diff options
| -rw-r--r-- | drivers/gpu/drm/drm_bridge.c | 34 | ||||
| -rw-r--r-- | include/drm/drm_bridge.h | 1 |
2 files changed, 35 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index 1868d512ffa1..30d957675d87 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -304,6 +304,9 @@ EXPORT_SYMBOL(drm_bridge_get); * * This function decrements the bridge's reference count and frees the * object if the reference count drops to zero. + * + * See also drm_bridge_clear_and_put() if you also need to set the pointer + * to NULL */ void drm_bridge_put(struct drm_bridge *bridge) { @@ -313,6 +316,37 @@ void drm_bridge_put(struct drm_bridge *bridge) EXPORT_SYMBOL(drm_bridge_put); /** + * drm_bridge_clear_and_put - Given a bridge pointer, clear the pointer + * then put the bridge + * @bridge_pp: pointer to pointer to a struct drm_bridge; ``bridge_pp`` + * must be non-NULL; if ``*bridge_pp`` is NULL this function + * does nothing + * + * Helper to put a DRM bridge, but only after setting its pointer to + * NULL. Useful when a struct drm_bridge reference must be dropped without + * leaving a use-after-free window where the pointed bridge might have been + * freed while still holding a pointer to it. + * + * For struct ``drm_bridge *some_bridge``, this code:: + * + * drm_bridge_clear_and_put(&some_bridge); + * + * is equivalent to the more complex:: + * + * struct drm_bridge *temp = some_bridge; + * some_bridge = NULL; + * drm_bridge_put(temp); + */ +void drm_bridge_clear_and_put(struct drm_bridge **bridge_pp) +{ + struct drm_bridge *bridge = *bridge_pp; + + *bridge_pp = NULL; + drm_bridge_put(bridge); +} +EXPORT_SYMBOL(drm_bridge_clear_and_put); + +/** * drm_bridge_put_void - wrapper to drm_bridge_put() taking a void pointer * * @data: pointer to @struct drm_bridge, cast to a void pointer diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index 4f19f7064ee3..66ab89cf48aa 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -1290,6 +1290,7 @@ void drm_bridge_unplug(struct drm_bridge *bridge); struct drm_bridge *drm_bridge_get(struct drm_bridge *bridge); void drm_bridge_put(struct drm_bridge *bridge); +void drm_bridge_clear_and_put(struct drm_bridge **bridge_pp); /* Cleanup action for use with __free() */ DEFINE_FREE(drm_bridge_put, struct drm_bridge *, if (_T) drm_bridge_put(_T)) |