Re: [PATCH RFC net-next 3/3] netfilter: uapi: Use UAPI definition of INT_MAX and INT_MIN

[Thomas Weißschuh]

On Fri, Jan 09, 2026 at 11:20:22AM +0100, Thomas Weißschuh wrote:
> On Mon, Jan 05, 2026 at 02:02:17PM +0100, Arnd Bergmann wrote:
> > On Mon, Jan 5, 2026, at 09:26, Thomas Weißschuh wrote:
> > > Using <limits.h> to gain access to INT_MAX and INT_MIN introduces a
> > > dependency on a libc, which UAPI headers should not do.
> > >
> > > Use the equivalent UAPI constants.
> > >
> > > Signed-off-by: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
> > 
> > I agree with the idea of the patch series, but I think this
> > introduces a different problem:
> > 
> > >  #include <linux/in.h>
> > > +#include <linux/limits.h>
> > 
> > linux/limits.h is not always clean against limits.h. In glibc,
> > you can include both in any order, but in musl, you cannot:

(...)

> > I can think of two alternative approaches here:
> > 
> > - put the __KERNEL_INT_MIN into a different header -- either a new one
> >   or maybe uapi/linux/types.h
> 
> > - use the compiler's built-in __INT_MIN__ instead of INT_MIN in
> >   UAPI headers.
> 
> If we can rely on compiler built-ins I would prefer this option.

It turns out that the compiler only provides __INT_MAX__, not __INT_MIN__.
We can derive INT_MIN from INT_MAX as done in the original commit, but
open-coding it is ugly as heck. So we are back to a definition in a header
file again.

What about putting them in uapi/linux/types.h or adding a new
uapi/linux/typelimits.h?


Thomas