Hi Dmitry, On Fri, 26 Sep 2025 01:07:26 +0300 Dmitry Baryshkov <[email protected]> wrote:
> On Thu, Sep 25, 2025 at 07:19:49PM +0200, Luca Ceresoli wrote: > > Some code is going to need connector-specific cleanup actions (namely > > drm_bridge_connector will need to put refcounted bridges). > > > > The .destroy callback is appropriate for this task but it is currently > > forbidden by drmm_connector_init(). Relax this limitation and document it. > > > > Signed-off-by: Luca Ceresoli <[email protected]> > > > > --- > > > > The other obvious approach would be adding a separate .cleanup callback for > > the cleanup-only actions. I tried both, they both apparently work, so any > > arguments and opinions on which approach is best within the overall DRM > > design would be very useful here. > > Would it be better to use drmm-reset actions. I think the check here > makes much more help overall than harm in your case, so I'd suggest > leaving it in place. Thanks for the feedback! I think using drmm_add_action[_or_reset]() here makes sense indeed. As I understand it, both .destroy and drmm_add_action[_or_reset]() actions will trigger when the drm_device is removed. This is not ideal for hotplugging because one would add/remove bridges while the drm_device is persistent, so on multiple hot plug/unplug loops stale resources would accumulate until the final card removal, perhaps at system shutdown. However for now my goal is to have bridges refcount in place to avoid use-after-free. Releasing resources for hot-unplugged bridges for this case is a further step. Bottom line: same drawback for both solutions, but the drmm action is cleaner. v2 incoming with a drmm action. Best regards, Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
