linux-kernel - Re: [PATCH 08/49] drm: replace bitmap_weight with bitmap

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Date:   Fri, 11 Feb 2022 05:11:45 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Yury Norov <yury.norov@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        David Laight <David.Laight@...lab.com>,
        Joe Perches <joe@...ches.com>, Dennis Zhou <dennis@...nel.org>,
        Emil Renner Berthing <kernel@...il.dk>,
        Nicholas Piggin <npiggin@...il.com>,
        Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        Alexey Klimov <aklimov@...hat.com>,
        linux-kernel@...r.kernel.org, Rob Clark <robdclark@...il.com>,
        Sean Paul <sean@...rly.run>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org
Subject: Re: [PATCH 08/49] drm: replace bitmap_weight with bitmap_empty where appropriate

On Fri, 11 Feb 2022 at 02:09, Yury Norov <yury.norov@...il.com> wrote:
>
> smp_request_block() in drivers/gpu/drm/msm/disp/mdp5/mdp5_smp.c calls
> bitmap_weight() to check if any bit of a given bitmap is set. It's
> better to use bitmap_empty() in that case because bitmap_empty() stops
> traversing the bitmap as soon as it finds first set bit, while
> bitmap_weight() counts all bits unconditionally.
>
> Signed-off-by: Yury Norov <yury.norov@...il.com>
> ---
>  drivers/gpu/drm/msm/disp/mdp5/mdp5_smp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_smp.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_smp.c
> index d7fa2c49e741..56a3063545ec 100644
> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_smp.c
> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_smp.c
> @@ -68,7 +68,7 @@ static int smp_request_block(struct mdp5_smp *smp,
>         uint8_t reserved;
>
>         /* we shouldn't be requesting blocks for an in-use client: */
> -       WARN_ON(bitmap_weight(cs, cnt) > 0);
> +       WARN_ON(!bitmap_empty(cs, cnt));

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

>
>         reserved = smp->reserved[cid];
>
> --
> 2.32.0
>


-- 
With best wishes
Dmitry