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From: Rik van Riel <riel@redhat.com>
Date: Wed, 16 Nov 2016 12:41:00 -0500
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Subject: Re: [kernel-hardening] Re: [RFC v4 PATCH 00/13] HARDENED_ATOMIC
To: kernel-hardening@lists.openwall.com
Cc: Will Deacon <will.deacon@arm.com>, Greg KH <gregkh@linuxfoundation.org>, David Windsor <dave@progbits.org>, Elena Reshetova <elena.reshetova@intel.com>, Arnd Bergmann <arnd@arndb.de>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter
 Anvin" <h.peter.anvin@intel.com>
List-ID: <kernel-hardening.lists.openwall.com>


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On Wed, 2016-11-16 at 18:32 +0100, Peter Zijlstra wrote:
> On Wed, Nov 16, 2016 at 12:09:16PM -0500, Rik van Riel wrote:
> > On Tue, 2016-11-15 at 09:23 -0800, Kees Cook wrote:
> > >=20
> > > Right, but it's the continuing atomic_t use that concerns me...
> >=20
> > Can we remove inc_not_zero and dec_and_test functionality
> > from the atomic_t macros?
> >=20
> > It would require fixing all of the in tree code, and after
> > that people with out of tree code would have to switch to
> > refcount_t to make their code work again.
>=20
> People will just use (atomic_add_return(-1, &refcount) =3D=3D 0) instead,
> or
> any other variant along those lines.

They could, but switching the variable type to refcount_t
seems like it would be the way of least resistance.

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