On Fri, 15 Nov 2024, Imre Deak <imre.deak@xxxxxxxxx> wrote:
> Atm when the connector is added to the drm_mode_config::connector_list,
> the connector may not be fully initialized yet. This is not a problem
> for user space, which will see the connector only after it's registered
> later, it could be a problem for in-kernel users looking up connectors
> via the above list.
>
> To resolve the above issue, add a way to separately initialize the DRM
> core specific parts of the connector and add it to the above list. This
> will move adding the connector to the list after the properties on the
> connector have been added, this is ok since these steps don't have a
> dependency.
>
> Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_connector.c | 103 ++++++++++++++++++++++++++------
> include/drm/drm_connector.h | 5 ++
> 2 files changed, 91 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index fc35f47e2849e..6132a7917b20c 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -218,11 +218,11 @@ void drm_connector_free_work_fn(struct work_struct *work)
> }
> }
>
> -static int __drm_connector_init(struct drm_device *dev,
> - struct drm_connector *connector,
> - const struct drm_connector_funcs *funcs,
> - int connector_type,
> - struct i2c_adapter *ddc)
> +static int __drm_connector_init_core(struct drm_device *dev,
> + struct drm_connector *connector,
> + const struct drm_connector_funcs *funcs,
> + int connector_type,
> + struct i2c_adapter *ddc)
> {
> struct drm_mode_config *config = &dev->mode_config;
> int ret;
> @@ -273,6 +273,7 @@ static int __drm_connector_init(struct drm_device *dev,
> /* provide ddc symlink in sysfs */
> connector->ddc = ddc;
>
> + INIT_LIST_HEAD(&connector->head);
> INIT_LIST_HEAD(&connector->global_connector_list_entry);
> INIT_LIST_HEAD(&connector->probed_modes);
> INIT_LIST_HEAD(&connector->modes);
> @@ -288,14 +289,6 @@ static int __drm_connector_init(struct drm_device *dev,
>
> drm_connector_get_cmdline_mode(connector);
>
> - /* We should add connectors at the end to avoid upsetting the connector
> - * index too much.
> - */
> - spin_lock_irq(&config->connector_list_lock);
> - list_add_tail(&connector->head, &config->connector_list);
> - config->num_connector++;
> - spin_unlock_irq(&config->connector_list_lock);
> -
> if (connector_type != DRM_MODE_CONNECTOR_VIRTUAL &&
> connector_type != DRM_MODE_CONNECTOR_WRITEBACK)
> drm_connector_attach_edid_property(connector);
> @@ -332,6 +325,84 @@ static int __drm_connector_init(struct drm_device *dev,
> return ret;
> }
>
> +/**
> + * drm_connector_init_core - Initialize the core state of a preallocated connector
> + * @dev: DRM device
> + * @connector: the connector to init
> + * @funcs: callbacks for this connector
> + * @connector_type: user visible type of the connector
> + *
> + * Initialises the core state of preallocated connector. This is
> + * equivalent to drm_connector_init(), without adding the connector to
> + * drm_mode_config::connector_list. This call must be followed by calling
> + * drm_connector_add() during initialization to expose the connector to
> + * in-kernel users via the above list.
> + *
> + * Returns:
> + * Zero on success, error code on failure.
> + */
> +int drm_connector_init_core(struct drm_device *dev,
> + struct drm_connector *connector,
> + const struct drm_connector_funcs *funcs,
> + int connector_type)
Please include the ddc parameter here, and have callers pass NULL. We
absolutely don't want to see drm_connector_init_core_with_ddc().
> +{
> + if (drm_WARN_ON(dev, !(funcs && funcs->destroy)))
> + return -EINVAL;
> +
> + return __drm_connector_init_core(dev, connector, funcs, connector_type, NULL);
> +}
> +EXPORT_SYMBOL(drm_connector_init_core);
> +
> +/**
> + * drm_connector_add - Add the connector
> + * @connector: the connector to add
> + *
> + * Add the connector to the drm_mode_config::connector_list, exposing the
> + * connector to in-kernel users. This call must be preceded by a call to
> + * drm_connector_init_core().
> + */
> +void drm_connector_add(struct drm_connector *connector)
> +{
> + struct drm_device *dev = connector->dev;
> + struct drm_mode_config *config = &dev->mode_config;
> +
> + spin_lock_irq(&config->connector_list_lock);
> + list_add_tail(&connector->head, &config->connector_list);
> + config->num_connector++;
> + spin_unlock_irq(&config->connector_list_lock);
> +}
> +EXPORT_SYMBOL(drm_connector_add);
> +
> +static void drm_connector_remove(struct drm_connector *connector)
> +{
> + struct drm_device *dev = connector->dev;
> +
> + if (list_empty(&connector->head))
> + return;
> +
> + spin_lock_irq(&dev->mode_config.connector_list_lock);
> + list_del_init(&connector->head);
> + dev->mode_config.num_connector--;
> + spin_unlock_irq(&dev->mode_config.connector_list_lock);
> +}
> +
> +static int __drm_connector_init(struct drm_device *dev,
> + struct drm_connector *connector,
> + const struct drm_connector_funcs *funcs,
> + int connector_type,
> + struct i2c_adapter *ddc)
I'd nuke this wrapper altogether, and put the stuff inline.
Which kind of highlights that drmm_connector_init() still has the same
problem, everyone's encouraged to move towards that, but then what?
> +{
> + int ret;
> +
> + ret = __drm_connector_init_core(dev, connector, funcs, connector_type, ddc);
> + if (ret)
> + return ret;
> +
> + drm_connector_add(connector);
> +
> + return 0;
> +}
> +
> /**
> * drm_connector_init - Init a preallocated connector
> * @dev: DRM device
> @@ -659,10 +730,8 @@ void drm_connector_cleanup(struct drm_connector *connector)
> connector->name = NULL;
> fwnode_handle_put(connector->fwnode);
> connector->fwnode = NULL;
> - spin_lock_irq(&dev->mode_config.connector_list_lock);
> - list_del(&connector->head);
> - dev->mode_config.num_connector--;
> - spin_unlock_irq(&dev->mode_config.connector_list_lock);
> +
> + drm_connector_remove(connector);
>
> WARN_ON(connector->state && !connector->funcs->atomic_destroy_state);
> if (connector->state && connector->funcs->atomic_destroy_state)
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index e3fa43291f449..8e8d130b40f98 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -2122,6 +2122,11 @@ struct drm_connector {
>
> #define obj_to_connector(x) container_of(x, struct drm_connector, base)
>
> +int drm_connector_init_core(struct drm_device *dev,
> + struct drm_connector *connector,
> + const struct drm_connector_funcs *funcs,
> + int connector_type);
> +void drm_connector_add(struct drm_connector *connector);
> int drm_connector_init(struct drm_device *dev,
> struct drm_connector *connector,
> const struct drm_connector_funcs *funcs,
--
Jani Nikula, Intel
