linux-kernel - Re: [PATCH] HID: microsoft, do not use compound literal

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Date:	Mon, 12 Nov 2012 10:23:44 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Jiri Slaby <jslaby@...e.cz>
Cc:	jkosina@...e.cz, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, jirislaby@...il.com
Subject: Re: [PATCH] HID: microsoft, do not use compound literal

On Mon, Nov 12, 2012 at 10:16 AM, Jiri Slaby <jslaby@...e.cz> wrote:
> In patch "HID: microsoft: fix invalid rdesc for 3k kbd" I fixed
> support for MS 3k keyboards. However the added check using memcmp and
> a compound statement breaks build on architectures where memcmp is a
> macro with parameters. The error looks there like (m68k-linux-gnu-gcc
> 4.1.2):
> hid-microsoft.c:51:18: error: macro "memcmp" passed 6 arguments, but takes just 3
> hid-microsoft.c: In function ‘ms_report_fixup’:
> drivers/hid/hid-microsoft.c:50: error: ‘memcmp’ undeclared (first use in this function)
> hid-microsoft.c:50: error: (Each undeclared identifier is reported only once
> /hid-microsoft.c:50: error: for each function it appears in.)

The above 3 lines were actually from a build with a different config
--- which I didn't
notice at that time --- where <linux/string.h> was not indirectly included.

> On x86_64, memcmp is a function, so I did not see the error.
>
> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> ---
>  drivers/hid/hid-microsoft.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hid/hid-microsoft.c b/drivers/hid/hid-microsoft.c
> index f676c01..6fcd466 100644
> --- a/drivers/hid/hid-microsoft.c
> +++ b/drivers/hid/hid-microsoft.c
> @@ -46,9 +46,9 @@ static __u8 *ms_report_fixup(struct hid_device *hdev, __u8 *rdesc,
>                 rdesc[559] = 0x45;
>         }
>         /* the same as above (s/usage/physical/) */
> -       if ((quirks & MS_RDESC_3K) && *rsize == 106 &&
> -                       !memcmp((char []){ 0x19, 0x00, 0x29, 0xff },
> -                               &rdesc[94], 4)) {
> +       if ((quirks & MS_RDESC_3K) && *rsize == 106 && rdesc[94] == 0x19 &&
> +                       rdesc[95] == 0x00 && rdesc[96] == 0x29 &&
> +                       rdesc[97] == 0xff) {
>                 rdesc[94] = 0x35;
>                 rdesc[96] = 0x45;
>         }
> --
> 1.8.0

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
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