Subject: Re: [RFC PATCH net-next 3/3] net: dsa: refine netdev event notifier

From: Ido Schimmel <[email-masked]>
Date: Sun, 13 Mar 2016 09:32:50 +0200

Hi Vivien,

Sun, Mar 13, 2016 at 08:42:26AM IST, [email-masked] wrote:
>Rework the netdev event handler, similar to what the Mellanox Spectrum
>driver does, to eventually welcome NETDEV_PRECHANGEUPPER actions and use
>netdev helpers, such as netif_is_bridge_master.
>
>Signed-off-by: Vivien Didelot <[email-masked]>
>---
> net/dsa/slave.c | 55 +++++++++++++++++++++++++++++++------------------------
> 1 file changed, 31 insertions(+), 24 deletions(-)
>
>diff --git a/net/dsa/slave.c b/net/dsa/slave.c
>index 54976c4..27f7886 100644
>--- a/net/dsa/slave.c
>+++ b/net/dsa/slave.c
>@@ -451,7 +451,7 @@ static int dsa_slave_bridge_port_join(struct net_device *dev,
> 	if (ds->drv->port_bridge_join)
> 		ret = ds->drv->port_bridge_join(ds, p->port, br);
> 
>-	return ret;
>+	return ret == -EOPNOTSUPP ? 0 : ret;
> }
> 
> static void dsa_slave_bridge_port_leave(struct net_device *dev)
>@@ -1139,40 +1139,47 @@ static bool dsa_slave_dev_check(struct net_device *dev)
> 	return dev->netdev_ops == &dsa_slave_netdev_ops;
> }
> 
>-static int dsa_slave_master_changed(struct net_device *dev)
>+static int dsa_slave_port_upper_event(struct net_device *dev,
>+				      unsigned long event, void *ptr)
> {
>-	struct net_device *master = netdev_master_upper_dev_get(dev);
>-	struct dsa_slave_priv *p = netdev_priv(dev);
>+	struct netdev_notifier_changeupper_info *info = ptr;
>+	struct net_device *upper = info->upper_dev;
> 	int err = 0;
> 
>-	if (master && master->rtnl_link_ops &&
>-	    !strcmp(master->rtnl_link_ops->kind, "bridge"))
>-		err = dsa_slave_bridge_port_join(dev, master);
>-	else if (dsa_port_is_bridged(p))
>-		dsa_slave_bridge_port_leave(dev);
>+	switch (event) {
>+	case NETDEV_CHANGEUPPER:
>+		if (netif_is_bridge_master(upper)) {
>+			if (info->linking)
>+				err = dsa_slave_bridge_port_join(dev, upper);
>+			else
>+				dsa_slave_bridge_port_leave(dev);
>+		}
> 
>-	return err;
>+		break;
>+	}
>+
>+	return notifier_from_errno(err);
> }
> 
>-int dsa_slave_netdevice_event(struct notifier_block *unused,
>-			      unsigned long event, void *ptr)
>+static int dsa_slave_port_event(struct net_device *dev, unsigned long event,
>+				void *ptr)
> {
>-	struct net_device *dev;
>-	int err = 0;
>-
> 	switch (event) {
>+	case NETDEV_PRECHANGEUPPER:

Why do you need this here? It seems you are always ignoring it in
dsa_slave_port_upper_event()? Probably better to introduce it when you
actually need it.

Other than that, it looks good to me.

> 	case NETDEV_CHANGEUPPER:
>-		dev = netdev_notifier_info_to_dev(ptr);
>-		if (!dsa_slave_dev_check(dev))
>-			goto out;
>+		return dsa_slave_port_upper_event(dev, event, ptr);
>+	}
> 
>-		err = dsa_slave_master_changed(dev);
>-		if (err && err != -EOPNOTSUPP)
>-			netdev_warn(dev, "failed to reflect master change\n");
>+	return NOTIFY_DONE;
>+}
> 
>-		break;
>-	}
>+int dsa_slave_netdevice_event(struct notifier_block *unused,
>+			      unsigned long event, void *ptr)
>+{
>+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
>+
>+	if (dsa_slave_dev_check(dev))
>+		return dsa_slave_port_event(dev, event, ptr);
> 
>-out:
> 	return NOTIFY_DONE;
> }
>-- 
>2.7.2
>