linux-kernel - Re: [PATCH] rcutorture: Fix rcu_torture_pipe_update_one()/rcu_torture

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Date: Wed, 6 Mar 2024 13:55:04 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: "Paul E. McKenney" <paulmck@...nel.org>, linke li <lilinke99@...com>,
 joel@...lfernandes.org, boqun.feng@...il.com, dave@...olabs.net,
 frederic@...nel.org, jiangshanlai@...il.com, josh@...htriplett.org,
 linux-kernel@...r.kernel.org, mathieu.desnoyers@...icios.com,
 qiang.zhang1211@...il.com, quic_neeraju@...cinc.com, rcu@...r.kernel.org
Subject: Re: [PATCH] rcutorture: Fix
 rcu_torture_pipe_update_one()/rcu_torture_writer() data race and
 concurrency bug

On Wed, 6 Mar 2024 10:43:25 -0800
Linus Torvalds <torvalds@...ux-foundation.org> wrote:

Thanks for the history lesson ;-)

> So yes, READ_ONCE/WRITE_ONCE do control "tearing", but realistically,
> it was always only about the "complex values" kind of tearing that the
> old ACCESS_ONCE() model silently and incorrectly allowed.

Now, are you OK with an addition of ADD_ONCE() and/or INC_ONCE()? So that we
don't have to look at:

	WRITE_ONCE(a, READ_ONCE(a) + 1);

?

-- Steve