Commit e5ca2635 authored by Johan Hovold's avatar Johan Hovold Committed by Dmitry Baryshkov
Browse files

drm/bridge: aux-hpd: separate allocation and registration 



Combining allocation and registration is an anti-pattern that should be
avoided. Add two new functions for allocating and registering an dp-hpd
bridge with a proper 'devm' prefix so that it is clear that these are
device managed interfaces.

	devm_drm_dp_hpd_bridge_alloc()
	devm_drm_dp_hpd_bridge_add()

The new interface will be used to fix a use-after-free bug in the
Qualcomm PMIC GLINK driver and may prevent similar issues from being
introduced elsewhere.

The existing drm_dp_hpd_bridge_register() is reimplemented using the
above and left in place for now.

Signed-off-by: default avatarJohan Hovold <johan+linaro@kernel.org>
Reviewed-by: default avatarBjorn Andersson <andersson@kernel.org>
Reviewed-by: default avatarDmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: default avatarDmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240217150228.5788-3-johan+linaro@kernel.org
parent 9ee485bd

drivers/gpu/drm/bridge/aux-hpd-bridge.c

+52 −15
Original line number Diff line number Diff line
@@ -30,16 +30,13 @@ static void drm_aux_hpd_bridge_release(struct device *dev) 
	kfree(adev);

}



static void drm_aux_hpd_bridge_unregister_adev(void *_adev)

static void drm_aux_hpd_bridge_free_adev(void *_adev)

{

	struct auxiliary_device *adev = _adev;



	auxiliary_device_delete(adev);

	auxiliary_device_uninit(adev);

	auxiliary_device_uninit(_adev);

}



/**

 * drm_dp_hpd_bridge_register - Create a simple HPD DisplayPort bridge

 * devm_drm_dp_hpd_bridge_alloc - allocate a HPD DisplayPort bridge

 * @parent: device instance providing this bridge

 * @np: device node pointer corresponding to this bridge instance

 *
@@ -47,11 +44,9 @@ static void drm_aux_hpd_bridge_unregister_adev(void *_adev) 
 * DRM_MODE_CONNECTOR_DisplayPort, which terminates the bridge chain and is

 * able to send the HPD events.

 *

 * Return: device instance that will handle created bridge or an error code

 * encoded into the pointer.

 * Return: bridge auxiliary device pointer or an error pointer

 */

struct device *drm_dp_hpd_bridge_register(struct device *parent,

					  struct device_node *np)

struct auxiliary_device *devm_drm_dp_hpd_bridge_alloc(struct device *parent, struct device_node *np)

{

	struct auxiliary_device *adev;

	int ret;
@@ -82,13 +77,55 @@ struct device *drm_dp_hpd_bridge_register(struct device *parent, 
		return ERR_PTR(ret);

	}



	ret = auxiliary_device_add(adev);

	if (ret) {

		auxiliary_device_uninit(adev);

	ret = devm_add_action_or_reset(parent, drm_aux_hpd_bridge_free_adev, adev);

	if (ret)

		return ERR_PTR(ret);



	return adev;

}

EXPORT_SYMBOL_GPL(devm_drm_dp_hpd_bridge_alloc);



static void drm_aux_hpd_bridge_del_adev(void *_adev)

{

	auxiliary_device_delete(_adev);

}



	ret = devm_add_action_or_reset(parent, drm_aux_hpd_bridge_unregister_adev, adev);

/**

 * devm_drm_dp_hpd_bridge_add - register a HDP DisplayPort bridge

 * @dev: struct device to tie registration lifetime to

 * @adev: bridge auxiliary device to be registered

 *

 * Returns: zero on success or a negative errno

 */

int devm_drm_dp_hpd_bridge_add(struct device *dev, struct auxiliary_device *adev)

{

	int ret;



	ret = auxiliary_device_add(adev);

	if (ret)

		return ret;



	return devm_add_action_or_reset(dev, drm_aux_hpd_bridge_del_adev, adev);

}

EXPORT_SYMBOL_GPL(devm_drm_dp_hpd_bridge_add);



/**

 * drm_dp_hpd_bridge_register - allocate and register a HDP DisplayPort bridge

 * @parent: device instance providing this bridge

 * @np: device node pointer corresponding to this bridge instance

 *

 * Return: device instance that will handle created bridge or an error pointer

 */

struct device *drm_dp_hpd_bridge_register(struct device *parent, struct device_node *np)

{

	struct auxiliary_device *adev;

	int ret;



	adev = devm_drm_dp_hpd_bridge_alloc(parent, np);

	if (IS_ERR(adev))

		return ERR_CAST(adev);



	ret = devm_drm_dp_hpd_bridge_add(parent, adev);

	if (ret)

		return ERR_PTR(ret);

include/drm/bridge/aux-bridge.h

+15 −0
Original line number Diff line number Diff line
@@ -9,6 +9,8 @@ 


#include <drm/drm_connector.h>



struct auxiliary_device;



#if IS_ENABLED(CONFIG_DRM_AUX_BRIDGE)

int drm_aux_bridge_register(struct device *parent);

#else
@@ -19,10 +21,23 @@ static inline int drm_aux_bridge_register(struct device *parent) 
#endif



#if IS_ENABLED(CONFIG_DRM_AUX_HPD_BRIDGE)

struct auxiliary_device *devm_drm_dp_hpd_bridge_alloc(struct device *parent, struct device_node *np);

int devm_drm_dp_hpd_bridge_add(struct device *dev, struct auxiliary_device *adev);

struct device *drm_dp_hpd_bridge_register(struct device *parent,

					  struct device_node *np);

void drm_aux_hpd_bridge_notify(struct device *dev, enum drm_connector_status status);

#else

static inline struct auxiliary_device *devm_drm_dp_hpd_bridge_alloc(struct device *parent,

								    struct device_node *np)

{

	return NULL;

}



static inline int devm_drm_dp_hpd_bridge_add(struct auxiliary_device *adev)

{

	return 0;

}



static inline struct device *drm_dp_hpd_bridge_register(struct device *parent,

							struct device_node *np)

{