Received-SPF: pass (google.com: domain of linux-kernel+bounces-148397-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Precedence: bulk
MIME-Version: 1.0
References: <20240416085454.3547175-1-dawei.li@shingroup.cn> <20240416085454.3547175-7-dawei.li@shingroup.cn>
In-Reply-To: <20240416085454.3547175-7-dawei.li@shingroup.cn>
From: Anup Patel <anup@brainfault.org>
Date: Wed, 17 Apr 2024 16:51:00 +0530
Message-ID: <CAAhSdy13UZ_iXp6_Q2RV1qHgbYc7S6VzENmz=vTezmc34uEwNg@mail.gmail.com>
Subject: Re: [PATCH v2 6/7] irqchip/sifive-plic: Avoid explicit cpumask
 allocation on stack
To: Dawei Li <dawei.li@shingroup.cn>
Cc: tglx@linutronix.de, yury.norov@gmail.com, rafael@kernel.org, 
	akpm@linux-foundation.org, maz@kernel.org, florian.fainelli@broadcom.com, 
	chenhuacai@kernel.org, jiaxun.yang@flygoat.com, palmer@dabbelt.com, 
	samuel.holland@sifive.com, linux@rasmusvillemoes.dk, 
	daniel.lezcano@linaro.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Tue, Apr 16, 2024 at 2:26=E2=80=AFPM Dawei Li <dawei.li@shingroup.cn> wr=
ote:
>
> In general it's preferable to avoid placing cpumasks on the stack, as
> for large values of NR_CPUS these can consume significant amounts of
> stack space and make stack overflows more likely.
>
> Use cpumask_first_and_and() to avoid the need for a temporary cpumask on
> the stack.
>
> Signed-off-by: Dawei Li <dawei.li@shingroup.cn>

LGTM.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup

> ---
>  drivers/irqchip/irq-sifive-plic.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifi=
ve-plic.c
> index f3d4cb9e34f7..8fb183ced1e7 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -164,15 +164,12 @@ static int plic_set_affinity(struct irq_data *d,
>                              const struct cpumask *mask_val, bool force)
>  {
>         unsigned int cpu;
> -       struct cpumask amask;
>         struct plic_priv *priv =3D irq_data_get_irq_chip_data(d);
>
> -       cpumask_and(&amask, &priv->lmask, mask_val);
> -
>         if (force)
> -               cpu =3D cpumask_first(&amask);
> +               cpu =3D cpumask_first_and(&priv->lmask, mask_val);
>         else
> -               cpu =3D cpumask_any_and(&amask, cpu_online_mask);
> +               cpu =3D cpumask_first_and_and(&priv->lmask, mask_val, cpu=
_online_mask);
>
>         if (cpu >=3D nr_cpu_ids)
>                 return -EINVAL;
> --
> 2.27.0
>