On Tue, Aug 25, 2020 at 10:15:55PM +0900, Masami Hiramatsu wrote: > > damn... one last problem is dangling instances.. so close. > > We can apparently unregister a kretprobe while there's still active > > kretprobe_instance's out referencing it. > > Yeah, kretprobe already provided the per-instance data (as far as > I know, only systemtap depends on it). We need to provide it for > such users. > But if we only have one lock, we can avoid checking NMI because > we can check the recursion with trylock. It is needed only if the > kretprobe uses per-instance data. Or we can just pass a dummy > instance on the stack.
I think it is true in general, you can unregister a rp while tasks are preempted. Anyway,. I think I have a solution, just need to talk to paulmck for a bit. > > Ignoring that issue for the moment, the below seems to actually work. > > OK, this looks good to me too. > I'll make a series to rewrite kretprobe based on this patch, OK? Please, I'll send the fix along when I have it.
