From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raghuram Kothakota Subject: Re: [PATCH net-next 2/2] sunvnet: vnet_start_xmit() must hold a refcnt on port. Date: Wed, 1 Oct 2014 20:36:38 -0700 Message-ID: <3DC66499-B569-4EB6-AB9B-D0F6415BAB78@oracle.com> References: <542C50A4.30304@oracle.com> <20141001192325.GK17706@oracle.com> <542C56A5.4070805@oracle.com> <20141001.155210.882272719949254470.davem@davemloft.net> Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: david.stevens@oracle.com, sowmini.varadhan@oracle.com, netdev@vger.kernel.org To: David Miller Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:41143 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751182AbaJBDgq convert rfc822-to-8bit (ORCPT ); Wed, 1 Oct 2014 23:36:46 -0400 In-Reply-To: <20141001.155210.882272719949254470.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Oct 1, 2014, at 12:52 PM, David Miller wrote: > From: David L Stevens > Date: Wed, 01 Oct 2014 15:31:49 -0400 > >> >> >> On 10/01/2014 03:23 PM, Sowmini Varadhan wrote: >>> On (10/01/14 15:06), David L Stevens wrote: >>>> >>>> This "vp->switch_port" addition doesn't appear to be related to the port refcnt >>>> change, and doesn't allow for multiple switch ports. >>> >>> The switch_port is the connection to Dom0. Do you envision us having more than >>> one switch_port? How? >> >> While Dom0 might only create one port with the "switch" flag, the flag just means >> "I can reach anybody" and is not inherently unique. I don't think an attached >> VM should assume there is always only one; it prevents multipath load balancing >> kinds of things in the future. >> >> Also, there is the broader point that this sort of change should be a separate patch. >> It isn't required for fixing the dangling reference -- it is an independent change. > > Multiple switch ports are absolutely allowed by the protocol spec and can > provide the suggested facilities David mentioned, don't prevent them from > being used. In reality, introducing multiple switch-ports will need Guest driver change as well. The existing sunvnet driver will not automatically utilize all switch-ports and requires changes. When we add the full support to use multiple switch-ports, I am sure we can change the current optimization for switch-port lookup with a different method probably with another optimized method than what it is today. -Raghuram