On Thu, Mar 27, 2025 at 10:55:39AM -0400, Anusha Srivatsa wrote:
> Introduce reference counted allocations for panels to avoid
> use-after-free. The patch adds the macro devm_drm_bridge_alloc()
> to allocate a new refcounted panel. Followed the documentation for
> drmm_encoder_alloc() and devm_drm_dev_alloc and other similar
> implementations for this purpose.
>
> v2: Better documentation for connector_type field - follow drm_panel_init
> documentation. (Luca)
> - Clarify the refcount initialisation in comments.(Maxime)
> - Correct the documentation of the return type (Maxime)
>
> Signed-off-by: Anusha Srivatsa <asriv...@redhat.com>
> ---
> drivers/gpu/drm/drm_panel.c | 25 +++++++++++++++++++++++++
> include/drm/drm_panel.h | 23 +++++++++++++++++++++++
> 2 files changed, 48 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
> index
> c627e42a7ce70459f50eb5095fffc806ca45dabf..bdeab5710ee324dc1742fbc77582250960556308
> 100644
> --- a/drivers/gpu/drm/drm_panel.c
> +++ b/drivers/gpu/drm/drm_panel.c
> @@ -355,6 +355,31 @@ struct drm_panel *of_drm_find_panel(const struct
> device_node *np)
> }
> EXPORT_SYMBOL(of_drm_find_panel);
>
> +void *__devm_drm_panel_alloc(struct device *dev, size_t size, size_t offset,
> + const struct drm_panel_funcs *funcs,
> + int connector_type)
> +{
> + void *container;
> + struct drm_panel *panel;
> +
> + if (!funcs) {
> + dev_warn(dev, "Missing funcs pointer\n");
> + return ERR_PTR(-EINVAL);
> + }
> +
> + container = devm_kzalloc(dev, size, GFP_KERNEL);
> + if (!container)
> + return ERR_PTR(-ENOMEM);
> +
> + panel = container + offset;
> + panel->funcs = funcs;
> +
> + drm_panel_init(panel, dev, funcs, connector_type);
> +
> + return container;
> +}
> +EXPORT_SYMBOL(__devm_drm_panel_alloc);
> +
> /**
> * of_drm_get_panel_orientation - look up the orientation of the panel
> through
> * the "rotation" binding from a device tree node
> diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
> index
> a9c042c8dea1a82ef979c7a68204e0b55483fc28..53251c6b11d78149ede3dad41ffa6a88f3c3c58b
> 100644
> --- a/include/drm/drm_panel.h
> +++ b/include/drm/drm_panel.h
> @@ -28,6 +28,7 @@
> #include <linux/errno.h>
> #include <linux/list.h>
> #include <linux/mutex.h>
> +#include <linux/kref.h>
>
> struct backlight_device;
> struct dentry;
> @@ -268,6 +269,28 @@ struct drm_panel {
> bool enabled;
> };
>
> +void *__devm_drm_panel_alloc(struct device *dev, size_t size, size_t offset,
> + const struct drm_panel_funcs *funcs,
> + int connector_type);
> +
> +/**
> + * devm_drm_panel_alloc - Allocate and initialize an refcounted panel
> + * @dev: struct device of the panel device
> + * @type: the type of the struct which contains struct &drm_panel
> + * @member: the name of the &drm_panel within @type
> + * @funcs: callbacks for this panel
> + * @connector_type: the connector type (DRM_MODE_CONNECTOR_*) corresponding
> to
> + * the panel interface
> + * Returns:
> + * Pointer to container structure embedding the panel, ERR_PTR on failure.
> + * The reference count is initialised to 1 and is automatically given back
> + * by devm action.Sorry, I noticed after the facts, but this can't be in the Returns section, it needs to be in the main one. Maxime
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