linux-kernel - Re: [PATCH] rcu: Remove some superfluous lines

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Message-ID: <20160310134146.GK3452@linux.vnet.ibm.com>
Date:	Thu, 10 Mar 2016 05:41:46 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rcu: Remove some superfluous lines

On Thu, Mar 10, 2016 at 09:49:04AM +0100, Peter Zijlstra wrote:
> 
> I think you'll find this condition is superfluous, as the whole function
> is under #ifdef of that same.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Right you are!  It got moved under that #ifdef in the process of merging
the RCU, hotplug, and swait changes, and I failed to notice.  Good catch!

I will apply this to my tree once -rc1 comes out, as it will apply to
-rcu at that point.

Or maybe we should remove the #ifdef and add IS_ENABLED() to the other
functions under that #ifdef.  Thoughts?

							Thanx, Paul

> ---
>  kernel/rcu/tree.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 4f7369d54de0..dd2646e56456 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -4237,9 +4237,6 @@ static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
>  	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
>  	struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */
> 
> -	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
> -		return;
> -
>  	/* Remove outgoing CPU from mask in the leaf rcu_node structure. */
>  	mask = rdp->grpmask;
>  	raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */
>