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From: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
To: Kees Cook <keescook@chromium.org>, Thomas Gleixner <tglx@linutronix.de>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] genirq: Make - vs ?: precedence explicit
Date: Tue, 28 Nov 2017 13:19:50 +0100	[thread overview]
Message-ID: <a3b338a1-95c5-1e7e-9b5c-d924a760078e@prevas.dk> (raw)
In-Reply-To: <20171122205645.GA27125@beast>

On 2017-11-22 21:56, Kees Cook wrote:
> Noticed with a Clang build. This improves the readability of the ?:
> expression, as it has lower precedence than the - expression. Show
> explicitly that - is evaluated first.
> 
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  kernel/irq/matrix.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c
> index a3cbbc8191c5..7df2480005f8 100644
> --- a/kernel/irq/matrix.c
> +++ b/kernel/irq/matrix.c
> @@ -384,7 +384,7 @@ unsigned int irq_matrix_available(struct irq_matrix *m, bool cpudown)
>  {
>  	struct cpumap *cm = this_cpu_ptr(m->maps);
>  
> -	return m->global_available - cpudown ? cm->available : 0;
> +	return (m->global_available - cpudown) ? cm->available : 0;
>  }

I see that this got applied, and that doesn't change the semantics of
the code. But surely the code is and was buggy, right? From the kernel
doc, I'm pretty sure the idea is to subtract cm->available if cpudown is
true, otherwise subtract 0, i.e.

  return m->global_available - (cpudown ? cm->available : 0);

Rasmus

  parent reply	other threads:[~2017-11-28 12:19 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-22 20:56 Kees Cook
2017-11-23 19:13 ` [tip:irq/urgent] genirq/matrix: Make - vs ?: Precedence explicit tip-bot for Kees Cook
2017-11-28 12:19 ` Rasmus Villemoes [this message]
2017-11-28 13:43   ` [PATCH] genirq: Make - vs ?: precedence explicit Thomas Gleixner

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