[PATCH net] ionic: don't remove netdev->dev_addr when syncing uc list

Bridging, and possibly other upper stack gizmos, adds the
lower device's netdev->dev_addr to its own uc list, and
then requests it be deleted when the upper bridge device is
removed.  This delete request also happens with the bridging
vlan_filtering is enabled and then disabled.

Bonding has a similar behavior with the uc list, but since it
also uses set_mac to manage netdev->dev_addr, it doesn't have
the same the failure case.

Because we store our netdev->dev_addr in our uc list, we need
to ignore the delete request from dev_uc_sync so as to not
lose the address and all hope of communicating.  Note that
ndo_set_mac_address is expressly changing netdev->dev_addr,
so no limitation is set there.

Fixes: 2a654540be10 ("ionic: Add Rx filter and rx_mode ndo support")
Signed-off-by: Shannon Nelson <redacted>
---
 drivers/net/ethernet/pensando/ionic/ionic_lif.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.c b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
index ccf3ffcd3939..7f3322ce044c 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.c

@@ -1379,6 +1379,10 @@ static int ionic_addr_add(struct net_device *netdev, const u8 *addr)
 
 static int ionic_addr_del(struct net_device *netdev, const u8 *addr)
 {
+	/* Don't delete our own address from the uc list */
+	if (ether_addr_equal(addr, netdev->dev_addr))
+		return 0;
+
 	return ionic_lif_list_addr(netdev_priv(netdev), addr, DEL_ADDR);
 }
 

-- 
2.17.1

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller [off-list ref]:

On Fri,  8 Oct 2021 12:38:01 -0700 you wrote:

Bridging, and possibly other upper stack gizmos, adds the
lower device's netdev->dev_addr to its own uc list, and
then requests it be deleted when the upper bridge device is
removed.  This delete request also happens with the bridging
vlan_filtering is enabled and then disabled.

Bonding has a similar behavior with the uc list, but since it
also uses set_mac to manage netdev->dev_addr, it doesn't have
the same the failure case.

[...]

Here is the summary with links:
  - [net] ionic: don't remove netdev->dev_addr when syncing uc list
    https://git.kernel.org/netdev/net/c/5c976a56570f

You are awesome, thank you!
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