linux-kernel - Re: [PATCH] x86/smpboot: Mark native_play_dead() as _

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Message-ID: <i4o6cr4x364xsk7ftas5guggjt4xdvawurrohveahi75iba5aj@dl6plusoxtin>
Date: Mon, 27 Oct 2025 12:28:49 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Thorsten Blum <thorsten.blum@...ux.dev>
Cc: 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>, Peter Zijlstra <peterz@...radead.org>, 
	Sean Christopherson <seanjc@...gle.com>, Kai Huang <kai.huang@...el.com>, Brian Gerst <brgerst@...il.com>, 
	Thomas Huth <thuth@...hat.com>, Patryk Wlazlyn <patryk.wlazlyn@...ux.intel.com>, 
	Zheyun Shen <szy0127@...u.edu.cn>, Kevin Loughlin <kevinloughlin@...gle.com>, 
	K Prateek Nayak <kprateek.nayak@....com>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, 
	Li Chen <chenl311@...natelecom.cn>, Tim Chen <tim.c.chen@...ux.intel.com>, 
	Ingo Molnar <mingo@...nel.org>, Tom Lendacky <thomas.lendacky@....com>, 
	Kevin Brodsky <kevin.brodsky@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/smpboot: Mark native_play_dead() as __noreturn

On Mon, Oct 27, 2025 at 04:51:02PM +0100, Thorsten Blum wrote:
> native_play_dead() ends by calling the non-returning function
> hlt_play_dead() and therefore also never returns.
> 
> The !CONFIG_HOTPLUG_CPU stub version of native_play_dead()
> unconditionally calls BUG() and does not return either.
> 
> Add the __noreturn attribute to both function definitions and their
> declaration to document this behavior and to potentially improve
> compiler optimizations.
> 
> Remove the obsolete comment, and add native_play_dead() to the objtool's
> list of __noreturn functions.
> 
> Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>

Is there an objtool warning that this fixes?  If so, it would be helpful
to put it in the description above.

And same for the other patch.

Otherwise it LGTM.  Thanks!

-- 
Josh