Messages in this thread |  | | Date | Sat, 10 Dec 2022 17:32:27 -0500 | From | Steven Rostedt <> | Subject | Re: [for-next][PATCH 13/25] x86/mm/kmmio: Use rcu_read_lock_sched_notrace() |
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On Sat, 10 Dec 2022 13:34:12 -0800 "Paul E. McKenney" <paulmck@kernel.org> wrote:
> > I was going to remove it, but then I realized that it would be a functional > > change, as from the comment above, it uses "preempt_enable_no_resched(), > > which there is not a rcu_read_unlock_sched() variant. > > If this happens often enough, it might be worth adding something like > rcu_read_unlock_sched_no_resched(), but we clearly are not there yet. > Especially not with a name like that! ;-)
Please don't ;-)
This is only to handle the bizarre case that mmio tracing does. Remember, this tracer is only for those that want to reverse engineer a binary driver. It's not even SMP safe! When you enable it, it shuts down all but one CPU. This is actually the reason I worked so hard to keep it working with lockdep. The shutting down of CPUs has caught so many bugs in other parts of the kernel! ;-)
Thus, anything that mmio tracer does, is considered niche, and not something to much care about.
-- Steve
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