Hi Yu,

Thank you for the patch.

On Thu, Sep 10, 2020 at 09:23:54PM +0800, Yu Kuai wrote:
> if of_find_device_by_node() succeed, rcar_du_vsp_init() doesn't have
> a corresponding put_device(). Thus add a jump target to fix the exception
> handling for this function implementation.
> 
> Fixes: 6d62ef3ac30b ("drm: rcar-du: Expose the VSP1 compositor through KMS 
> planes")
> Signed-off-by: Yu Kuai <yuku...@huawei.com>
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_vsp.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c 
> b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
> index f1a81c9b184d..172ee3f3b21c 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
> @@ -352,14 +352,16 @@ int rcar_du_vsp_init(struct rcar_du_vsp *vsp, struct 
> device_node *np,
>  
>       /* Find the VSP device and initialize it. */
>       pdev = of_find_device_by_node(np);
> -     if (!pdev)
> -             return -ENXIO;
> +     if (!pdev) {
> +             ret = -ENXIO;
> +             goto put_device;
> +     }

This change isn't needed, and will actually cause a crash, as pdev is
NULL.

>  
>       vsp->vsp = &pdev->dev;
>  
>       ret = vsp1_du_init(vsp->vsp);
>       if (ret < 0)
> -             return ret;
> +             goto put_device;
>  
>        /*
>         * The VSP2D (Gen3) has 5 RPFs, but the VSP1D (Gen2) is limited to
> @@ -369,8 +371,10 @@ int rcar_du_vsp_init(struct rcar_du_vsp *vsp, struct 
> device_node *np,
>  
>       vsp->planes = devm_kcalloc(rcdu->dev, vsp->num_planes,
>                                  sizeof(*vsp->planes), GFP_KERNEL);
> -     if (!vsp->planes)
> -             return -ENOMEM;
> +     if (!vsp->planes) {
> +             ret = -ENOMEM;
> +             goto put_device;
> +     }
>  
>       for (i = 0; i < vsp->num_planes; ++i) {
>               enum drm_plane_type type = i < num_crtcs
> @@ -387,7 +391,7 @@ int rcar_du_vsp_init(struct rcar_du_vsp *vsp, struct 
> device_node *np,
>                                              ARRAY_SIZE(rcar_du_vsp_formats),
>                                              NULL, type, NULL);
>               if (ret < 0)
> -                     return ret;
> +                     goto put_device;
>  
>               drm_plane_helper_add(&plane->plane,
>                                    &rcar_du_vsp_plane_helper_funcs);
> @@ -403,4 +407,7 @@ int rcar_du_vsp_init(struct rcar_du_vsp *vsp, struct 
> device_node *np,
>       }
>  
>       return 0;

I would add a blank line here.

> +put_device:

And maybe name the label "error" ?

> +     put_device(&pdev->dev);
> +     return ret;
>  }

We need more than this, we also need to call put_device() when the
driver is unloaded. The way to handle cleanup in DRM is through
drmm_add_action() nowadays, and I think we could thus simply replace the
change above with a cleanup action that is run both in the error path
and at driver remove.

I'll post a proposal in a reply to this e-mail.

-- 
Regards,

Laurent Pinchart
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