From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH v3 1/2] macvtap: include all checksum offloads in TUN_OFFLOAD mask Date: Thu, 15 Aug 2013 22:20:46 +0300 Message-ID: <20130815192046.GA11788@redhat.com> References: <1376586173-4242-1-git-send-email-vyasevic@redhat.com> <1376586173-4242-2-git-send-email-vyasevic@redhat.com> <20130815182430.GB10265@redhat.com> <520D21CA.4090400@redhat.com> <20130815190945.GA11569@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]:56396 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755215Ab3HOTTB (ORCPT ); Thu, 15 Aug 2013 15:19:01 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r7FJJ1Vw020817 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 15 Aug 2013 15:19:01 -0400 Content-Disposition: inline In-Reply-To: <20130815190945.GA11569@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Aug 15, 2013 at 10:09:45PM +0300, Michael S. Tsirkin wrote: > On Thu, Aug 15, 2013 at 02:45:30PM -0400, Vlad Yasevich wrote: > > On 08/15/2013 02:24 PM, Michael S. Tsirkin wrote: > > >On Thu, Aug 15, 2013 at 01:02:52PM -0400, Vlad Yasevich wrote: > > >>The features of the macvlan are based on the features of lower > > >>device and thus can have checksum featurs other then IFF_F_HW_CSUM > > > > > >s/featurs/features/ > > > > > >:set spell spelllang=en_us > > > > > >or whatever's the equivalent in your editor of choice. > > > > > >>set. However, TUN_OFFLOAD mask only includes IFF_F_HW_CSUM. Thus > > >>when performing gso segmentation during macvtap_forward(), > > >>it is possbile to end up with skbs that have ip_summed set > > >>to CHECKSUM_PARTIAL. This is incorrect when the user > > >>turns off checksum offloading. > > >> > > >>Include all possible checksum offload values so that > > >>we'll properly mask them off when performing GSO. > > >> > > >>Signed-off-by: Vlad Yasevich > > >>--- > > >> drivers/net/macvtap.c | 2 +- > > >> 1 file changed, 1 insertion(+), 1 deletion(-) > > >> > > >>diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c > > >>index b51db2a..8121358 100644 > > >>--- a/drivers/net/macvtap.c > > >>+++ b/drivers/net/macvtap.c > > >>@@ -65,7 +65,7 @@ static struct cdev macvtap_cdev; > > >> > > >> static const struct proto_ops macvtap_socket_ops; > > >> > > >>-#define TUN_OFFLOADS (NETIF_F_HW_CSUM | NETIF_F_TSO_ECN | NETIF_F_TSO | \ > > >>+#define TUN_OFFLOADS (NETIF_F_ALL_CSUM | NETIF_F_TSO_ECN | NETIF_F_TSO | \ > > >> NETIF_F_TSO6 | NETIF_F_UFO) > > >> #define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO) > > >> /* > > > > > >Okay so you are talking about hardware that sets some other > > >checksum bit besides HW_CSUM, e.g. IP_CSUM, so > > > > > > vlan->tap_features = vlan->dev->features & > > > (feature_mask | ~TUN_OFFLOADS); > > > > > >will not clear IP_CSUM even if feature_mask is 0. > > > > > >Maybe mention this in the changelog, in case user > > >will wonder whether his hardware is affected. > > > > > >So I agree, that's a bug, but if you make this change the reverse will hold > > >(on this hardware): > > >if user sets TUN_F_CSUM, we won't set NETIF_F_IP_CSUM > > >so checksum offloading won't work. > > > > > >So I think you want s/NETIF_F_HW_CSUM/NETIF_F_ALL_CSUM/ everywhere > > >and not just in this place. > > > > Yes. I thought about that, but forgot to do in this patch set. > > In fact I wonder why do we do it like this at all. > tap_features have nothing to do with the device, > they only have to do with tap. > For example, you might have a dumb device with no > checksum support but userspace said it does not need a checksum, > we can have NETIF_F_HW_CSUM there anyway. > > So why don't we just > vlan->tap_features = feature_mask; > ? > In fact, this is exactly set_features, so why don't > we just use set_features everywhere? > Then this patch won't be needed at all. > > Kind of like this - compile-tested only - do you have a setup with > IP_CSUM which you can use to test? Ugh this does not work even on a simple setup, sorry about the noise. Maybe like this? Does this work for you? --> macvtap: fix up tap features There's no apparent need to have tap features masked according to the lowerdev config: we only use them in software so hardware configuration does not matter. This patch fixes bugs for some unusual hardware configurations, for example, we only masked HW_CSUM so for hardware with e.g. IP_CSUM the checksum bit remained set, which would cause packets with CHECKSUM_PARTIAL to be sent to userspace even when offloads are disabled. Signed-off-by: Michael S. Tsirkin --- diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index a98ed9f..3c18f12 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -1058,8 +1058,7 @@ static int set_offload(struct macvtap_queue *q, unsigned long arg) /* tap_features are the same as features on tun/tap and * reflect user expectations. */ - vlan->tap_features = vlan->dev->features & - (feature_mask | ~TUN_OFFLOADS); + vlan->tap_features = feature_mask; vlan->set_features = features; netdev_update_features(vlan->dev);