linux-kernel - Re: [PATCH 7/8] x86,fpu: use disable_task_lazy_fpu

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Message-ID: <20150217110405.GC22233@redhat.com>
Date:	Tue, 17 Feb 2015 12:04:05 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	riel@...hat.com, dave.hansen@...ux.intel.com, sbsiddha@...il.com,
	luto@...capital.net, tglx@...utronix.de, mingo@...nel.org,
	hpa@...or.com, fenghua.yu@...el.com, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/8] x86,fpu: use disable_task_lazy_fpu_restore helper

On 02/17, Borislav Petkov wrote:
>
> On Fri, Feb 06, 2015 at 03:02:04PM -0500, riel@...hat.com wrote:
> > From: Rik van Riel <riel@...hat.com>
> >
> > Replace magic assignments of fpu.last_cpu = ~0 with more explicit
> > disable_task_lazy_fpu_restore calls.
> >
> > This also fixes the lazy FPU restore disabling in drop_fpu, which
> > only really works when !use_eager_fpu().  This is fine for now,
> > because fpu_lazy_restore() is only used when !use_eager_fpu()
> > currently, but we may want to expand that.
>
> Sorry, I can't follow here. The only non-trivial change below is in
> arch_dup_task_struct(). Please clarify.

I guess Rik forgot to update the changelog ;)

Initial version of this patch played with drop_fpu() as well, this part
was removed after discussion. So I guess the last sentence in the changelog
should go away too.

Oleg.

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