linux-kernel - Re: [PATCH 6/7] rcu: rename some CONFIG_PREEMPTION to CONFIG_PREEMPT

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Message-ID: <20191016035407.GB2689@paulmck-ThinkPad-P72>
Date:   Tue, 15 Oct 2019 20:54:07 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     20191015102402.1978-1-laijs@...ux.alibaba.com
Cc:     linux-kernel@...r.kernel.org,
        Lai Jiangshan <laijs@...ux.alibaba.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Joel Fernandes <joel@...lfernandes.org>, rcu@...r.kernel.org
Subject: Re: [PATCH 6/7] rcu: rename some CONFIG_PREEMPTION to
 CONFIG_PREEMPT_RCU

On Tue, Oct 15, 2019 at 10:28:48AM +0000, Lai Jiangshan wrote:
> CONFIG_PREEMPTION and CONFIG_PREEMPT_RCU are always identical,
> but some code depends on CONFIG_PREEMPTION to access to
> rcu_preempt functionalitis. This patch changes CONFIG_PREEMPTION
> to CONFIG_PREEMPT_RCU in these cases.
> 
> Signed-off-by: Lai Jiangshan <jiangshanlai@...il.com>
> Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>

I believe that this does not cause problems with Sebastian's patch
"[PATCH 27/34] rcu: Use CONFIG_PREEMPTION where appropriate", but could
you please check?

							Thanx, Paul

> ---
>  kernel/rcu/tree.c       | 4 ++--
>  kernel/rcu/tree_stall.h | 6 +++---
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 7db5ea06a9ed..81eb64fcf5ab 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1926,7 +1926,7 @@ rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags)
>  	struct rcu_node *rnp_p;
>  
>  	raw_lockdep_assert_held_rcu_node(rnp);
> -	if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_PREEMPTION)) ||
> +	if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_PREEMPT_RCU)) ||
>  	    WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp)) ||
>  	    rnp->qsmask != 0) {
>  		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
> @@ -2294,7 +2294,7 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp))
>  		mask = 0;
>  		raw_spin_lock_irqsave_rcu_node(rnp, flags);
>  		if (rnp->qsmask == 0) {
> -			if (!IS_ENABLED(CONFIG_PREEMPTION) ||
> +			if (!IS_ENABLED(CONFIG_PREEMPT_RCU) ||
>  			    rcu_preempt_blocked_readers_cgp(rnp)) {
>  				/*
>  				 * No point in scanning bits because they
> diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
> index 0b75426ebb3e..55f9b84790d3 100644
> --- a/kernel/rcu/tree_stall.h
> +++ b/kernel/rcu/tree_stall.h
> @@ -163,7 +163,7 @@ static void rcu_iw_handler(struct irq_work *iwp)
>  //
>  // Printing RCU CPU stall warnings
>  
> -#ifdef CONFIG_PREEMPTION
> +#ifdef CONFIG_PREEMPT_RCU
>  
>  /*
>   * Dump detailed information for all tasks blocking the current RCU
> @@ -215,7 +215,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp)
>  	return ndetected;
>  }
>  
> -#else /* #ifdef CONFIG_PREEMPTION */
> +#else /* #ifdef CONFIG_PREEMPT_RCU */
>  
>  /*
>   * Because preemptible RCU does not exist, we never have to check for
> @@ -233,7 +233,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp)
>  {
>  	return 0;
>  }
> -#endif /* #else #ifdef CONFIG_PREEMPTION */
> +#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
>  
>  /*
>   * Dump stacks of all tasks running on stalled CPUs.  First try using
> -- 
> 2.20.1
>