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From: Lai Jiangshan <jiangshanlai@gmail.com>
Date: Mon, 1 Apr 2024 00:16:42 +0800
Message-ID: <CAJhGHyDjoQ3TrApksYJ5o1ooU4s8rzys2UnfF6EFzGwkaSVaKA@mail.gmail.com>
Subject: Re: [PATCH 02/10] rcu: Move rcu_preempt_depth_set() to rcupdate.h
To: Joel Fernandes <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org, x86@kernel.org, 
	Lai Jiangshan <jiangshan.ljs@antgroup.com>, "Paul E. McKenney" <paulmck@kernel.org>, 
	Peter Zijlstra <peterz@infradead.org>, Frederic Weisbecker <frederic@kernel.org>, 
	Neeraj Upadhyay <quic_neeraju@quicinc.com>, Josh Triplett <josh@joshtriplett.org>, 
	Boqun Feng <boqun.feng@gmail.com>, Steven Rostedt <rostedt@goodmis.org>, 
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Zqiang <qiang.zhang1211@gmail.com>
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On Sun, Mar 31, 2024 at 7:10=E2=80=AFPM Joel Fernandes <joel@joelfernandes.=
org> wrote:
>
>
>
> > On Mar 28, 2024, at 1:20=E2=80=AFPM, Lai Jiangshan <jiangshanlai@gmail.=
com> wrote:
> >
> > =EF=BB=BFFrom: Lai Jiangshan <jiangshan.ljs@antgroup.com>
> >
> > Prepare for arch-specific-defined rcu_preempt_depth_set().
> >
> > No functionality change intended, but it has to be defined as a macro
> > as rcupdate.h is a very low level header included from areas that don't
> > even know about the task struct "current".
>
> Sorry I did not follow changelog. If some rcupdate.h includers do not kno=
w
> about task_struct, how does adding a macro that uses current help?
>

Hello

This is how macro works and it expands blindly based on tokens on the
usage-sites.

And rcu_preempt_depth() & rcu_preempt_depth_set() are not universally
used wrappers, the user can simply also include linux/sched.h to make
they work.

Thanks
Lai