team: fix mtu setting

Now it is not possible to set mtu to team device which has a port
enslaved to it. The reason is that when team_change_mtu() calls
dev_set_mtu() for port device, notificator for NETDEV_PRECHANGEMTU
event is called and team_device_event() returns NOTIFY_BAD forbidding
the change. So fix this by returning NOTIFY_DONE here in case team is
changing mtu in team_change_mtu().

Introduced-by: 3d249d4c "net: introduce ethernet teaming device"
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Flavio Leitner <fbl@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 7 insertions, 1 deletions

diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index 767fe61b5ac9..ce4989be86d9 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -1724,6 +1724,7 @@ static int team_change_mtu(struct net_device *dev, int new_mtu)
          * to traverse list in reverse under rcu_read_lock
          */
         mutex_lock(&team->lock);
+        team->port_mtu_change_allowed = true;
         list_for_each_entry(port, &team->port_list, list) {
                 err = dev_set_mtu(port->dev, new_mtu);
                 if (err) {
@@ -1732,6 +1733,7 @@ static int team_change_mtu(struct net_device *dev, int new_mtu)
                         goto unwind;
                 }
         }
+        team->port_mtu_change_allowed = false;
         mutex_unlock(&team->lock);
 
         dev->mtu = new_mtu;
@@ -1741,6 +1743,7 @@ static int team_change_mtu(struct net_device *dev, int new_mtu)
 unwind:
         list_for_each_entry_continue_reverse(port, &team->port_list, list)
                 dev_set_mtu(port->dev, dev->mtu);
+        team->port_mtu_change_allowed = false;
         mutex_unlock(&team->lock);
 
         return err;
@@ -2851,7 +2854,9 @@ static int team_device_event(struct notifier_block *unused,
                 break;
         case NETDEV_PRECHANGEMTU:
                 /* Forbid to change mtu of underlaying device */
-                return NOTIFY_BAD;
+                if (!port->team->port_mtu_change_allowed)
+                        return NOTIFY_BAD;
+                break;
         case NETDEV_PRE_TYPE_CHANGE:
                 /* Forbid to change type of underlaying device */
                 return NOTIFY_BAD;
diff --git a/include/linux/if_team.h b/include/linux/if_team.h
index a899dc24be15..a6aa970758a2 100644
--- a/include/linux/if_team.h
+++ b/include/linux/if_team.h
@@ -194,6 +194,7 @@ struct team {
         bool user_carrier_enabled;
         bool queue_override_enabled;
         struct list_head *qom_lists; /* array of queue override mapping lists */
+        bool port_mtu_change_allowed;
         struct {
                 unsigned int count;
                 unsigned int interval; /* in ms */