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

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Le mer. 20 janv. 2021 à 15:04, Daniel Vetter <daniel@xxxxxxxx> a écrit :
On Wed, Jan 20, 2021 at 2:21 PM Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote:



 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.

Hm, but using the internal one is also a bit too ugly. A
drm_plain_simple_enocder_alloc(drm, type) wrapper would be the right
thing here I think? Setting the offsets and struct sizes directly in
these in drivers really doesn't feel like a good idea. I think simple
encoder is the only case where we really have a need for a
non-embeddable struct.
-Daniel

Alright, I will add a wrapper.

Cheers,
-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




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





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