linux-kernel - Re: [PATCH v2 1/1] x86/reboot: KVM: Guard nmi_shootdown_cpus_on

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Message-ID: <ba00197d-dc21-47bd-b183-4971038d9a8d@intel.com>
Date: Fri, 2 May 2025 07:24:37 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Sean Christopherson <seanjc@...gle.com>, 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,
 "H. Peter Anvin" <hpa@...or.com>, Nathan Chancellor <nathan@...nel.org>,
 Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling
 <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>
Subject: Re: [PATCH v2 1/1] x86/reboot: KVM: Guard
 nmi_shootdown_cpus_on_restart() with ifdeffery

On 5/2/25 07:04, Andy Shevchenko wrote:
> Can it be applied, please? The problem still persists as of today (v6.15-rc4).

I fundamentally disagree with the idea that the kernel programmer should
be doing the work of telling the compiler *exactly* when a static inline
function is unused. Compilers are good at that, humans are not.

The "fixes" for these issues generally make the code worse, not better.

I'd frankly rather have a kernel with some unused 'static inline'
functions in .c files than one filled with #ifdefs to shut up the compiler.