stmmac: fix suspend/resume locking

Upon resume from standby, there is a possible interrupt
unsafe locking scenario raised when configure the Kernel
with CONFIG_PROVE_LOCKING. So this patch fixes that in
PM driver stuff by calling lock/unlock_irqsave/restore.

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -1989,6 +1989,7 @@ int stmmac_suspend(struct net_device *ndev)
 {
 	struct stmmac_priv *priv = netdev_priv(ndev);
 	int dis_ic = 0;
+	unsigned long flags;
 
 	if (!ndev || !netif_running(ndev))
 		return 0;
@@ -1996,7 +1997,7 @@ int stmmac_suspend(struct net_device *ndev)
 	if (priv->phydev)
 		phy_stop(priv->phydev);
 
-	spin_lock(&priv->lock);
+	spin_lock_irqsave(&priv->lock, flags);
 
 	netif_device_detach(ndev);
 	netif_stop_queue(ndev);
@@ -2024,18 +2025,19 @@ int stmmac_suspend(struct net_device *ndev)
 		/* Disable clock in case of PWM is off */
 		stmmac_clk_disable(priv);
 	}
-	spin_unlock(&priv->lock);
+	spin_unlock_irqrestore(&priv->lock, flags);
 	return 0;
 }
 
 int stmmac_resume(struct net_device *ndev)
 {
 	struct stmmac_priv *priv = netdev_priv(ndev);
+	unsigned long flags;
 
 	if (!netif_running(ndev))
 		return 0;
 
-	spin_lock(&priv->lock);
+	spin_lock_irqsave(&priv->lock, flags);
 
 	/* Power Down bit, into the PM register, is cleared
 	 * automatically as soon as a magic packet or a Wake-up frame
@@ -2063,7 +2065,7 @@ int stmmac_resume(struct net_device *ndev)
 
 	netif_start_queue(ndev);
 
-	spin_unlock(&priv->lock);
+	spin_unlock_irqrestore(&priv->lock, flags);
 
 	if (priv->phydev)
 		phy_start(priv->phydev);