Re: [PATCH v2 6/6] of/device: Don't NULLify match table in of_match_device() with CONFIG_OF=n

From: Geert Uytterhoeven
Date: Mon Jan 25 2021 - 04:01:27 EST


On Sat, Jan 23, 2021 at 4:44 AM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote:
> This effectively reverts 1db73ae39a97 ("of/device: Nullify match table
> in of_match_device() for CONFIG_OF=n") because that commit makes it more
> surprising to users of this API that the arguments may never be
> referenced by any code. This is because the pre-processor will replace
> the argument with NULL and then the match table will be left unreferenced
> by any code but the compiler optimizer doesn't know to drop it. This can
> lead to compilers warning that match tables are unused, when we really
> want to pass the match table to the API but have the compiler see that
> it's all inlined and not used and then drop the match table while
> silencing the warning. We're being too smart here and not giving the
> compiler the chance to do dead code elimination.
>
> Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
> Acked-by: Frank Rowand <frowand.list@xxxxxxxxx>

Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Acked-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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