net: stmmac: Hold rtnl lock in suspend/resume callbacks

We need to hold rnl lock in suspend and resume callbacks because phylink
requires it. Otherwise we will get a WARN() in suspend and resume.

Also, move phylink start and stop callbacks to inside device's internal
lock so that we prevent concurrent HW accesses.

Fixes: 74371272 ("net: stmmac: Convert to phylink and remove phylib logic")
Reported-by: Christophe ROULLIER <christophe.roullier@st.com>
Tested-by: Christophe ROULLIER <christophe.roullier@st.com>
Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -4451,10 +4451,12 @@ int stmmac_suspend(struct device *dev)
 	if (!ndev || !netif_running(ndev))
 		return 0;
 
-	phylink_stop(priv->phylink);
-
 	mutex_lock(&priv->lock);
 
+	rtnl_lock();
+	phylink_stop(priv->phylink);
+	rtnl_unlock();
+
 	netif_device_detach(ndev);
 	stmmac_stop_all_queues(priv);
 
@@ -4558,9 +4560,11 @@ int stmmac_resume(struct device *dev)
 
 	stmmac_start_all_queues(priv);
 
-	mutex_unlock(&priv->lock);
-
+	rtnl_lock();
 	phylink_start(priv->phylink);
+	rtnl_unlock();
+
+	mutex_unlock(&priv->lock);
 
 	return 0;
 }