[PATCH net-next v4 02/13] dpaa2-switch: avoid holding rtnl_lock in dpaa2_switch_event_work()

[Ioana Ciornei]

The only reason why the rtnl_lock is held in the
dpaa2_switch_event_work() is so that there is no concurency between the
changeupper notifier which manages the per port FDB assignment and the
workqueue which adds / deletes addresses into that forwarding database.

To avoid this kind of concurency without a rtnl_lock, flush the event
workqueue as the last step from the pre_bridge_leave so that any
in-flight operations targeting the current FDB are finalized before the
bridge layout (and the per port FDB assignment) changes.

Signed-off-by: Ioana Ciornei <ioana.ciornei@xxxxxxx>
---
Changes in v4:
- New patch.
---
 drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
index d70e6f06ac15..67c639fad0db 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
@@ -2069,7 +2069,15 @@ static int dpaa2_switch_port_restore_rxvlan(struct net_device *vdev, int vid, vo
 
 static void dpaa2_switch_port_pre_bridge_leave(struct net_device *netdev)
 {
+	struct ethsw_port_priv *port_priv = netdev_priv(netdev);
+	struct ethsw_core *ethsw = port_priv->ethsw_data;
+
 	switchdev_bridge_port_unoffload(netdev, NULL, NULL, NULL);
+
+	/* Make sure that any FDB add/del operations are completed before the
+	 * bridge layout changes
+	 */
+	flush_workqueue(ethsw->workqueue);
 }
 
 static int dpaa2_switch_port_bridge_leave(struct net_device *netdev)
@@ -2281,7 +2289,6 @@ static void dpaa2_switch_event_work(struct work_struct *work)
 	struct switchdev_notifier_fdb_info *fdb_info;
 	int err;
 
-	rtnl_lock();
 	fdb_info = &switchdev_work->fdb_info;
 
 	switch (switchdev_work->event) {
@@ -2310,7 +2317,6 @@ static void dpaa2_switch_event_work(struct work_struct *work)
 		break;
 	}
 
-	rtnl_unlock();
 	kfree(switchdev_work->fdb_info.addr);
 	kfree(switchdev_work);
 	dev_put(dev);
-- 
2.25.1