linux-kernel - Re: [PATCH] powerpc: ps3: mark ps3_notification

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Message-ID: <CAMuHMdW41e+DSBKBgugTkjoLy6bXfji-KWmB_d9EstEv01eC6w@mail.gmail.com>
Date: Thu, 21 Mar 2024 09:32:33 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Arnd Bergmann <arnd@...nel.org>
Cc: Geoff Levand <geoff@...radead.org>, Michael Ellerman <mpe@...erman.id.au>, 
	Nathan Chancellor <nathan@...nel.org>, Paul Mackerras <paulus@...abs.org>, 
	Geert Uytterhoeven <Geert.Uytterhoeven@...ycom.com>, Arnd Bergmann <arnd@...db.de>, 
	Nicholas Piggin <npiggin@...il.com>, Christophe Leroy <christophe.leroy@...roup.eu>, 
	"Aneesh Kumar K.V" <aneesh.kumar@...nel.org>, "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>, 
	Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>, Kevin Hao <haokexin@...il.com>, 
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, 
	llvm@...ts.linux.dev
Subject: Re: [PATCH] powerpc: ps3: mark ps3_notification_device static for
 stack usage

Hi Arnd,

On Wed, Mar 20, 2024 at 7:03 PM Arnd Bergmann <arnd@...nel.org> wrote:
> From: Arnd Bergmann <arnd@...db.de>
>
> The device is way too large to be on the stack, causing a warning for
> an allmodconfig build with clang:
>
> arch/powerpc/platforms/ps3/device-init.c:771:12: error: stack frame size (2064) exceeds limit (2048) in 'ps3_probe_thread' [-Werror,-Wframe-larger-than]
>   771 | static int ps3_probe_thread(void *data)
>
> There is only a single thread that ever accesses this, so it's fine to
> make it static, which avoids the warning.
>
> Fixes: b4cb2941f855 ("[POWERPC] PS3: Use the HVs storage device notification mechanism properly")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Thanks for your patch!

> --- a/arch/powerpc/platforms/ps3/device-init.c
> +++ b/arch/powerpc/platforms/ps3/device-init.c
> @@ -770,7 +770,7 @@ static struct task_struct *probe_task;
>
>  static int ps3_probe_thread(void *data)
>  {
> -       struct ps3_notification_device dev;
> +       static struct ps3_notification_device dev;
>         int res;
>         unsigned int irq;
>         u64 lpar;

Making it static increases kernel size for everyone.  So I'd rather
allocate it dynamically. The thread already allocates a buffer, which
can be replaced at no cost by allocating a structure containing both
the ps3_notification_device and the buffer.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68korg

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