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

[Andy Shevchenko]

On Tue, Apr 15, 2025 at 03:06:45PM +0300, Andy Shevchenko wrote:
> On Tue, Apr 15, 2025 at 06:39:03AM -0500, Corey Minyard wrote:
> > 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@xxxxxxxxx/#24899749
> 
> I'm not sure I got your point. That discussion seems irrelevant to me.
> They are talking about pointer-as-an-integer cases. Here we already know
> that we are passing integer-as-a-pointer and this is the opposite
> conversion.
> 
> > And it would match what is in the match table.
> 
> Match tables are tend to move to pointers, enum is usually goes to int.
> 
> > Is that change ok?
> 
> If you don't like my change, please do yours and consider this as
> a bug report that needs to be addressed. I prefer more my solution
> as we do that in many places for the exact scenario.

Note, the proper solution to the cases like this is to move to info-like
structure and actually operate with the pointers instead of enums, longs, etc.

That's what's slowly moving on in IIO subsystem, for instance.

-- 
With Best Regards,
Andy Shevchenko