From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH v3 2/2] macvtap: Allow tap features change when IFF_VNET_HDR is disabled. Date: Thu, 15 Aug 2013 22:27:04 +0300 Message-ID: <20130815192704.GA11826@redhat.com> References: <1376586173-4242-1-git-send-email-vyasevic@redhat.com> <1376586173-4242-3-git-send-email-vyasevic@redhat.com> <20130815173347.GA10265@redhat.com> <520D206B.3000203@redhat.com> <20130815184844.GB11350@redhat.com> <520D24F5.3000602@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: Vlad Yasevich Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47530 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753690Ab3HOTZT (ORCPT ); Thu, 15 Aug 2013 15:25:19 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r7FJPIMM022703 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 15 Aug 2013 15:25:18 -0400 Content-Disposition: inline In-Reply-To: <520D24F5.3000602@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Aug 15, 2013 at 02:59:01PM -0400, Vlad Yasevich wrote: > On 08/15/2013 02:48 PM, Michael S. Tsirkin wrote: > >On Thu, Aug 15, 2013 at 02:39:39PM -0400, Vlad Yasevich wrote: > >>On 08/15/2013 01:33 PM, Michael S. Tsirkin wrote: > >>>On Thu, Aug 15, 2013 at 01:02:53PM -0400, Vlad Yasevich wrote: > >>>>When the user turns off IFF_VNET_HDR flag, attempts to change > >>>>offload features via TUNSETOFFLOAD do not work. This could cause > >>>>GSO packets to be delivered to the user when the user is > >>>>not prepared to handle them. > >>>> > >>>>To solve, allow processing of TUNSETOFFLOAD when IFF_VNET_HDR is > >>>>disabled. Also, take the setting of IFF_VNET_HDR into consideration > >>>>when determining the feature set to apply to incommig traffic. > >>>>If IFF_VNET_HDR is set, we use user-specfied feature set. if the > >>>>IFF_VNET_HDR is clear, we mask off all tun-specific offload features, > >>>>since user can not be notified of the possbile offloads. > >>>> > >>>>Signed-off-by: Vlad Yasevich > >>>>--- > >>>> drivers/net/macvtap.c | 30 ++++++++++++++++++++++++------ > >>>> 1 file changed, 24 insertions(+), 6 deletions(-) > >>>> > >>>>diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c > >>>>index 8121358..df45a59 100644 > >>>>--- a/drivers/net/macvtap.c > >>>>+++ b/drivers/net/macvtap.c > >>>>@@ -269,6 +269,28 @@ static void macvtap_del_queues(struct net_device *dev) > >>>> sock_put(&qlist[j]->sk); > >>>> } > >>>> > >>>>+/* Determine features to be applied to the packet as it > >>> > >>>/* > >>> * Please use comments > >>> * like this > >>> */ > >>> > >>>>+ * gets sent to the tap. The features depend on the offloads > >>>>+ * set by user and by whether or not IFF_VNET_HDR is enabled. > >>>>+ */ > >>>>+static netdev_features_t macvtap_skb_features(struct sk_buff *skb, > >>>>+ struct macvtap_queue *q) > >>>>+{ > >>>>+ struct macvlan_dev *vlan = netdev_priv(skb->dev); > >>>>+ netdev_features_t features = netif_skb_features(skb); > >>>>+ > >>>>+ /* If VNET_HDR is enabled, user can receive offload info so > >>>>+ * use user-specified tap_features. > >>>>+ * Otherwise, mask off all tap offload features. > >>>>+ */ > >>>>+ if (q->flags & IFF_VNET_HDR) > >>>>+ features &= vlan->tap_features; > >>>>+ else > >>>>+ features &= ~TUN_OFFLOADS; > >>>>+ > >>>>+ return features; > >>>>+} > >>>>+ > >>> > >>>Okay, but this means we need to do netdev_update_features > >>>on SETIFF since it changes q->flags. > >> > >>Why? > >> The whole point it not to change features on SETIFF, so that > >>they are preserved for when the flags change again. It just that > >>flag values either allow whatever offload user specified (correctly > >>masked via netdev_update_features) or turn off all offloads at the tap. > >> > >>-vlad > > > >That's the point. As it is, if flag value changes, we don't call > >netdev_update_features so offloads aren't masked/unmasked. > > > >Example: > > > >1. SETOFFLOADS to enable > >2. VNET = 0 > > > >offloads are still enabled > > > > But unused since since VNET=0. Well, I think that's true but it would still be better to disable RX offloads, no? > I am trying to be careful not to > break things when ioctl calls get all inverted and reversed, but > may be I am trying too hard and we should just let things break. What exactly will break by call to netdev_update_features? > I just feels kinds of silly since the app may now know all the > details, but the kernel does and can do the "right thing". > > -vlad > > > > >>>> /* > >>>> * Forward happens for data that gets sent from one macvlan > >>>> * endpoint to another one in bridge mode. We just take > >>>>@@ -276,9 +298,9 @@ static void macvtap_del_queues(struct net_device *dev) > >>>> */ > >>>> static int macvtap_forward(struct net_device *dev, struct sk_buff *skb) > >>>> { > >>>>- struct macvlan_dev *vlan = netdev_priv(dev); > >>>> struct macvtap_queue *q = macvtap_get_queue(dev, skb); > >>>> netdev_features_t features; > >>>>+ > >>>> if (!q) > >>>> goto drop; > >>>> > >>>>@@ -289,7 +311,7 @@ static int macvtap_forward(struct net_device *dev, struct sk_buff *skb) > >>>> /* Apply the forward feature mask so that we perform segmentation > >>>> * according to users wishes. > >>>> */ > >>>>- features = netif_skb_features(skb) & vlan->tap_features; > >>>>+ features = macvtap_skb_features(skb, q); > >>>> if (netif_needs_gso(skb, features)) { > >>>> struct sk_buff *segs = __skb_gso_segment(skb, features, false); > >>>> > >>>>@@ -1161,10 +1183,6 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd, > >>>> TUN_F_TSO_ECN | TUN_F_UFO)) > >>>> return -EINVAL; > >>>> > >>>>- /* TODO: only accept frames with the features that > >>>>- got enabled for forwarded frames */ > >>>>- if (!(q->flags & IFF_VNET_HDR)) > >>>>- return -EINVAL; > >>>> rtnl_lock(); > >>>> ret = set_offload(q, arg); > >>>> rtnl_unlock(); > >>>>-- > >>>>1.8.1.4