On Wednesday, May 20, 2020 2:55 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > Maybe we should add an explicit note that there's no guarantee about the > new chardev minor this new device will get, it could both inherit the > existing one (you can't open the old one anymore anyway) or get a new one? > > Or does userspace want a guarantee, i.e. as long as there's still a handle > open kernel guarantees to not recycle the chardev minor (which is what we > currently do). In that case better to add that to your list of guarantees > above. The are race conditions to consider too, e.g. - Compositor sends /dev/dri/card0 to a client - card0 goes away - Another device takes card0 - Client receives /dev/dri/card0 and then starts using it, but it's the wrong device At first glance these seem like edge-cases that almost never happen. However I've seen these happen in practice with connectors, especially with docks. One solution would be to number minor numbers like PIDs: don't recycle card0 before we've reached the upper minor number limit. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
