linux-kernel - Re: [PATCH v4 1/1] x86/cpu: Make sure flag_is_changeable

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Message-ID: <Zy4rw-yx0JL7_-lk@smile.fi.intel.com>
Date: Fri, 8 Nov 2024 17:18:27 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Dave Hansen <dave.hansen@...el.com>
Subject: Re: [PATCH v4 1/1] x86/cpu: Make sure flag_is_changeable_p() is
 always being used

On Fri, Nov 08, 2024 at 04:13:05PM +0100, H. Peter Anvin wrote:
> On November 8, 2024 3:11:46 PM GMT+01:00, Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> >When flag_is_changeable_p() is unused, it prevents kernel builds
> >with clang, `make W=1` and CONFIG_WERROR=y:
> >
> >arch/x86/kernel/cpu/common.c:351:19: error: unused function 'flag_is_changeable_p' [-Werror,-Wunused-function]
> >  351 | static inline int flag_is_changeable_p(u32 flag)
> >      |                   ^~~~~~~~~~~~~~~~~~~~
> >
> >Fix this by moving core around to make sure flag_is_changeable_p() is
> >always being used.
> >
> >See also commit 6863f5643dd7 ("kbuild: allow Clang to find unused static
> >inline functions for W=1 build").
> >
> >While at it, fix the argument type to be unsigned long, although it currently
> >only runs in 32-bit cases.

...

> It's good that you are changing the return type, but we need to be consistent
> and change f1, f2 to match. At the same time, I suggest changing the return
> type to bool.

Ah, that makes sense!

-- 
With Best Regards,
Andy Shevchenko