linux-kernel - Re: [PATCH tip/core/rcu 16/26] rcu: Mark rcu_nmi_enter() call to rcu_cleanup_after

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Message-ID: <20200623175043.GQ9247@paulmck-ThinkPad-P72>
Date:   Tue, 23 Jun 2020 10:50:43 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     rcu@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-team@...com, mingo@...nel.org, jiangshanlai@...il.com,
        dipankar@...ibm.com, akpm@...ux-foundation.org,
        mathieu.desnoyers@...icios.com, josh@...htriplett.org,
        tglx@...utronix.de, rostedt@...dmis.org, dhowells@...hat.com,
        edumazet@...gle.com, fweisbec@...il.com, oleg@...hat.com,
        joel@...lfernandes.org
Subject: Re: [PATCH tip/core/rcu 16/26] rcu: Mark rcu_nmi_enter() call to
 rcu_cleanup_after_idle() noinstr

On Tue, Jun 23, 2020 at 07:04:25PM +0200, Peter Zijlstra wrote:
> On Mon, Jun 22, 2020 at 05:21:37PM -0700, paulmck@...nel.org wrote:
> > From: "Paul E. McKenney" <paulmck@...nel.org>
> > 
> > The objtool complains about the call to rcu_cleanup_after_idle() from
> > rcu_nmi_enter(), so this commit adds instrumentation_begin() before that
> > call and instrumentation_end() after it.
> 
> Hmm, I've not seen this one. Still,

I am still based off of v5.8-rc1, so I might be missing some commits.
Not seeing any that would affect this, but that doesn't mean that
there aren't any.  ;-)

> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>

I will apply this on my next rebase, thank you!

							Thanx, Paul

> > Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> > ---
> >  kernel/rcu/tree.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 08e3648..67912ad 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -980,8 +980,11 @@ noinstr void rcu_nmi_enter(void)
> >  		rcu_dynticks_eqs_exit();
> >  		// ... but is watching here.
> >  
> > -		if (!in_nmi())
> > +		if (!in_nmi()) {
> > +			instrumentation_begin();
> >  			rcu_cleanup_after_idle();
> > +			instrumentation_end();
> > +		}
> >  
> >  		incby = 1;
> >  	} else if (!in_nmi()) {
> > -- 
> > 2.9.5
> >