[PATCH net-next] rocker: move netevent neigh update to processes context

[sfeldma@gmail.com]

From: Scott Feldman <sfeldma@gmail.com>

In review of Simon's patchset "rocker: transaction fixes". it was noted
that rocker->neigh_tbl_next_index was unprotected in the call path below
and could race with other contexts calling rocker_port_ipv4_neigh():

	arp_process()
	neigh_update()
	rocker_neigh_update()
	rocker_port_ipv4_neigh()

To fix, move the neigh_update() event processing to process contexts and
hold rtnl_lock to call rocker_port_ipv4_neigh().  This will protect
rocker->neigh_tbl_next_index accesses and is more consistent with the rest
of the driver code where non-I/O processing is done under process context
with rtnl_lock held.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
---
 drivers/net/ethernet/rocker/rocker.c |   52 +++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/rocker/rocker.c b/drivers/net/ethernet/rocker/rocker.c
index 0f5e962..4cff2f6 100644
--- a/drivers/net/ethernet/rocker/rocker.c
+++ b/drivers/net/ethernet/rocker/rocker.c
@@ -5240,14 +5240,52 @@ static struct notifier_block rocker_netdevice_nb __read_mostly = {
  * Net event notifier event handler
  ************************************/
 
-static int rocker_neigh_update(struct net_device *dev, struct neighbour *n)
+struct rocker_neigh_update_work {
+	struct work_struct work;
+	struct rocker_port *rocker_port;
+	int flags;
+	__be32 ip_addr;
+	unsigned char ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))];
+};
+
+static void rocker_event_neigh_update_work(struct work_struct *work)
 {
-	struct rocker_port *rocker_port = netdev_priv(dev);
-	int flags = (n->nud_state & NUD_VALID) ? 0 : ROCKER_OP_FLAG_REMOVE;
-	__be32 ip_addr = *(__be32 *)n->primary_key;
+	struct rocker_neigh_update_work *nw =
+		container_of(work, struct rocker_neigh_update_work, work);
+	int err;
+
+	rtnl_lock();
+	err = rocker_port_ipv4_neigh(nw->rocker_port, SWITCHDEV_TRANS_NONE,
+				     nw->flags, nw->ip_addr, nw->ha);
+	rtnl_unlock();
+
+	if (err)
+		netdev_warn(nw->rocker_port->dev,
+			    "failed to handle neigh %pI4 update (err %d)\n",
+			    &nw->ip_addr, err);
 
-	return rocker_port_ipv4_neigh(rocker_port, SWITCHDEV_TRANS_NONE,
-				      flags, ip_addr, n->ha);
+	kfree(work);
+}
+
+static int rocker_event_neigh_update(struct net_device *dev,
+				     struct neighbour *n)
+{
+	struct rocker_neigh_update_work *nw;
+
+	nw = kmalloc(sizeof(*nw), GFP_ATOMIC);
+	if (!nw)
+		return -ENOMEM;
+
+	INIT_WORK(&nw->work, rocker_event_neigh_update_work);
+
+	nw->rocker_port = netdev_priv(dev);
+	nw->flags = (n->nud_state & NUD_VALID) ? 0 : ROCKER_OP_FLAG_REMOVE;
+	nw->ip_addr = *(__be32 *)n->primary_key;
+	memcpy(nw->ha, n->ha, sizeof(nw->ha));
+
+	schedule_work(&nw->work);
+
+	return 0;
 }
 
 static int rocker_netevent_event(struct notifier_block *unused,
@@ -5264,7 +5302,7 @@ static int rocker_netevent_event(struct notifier_block *unused,
 		dev = n->dev;
 		if (!rocker_port_dev_check(dev))
 			return NOTIFY_DONE;
-		err = rocker_neigh_update(dev, n);
+		err = rocker_event_neigh_update(dev, n);
 		if (err)
 			netdev_warn(dev,
 				    "failed to handle neigh update (err %d)\n",
-- 
1.7.10.4