On Mon, 21 Jun 2021 13:34:44 +0200 Daniel Bristot de Oliveira <bristot@xxxxxxxxxx> wrote: > > And of course, because get_online_cpus() is called within > > trace_types_lock, doing this check is going to cause a lock inversion. > > > > Yep! I tried to take the trace_type_lock here, and got the lockdep info about > this problem. > > > The only thing I could think of is to wake up a worker thread to do the > > work. That is, this just wakes the worker thread, then the worker grabs > > the trace_types_lock, iterates through the cpu mask of expect running > > threads, and then starts or kills them depending on the hwlat_busy > > value. > > So, it will not wait for the kworker to run? What wont wait? -- Steve
