linux-kernel - Re: [PATCH 1/2] pinctrl: pinconf-generic: resize the pin config array directly

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Date:   Sun, 26 Nov 2023 03:03:50 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] pinctrl: pinconf-generic: resize the pin config array directly

On Fri, Nov 24, 2023 at 8:25 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Fri, Nov 24, 2023 at 11:06:50AM +0100, Linus Walleij wrote:
> > On Tue, Nov 21, 2023 at 11:21 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
> > > On Tue, Nov 21, 2023 at 7:28 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
> > > >
> > > > pinconf_generic_parse_dt_config() allocates memory that is large enough
> > > > to contain all the config parameters. Then, kmemdup() copies the found
> > > > configs to the memory with the exact size.
> > > >
> > > > There is no need to allocate memory twice; you can directly resize the
> > > > initial memory using krealloc_array().
> > > >
> > > > I also changed kcalloc() to kmalloc_array() to keep the consistency with
> > > > krealloc_array(). This change has no impact because you do not need to
> > > > zero out the 'cfg' array.
> > > >
> > > > Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> > >
> > > Sorry, I retract this patch set.
> > >
> > > krealloc() does not save any memory
> > > when the new_size is smaller than the current size.
> >
> > But the first part where you switch to kmalloc_array() is still a nice change.
> >
> > The fact that we use kmemdup to be able to also shrink the allocation is a
> > bit of an oddity I guess, but let's run this patch by Andy Shevchenko, and
> > ask what he thinks about simply introducing kmemdup_array() or if he
> > has other ideas for this.
>
> https://lore.kernel.org/all/20231017052322.2636-2-kkartik@nvidia.com/


Ok, I will come back when kmemdup_array() is upstreamed.



> --
> With Best Regards,
> Andy Shevchenko
>
>


-- 
Best Regards
Masahiro Yamada