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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 8BEB6C2D0D0 for ; Mon, 23 Dec 2019 11:35:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 631A82063A for ; Mon, 23 Dec 2019 11:35:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577100955; bh=uEFO2Yo2axiENJZnZufLZNM9xiwL3h2PZxVd19dYCp0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=jeZa5Dbu9ekLfsS4alLueEM7NzuKpAhNwPZQ3tlCa1rpEqm7BsnV+/pC1zCADJThu jez7oSsWE13n0rCwoRftW/FgEMvxpu7CDpy1PZnOy49UmlE/U5XDG4zPmblxCXr5hg Ugpn+Le6slUqqb+8ufgnOzJRzhV4GJJ8nZFzPEkI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727395AbfLWLfy (ORCPT ); Mon, 23 Dec 2019 06:35:54 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:36455 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726680AbfLWLfu (ORCPT ); Mon, 23 Dec 2019 06:35:50 -0500 Received: by mail-wr1-f67.google.com with SMTP id z3so16297054wru.3; Mon, 23 Dec 2019 03:35:48 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=HLf7UDzjHO46QZ+r4g/DQtLvnK9ZgG13FP1Rb0ijduQ=; b=qPRER4TqbjX+h4OFzgVXBSmWL2Bth5zX/084Jq9f8xbNHxRq/1L7+FlpFEqRhAHP9h wVGfgxzHihmkNi66DSmcWcdy4YJ8B9C4GCl6uVrPL84+05es37WrjcH0BXo2GK8D06nt 1zkXHeaiKSsPTq58K6gsU3guU1GBFYrcaB0oBXUtEPeqBGGBFhsWpCLrAOUIJJ5UyHWG +v6WHXH25czYVKkEIWahWpcKrIWjq4x9GYoJ7Qq7NpOgcvLPT+e5Wtp8b5YEMcEoc8ja J5GkGqoZou+CODfC85Cp3kNd9g92AJ2laNbpLlYEyivhf1fZlMjyWfJ+EKJntENxP1QJ pHlA== X-Gm-Message-State: APjAAAUBGnjW/C7AfBxFxUW5LQEhjvJUEtJzhFvj/u12dKYWg40mTBUR FDt5/fkuaZuCsph3rLjY1C8= X-Google-Smtp-Source: APXvYqz93/AcG8Tzkn6CEiCbg3U9AEeAW5KZcv3jLL8eB1/yo9AokuwM9YpW25WmFlKY/8HxY5MEzA== X-Received: by 2002:adf:fc0c:: with SMTP id i12mr31296335wrr.74.1577100948094; Mon, 23 Dec 2019 03:35:48 -0800 (PST) Received: from debian (38.163.200.146.dyn.plus.net. [146.200.163.38]) by smtp.gmail.com with ESMTPSA id c15sm20231097wrt.1.2019.12.23.03.35.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Dec 2019 03:35:47 -0800 (PST) Date: Mon, 23 Dec 2019 11:35:45 +0000 From: Wei Liu To: Paul Durrant 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 Message-ID: <20191223113545.nwugg7lsorttunuu@debian> References: <20191223095923.2458-1-pdurrant@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191223095923.2458-1-pdurrant@amazon.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 = vif->dev; > void *addr; > struct xen_netif_ctrl_sring *shared; > + RING_IDX rsp_prod, req_prod; > int err; > > err = 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 = (struct xen_netif_ctrl_sring *)addr; > - BACK_RING_INIT(&vif->ctrl, shared, XEN_PAGE_SIZE); > + rsp_prod = READ_ONCE(shared->rsp_prod); > + req_prod = READ_ONCE(shared->req_prod); > + > + BACK_RING_ATTACH(&vif->ctrl, shared, rsp_prod, XEN_PAGE_SIZE); > + > + err = -EIO; > + if (req_prod - rsp_prod > RING_SIZE(&vif->ctrl)) > + goto err_unmap; 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. So: Reviewed-by: Wei Liu Nice work btw.