Le 26/03/2025 à 18:47, Luca Ceresoli a écrit :
This series improves the way DRM bridges are allocated and initialized and makes them reference-counted. The goal of reference counting is to avoid use-after-free by drivers which got a pointer to a bridge and keep it stored and used even after the bridge has been deallocated. The overall goal is supporting Linux devices with a DRM pipeline whose final components can be hot-plugged and hot-unplugged, including one or more bridges. For more details see the big picture [0]. DRM bridge drivers will have to be adapted to the new API -- the change is trivial for most cases. This series converts two of them to serve as an example. The remaining ones will be done as a follow-up after this first part is merged. After that, refcounting will have to be added on the two sides: all functions returning a bridge pointer and all code obtaining such a pointer. A few examples have been sent in v7 (link below), they are OK, but I removed them since v8 because they must be merged only after converting all bridges. Here's the grand plan: A. add new alloc API and refcounting (this series, at least patches 1-3) B. after (A), convert all bridge drivers to new API C. after (A), add documentation and kunit tests D. after (B), add get/put to drm_bridge_add/remove() + attach/detech() (patches 3-4 in the v7 series) E. after (B), convert accessors (including patches 5-9 in the v7 series which convert drm_bridge_chain_get_first_bridge() and its users); this is a large work and can be done in chunks F. after (A), debugfs: show refcount, show removed bridgesLayout of this:1. Add the new API and refcounting: drm/bridge: add devm_drm_bridge_alloc() drm/bridge: add support for refcounting drm/bridge: deprecate old-style bridge allocation 2. convert a few bridge drivers (bridge providers) to the new API: drm/bridge: ti-sn65dsi83: use dynamic lifetime management drm/bridge: samsung-dsim: use dynamic lifetime management [0] https://lore.kernel.org/dri-devel/20250206-hotplug-drm-bridge-v6-0-9d6f2c9c3...@bootlin.com/ Signed-off-by: Luca Ceresoli <luca.ceres...@bootlin.com>
Applied on drm-misc-next, thanks! -- Louis Chauvet, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
