[PATCH v3] drm/rockchip: Refactor the component match logic.

Heiko Stuebner
2017-03-15T17:23:27Z

Am Mittwoch, 15. M?rz 2017, 18:00:04 CET schrieb Heiko Stuebner:
> Am Mittwoch, 15. M?rz 2017, 18:20:47 CET schrieb Jeffy Chen:
> > Currently we are adding all components from the dts, if one of their
> > drivers been disabled, we would not be able to bring up others.
> >
> > Refactor component match logic, follow exynos drm.
> >
> > Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
> > Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
>
> This reliably produces null pointer dereference errors in
> __platform_driver_register called from rockchip_drm_init
> on at least rk3036 and rk3288 (probably more) when applied on top of
> Linus' tree from today. Log attached and Rockchip drm compiled as module.
>
> I'm currently dug into other areas, so hadn't have time to investigate
> further yet.

> +#define DRV_PTR(drv, cond) (IS_ENABLED(cond) ? &drv : NULL)
> +
> +static struct platform_driver *rockchip_drm_comp_drvs[] = {
> + &vop_platform_driver,
> + DRV_PTR(rockchip_dp_driver, CONFIG_ROCKCHIP_ANALOGIX_DP),
> + DRV_PTR(cdn_dp_driver, CONFIG_ROCKCHIP_CDN_DP),
> + DRV_PTR(dw_hdmi_rockchip_pltfm_driver, CONFIG_ROCKCHIP_DW_HDMI),
> + DRV_PTR(dw_mipi_dsi_driver, CONFIG_ROCKCHIP_DW_MIPI_DSI),
> + DRV_PTR(inno_hdmi_driver, CONFIG_ROCKCHIP_INNO_HDMI),
> +};

[...]

> +static int rockchip_drm_register_drivers(void)
> +{
> + int i, ret;
> +
> + for (i = 0; i < ARRAY_SIZE(rockchip_drm_comp_drvs); i++) {
> + ret = platform_driver_register(rockchip_drm_comp_drvs[i]);
> + if (ret)
> + goto err_unreg;
> + }

This of course won't work in the NULL case, as platform_driver_register always
dereferences its parameter [0], so you should only call it for the actual non-
null array elements - of course same for unregister.

Heiko

[0] http://lxr.free-electrons.com/source/drivers/base/platform.c#L617