From 80805b62ea5b95eda54c225b989f929ca0691ab0 Mon Sep 17 00:00:00 2001 From: AngeloGioacchino Del Regno Date: Thu, 3 Apr 2025 12:47:38 +0200 Subject: [PATCH] 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: 1ef7ed48356c ("drm/mediatek: Modify mediatek-drm for mt8195 multi mmsys support") Reviewed-by: Chen-Yu Tsai Signed-off-by: AngeloGioacchino Del Regno Link: https://patchwork.kernel.org/project/dri-devel/patch/20250403104741.71045-3-angelogioacchino.delregno@collabora.com/ Signed-off-by: Chun-Kuang Hu --- drivers/gpu/drm/mediatek/mtk_drm_drv.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c index 5994e2a97dc1..593193555c07 100644 --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -682,6 +682,10 @@ err_free: 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 @@ err_put_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; -- 2.25.1