From e5ca263508f7e9d2cf711edf3258d11ca087885c Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Sat, 17 Feb 2024 16:02:24 +0100 Subject: 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: Johan Hovold Reviewed-by: Bjorn Andersson Reviewed-by: Dmitry Baryshkov Signed-off-by: Dmitry Baryshkov Link: https://patchwork.freedesktop.org/patch/msgid/20240217150228.5788-3-johan+linaro@kernel.org --- drivers/gpu/drm/bridge/aux-hpd-bridge.c | 67 +++++++++++++++++++++++++-------- 1 file changed, 52 insertions(+), 15 deletions(-) (limited to 'drivers/gpu/drm/bridge') diff --git a/drivers/gpu/drm/bridge/aux-hpd-bridge.c b/drivers/gpu/drm/bridge/aux-hpd-bridge.c index 9e71daf95bde..6886db2d9e00 100644 --- a/drivers/gpu/drm/bridge/aux-hpd-bridge.c +++ b/drivers/gpu/drm/bridge/aux-hpd-bridge.c @@ -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); - } - ret = devm_add_action_or_reset(parent, drm_aux_hpd_bridge_unregister_adev, adev); + 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); +} + +/** + * 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); -- cgit v1.2.3