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

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Message-ID: <ZWCIChQ3TKtxv2b-@smile.fi.intel.com>
Date:   Fri, 24 Nov 2023 13:24:58 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Masahiro Yamada <masahiroy@...nel.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 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/

-- 
With Best Regards,
Andy Shevchenko