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 <johan+linaro@xxxxxxxxxx>
---
drivers/gpu/drm/bridge/aux-hpd-bridge.c | 67 +++++++++++++++++++------
include/drm/bridge/aux-bridge.h | 15 ++++++
2 files changed, 67 insertions(+), 15 deletions(-)
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);
diff --git a/include/drm/bridge/aux-bridge.h b/include/drm/bridge/aux-bridge.h
index c4c423e97f06..4453906105ca 100644
--- a/include/drm/bridge/aux-bridge.h
+++ b/include/drm/bridge/aux-bridge.h
@@ -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)
{
--
2.43.0
