linux-kernel - Re: [PATCH V2 03/11] rcu: Reorder tree_exp.h after tree

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Date: Wed, 24 Apr 2024 10:47:03 +0800
From: Lai Jiangshan <jiangshanlai@...il.com>
To: Joel Fernandes <joel@...lfernandes.org>
Cc: linux-kernel@...r.kernel.org, rcu@...r.kernel.org, x86@...nel.org, 
	Lai Jiangshan <jiangshan.ljs@...group.com>, "Paul E. McKenney" <paulmck@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Frederic Weisbecker <frederic@...nel.org>, 
	Neeraj Upadhyay <quic_neeraju@...cinc.com>, Josh Triplett <josh@...htriplett.org>, 
	Boqun Feng <boqun.feng@...il.com>, Steven Rostedt <rostedt@...dmis.org>, 
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Zqiang <qiang.zhang1211@...il.com>
Subject: Re: [PATCH V2 03/11] rcu: Reorder tree_exp.h after tree_plugin.h

On Wed, Apr 24, 2024 at 1:58 AM Joel Fernandes <joel@...lfernandes.org> wrote:
>
> On Sun, Apr 7, 2024 at 5:03 AM Lai Jiangshan <jiangshanlai@...il.com> wrote:
> >
> > From: Lai Jiangshan <jiangshan.ljs@...group.com>
> >
> > Enable tree_exp.h using some rcu preempt macros introduced in
> > the next patch. The new macros touch core rcu-preempt fields
> > and are better to be implemented in tree_plugin.h.
> >
> > Cc: "Paul E. McKenney" <paulmck@...nel.org>
> > Cc: Peter Zijlstra <peterz@...radead.org>
> > Cc: Frederic Weisbecker <frederic@...nel.org>
> > Signed-off-by: Lai Jiangshan <jiangshan.ljs@...group.com>
> > ---
> >  kernel/rcu/tree.c        | 2 +-
> >  kernel/rcu/tree_plugin.h | 1 +
> >  2 files changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index d9642dd06c25..57d1ae26861f 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -5245,6 +5245,6 @@ void __init rcu_init(void)
> >  }
> >
> >  #include "tree_stall.h"
> > -#include "tree_exp.h"
> >  #include "tree_nocb.h"
> >  #include "tree_plugin.h"
> > +#include "tree_exp.h"
> > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> > index b1264096d03a..d899b4afc21c 100644
> > --- a/kernel/rcu/tree_plugin.h
> > +++ b/kernel/rcu/tree_plugin.h
> > @@ -103,6 +103,7 @@ static void __init rcu_bootup_announce_oddness(void)
> >  #ifdef CONFIG_PREEMPT_RCU
> >
> >  static void rcu_report_exp_rnp(struct rcu_node *rnp, bool wake);
> > +static bool sync_rcu_exp_done(struct rcu_node *rnp);
> >  static void rcu_read_unlock_special(struct task_struct *t);
>
> OK with me, but not sure if the reordering of header inclusion is
> needed? You could get the same results by just adding declarations of
> the new helpers to tree_exp.h.

The new macros (in later patch) touch core rcu-preempt fields
and are better to be implemented in tree_plugin.h.

>
> Not sure if tree_plugin.h needs to be included last, I for some reason
> thought it needed to be - but looks like not. I found a thread that
> shed some light into the header file including C code thing as well,
> which may or may not help:
> https://lore.kernel.org/all/8ab3ca72-e20c-4b18-803f-bf6937c2cd70@paulmck-laptop/#t
>
> Thanks.