linux-kernel - Re: [PATCH 5/7] linux/bitmap.h: relax comment on compile-time constant nbits

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Message-ID: <20180904110859.GA4992@yury-thinkpad>
Date:   Tue, 4 Sep 2018 14:08:59 +0300
From:   Yury Norov <ynorov@...iumnetworks.com>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] linux/bitmap.h: relax comment on compile-time
 constant nbits

On Sat, Aug 18, 2018 at 03:16:21PM +0200, Rasmus Villemoes wrote:
> It's not clear what's so horrible about emitting a function call to
> handle a run-time sized bitmap. Moreover, gcc also emits a function call
> for a compile-time-constant-but-huge nbits, so the comment isn't even
> accurate.
> 
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>

Hi Rasmus,

Maybe too late, but 

Acked-by: Yury Norov <ynorov@...iumnetworks.com>
> ---
>  include/linux/bitmap.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
> index e34c361f4a92..3f0cac3aedca 100644
> --- a/include/linux/bitmap.h
> +++ b/include/linux/bitmap.h
> @@ -28,8 +28,8 @@
>   * The available bitmap operations and their rough meaning in the
>   * case that the bitmap is a single unsigned long are thus:
>   *
> - * Note that nbits should be always a compile time evaluable constant.
> - * Otherwise many inlines will generate horrible code.
> + * The generated code is more efficient when nbits is known at
> + * compile-time and at most BITS_PER_LONG.
>   *
>   * ::
>   *
> --
> 2.16.4