linux-kernel - Re: [PATCH] ARM: 6214/2: fix release_mem

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Message-ID: <CAMuHMdX2GeDYWXAK3+Vu9ENSUzUbqQSqfNNGS30atVw+=mvrFQ@mail.gmail.com>
Date: Sat, 27 Dec 2025 19:39:24 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: Thomas Fourier <fourier.thomas@...il.com>, Andy Shevchenko <andy@...nel.org>, 
	Linus Walleij <linus.walleij@...ricsson.com>, Russell King <rmk+kernel@....linux.org.uk>, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: 6214/2: fix release_mem_region() size

Hi Andy,

On Sat, 27 Dec 2025 at 17:01, Andy Shevchenko
<andriy.shevchenko@...el.com> wrote:
> On Wed, Dec 17, 2025 at 08:28:27AM +0100, Geert Uytterhoeven wrote:
> > On Tue, 16 Dec 2025 at 18:49, Thomas Fourier <fourier.thomas@...il.com> wrote:
> > > It seems like, after the request_mem_region(), the corresponding
> > > release_mem_region() must take the same size. This was done
> > > in charlcd_remove() but not in the error path in charlcd_probe().
> >
> > Unfortunately charlcd_remove() was removed in one of these silly
> > "make <foo> explicitly non-modular" patches...
> >
> > > Fixes: ce8962455e90 ("ARM: 6214/2: driver for the character LCD found in ARM refdesigns")
> > > Signed-off-by: Thomas Fourier <fourier.thomas@...il.com>
> >
> > > --- a/drivers/auxdisplay/arm-charlcd.c
> > > +++ b/drivers/auxdisplay/arm-charlcd.c
> > > @@ -323,7 +323,7 @@ static int __init charlcd_probe(struct platform_device *pdev)
> > >  out_no_irq:
> > >         iounmap(lcd->virtbase);
> > >  out_no_memregion:
> >
> > Looks like the first "goto out_no_memregion" is incorrect, and should be
> > "goto out_no_resource".
>
> Should it be in this change or in a separate change? I'm not sure I got what
> should be done about this.

Separate change.

> > > -       release_mem_region(lcd->phybase, SZ_4K);
> > > +       release_mem_region(lcd->phybase, lcd->physize);
> > >  out_no_resource:
> > >         kfree(lcd);
> > >         return ret;
> >
> > The actual change LGTM to me, so
> > Reviewed-by: Geert Uytterhoeven <geert@...ux-m68k.org>
>
> Reading between the lines, should I alter the commit message to mention that
> there is no more charlcd_remove()? Something like:
>
>     It seems like, after the request_mem_region(), the corresponding
>     release_mem_region() must take the same size. This was done
>     in recently dropped charlcd_remove() but not in the error path
>     in charlcd_probe().
>
> (and Subject line)?

Yes please.  It is very confusing to refer to a function that no longer exists.

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds