2025년 9월 29일 (월) 오후 1:54, Hoyoung Lee <[email protected]>님이 작성: > > Switch mode-config initialization to drmm_mode_config_init() so that the > lifetime is tied to drm_device. Remove explicit drm_mode_config_cleanup() > from error and unbind paths since cleanup is now managed by DRM. > > No functional change intended. > > Signed-off-by: Hoyoung Lee <[email protected]> > --- > drivers/gpu/drm/exynos/exynos_drm_drv.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c > b/drivers/gpu/drm/exynos/exynos_drm_drv.c > index 6cc7bf77bcac..1aea71778ab1 100644 > --- a/drivers/gpu/drm/exynos/exynos_drm_drv.c > +++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c > @@ -257,7 +257,7 @@ static int exynos_drm_bind(struct device *dev) > dev_set_drvdata(dev, drm); > drm->dev_private = (void *)private; > > - drm_mode_config_init(drm); > + drmm_mode_config_init(drm); > > exynos_drm_mode_config_init(drm); > > @@ -297,7 +297,6 @@ static int exynos_drm_bind(struct device *dev) > err_unbind_all: > component_unbind_all(drm->dev, drm); > err_mode_config_cleanup: > - drm_mode_config_cleanup(drm);
In the current implementation, there is a potential dereference issue because the private object may be freed before to_dma_dev(dev) is called. When drmm_mode_config_init() is invoked, it registers drm_mode_config_cleanup() as a managed action. This means that the cleanup function will be automatically executed later when drm_dev_put() is called. The problem arises when drm_dev_put() is called without explicitly invoking drm_mode_config_cleanup() first, as in the original code. In that case, the managed cleanup is performed later, which allows to_dma_dev(dev) to be called after the private object has already been released. For reference, the following sequence may occur internally when drm_mode_config_cleanup() is executed: 1. drm_mode_config_cleanup() is called. 2. During the cleanup of FBs, planes, CRTCs, encoders, and connectors, framebuffers or GEM objects may be released. 3. At this point, Exynos-specific code could invoke to_dma_dev(dev). Therefore, the private object must remain valid until drm_mode_config_cleanup() completes. It would be safer to adjust the code so that kfree(private) is performed after drm_dev_put(drm) to ensure the private data remains available during cleanup. Thanks, Inki Dae > exynos_drm_cleanup_dma(drm); > kfree(private); > dev_set_drvdata(dev, NULL); > @@ -317,7 +316,6 @@ static void exynos_drm_unbind(struct device *dev) > drm_atomic_helper_shutdown(drm); > > component_unbind_all(drm->dev, drm); > - drm_mode_config_cleanup(drm); Ditto. > exynos_drm_cleanup_dma(drm); > > kfree(drm->dev_private); > -- > 2.34.1 > >
