On Wed, Jan 19, 2022 at 08:30:43AM -1000, Tejun Heo <tj@xxxxxxxxxx> wrote: > It'd be nicer if we can make kthread_stop() waiting more regular but I > couldn't find a good existing place and routing the usual parent > signaling might be too complicated. Anyone has better ideas? The regular way is pictured in Paolo's diagram already, the exit_notify/do_signal_parent -> wait4 path. Actually, I can see that there exists already kernel_wait() and is used by a UMH wrapper kthread. kthreadd issues ignore_signals() so (besides no well defined point of signalling a kthread) the signal notification is moot and only waking up the waiter is relevant. So kthread_stop() could wait via kernel_wait() based on pid (extracted from task_struct). Have I missed an obstacle? Michal
