linux-kernel - Re: [PATCH 6/6] rcu/nocb: Merge rcu_spawn_cpu_nocb_kthread() and rcu_spawn_one_nocb

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Message-ID: <f067a100-baac-5c08-f432-8475667ad762@quicinc.com>
Date:   Wed, 1 Dec 2021 14:58:07 +0530
From:   Neeraj Upadhyay <quic_neeraju@...cinc.com>
To:     Frederic Weisbecker <frederic@...nel.org>,
        "Paul E . McKenney" <paulmck@...nel.org>
CC:     LKML <linux-kernel@...r.kernel.org>,
        Uladzislau Rezki <urezki@...il.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Josh Triplett <josh@...htriplett.org>,
        Joel Fernandes <joel@...lfernandes.org>, <rcu@...r.kernel.org>
Subject: Re: [PATCH 6/6] rcu/nocb: Merge rcu_spawn_cpu_nocb_kthread() and
 rcu_spawn_one_nocb_kthread()



On 11/23/2021 6:07 AM, Frederic Weisbecker wrote:
> rcu_spawn_one_nocb_kthread() is only called by
> rcu_spawn_cpu_nocb_kthread(). Don't bother with two separate functions
> and merge them.
> 
> Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
> Cc: Neeraj Upadhyay <quic_neeraju@...cinc.com>
> Cc: Boqun Feng <boqun.feng@...il.com>
> Cc: Uladzislau Rezki <urezki@...il.com>
> Cc: Josh Triplett <josh@...htriplett.org>
> Cc: Joel Fernandes <joel@...lfernandes.org>
> ---


Reviewed-by: Neeraj Upadhyay <quic_neeraju@...cinc.com>

>   kernel/rcu/tree_nocb.h | 15 ++++-----------
>   1 file changed, 4 insertions(+), 11 deletions(-)
> 
> diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
> index d915780d40c8..7e8da346127a 100644
> --- a/kernel/rcu/tree_nocb.h
> +++ b/kernel/rcu/tree_nocb.h
> @@ -1225,12 +1225,15 @@ static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
>    * rcuo CB kthread, spawn it.  Additionally, if the rcuo GP kthread
>    * for this CPU's group has not yet been created, spawn it as well.
>    */
> -static void rcu_spawn_one_nocb_kthread(int cpu)
> +static void rcu_spawn_cpu_nocb_kthread(int cpu)
>   {
>   	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
>   	struct rcu_data *rdp_gp;
>   	struct task_struct *t;
>   
> +	if (!rcu_scheduler_fully_active || !rcu_nocb_is_setup)
> +		return;
> +
>   	/* If it already has an rcuo kthread, then nothing to do. */
>   	if (rdp->nocb_cb_kthread)
>   		return;
> @@ -1254,16 +1257,6 @@ static void rcu_spawn_one_nocb_kthread(int cpu)
>   	WRITE_ONCE(rdp->nocb_gp_kthread, rdp_gp->nocb_gp_kthread);
>   }
>   
> -/*
> - * If the specified CPU is a no-CBs CPU that does not already have its
> - * rcuo kthread, spawn it.
> - */
> -static void rcu_spawn_cpu_nocb_kthread(int cpu)
> -{
> -	if (rcu_scheduler_fully_active && rcu_nocb_is_setup)
> -		rcu_spawn_one_nocb_kthread(cpu);
> -}
> -
>   /*
>    * Once the scheduler is running, spawn rcuo kthreads for all online
>    * no-CBs CPUs.  This assumes that the early_initcall()s happen before
>