linux-kernel - Re: [PATCH v1 1/1] ipmi: si: Cast to smaller integer type without warning

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Message-ID: <Z_5FV65cyIwiI9rs@mail.minyard.net>
Date: Tue, 15 Apr 2025 06:39:03 -0500
From: Corey Minyard <corey@...yard.net>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: openipmi-developer@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev, Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>
Subject: Re: [PATCH v1 1/1] ipmi: si: Cast to smaller integer type without
 warning

On Tue, Apr 15, 2025 at 11:51:56AM +0300, Andy Shevchenko wrote:
> Debian clang version 19.1.7 is not happy when compiled with
> `make W=1` (note, CONFIG_WERROR=y is the default):
> 
> ipmi_si_platform.c:268:15: error: cast to smaller integer type 'enum si_type' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast]
>   268 |         io.si_type      = (enum si_type)device_get_match_data(&pdev->dev);
> 
> Fix this by intermediate cast to the uintptr_t, that makes compiler happy.

Unless things have changed recently, Linus prefers "unsigned long" per
https://patchwork.kernel.org/project/linux-hardening/patch/20220616143617.449094-1-Jason@zx2c4.com/#24899749

And it would match what is in the match table.

Is that change ok?

-corey

> 
> Fixes: 5be50eb5ae99 ("ipmi: si: Use device_get_match_data()")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/char/ipmi/ipmi_si_platform.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/ipmi/ipmi_si_platform.c b/drivers/char/ipmi/ipmi_si_platform.c
> index 550cabd43ae6..47d3cbeb3fa0 100644
> --- a/drivers/char/ipmi/ipmi_si_platform.c
> +++ b/drivers/char/ipmi/ipmi_si_platform.c
> @@ -265,7 +265,7 @@ static int of_ipmi_probe(struct platform_device *pdev)
>  	}
>  
>  	memset(&io, 0, sizeof(io));
> -	io.si_type	= (enum si_type)device_get_match_data(&pdev->dev);
> +	io.si_type	= (enum si_type)(uintptr_t)device_get_match_data(&pdev->dev);
>  	io.addr_source	= SI_DEVICETREE;
>  	io.irq_setup	= ipmi_std_irq_setup;
>  
> -- 
> 2.47.2
>