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

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Message-ID: <20180904113046.GQ11447@smile.fi.intel.com>
Date:   Tue, 4 Sep 2018 14:30:46 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Yury Norov <ynorov@...iumnetworks.com>
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] linux/bitmap.h: relax comment on compile-time
 constant nbits

On Tue, Sep 04, 2018 at 02:08:59PM +0300, Yury Norov wrote:
> 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>

Actually not, I don't see this in linux-next.

Rasmus, do you know what happened to the series? Is it got stuck by unknown reasons?

> > ---
> >  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

-- 
With Best Regards,
Andy Shevchenko