[PATCH 4.13 035/160] net: dsa: Fix network device registration order

From: Greg Kroah-Hartman
Date: Tue Oct 10 2017 - 16:36:45 EST


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

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

From: Florian Fainelli <f.fainelli@xxxxxxxxx>


[ 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@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/dsa/slave.c | 28 +++++++++++++++++-----------
1 file changed, 17 insertions(+), 11 deletions(-)

--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -1180,26 +1180,32 @@ 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(p->dp->dn))
+ of_phy_deregister_fixed_link(p->dp->dn);
+out_free:
+ free_netdev(slave_dev);
+ ds->ports[port].netdev = NULL;
+ return ret;
}

void dsa_slave_destroy(struct net_device *slave_dev)