[PATCH net-next v2 06/11] net: team: don't recurse on the port's netdev ops lock

[Jakub Kicinski <kuba@kernel.org>]

__team_port_change_send() calls __ethtool_get_link_ksettings() on
the port, which will soon take the port's ops lock. The notifier
caller already holds it while the slave-add/del callers do not,
so the function would either deadlock or run unprotected depending
on the path.

Make __team_port_change_send() expect the port's ops lock held and
switch to netif_get_link_ksettings(). team_device_event()'s NETDEV_UP /
NETDEV_CHANGE already arrive with the port's ops lock held.
team_port_add() now take it explicitly.

Note that NETDEV_DOWN and team_port_del() will pass false as @linkup
so they will not execute netif_get_link_ksettings(). This is fortunate
as NETDEV_DOWN has somewhat mixed locking right now.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 drivers/net/team/team_core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/team/team_core.c b/drivers/net/team/team_core.c
index f51388d50307..feaa75fbf8fc 100644
--- a/drivers/net/team/team_core.c
+++ b/drivers/net/team/team_core.c
@@ -1375,7 +1375,9 @@ static int team_port_add(struct team *team, struct net_device *port_dev,
 	list_add_tail_rcu(&port->list, &team->port_list);
 	team_port_enable(team, port);
 	netdev_compute_master_upper_features(dev, true);
+	netdev_lock_ops(port_dev);
 	__team_port_change_port_added(port, !!netif_oper_up(port_dev));
+	netdev_unlock_ops(port_dev);
 	__team_options_change_check(team);
 
 	netdev_info(dev, "Port device %s added\n", portname);
@@ -3090,7 +3092,7 @@ static void __team_port_change_send(struct team_port *port, bool linkup)
 	if (linkup) {
 		struct ethtool_link_ksettings ecmd;
 
-		err = __ethtool_get_link_ksettings(port->dev, &ecmd);
+		err = netif_get_link_ksettings(port->dev, &ecmd);
 		if (!err) {
 			port->state.speed = ecmd.base.speed;
 			port->state.duplex = ecmd.base.duplex;
-- 
2.54.0