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Date: Fri, 9 Mar 2018 16:38:30 -0800
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Kees Cook <keescook@...omium.org>, 
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Josh Poimboeuf <jpoimboe@...hat.com>, 
	Rasmus Villemoes <linux@...musvillemoes.dk>, "Gustavo A. R. Silva" <gustavo@...eddedor.com>, 
	"Tobin C. Harding" <me@...in.cc>, Steven Rostedt <rostedt@...dmis.org>, Jonathan Corbet <corbet@....net>, 
	Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>, David Sterba <dsterba@...e.com>, 
	"David S. Miller" <davem@...emloft.net>, Alexey Kuznetsov <kuznet@....inr.ac.ru>, 
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>, Ingo Molnar <mingo@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>, 
	Masahiro Yamada <yamada.masahiro@...ionext.com>, Borislav Petkov <bp@...e.de>, 
	Randy Dunlap <rdunlap@...radead.org>, Ian Abbott <abbotti@....co.uk>, 
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>, Petr Mladek <pmladek@...e.com>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
	Pantelis Antoniou <pantelis.antoniou@...sulko.com>, Linux Btrfs <linux-btrfs@...r.kernel.org>, 
	Network Development <netdev@...r.kernel.org>, 
	Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH v3] kernel.h: Skip single-eval logic on literals in min()/max()

On Fri, Mar 9, 2018 at 4:32 PM, Andrew Morton <akpm@...ux-foundation.org> wrote:
>
> I wonder which gcc versions actually accept Kees's addition.

Note that we already do have this pattern, as seen by:

  git grep -2  __builtin_choose_expr | grep -2 __builtin_constant_p

which show drivers/pinctrl/intel/pinctrl-intel.h, so the pattern
already exists current kernels and _works_ - it apparently just
doesn't work in slightly more complicated cases.

It's one reason why I wondered if simplifying the expression to have
just that single __builtin_constant_p() might not end up working..

              Linus

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