linux-kernel - Re: [PATCH] platform/x86: thinkpad_acpi: Fix bitwise vs. logical warning

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Date:   Mon, 18 Oct 2021 11:34:33 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Nathan Chancellor <nathan@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Henrique de Moraes Holschuh <hmh@....eng.br>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <markgross@...nel.org>,
        ibm-acpi-devel@...ts.sourceforge.net,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Tor Vic <torvic9@...lbox.org>
Subject: Re: [PATCH] platform/x86: thinkpad_acpi: Fix bitwise vs. logical warning

On Mon, Oct 18, 2021 at 11:26 AM Nathan Chancellor <nathan@...nel.org> wrote:
>
> A new warning in clang points out a use of bitwise OR with boolean
> expressions in this driver:
>
> drivers/platform/x86/thinkpad_acpi.c:9061:11: error: use of bitwise '|' with boolean operands [-Werror,-Wbitwise-instead-of-logical]
>         else if ((strlencmp(cmd, "level disengaged") == 0) |
>                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>                                                            ||
> drivers/platform/x86/thinkpad_acpi.c:9061:11: note: cast one or both operands to int to silence this warning
> 1 error generated.
>
> This should clearly be a logical OR so change it to fix the warning.
>
> Fixes: fe98a52ce754 ("ACPI: thinkpad-acpi: add sysfs support to fan subdriver")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1476
> Reported-by: Tor Vic <torvic9@...lbox.org>
> Signed-off-by: Nathan Chancellor <nathan@...nel.org>

LGTM, thanks for the patch! I guess this would be the first
"interesting" case this warning has found in kernel sources?
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>

> ---
>  drivers/platform/x86/thinkpad_acpi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index 07b9710d500e..7442c3bb446a 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -9058,7 +9058,7 @@ static int fan_write_cmd_level(const char *cmd, int *rc)
>
>         if (strlencmp(cmd, "level auto") == 0)
>                 level = TP_EC_FAN_AUTO;
> -       else if ((strlencmp(cmd, "level disengaged") == 0) |
> +       else if ((strlencmp(cmd, "level disengaged") == 0) ||
>                         (strlencmp(cmd, "level full-speed") == 0))
>                 level = TP_EC_FAN_FULLSPEED;
>         else if (sscanf(cmd, "level %d", &level) != 1)
>
> base-commit: 85303db36b6e170917a7bc6aae4898c31a5272a0
> --
> 2.33.1.637.gf443b226ca
>


-- 
Thanks,
~Nick Desaulniers