<div dir="ltr"><div dir="ltr"> </div> <div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Thu, Mar 27, 2025 at 11:58 AM Maxime Ripard <<a href="mailto:mripard@kernel.org">mripard@kernel.org</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">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 <<a href="mailto:asrivats@redhat.com" target="_blank">asrivats@redhat.com</a>> > --- > 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. </blockquote><div>Maxime, Not really following you. Are you suggesting this explanation needs to be in the helper documentation </div><div>instead of in returns?</div><div> </div><div>Anusha</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> Maxime </blockquote></div></div>