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Date:   Mon, 6 Dec 2021 19:55:26 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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On Mon, Dec 06, 2021 at 11:52:09AM -0800, Nick Desaulniers wrote:
> On Mon, Dec 6, 2021 at 8:14 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Mon, Dec 06, 2021 at 04:56:32PM +0100, Miguel Ojeda wrote:
> > > On Mon, Dec 6, 2021 at 4:46 PM Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > That should be in a .h file somewhere.  Remember, don't put #ifdef in .c
> > > > files please.
> 
> Why not put #ifdef in .c files?
> 
> > > Will do, thanks for reviewing!
> > >
> > > > Same here, this should not be needed if you put it in a .h file
> > > > correctly.
> 
> I guess IS_ENABLED could be used in the .c code, but I don't see how
> they could move the dispatch to rust_fmt_argument to a header without
> moving the definition of pointer() to a header, which they probably
> _cant_ do because it's noinline_for_stack.

In the header file, you put:

#ifdef CONFIG_FOO
int foo(void);
#else
static inline int foo(void) { }
#endif

and then in your .c file, you call foo() unconditionally, and everything
works beautifully.