[PATCH AUTOSEL 4.14 20/59] i40e: fix mac filter delete when setting mac address

[Sasha Levin]

From: Stefan Assmann <sassmann@xxxxxxxxx>

[ Upstream commit 158daed16efb1170694e420ae06ba8ba954d82e5 ]

A previous commit moved the ether_addr_copy() in i40e_set_mac() before
the mac filter del/add to avoid a race. However it wasn't taken into
account that this alters the mac address being handed to
i40e_del_mac_filter().

Also changed i40e_add_mac_filter() to operate on netdev->dev_addr,
hopefully that makes the code easier to read.

Fixes: 458867b2ca0c ("i40e: don't remove netdev->dev_addr when syncing uc list")

Signed-off-by: Stefan Assmann <sassmann@xxxxxxxxx>
Tested-by: Andrew Bowers <andrewx.bowers@xxxxxxxxx>
Acked-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/intel/i40e/i40e_main.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 176c99b8251d..904b42becd45 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -1554,17 +1554,17 @@ static int i40e_set_mac(struct net_device *netdev, void *p)
 		netdev_info(netdev, "set new mac address %pM\n", addr->sa_data);
 
 	/* Copy the address first, so that we avoid a possible race with
-	 * .set_rx_mode(). If we copy after changing the address in the filter
-	 * list, we might open ourselves to a narrow race window where
-	 * .set_rx_mode could delete our dev_addr filter and prevent traffic
-	 * from passing.
+	 * .set_rx_mode().
+	 * - Remove old address from MAC filter
+	 * - Copy new address
+	 * - Add new address to MAC filter
 	 */
-	ether_addr_copy(netdev->dev_addr, addr->sa_data);
-
 	spin_lock_bh(&vsi->mac_filter_hash_lock);
 	i40e_del_mac_filter(vsi, netdev->dev_addr);
-	i40e_add_mac_filter(vsi, addr->sa_data);
+	ether_addr_copy(netdev->dev_addr, addr->sa_data);
+	i40e_add_mac_filter(vsi, netdev->dev_addr);
 	spin_unlock_bh(&vsi->mac_filter_hash_lock);
+
 	if (vsi->type == I40E_VSI_MAIN) {
 		i40e_status ret;
 
-- 
2.19.1