netdev - [PATCH] net/ncsi: use dev_set_mac_address() for Get MC MAC Address handling

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Message-Id: <20250120133536.29184-1-fercerpav@gmail.com>
Date: Mon, 20 Jan 2025 16:35:36 +0300
From: Paul Fertser <fercerpav@...il.com>
To: Peter Delevoryas <peter@....dev>,
        Samuel Mendoza-Jonas <sam@...dozajonas.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ivan Mikhaylov <fr0st61te@...il.com>,
        Paul Fertser <fercerpav@...il.com>
Subject: [PATCH] net/ncsi: use dev_set_mac_address() for Get MC MAC Address handling

Copy of the rationale from 790071347a0a1a89e618eedcd51c687ea783aeb3:

Change ndo_set_mac_address to dev_set_mac_address because
dev_set_mac_address provides a way to notify network layer about MAC
change. In other case, services may not aware about MAC change and keep
using old one which set from network adapter driver.

As example, DHCP client from systemd do not update MAC address without
notification from net subsystem which leads to the problem with acquiring
the right address from DHCP server.

Since dev_set_mac_address requires RTNL lock the operation can not be
performed directly in the response handler, see
9e2bbab94b88295dcc57c7580393c9ee08d7314d.

The way of selecting the first suitable MAC address from the list is
changed, instead of having the driver check it this patch just assumes
any valid MAC should be good.

Fixes: b8291cf3d118 ("net/ncsi: Add NC-SI 1.2 Get MC MAC Address command")
Signed-off-by: Paul Fertser <fercerpav@...il.com>
---

Peter, this is compile-tested only as I do not have a suitable
hardware setup to try it on. Please also pick
https://patchwork.kernel.org/project/netdevbpf/patch/20250116152900.8656-1-fercerpav@gmail.com/
if you happen to be able to test this before that fix is merged.

 net/ncsi/ncsi-rsp.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/net/ncsi/ncsi-rsp.c b/net/ncsi/ncsi-rsp.c
index 14bd66909ca4..4a8ce2949fae 100644
--- a/net/ncsi/ncsi-rsp.c
+++ b/net/ncsi/ncsi-rsp.c
@@ -1089,14 +1089,12 @@ static int ncsi_rsp_handler_netlink(struct ncsi_request *nr)
 static int ncsi_rsp_handler_gmcma(struct ncsi_request *nr)
 {
 	struct ncsi_dev_priv *ndp = nr->ndp;
+	struct sockaddr *saddr = &ndp->pending_mac;
 	struct net_device *ndev = ndp->ndev.dev;
 	struct ncsi_rsp_gmcma_pkt *rsp;
-	struct sockaddr saddr;
-	int ret = -1;
 	int i;

 	rsp = (struct ncsi_rsp_gmcma_pkt *)skb_network_header(nr->rsp);
-	saddr.sa_family = ndev->type;
 	ndev->priv_flags |= IFF_LIVE_ADDR_CHANGE;

 	netdev_info(ndev, "NCSI: Received %d provisioned MAC addresses\n",
@@ -1108,20 +1106,20 @@ static int ncsi_rsp_handler_gmcma(struct ncsi_request *nr)
 			    rsp->addresses[i][4], rsp->addresses[i][5]);
 	}

+	saddr->sa_family = ndev->type;
 	for (i = 0; i < rsp->address_count; i++) {
-		memcpy(saddr.sa_data, &rsp->addresses[i], ETH_ALEN);
-		ret = ndev->netdev_ops->ndo_set_mac_address(ndev, &saddr);
-		if (ret < 0) {
+		if (!is_valid_ether_addr(rsp->addresses[i])) {
 			netdev_warn(ndev, "NCSI: Unable to assign %pM to device\n",
-				    saddr.sa_data);
+				    rsp->addresses[i]);
 			continue;
 		}
-		netdev_warn(ndev, "NCSI: Set MAC address to %pM\n", saddr.sa_data);
+		memcpy(saddr->sa_data, rsp->addresses[i], ETH_ALEN);
+		netdev_warn(ndev, "NCSI: Will set MAC address to %pM\n", saddr->sa_data);
 		break;
 	}

-	ndp->gma_flag = ret == 0;
-	return ret;
+	ndp->gma_flag = 1;
+	return 0;
 }

 static struct ncsi_rsp_handler {
-- 
2.34.1