linux-kernel - Re: [PATCH] srcu: Remove dead code in srcu_gp

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Date:   Wed, 14 Feb 2018 10:00:54 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Byungchul Park <byungchul.park@....com>
Cc:     jiangshanlai@...il.com, paulmck@...ux.vnet.ibm.com,
        josh@...htriplett.org, mathieu.desnoyers@...icios.com,
        linux-kernel@...r.kernel.org, kernel-team@....com
Subject: Re: [PATCH] srcu: Remove dead code in srcu_gp_end()

On Wed, 14 Feb 2018 18:05:24 +0900
Byungchul Park <byungchul.park@....com> wrote:

> Of course, compilers will optimize out a dead code. Anyway, remove
> any dead code for better readibility.
> 
> Signed-off-by: Byungchul Park <byungchul.park@....com>
> ---
>  kernel/rcu/srcutree.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
> index 44bc0fa..829453b 100644
> --- a/kernel/rcu/srcutree.c
> +++ b/kernel/rcu/srcutree.c
> @@ -531,7 +531,6 @@ static void srcu_gp_end(struct srcu_struct *sp)
>  	unsigned long flags;
>  	unsigned long gpseq;
>  	int idx;
> -	int idxnext;

Interesting. According to git history, idxnext was never actually used.

Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>

-- Steve

>  	unsigned long mask;
>  	struct srcu_data *sdp;
>  	struct srcu_node *snp;
> @@ -555,7 +554,6 @@ static void srcu_gp_end(struct srcu_struct *sp)
>  
>  	/* Initiate callback invocation as needed. */
>  	idx = rcu_seq_ctr(gpseq) % ARRAY_SIZE(snp->srcu_have_cbs);
> -	idxnext = (idx + 1) % ARRAY_SIZE(snp->srcu_have_cbs);
>  	rcu_for_each_node_breadth_first(sp, snp) {
>  		spin_lock_irq_rcu_node(snp);
>  		cbs = false;