linux-kernel - Re: [PATCH 31/38] rcu: Replace deprecated CPU-hotplug functions.

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Message-ID: <20210803160021.GR4397@paulmck-ThinkPad-P17-Gen-1>
Date:   Tue, 3 Aug 2021 09:00:21 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>, rcu@...r.kernel.org
Subject: Re: [PATCH 31/38] rcu: Replace deprecated CPU-hotplug functions.

On Tue, Aug 03, 2021 at 04:16:14PM +0200, Sebastian Andrzej Siewior wrote:
> The functions get_online_cpus() and put_online_cpus() have been
> deprecated during the CPU hotplug rework. They map directly to
> cpus_read_lock() and cpus_read_unlock().
> 
> Replace deprecated CPU-hotplug functions with the official version.
> The behavior remains unchanged.
> 
> Cc: "Paul E. McKenney" <paulmck@...nel.org>
> Cc: Josh Triplett <josh@...htriplett.org>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> Cc: Lai Jiangshan <jiangshanlai@...il.com>
> Cc: Joel Fernandes <joel@...lfernandes.org>
> Cc: rcu@...r.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

I have queued this one and 35/38 (rcutorture) for v5.16.  If you would
prefer to send them some other route, please let me know and:

Acked-by: Paul E. McKenney <paulmck@...nel.org>

> ---
>  kernel/rcu/tree.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 51f24ecd94b26..f116ce58f4e68 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -4050,7 +4050,7 @@ void rcu_barrier(void)
>  	 */
>  	init_completion(&rcu_state.barrier_completion);
>  	atomic_set(&rcu_state.barrier_cpu_count, 2);
> -	get_online_cpus();
> +	cpus_read_lock();
>  
>  	/*
>  	 * Force each CPU with callbacks to register a new callback.
> @@ -4081,7 +4081,7 @@ void rcu_barrier(void)
>  					  rcu_state.barrier_sequence);
>  		}
>  	}
> -	put_online_cpus();
> +	cpus_read_unlock();
>  
>  	/*
>  	 * Now that we have an rcu_barrier_callback() callback on each
> -- 
> 2.32.0
>