[PATCH] drm/fb-helper: generic: Call drm_client_add() after setup is done

[Daniel Vetter]

On Mon, Apr 01, 2019 at 04:13:58PM +0200, Noralf Trønnes wrote:
> Hotplug can happen while drm_fbdev_generic_setup() is running so move
> drm_client_add() call after setup is done to avoid
> drm_fbdev_client_hotplug() running in two threads at the same time.
> 
> Fixes: 9060d7f49376 ("drm/fb-helper: Finish the generic fbdev emulation")
> Reported-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>

Not sure we even want a cc: stable on this, things could go boom. I guess
we could backport once there's a bug report, up to you.

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  drivers/gpu/drm/drm_fb_helper.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 03749a24e4dd..601b17310411 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -3317,8 +3317,6 @@ int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
>  		return ret;
>  	}
>  
> -	drm_client_add(&fb_helper->client);
> -
>  	if (!preferred_bpp)
>  		preferred_bpp = dev->mode_config.preferred_depth;
>  	if (!preferred_bpp)
> @@ -3329,6 +3327,8 @@ int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
>  	if (ret)
>  		DRM_DEV_DEBUG(dev->dev, "client hotplug ret=%d\n", ret);
>  
> +	drm_client_add(&fb_helper->client);
> +
>  	return 0;
>  }
>  EXPORT_SYMBOL(drm_fbdev_generic_setup);
> -- 
> 2.20.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch