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

From: Paul Cercueil
Date: Wed Jan 20 2021 - 09:47:46 EST




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