lkml.org 
[lkml]   [2022]   [Dec]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [for-next][PATCH 13/25] x86/mm/kmmio: Use rcu_read_lock_sched_notrace()
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

\
 
 \ /
  Last update: 2022-12-10 23:35    [W:1.434 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site