From: Eric Dumazet <edumazet@google.com> To: Heiner Kallweit <hkallweit1@gmail.com> Cc: Charles Daymand <charles.daymand@wifirst.fr>, netdev <netdev@vger.kernel.org> Subject: Re: [PATCH net] r8169: fix multicast tx issue with macvlan interface Date: Fri, 27 Mar 2020 12:42:51 -0700 Message-ID: <CANn89i+A=Mu=9LMscd2Daqej+uVLc3E6w33MZzTwpe2v+k89Mw@mail.gmail.com> (raw) In-Reply-To: <42f81a4a-24fc-f1fb-11db-ea90a692f249@gmail.com> On Fri, Mar 27, 2020 at 12:17 PM Heiner Kallweit <hkallweit1@gmail.com> wrote: > > On 27.03.2020 19:52, Eric Dumazet wrote: > > On Fri, Mar 27, 2020 at 10:41 AM Heiner Kallweit <hkallweit1@gmail.com> wrote: > >> > >> On 27.03.2020 10:39, Heiner Kallweit wrote: > >>> On 27.03.2020 10:08, Charles Daymand wrote: > >>>> During kernel upgrade testing on our hardware, we found that macvlan > >>>> interface were no longer able to send valid multicast packet. > >>>> > >>>> tcpdump run on our hardware was correctly showing our multicast > >>>> packet but when connecting a laptop to our hardware we didn't see any > >>>> packets. > >>>> > >>>> Bisecting turned up commit 93681cd7d94f > >>>> "r8169: enable HW csum and TSO" activates the feature NETIF_F_IP_CSUM > >>>> which is responsible for the drop of packet in case of macvlan > >>>> interface. Note that revision RTL_GIGA_MAC_VER_34 was already a specific > >>>> case since TSO was keep disabled. > >>>> > >>>> Deactivating NETIF_F_IP_CSUM using ethtool is correcting our multicast > >>>> issue, but we believe that this hardware issue is important enough to > >>>> keep tx checksum off by default on this revision. > >>>> > >>>> The change is deactivating the default value of NETIF_F_IP_CSUM for this > >>>> specific revision. > >>>> > >>> > >>> The referenced commit may not be the root cause but just reveal another > >>> issue that has been existing before. Root cause may be in the net core > >>> or somewhere else. Did you check with other RTL8168 versions to verify > >>> that it's indeed a HW issue with this specific chip version? > >>> > >>> What you could do: Enable tx checksumming manually (via ethtool) on > >>> older kernel versions and check whether they are fine or not. > >>> If an older version is fine, then you can start a new bisect with tx > >>> checksumming enabled. > >>> > >>> And did you capture and analyze traffic to verify that actually the > >>> checksum is incorrect (and packets discarded therefore on receiving end)? > >>> > >>> > >>>> Fixes: 93681cd7d94f ("r8169: enable HW csum and TSO") > >>>> Signed-off-by: Charles Daymand <charles.daymand@wifirst.fr> > >>>> --- > >>>> net/drivers/net/ethernet/realtek/r8169_main.c | 3 +++ > >>>> 1 file changed, 3 insertions(+) > >>>> > >>>> diff --git a/net/drivers/net/ethernet/realtek/r8169_main.c b/net/drivers/net/ethernet/realtek/r8169_main.c > >>>> index a9bdafd15a35..3b69135fc500 100644 > >>>> --- a/net/drivers/net/ethernet/realtek/r8169_main.c > >>>> +++ b/net/drivers/net/ethernet/realtek/r8169_main.c > >>>> @@ -5591,6 +5591,9 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) > >>>> dev->vlan_features &= ~(NETIF_F_ALL_TSO | NETIF_F_SG); > >>>> dev->hw_features &= ~(NETIF_F_ALL_TSO | NETIF_F_SG); > >>>> dev->features &= ~(NETIF_F_ALL_TSO | NETIF_F_SG); > >>>> + if (tp->mac_version == RTL_GIGA_MAC_VER_34) { > >>>> + dev->features &= ~NETIF_F_IP_CSUM; > >>>> + } > >>>> } > >>>> > >>>> dev->hw_features |= NETIF_F_RXALL; > >>>> > >>> > >> > >> After looking a little bit at the macvlen code I think there might be an > >> issue in it, but I'm not sure, therefore let me add Eric (as macvlen doesn't > >> seem to have a dedicated maintainer). > >> > >> r8169 implements a ndo_features_check callback that disables tx checksumming > >> for the chip version in question and small packets (due to a HW issue). > >> macvlen uses passthru_features_check() as ndo_features_check callback, this > >> seems to indicate to me that the ndo_features_check callback of lowerdev is > >> ignored. This could explain the issue you see. > >> > > > > macvlan_queue_xmit() calls dev_queue_xmit_accel() after switching skb->dev, > > so the second __dev_queue_xmit() should eventually call the real_dev > > ndo_features_check() > > > Thanks, Eric. There's a second path in macvlan_queue_xmit() calling > dev_forward_skb(vlan->lowerdev, skb). Does what you said apply also there? This path wont send packets to the physical NIC, packets are injected back via dev_forward_skb() > > Still I find it strange that a tx hw checksumming issue should affect multicasts > only. Also the chip version in question is quite common and I would expect > others to have hit the same issue. > Maybe best would be to re-test on the affected system w/o involving macvlen. > > > > > > >> Would be interesting to see whether it fixes your issue if you let the > >> macvlen ndo_features_check call lowerdev's ndo_features_check. Can you try this? > >> > >> By the way: > >> Also the ndo_fix_features callback of lowerdev seems to be ignored. >
next prev parent reply index Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-27 9:08 Charles Daymand 2020-03-27 9:39 ` Heiner Kallweit 2020-03-27 17:41 ` Heiner Kallweit 2020-03-27 18:52 ` Eric Dumazet 2020-03-27 19:17 ` Heiner Kallweit 2020-03-27 19:42 ` Eric Dumazet [this message] [not found] ` <CAFJtzm03QpjGRs70tth26BdUFN_o8zsJOccbnA58ma+2uwiGcg@mail.gmail.com> 2020-03-31 13:48 ` Charles DAYMAND 2020-03-31 14:07 ` Heiner Kallweit 2020-04-06 14:12 ` Charles DAYMAND 2020-04-06 22:16 ` Heiner Kallweit 2020-04-06 23:20 ` Eric Dumazet 2020-04-07 6:22 ` Heiner Kallweit 2020-04-07 22:40 ` Heiner Kallweit 2020-04-10 9:53 ` Charles DAYMAND 2020-04-13 18:06 ` Heiner Kallweit 2020-04-13 18:20 ` Eric Dumazet 2020-04-15 11:55 ` Charles Daymand 2020-05-12 18:37 ` Heiner Kallweit 2020-04-27 21:12 ` Florent Fourcot 2020-04-30 16:50 ` Heiner Kallweit
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