From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754124AbaLWCSB (ORCPT ); Mon, 22 Dec 2014 21:18:01 -0500 Received: from ozlabs.org ([103.22.144.67]:39035 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751241AbaLWCR7 (ORCPT ); Mon, 22 Dec 2014 21:17:59 -0500 Date: Tue, 23 Dec 2014 13:17:49 +1100 From: Stephen Rothwell To: Linus Cc: Christian Borntraeger , , LKML Subject: linux-next: missing merge fix for the access_once tree Message-ID: <20141223131749.78087632@canb.auug.org.au> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; i586-pc-linux-gnu) MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; boundary="Sig_/qLiucl.aJ_LaTPkYLOkWgQW"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/qLiucl.aJ_LaTPkYLOkWgQW Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Hi Linus, I have been carrying this merge fix patch for some time. It should have gone into the merge of the access_once tree. From: Christian Borntraeger Date: Sun, 7 Dec 2014 22:01:59 +0100 Subject: [PATCH] x86/xen/p2m: Replace ACCESS_ONCE with READ_ONCE ACCESS_ONCE does not work reliably on non-scalar types. For example gcc 4.6 and 4.7 might remove the volatile tag for such accesses during the SRA (scalar replacement of aggregates) step (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D58145) Change the p2m code to replace ACCESS_ONCE with READ_ONCE. Signed-off-by: Christian Borntraeger --- arch/x86/xen/p2m.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 8b5db51..08ddf91 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -554,7 +554,7 @@ static bool alloc_p2m(unsigned long pfn) mid_mfn =3D NULL; } =20 - p2m_pfn =3D pte_pfn(ACCESS_ONCE(*ptep)); + p2m_pfn =3D pte_pfn(READ_ONCE(*ptep)); if (p2m_pfn =3D=3D PFN_DOWN(__pa(p2m_identity)) || p2m_pfn =3D=3D PFN_DOWN(__pa(p2m_missing))) { /* p2m leaf page is missing */ --=20 1.8.5.5 --=20 Cheers, Stephen Rothwell sfr@canb.auug.org.au --Sig_/qLiucl.aJ_LaTPkYLOkWgQW Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJUmNDSAAoJEMDTa8Ir7ZwVAf4P/2f3c2K4almHPEGFn0tHrMFP EY3wBiuUh1qgdxW5MGritGm3WlrsfN50uBxYR5Vil+HF1BnU4rw49PGz9A+F+M96 enC2Xg8FcUgfTFj5Efwg+U4MEfbV6JMHtlYMlDDypNvcY8r09lmHBkyh0GM3nn4x q50UMQ7AC0knMO1ExGSys/rNuB0NgICF4vnegbirzHScwcFyquu9Z621HFECDR1o IVOxN8Yqs3sbYEncF8KaYWClJVQ0zlM1Fuysr/rMxjU0L31GoLFPGcNhMFDt1c5W qaXNMOd8e7qZ1jQJqPCg+KsR1mqcqjNGLCxmdH+PBhFd3tLIoUacXyQG3i0CjT4Y 6WMJje4QTTfLAO2+W1l8Ks5cOThY8h0QqjEfIi+mXEWz9u6mtyqmBmaOy0dX/q3/ VCVb1pn/KM0Os9nBMxFAYIiyjV4kfjWWK86xRRIUWDWZYeT6nbFEOvbOFuAUh9SZ K3bumluc2PsyMgpyuL0Hbd6fhvxNvXn80MXEZWNJfBUHQT3b8qQYb2tcNF5FOfqk i/nvFLSysmNUheafzeXs2mRQkQUhleCbPelTzOyszWTg3AfhWetz8LCabr2T1iWQ 3OYeqFC/ddBnZncNhD2zcSH+ttOx8sTJmZLkT4KhbyZJBjKcro1XT57jFobX/8oH e+C6LDxlQJJSWx/aKr+l =1yAo -----END PGP SIGNATURE----- --Sig_/qLiucl.aJ_LaTPkYLOkWgQW--