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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Shannon Nelson <snelson@pensando.io>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.10 102/103] ionic: dont remove netdev->dev_addr when syncing uc list
Date:   Mon, 18 Oct 2021 15:25:18 +0200
Message-Id: <20211018132338.173418397@linuxfoundation.org>
In-Reply-To: <20211018132334.702559133@linuxfoundation.org>
References: <20211018132334.702559133@linuxfoundation.org>
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From: Shannon Nelson <snelson@pensando.io>

commit 5c976a56570f29aaf4a2f9a1bf99789c252183c9 upstream.

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 <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/pensando/ionic/ionic_lif.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
@@ -1096,6 +1096,10 @@ static int ionic_ndo_addr_add(struct net
 
 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_addr(netdev_priv(netdev), addr, false, true);
 }