team: fix team_adjust_ops with regard to enabled ports

team_adjust_ops should check for enabled ports, not all ports.
This may lead to division by zero. This patch fixes this.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 11 deletions

diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index 3a4a74be52d9..6b4cf6eca238 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -508,26 +508,31 @@ static void team_set_no_mode(struct team *team)
         team->mode = &__team_no_mode;
 }
 
-static void team_adjust_ops(struct team *team)
+static void __team_adjust_ops(struct team *team, int en_port_count)
 {
         /*
          * To avoid checks in rx/tx skb paths, ensure here that non-null and
          * correct ops are always set.
          */
 
-        if (list_empty(&team->port_list) ||
-            !team_is_mode_set(team) || !team->mode->ops->transmit)
+        if (!en_port_count || !team_is_mode_set(team) ||
+            !team->mode->ops->transmit)
                 team->ops.transmit = team_dummy_transmit;
         else
                 team->ops.transmit = team->mode->ops->transmit;
 
-        if (list_empty(&team->port_list) ||
-            !team_is_mode_set(team) || !team->mode->ops->receive)
+        if (!en_port_count || !team_is_mode_set(team) ||
+            !team->mode->ops->receive)
                 team->ops.receive = team_dummy_receive;
         else
                 team->ops.receive = team->mode->ops->receive;
 }
 
+static void team_adjust_ops(struct team *team)
+{
+        __team_adjust_ops(team, team->en_port_count);
+}
+
 /*
  * We can benefit from the fact that it's ensured no port is present
  * at the time of mode change. Therefore no packets are in fly so there's no
@@ -687,6 +692,7 @@ static void team_port_enable(struct team *team,
         port->index = team->en_port_count++;
         hlist_add_head_rcu(&port->hlist,
                            team_port_index_hash(team, port->index));
+        team_adjust_ops(team);
         if (team->ops.port_enabled)
                 team->ops.port_enabled(team, port);
 }
@@ -708,16 +714,20 @@ static void __reconstruct_port_hlist(struct team *team, int rm_index)
 static void team_port_disable(struct team *team,
                               struct team_port *port)
 {
-        int rm_index = port->index;
-
         if (!team_port_enabled(port))
                 return;
         if (team->ops.port_disabled)
                 team->ops.port_disabled(team, port);
         hlist_del_rcu(&port->hlist);
-        __reconstruct_port_hlist(team, rm_index);
-        team->en_port_count--;
+        __reconstruct_port_hlist(team, port->index);
         port->index = -1;
+        __team_adjust_ops(team, team->en_port_count - 1);
+        /*
+         * Wait until readers see adjusted ops. This ensures that
+         * readers never see team->en_port_count == 0
+         */
+        synchronize_rcu();
+        team->en_port_count--;
 }
 
 #define TEAM_VLAN_FEATURES (NETIF_F_ALL_CSUM | NETIF_F_SG | \
@@ -874,7 +884,6 @@ static int team_port_add(struct team *team, struct net_device *port_dev)
         port->index = -1;
         team_port_enable(team, port);
         list_add_tail_rcu(&port->list, &team->port_list);
-        team_adjust_ops(team);
         __team_compute_features(team);
         __team_port_change_check(port, !!netif_carrier_ok(port_dev));
         __team_options_change_check(team);
@@ -928,7 +937,6 @@ static int team_port_del(struct team *team, struct net_device *port_dev)
         __team_port_change_check(port, false);
         team_port_disable(team, port);
         list_del_rcu(&port->list);
-        team_adjust_ops(team);
         netdev_rx_handler_unregister(port_dev);
         netdev_set_master(port_dev, NULL);
         vlan_vids_del_by_dev(port_dev, dev);