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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 D93B4C2D0C0 for ; Mon, 23 Dec 2019 11:46:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A8910206D3 for ; Mon, 23 Dec 2019 11:46:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="RZW9Py3q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726853AbfLWLqe (ORCPT ); Mon, 23 Dec 2019 06:46:34 -0500 Received: from smtp-fw-2101.amazon.com ([72.21.196.25]:18754 "EHLO smtp-fw-2101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726257AbfLWLqe (ORCPT ); Mon, 23 Dec 2019 06:46:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1577101593; x=1608637593; h=from:to:cc:subject:date:message-id:references: in-reply-to:content-transfer-encoding:mime-version; bh=vvmp92KNUpBEgXRjRfQ+MICqzu1qMXT+80kMSZKetok=; b=RZW9Py3q1sMRx2fvzBMpOvftnXSo81qErb5ABgPl+oRDP9t8NhXWApz2 Q8F6t/xTfHT8SxKkqfDJRWZoSSj73vHx32YEca4m+MMyUEsRnrM/4+ANe SN5o3jTi/ySnfJgxaverB1KgHnaH33qGUMj4Hv18UGO9ayXEc3vcUGlPk 8=; IronPort-SDR: bYFdawsqLJaf///3+Xmev8apsMjp4iYZk+WyLjr5J5nVgZ60Q04Yv7ot07mFMeKy50f3Bvfqg2 YdpJMNxOkl2g== X-IronPort-AV: E=Sophos;i="5.69,347,1571702400"; d="scan'208";a="9790850" Received: from iad12-co-svc-p1-lb1-vlan2.amazon.com (HELO email-inbound-relay-1d-38ae4ad2.us-east-1.amazon.com) ([10.43.8.2]) by smtp-border-fw-out-2101.iad2.amazon.com with ESMTP; 23 Dec 2019 11:46:31 +0000 Received: from EX13MTAUEA002.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan3.iad.amazon.com [10.40.159.166]) by email-inbound-relay-1d-38ae4ad2.us-east-1.amazon.com (Postfix) with ESMTPS id 6C2C1A27B1; Mon, 23 Dec 2019 11:46:31 +0000 (UTC) Received: from EX13D32EUC002.ant.amazon.com (10.43.164.94) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1236.3; Mon, 23 Dec 2019 11:46:30 +0000 Received: from EX13D32EUC003.ant.amazon.com (10.43.164.24) by EX13D32EUC002.ant.amazon.com (10.43.164.94) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 23 Dec 2019 11:46:29 +0000 Received: from EX13D32EUC003.ant.amazon.com ([10.43.164.24]) by EX13D32EUC003.ant.amazon.com ([10.43.164.24]) with mapi id 15.00.1367.000; Mon, 23 Dec 2019 11:46:29 +0000 From: "Durrant, Paul" To: Wei Liu CC: "xen-devel@lists.xenproject.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Paul Durrant , "David S. Miller" Subject: RE: [PATCH net-next] xen-netback: support dynamic unbind/bind Thread-Topic: [PATCH net-next] xen-netback: support dynamic unbind/bind Thread-Index: AQHVuXeo48GmlxuNH0abtWhDKbfEbafHl0uAgAACIOA= Date: Mon, 23 Dec 2019 11:46:29 +0000 Message-ID: <1d1189a3acd8473fadc420d902fd4692@EX13D32EUC003.ant.amazon.com> References: <20191223095923.2458-1-pdurrant@amazon.com> <20191223113545.nwugg7lsorttunuu@debian> In-Reply-To: <20191223113545.nwugg7lsorttunuu@debian> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.43.165.29] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Wei Liu > Sent: 23 December 2019 11:36 > To: Durrant, Paul > Cc: xen-devel@lists.xenproject.org; netdev@vger.kernel.org; linux- > kernel@vger.kernel.org; Wei Liu ; Paul Durrant > ; David S. Miller > Subject: Re: [PATCH net-next] xen-netback: support dynamic unbind/bind >=20 > On Mon, Dec 23, 2019 at 09:59:23AM +0000, Paul Durrant wrote: > [...] > > diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen- > netback/interface.c > > index f15ba3de6195..0c8a02a1ead7 100644 > > --- a/drivers/net/xen-netback/interface.c > > +++ b/drivers/net/xen-netback/interface.c > > @@ -585,6 +585,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, > grant_ref_t ring_ref, > > struct net_device *dev =3D vif->dev; > > void *addr; > > struct xen_netif_ctrl_sring *shared; > > + RING_IDX rsp_prod, req_prod; > > int err; > > > > err =3D xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif), > > @@ -593,7 +594,14 @@ int xenvif_connect_ctrl(struct xenvif *vif, > grant_ref_t ring_ref, > > goto err; > > > > shared =3D (struct xen_netif_ctrl_sring *)addr; > > - BACK_RING_INIT(&vif->ctrl, shared, XEN_PAGE_SIZE); > > + rsp_prod =3D READ_ONCE(shared->rsp_prod); > > + req_prod =3D READ_ONCE(shared->req_prod); > > + > > + BACK_RING_ATTACH(&vif->ctrl, shared, rsp_prod, XEN_PAGE_SIZE); > > + > > + err =3D -EIO; > > + if (req_prod - rsp_prod > RING_SIZE(&vif->ctrl)) > > + goto err_unmap; >=20 > I think it makes more sense to attach the ring after this check has been > done, but I can see you want to structure code like this to reuse the > unmap error path. Looks a little odd, agreed. The reason I did it this way is so that I can u= se RING_SIZE() rather than having to use __RING_SIZE(); makes the code just= a little bit shorter... which reminds me I ought to neaten up blkback simi= larly. >=20 > So: >=20 > Reviewed-by: Wei Liu >=20 > Nice work btw. Thanks :-) Paul