linux-kernel - [PATCH 4.9 068/105] net: dsa: Fix network device registration order

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Date:   Tue, 10 Oct 2017 21:50:39 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 068/105] net: dsa: Fix network device registration order

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Fainelli <f.fainelli@...il.com>


[ Upstream commit e804441cfe0b60f6c430901946a69c01eac09df1 ]

We cannot be registering the network device first, then setting its
carrier off and finally connecting it to a PHY, doing that leaves a
window during which the carrier is at best inconsistent, and at worse
the device is not usable without a down/up sequence since the network
device is visible to user space with possibly no PHY device attached.

Re-order steps so that they make logical sense. This fixes some devices
where the port was not usable after e.g: an unbind then bind of the
driver.

Fixes: 0071f56e46da ("dsa: Register netdev before phy")
Fixes: 91da11f870f0 ("net: Distributed Switch Architecture protocol support")
Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/dsa/slave.c |   28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -1269,26 +1269,32 @@ int dsa_slave_create(struct dsa_switch *
 	p->old_duplex = -1;
 
 	ds->ports[port].netdev = slave_dev;
-	ret = register_netdev(slave_dev);
-	if (ret) {
-		netdev_err(master, "error %d registering interface %s\n",
-			   ret, slave_dev->name);
-		ds->ports[port].netdev = NULL;
-		free_netdev(slave_dev);
-		return ret;
-	}
 
 	netif_carrier_off(slave_dev);
 
 	ret = dsa_slave_phy_setup(p, slave_dev);
 	if (ret) {
 		netdev_err(master, "error %d setting up slave phy\n", ret);
-		unregister_netdev(slave_dev);
-		free_netdev(slave_dev);
-		return ret;
+		goto out_free;
+	}
+
+	ret = register_netdev(slave_dev);
+	if (ret) {
+		netdev_err(master, "error %d registering interface %s\n",
+			   ret, slave_dev->name);
+		goto out_phy;
 	}
 
 	return 0;
+
+out_phy:
+	phy_disconnect(p->phy);
+	if (of_phy_is_fixed_link(ds->ports[port].dn))
+		of_phy_deregister_fixed_link(ds->ports[port].dn);
+out_free:
+	free_netdev(slave_dev);
+	ds->ports[port].netdev = NULL;
+	return ret;
 }
 
 void dsa_slave_destroy(struct net_device *slave_dev)