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References: <20210126171141.122639-1-paul.gortmaker@windriver.com> <20210126171141.122639-5-paul.gortmaker@windriver.com>
In-Reply-To: <20210126171141.122639-5-paul.gortmaker@windriver.com>
From:   Yury Norov <yury.norov@gmail.com>
Date:   Tue, 26 Jan 2021 19:12:58 -0800
Message-ID: <CAAH8bW_BCPTK4H4CFShbfEv-cV6tiqXNMh_xNRbJV+gkjyw+mg@mail.gmail.com>
Subject: Re: [PATCH 4/8] lib: bitmap: move ERANGE check from set_region to check_region
To:     Paul Gortmaker <paul.gortmaker@windriver.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        lizefan@huawei.com, Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, josh@joshtriplett.org,
        Peter Zijlstra <peterz@infradead.org>,
        "Paul E. McKenney" <paulmck@kernel.org>, fweisbec@gmail.com,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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Precedence: bulk

On Tue, Jan 26, 2021 at 9:12 AM Paul Gortmaker
<paul.gortmaker@windriver.com> wrote:
>
> It makes sense to do all the checks in check_region() and not 1/2
> in check_region and 1/2 in set_region.
>
> Since set_region is called immediately after check_region, the net
> effect on runtime is zero, but it gets rid of an if (...) return...
>
> Cc: Yury Norov <yury.norov@gmail.com>
> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> ---
>  lib/bitmap.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index 162e2850c622..833f152a2c43 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -500,17 +500,12 @@ struct region {
>         unsigned int nbits;
>  };
>
> -static int bitmap_set_region(const struct region *r, unsigned long *bitmap)
> +static void bitmap_set_region(const struct region *r, unsigned long *bitmap)
>  {
>         unsigned int start;
>
> -       if (r->end >= r->nbits)
> -               return -ERANGE;
> -
>         for (start = r->start; start <= r->end; start += r->group_len)
>                 bitmap_set(bitmap, start, min(r->end - start + 1, r->off));
> -
> -       return 0;
>  }
>
>  static int bitmap_check_region(const struct region *r)
> @@ -518,6 +513,9 @@ static int bitmap_check_region(const struct region *r)
>         if (r->start > r->end || r->group_len == 0 || r->off > r->group_len)
>                 return -EINVAL;
>
> +       if (r->end >= r->nbits)
> +               return -ERANGE;
> +
>         return 0;
>  }
>
> @@ -656,9 +654,7 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
>                 if (ret)
>                         return ret;
>
> -               ret = bitmap_set_region(&r, maskp);
> -               if (ret)
> -                       return ret;
> +               bitmap_set_region(&r, maskp);
>         }
>
>         return 0;
> --
> 2.17.1

Acked-by: Yury Norov <yury.norov@gmail.com>