[PATCH 5.15.y] net: cpsw_new: Fix potential unregister of netdev that has not been registered yet

[Wenshan Lan]

From: Kevin Hao <haokexin@xxxxxxxxx>

[ Upstream commit 9d724b34fbe13b71865ad0906a4be97571f19cf5 ]

If an error occurs during register_netdev() for the first MAC in
cpsw_register_ports(), even though cpsw->slaves[0].ndev is set to NULL,
cpsw->slaves[1].ndev would remain unchanged. This could later cause
cpsw_unregister_ports() to attempt unregistering the second MAC.
To address this, add a check for ndev->reg_state before calling
unregister_netdev(). With this change, setting cpsw->slaves[i].ndev
to NULL becomes unnecessary and can be removed accordingly.

Fixes: ed3525eda4c4 ("net: ethernet: ti: introduce cpsw switchdev based driver part 1 - dual-emac")
Signed-off-by: Kevin Hao <haokexin@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx>
Link: https://patch.msgid.link/20260205-cpsw-error-path-v1-2-6e58bae6b299@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Wenshan Lan <jetlan9@xxxxxxx>
---
 drivers/net/ethernet/ti/cpsw_new.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ti/cpsw_new.c b/drivers/net/ethernet/ti/cpsw_new.c
index 9d52b949ae3f..bef2c71b9059 100644
--- a/drivers/net/ethernet/ti/cpsw_new.c
+++ b/drivers/net/ethernet/ti/cpsw_new.c
@@ -1447,7 +1447,8 @@ static void cpsw_unregister_ports(struct cpsw_common *cpsw)
 	int i = 0;
 
 	for (i = 0; i < cpsw->data.slaves; i++) {
-		if (!cpsw->slaves[i].ndev)
+		if (!cpsw->slaves[i].ndev ||
+		    cpsw->slaves[i].ndev->reg_state != NETREG_REGISTERED)
 			continue;
 
 		unregister_netdev(cpsw->slaves[i].ndev);
@@ -1467,7 +1468,6 @@ static int cpsw_register_ports(struct cpsw_common *cpsw)
 		if (ret) {
 			dev_err(cpsw->dev,
 				"cpsw: err registering net device%d\n", i);
-			cpsw->slaves[i].ndev = NULL;
 			break;
 		}
 	}
-- 
2.43.0