From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Samudrala, Sridhar" Subject: Re: [RFC PATCH net-next v5 3/4] virtio_net: Extend virtio to use VF datapath when available Date: Tue, 10 Apr 2018 08:13:40 -0700 Message-ID: <2ccfad76-589d-9dca-7e4b-9bafee41f844@intel.com> References: <1522962503-3963-1-git-send-email-sridhar.samudrala@intel.com> <1522962503-3963-4-git-send-email-sridhar.samudrala@intel.com> <20180406124814.GA24525@nanopsycho> <20180409080751.GE19345@nanopsycho> <16b2e531-7bfa-7f25-2702-f3f8069663ee@intel.com> <20180410105504.GA2028@nanopsycho> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: mst@redhat.com, stephen@networkplumber.org, davem@davemloft.net, netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org, jesse.brandeburg@intel.com, alexander.h.duyck@intel.com, kubakici@wp.pl, jasowang@redhat.com, loseweigh@gmail.com To: Jiri Pirko Return-path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: In-Reply-To: <20180410105504.GA2028@nanopsycho> Content-Language: en-US List-Id: netdev.vger.kernel.org On 4/10/2018 3:55 AM, Jiri Pirko wrote: > Mon, Apr 09, 2018 at 08:47:06PM CEST, sridhar.samudrala@intel.com wrote: >> On 4/9/2018 1:07 AM, Jiri Pirko wrote: >>> Sat, Apr 07, 2018 at 12:59:14AM CEST, sridhar.samudrala@intel.com wrote: >>>> On 4/6/2018 5:48 AM, Jiri Pirko wrote: >>>>> Thu, Apr 05, 2018 at 11:08:22PM CEST, sridhar.samudrala@intel.com wrote: >>> [...] >>> >>>>>> +static int virtnet_bypass_join_child(struct net_device *bypass_netdev, >>>>>> + struct net_device *child_netdev) >>>>>> +{ >>>>>> + struct virtnet_bypass_info *vbi; >>>>>> + bool backup; >>>>>> + >>>>>> + vbi = netdev_priv(bypass_netdev); >>>>>> + backup = (child_netdev->dev.parent == bypass_netdev->dev.parent); >>>>>> + if (backup ? rtnl_dereference(vbi->backup_netdev) : >>>>>> + rtnl_dereference(vbi->active_netdev)) { >>>>>> + netdev_info(bypass_netdev, >>>>>> + "%s attempting to join bypass dev when %s already present\n", >>>>>> + child_netdev->name, backup ? "backup" : "active"); >>>>> Bypass module should check if there is already some other netdev >>>>> enslaved and refuse right there. >>>> This will work for virtio-net with 3 netdev model, but this check has to be done by netvsc >>>> as its bypass_netdev is same as the backup_netdev. >>>> Will add a flag while registering with the bypass module to indicate if the driver is doing >>>> a 2 netdev or 3 netdev model and based on that flag this check can be done in bypass module >>>> for 3 netdev scenario. >>> Just let me undestand it clearly. What I expect the difference would be >>> between 2netdev and3 netdev model is this: >>> 2netdev: >>> bypass_master >>> / >>> / >>> VF_slave >>> >>> 3netdev: >>> bypass_master >>> / \ >>> / \ >>> VF_slave backup_slave >>> >>> Is that correct? If not, how does it look like? >>> >>> >> Looks correct. >> VF_slave and backup_slave are the original netdevs and are present in both the models. >> In the 3 netdev model, bypass_master netdev is created and VF_slave and backup_slave are >> marked as the 2 slaves of this new netdev. > You say it looks correct and in another sentence you provide completely > different description. Could you please look again? > To be exact, 2 netdev model with netvsc looks like this. netvsc_netdev / / VF_slave With virtio_net, 3 netdev model bypass_netdev / \ / \ VF_slave virtio_net netdev