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Date: Fri, 19 Apr 2024 16:31:39 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, 
	Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org, "Rafael J. Wysocki" <rafael@kernel.org>, 
	Peter Zijlstra <peterz@infradead.org>, Adrian Hunter <adrian.hunter@intel.com>, 
	Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>, Elena Reshetova <elena.reshetova@intel.com>, 
	Jun Nakajima <jun.nakajima@intel.com>, Rick Edgecombe <rick.p.edgecombe@intel.com>, 
	Tom Lendacky <thomas.lendacky@amd.com>, "Kalra, Ashish" <ashish.kalra@amd.com>, 
	Sean Christopherson <seanjc@google.com>, "Huang, Kai" <kai.huang@intel.com>, Baoquan He <bhe@redhat.com>, 
	kexec@lists.infradead.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, 
	Tao Liu <ltao@redhat.com>
Subject: Re: [PATCHv10 03/18] cpu/hotplug: Add support for declaring CPU
 offlining not supported
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On Thu, Apr 18, 2024 at 04:37:09PM +0200, Borislav Petkov wrote:
> On Tue, Apr 09, 2024 at 02:29:55PM +0300, Kirill A. Shutemov wrote:
> > +/* Declare CPU offlining not supported */
> > +void cpu_hotplug_disable_offlining(void)
> > +{
> > +	cpu_maps_update_begin();
> 
> "/*
>  * The following two APIs (cpu_maps_update_begin/done) must be used when
>  * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
>  */
> void cpu_maps_update_begin(void)
> ..."
> 
> > +	cpu_hotplug_offline_disabled = true;
> 
> but this doesn't do that here.
> 
> Are we doing a one-off here for that variable or what?

Yes, it is one-off. I guess we could use READ_ONCE()/WRITE_ONCE() to
access the variable with the same result. I am not sure why it would be
better.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov