80805b62 authored by AngeloGioacchino Del Regno's avatar AngeloGioacchino Del Regno Committed by Chun-Kuang Hu
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drm/mediatek: Fix kobject put for component sub-drivers 



In function mtk_drm_get_all_drm_priv(), this driver is incrementing
the refcount for the sub-drivers of mediatek-drm with a call to
device_find_child() when taking a reference to all of those child
devices.

When the component bind fails multiple times this results in a
refcount_t overflow, as the reference count is never decremented:
fix that by adding a call to put_device() for all of the mmsys
devices in a loop, in error cases of mtk_drm_bind() and in the
mtk_drm_unbind() callback.

Fixes: 1ef7ed48 ("drm/mediatek: Modify mediatek-drm for mt8195 multi mmsys support")
Reviewed-by: default avatarChen-Yu Tsai <wenst@chromium.org>
Signed-off-by: default avatarAngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20250403104741.71045-3-angelogioacchino.delregno@collabora.com/


Signed-off-by: default avatarChun-Kuang Hu <chunkuang.hu@kernel.org>
parent 22918591

drivers/gpu/drm/mediatek/mtk_drm_drv.c

+9 −0
Original line number Diff line number Diff line
@@ -682,6 +682,10 @@ static int mtk_drm_bind(struct device *dev) 
	for (i = 0; i < private->data->mmsys_dev_num; i++)

		private->all_drm_private[i]->drm = NULL;

err_put_dev:

	for (i = 0; i < private->data->mmsys_dev_num; i++) {

		/* For device_find_child in mtk_drm_get_all_priv() */

		put_device(private->all_drm_private[i]->dev);

	}

	put_device(private->mutex_dev);

	return ret;

}
@@ -689,6 +693,7 @@ static int mtk_drm_bind(struct device *dev) 
static void mtk_drm_unbind(struct device *dev)

{

	struct mtk_drm_private *private = dev_get_drvdata(dev);

	int i;



	/* for multi mmsys dev, unregister drm dev in mmsys master */

	if (private->drm_master) {
@@ -696,6 +701,10 @@ static void mtk_drm_unbind(struct device *dev) 
		mtk_drm_kms_deinit(private->drm);

		drm_dev_put(private->drm);



		for (i = 0; i < private->data->mmsys_dev_num; i++) {

			/* For device_find_child in mtk_drm_get_all_priv() */

			put_device(private->all_drm_private[i]->dev);

		}

		put_device(private->mutex_dev);

	}

	private->mtk_drm_bound = false;