net: dpaa2-mac: move rtnl_lock() only around phylink_{,dis}connect_phy()

After the introduction of a private mac_lock that serializes access to
priv->mac (and port_priv->mac in the switch), the only remaining purpose
of rtnl_lock() is to satisfy the locking requirements of
phylink_fwnode_phy_connect() and phylink_disconnect_phy().

But the functions these live in, dpaa2_mac_connect() and
dpaa2_mac_disconnect(), have contradictory locking requirements.
While phylink_fwnode_phy_connect() wants rtnl_lock() to be held,
phylink_create() wants it to not be held.

Move the rtnl_lock() from top-level (in the dpaa2-eth and dpaa2-switch
drivers) to only surround the phylink calls that require it, in the
dpaa2-mac library code.

This is possible because dpaa2_mac_connect() and dpaa2_mac_disconnect()
run unlocked, and there isn't any danger of an AB/BA deadlock between
the rtnl_mutex and other private locks.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
index 3096810120ee..c886f33f8c6f 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
@@ -430,7 +430,9 @@ int dpaa2_mac_connect(struct dpaa2_mac *mac)
 	}
 	mac->phylink = phylink;
 
+	rtnl_lock();
 	err = phylink_fwnode_phy_connect(mac->phylink, dpmac_node, 0);
+	rtnl_unlock();
 	if (err) {
 		netdev_err(net_dev, "phylink_fwnode_phy_connect() = %d\n", err);
 		goto err_phylink_destroy;
@@ -448,7 +450,10 @@ err_pcs_destroy:
 
 void dpaa2_mac_disconnect(struct dpaa2_mac *mac)
 {
+	rtnl_lock();
 	phylink_disconnect_phy(mac->phylink);
+	rtnl_unlock();
+
 	phylink_destroy(mac->phylink);
 	dpaa2_pcs_destroy(mac);
 	of_phy_put(mac->serdes_phy);