Messages in this thread | | | From | Jay Vosburgh <> | Subject | Re: [PATCH 2/4] bond_alb: don't rewrite bridged non-local MACs | Date | Wed, 19 May 2021 15:31:59 -0700 |
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Jarod Wilson <jarod@redhat.com> wrote:
>With a virtual machine behind a bridge on top of a bond, outgoing traffic >should retain the VM's source MAC. That works fine most of the time, until >doing a failover, and then the MAC gets rewritten to the bond slave's MAC, >and the return traffic gets dropped. If we don't rewrite the MAC there, we >don't lose any traffic.
Please have the log message here specify that this applies only to balance-alb mode, and, the usual nomenclature for bonding patches is "[PATCH] bonding:"; for this case, I'd suggest "balance-alb:" right afterwards to be clear that it's only for alb mode. I didn't really spot the "bond_alb" tag for what it was on first read, and it is the only indication that this change is specific to alb mode other than the patch itself.
>Cc: Jay Vosburgh <j.vosburgh@gmail.com> >Cc: Veaceslav Falico <vfalico@gmail.com> >Cc: Andy Gospodarek <andy@greyhouse.net> >Cc: "David S. Miller" <davem@davemloft.net> >Cc: Jakub Kicinski <kuba@kernel.org> >Cc: Thomas Davis <tadavis@lbl.gov> >Cc: netdev@vger.kernel.org >Signed-off-by: Jarod Wilson <jarod@redhat.com> >--- > drivers/net/bonding/bond_alb.c | 23 ++++++++++++++++++++++- > 1 file changed, 22 insertions(+), 1 deletion(-) > >diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c >index 3455f2cc13f2..ce8257c7cbea 100644 >--- a/drivers/net/bonding/bond_alb.c >+++ b/drivers/net/bonding/bond_alb.c >@@ -1302,6 +1302,26 @@ void bond_alb_deinitialize(struct bonding *bond) > rlb_deinitialize(bond); > } > >+static bool bond_alb_bridged_mac(struct bonding *bond, struct ethhdr *eth_data) >+{ >+ struct list_head *iter; >+ struct slave *slave; >+ >+ if (BOND_MODE(bond) != BOND_MODE_ALB) >+ return false; >+ >+ /* Don't modify source MACs that do not originate locally >+ * (e.g.,arrive via a bridge). >+ */ >+ if (!netif_is_bridge_port(bond->dev)) >+ return false;
I believe this logic will fail if the plumbing is, e.g., bond -> vlan -> bridge, as netif_is_bridge_port() would not return true for the bond in that case.
Making this reliable is tricky at best, and may be impossible to be correct for all possible cases. As such, I think the comment above should reflect the limited scope of what is actually being checked here (i.e., the bond itself is directly a bridge port).
-J
>+ >+ if (bond_slave_has_mac_rx(bond, eth_data->h_source)) >+ return false; >+ >+ return true; >+} >+ > static netdev_tx_t bond_do_alb_xmit(struct sk_buff *skb, struct bonding *bond, > struct slave *tx_slave) > { >@@ -1316,7 +1336,8 @@ static netdev_tx_t bond_do_alb_xmit(struct sk_buff *skb, struct bonding *bond, > } > > if (tx_slave && bond_slave_can_tx(tx_slave)) { >- if (tx_slave != rcu_access_pointer(bond->curr_active_slave)) { >+ if (tx_slave != rcu_access_pointer(bond->curr_active_slave) && >+ !bond_alb_bridged_mac(bond, eth_data)) { > ether_addr_copy(eth_data->h_source, > tx_slave->dev->dev_addr); > } >-- >2.30.2 >
--- -Jay Vosburgh, jay.vosburgh@canonical.com
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