linux-kernel - RE: [PATCH next 2/5] minmax: Allow min()/max()/clamp() if the arguments have the same signedness.

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Message-ID: <c7e4b886eae04d3f9ea50be0685839e9@AcuMS.aculab.com>
Date:   Thu, 27 Jul 2023 14:01:48 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Andy Shevchenko' <andriy.shevchenko@...ux.intel.com>
CC:     'kernel test robot' <lkp@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        'Andrew Morton' <akpm@...ux-foundation.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Christoph Hellwig <hch@...radead.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        "llvm@...ts.linux.dev" <llvm@...ts.linux.dev>,
        "oe-kbuild-all@...ts.linux.dev" <oe-kbuild-all@...ts.linux.dev>,
        "Linux Memory Management List" <linux-mm@...ck.org>
Subject: RE: [PATCH next 2/5] minmax: Allow min()/max()/clamp() if the
 arguments have the same signedness.

From: 'Andy Shevchenko'
> Sent: 26 July 2023 17:20
> 
> On Wed, Jul 26, 2023 at 08:30:59AM +0000, David Laight wrote:
> > From: kernel test robot
> > > Sent: 25 July 2023 16:58
> > >
> > > kernel test robot noticed the following build errors:
> 
> ...
> 
> > >    In file included from init/calibrate.c:8:
> > > >> include/linux/jiffies.h:427:28: error: call to undeclared function 'static_assert'; ISO C99 and
> > > later do not support implicit function declarations [-Wimplicit-function-declaration]
> > >      427 |         return jiffies_to_clock_t(max(0L, delta));
> > >          |                                   ^
> > ...
> > >    include/linux/minmax.h:29:3: note: expanded from macro '__cmp_once'
> > >       29 |                 static_assert(__types_ok(x, y),         \
> >
> > This is fixed by the earlier patch:
> > [PATCH v1 1/1] minmax: Fix header inclusions
> >
> > which adds #include <linux/build_bug.h> and thus defines static_assert().
> >
> > Can I just assume that will be applied?
> 
> You can test that and reply there with your Tested-by there, it will help it
> to be applied.

I can check it doesn't break my x86-64 build.

I think the build error was on a 'um' build - not really obvious
in the report.

I suspect everything else gets build_bug.h included from a very
common header file.

On x86-64 (5.10.xxx) by forcing an error I get:
  CC      init/calibrate.o
In file included from linux/include/linux/bits.h:22,
                 from linux/include/linux/bitops.h:5,
                 from linux/include/linux/kernel.h:12,
                 from linux/arch/x86/include/asm/percpu.h:27,
                 from linux/arch/x86/include/asm/current.h:6,
                 from linux/arch/x86/include/asm/processor.h:17,
                 from linux/arch/x86/include/asm/timex.h:5,
                 from linux/include/linux/timex.h:67,
                 from linux/include/linux/time32.h:13,
                 from linux/include/linux/time.h:73,
                 from linux/include/linux/jiffies.h:10,
                 from linux/init/calibrate.c:9:
linux/include/linux/build_bug.h: ...

I can't help feeling some of that chain isn't needed :-)

	David

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