Re: [PATCH v2 2/3] drm/ingenic: Register devm action to cleanup encoders

[Paul Cercueil]

Le mer. 20 janv. 2021 à 14:01, Daniel Vetter <daniel@xxxxxxxx> a 
écrit :
> On Wed, Jan 20, 2021 at 1:36 PM Paul Cercueil <paul@xxxxxxxxxxxxxxx> 
> wrote:
> >  Since the encoders have been devm-allocated, they will be freed way
> >  before drm_mode_config_cleanup() is called. To avoid use-after-free
> >  conditions, we then must ensure that drm_encoder_cleanup() is called
> >  before the encoders are freed.
> >
> >  v2: Use the new __drmm_simple_encoder_alloc() function
> >
> >  Fixes: c369cb27c267 ("drm/ingenic: Support multiple panels/bridges")
> >  Cc: <stable@xxxxxxxxxxxxxxx> # 5.8+
> >  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >  ---
> >
> >  Notes:
> >      Use the V1 of this patch to fix v5.11 and older kernels. This 
> > V2 only
> >      applies on the current drm-misc-next branch.
> >
> >   drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 16 +++++++---------
> >   1 file changed, 7 insertions(+), 9 deletions(-)
> >
> >  diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c 
> > b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> >  index 7bb31fbee29d..158433b4c084 100644
> >  --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> >  +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> >  @@ -1014,20 +1014,18 @@ static int ingenic_drm_bind(struct device 
> > *dev, bool has_components)
> >                          bridge = 
> > devm_drm_panel_bridge_add_typed(dev, panel,
> >                                                                   
> > DRM_MODE_CONNECTOR_DPI);
> >
> >  -               encoder = devm_kzalloc(dev, sizeof(*encoder), 
> > GFP_KERNEL);
> >  -               if (!encoder)
> >  -                       return -ENOMEM;
> >  +               encoder = __drmm_simple_encoder_alloc(drm, 
> > sizeof(*encoder), 0,
>
> Please don't use the __ prefixed functions, those are the internal
> ones. The official one comes with type checking and all that included.
> Otherwise lgtm.
> -Daniel

The non-prefixed one assumes that I want to allocate a struct that 
contains the encoder, not just the drm_encoder itself.

-Paul

> >  +                                                     
> > DRM_MODE_ENCODER_DPI);
> >  +               if (IS_ERR(encoder)) {
> >  +                       ret = PTR_ERR(encoder);
> >  +                       dev_err(dev, "Failed to init encoder: 
> > %d\n", ret);
> >  +                       return ret;
> >  +               }
> >
> >                  encoder->possible_crtcs = 1;
> >
> >                  drm_encoder_helper_add(encoder, 
> > &ingenic_drm_encoder_helper_funcs);
> >
> >  -               ret = drm_simple_encoder_init(drm, encoder, 
> > DRM_MODE_ENCODER_DPI);
> >  -               if (ret) {
> >  -                       dev_err(dev, "Failed to init encoder: 
> > %d\n", ret);
> >  -                       return ret;
> >  -               }
> >  -
> >                  ret = drm_bridge_attach(encoder, bridge, NULL, 0);
> >                  if (ret) {
> >                          dev_err(dev, "Unable to attach bridge\n");
> >  --
> >  2.29.2
>
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch