From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F15F2C07E97 for ; Sat, 3 Jul 2021 15:22:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D7F2B6192E for ; Sat, 3 Jul 2021 15:22:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230033AbhGCPYy (ORCPT ); Sat, 3 Jul 2021 11:24:54 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:39214 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230009AbhGCPYy (ORCPT ); Sat, 3 Jul 2021 11:24:54 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 4C3431C0B81; Sat, 3 Jul 2021 17:22:19 +0200 (CEST) Date: Sat, 3 Jul 2021 17:22:18 +0200 From: Pavel Machek To: Sasha Levin Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Esben Haabendal , "David S . Miller" Subject: Re: [PATCH 5.10 055/101] net: ll_temac: Add memory-barriers for TX BD access Message-ID: <20210703152218.GD3004@amd> References: <20210628142607.32218-1-sashal@kernel.org> <20210628142607.32218-56-sashal@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="vni90+aGYgRvsTuO" Content-Disposition: inline In-Reply-To: <20210628142607.32218-56-sashal@kernel.org> User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org --vni90+aGYgRvsTuO Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > Add a couple of memory-barriers to ensure correct ordering of read/write > access to TX BDs. So... this is dealing with CPU-to-device consistency, not CPU-to-CPU, right? > +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c > @@ -774,12 +774,15 @@ static void temac_start_xmit_done(struct net_device= *ndev) > stat =3D be32_to_cpu(cur_p->app0); > =20 > while (stat & STS_CTRL_APP0_CMPLT) { > + /* Make sure that the other fields are read after bd is > + * released by dma > + */ > + rmb(); > dma_unmap_single(ndev->dev.parent, Full barrier, as expected. > @@ -788,6 +791,12 @@ static void temac_start_xmit_done(struct net_device = *ndev) > ndev->stats.tx_packets++; > ndev->stats.tx_bytes +=3D be32_to_cpu(cur_p->len); > =20 > + /* app0 must be visible last, as it is used to flag > + * availability of the bd > + */ > + smp_mb(); SMP-only barrier, but full barrier is needed here AFAICT. Pavel --=20 DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany --vni90+aGYgRvsTuO Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAmDggKoACgkQMOfwapXb+vLB9QCgjq4eIi/uFYHs2xZAShWTlO9G WMIAn3jtHyDFjeYsVzCIwEmzWCcIKzHA =R+tk -----END PGP SIGNATURE----- --vni90+aGYgRvsTuO--