sh_eth: fix invalid context bug while changing link options by ethtool

The change fixes sleep in atomic context bug, which is encountered
every time when link settings are changed by ethtool.

Since commit 35b5f6b1 ("PHYLIB: Locking fixes for PHY I/O
potentially sleeping") phy_start_aneg() function utilizes a mutex
to serialize changes to phy state, however that helper function is
called in atomic context under a grabbed spinlock, because
phy_start_aneg() is called by phy_ethtool_ksettings_set() and by
replaced phy_ethtool_sset() helpers from phylib.

Now duplex mode setting is enforced in sh_eth_adjust_link() only,
also now RX/TX is disabled when link is put down or modifications
to E-MAC registers ECMR and GECMR are expected for both cases of
checked and ignored link status pin state from E-MAC interrupt handler.

For reference the change is a partial rework of commit 1e1b812b
("sh_eth: fix handling of no LINK signal").

Fixes: dc19e4e5 ("sh: sh_eth: Add support ethtool")
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -1927,8 +1927,15 @@ static void sh_eth_adjust_link(struct net_device *ndev)
 {
 	struct sh_eth_private *mdp = netdev_priv(ndev);
 	struct phy_device *phydev = ndev->phydev;
+	unsigned long flags;
 	int new_state = 0;
 
+	spin_lock_irqsave(&mdp->lock, flags);
+
+	/* Disable TX and RX right over here, if E-MAC change is ignored */
+	if (mdp->cd->no_psr || mdp->no_ether_link)
+		sh_eth_rcv_snd_disable(ndev);
+
 	if (phydev->link) {
 		if (phydev->duplex != mdp->duplex) {
 			new_state = 1;
@@ -1947,18 +1954,21 @@ static void sh_eth_adjust_link(struct net_device *ndev)
 			sh_eth_modify(ndev, ECMR, ECMR_TXF, 0);
 			new_state = 1;
 			mdp->link = phydev->link;
-			if (mdp->cd->no_psr || mdp->no_ether_link)
-				sh_eth_rcv_snd_enable(ndev);
 		}
 	} else if (mdp->link) {
 		new_state = 1;
 		mdp->link = 0;
 		mdp->speed = 0;
 		mdp->duplex = -1;
-		if (mdp->cd->no_psr || mdp->no_ether_link)
-			sh_eth_rcv_snd_disable(ndev);
 	}
 
+	/* Enable TX and RX right over here, if E-MAC change is ignored */
+	if ((mdp->cd->no_psr || mdp->no_ether_link) && phydev->link)
+		sh_eth_rcv_snd_enable(ndev);
+
+	mmiowb();
+	spin_unlock_irqrestore(&mdp->lock, flags);
+
 	if (new_state && netif_msg_link(mdp))
 		phy_print_status(phydev);
 }
@@ -2049,39 +2059,10 @@ static int sh_eth_get_link_ksettings(struct net_device *ndev,
 static int sh_eth_set_link_ksettings(struct net_device *ndev,
 				     const struct ethtool_link_ksettings *cmd)
 {
-	struct sh_eth_private *mdp = netdev_priv(ndev);
-	unsigned long flags;
-	int ret;
-
 	if (!ndev->phydev)
 		return -ENODEV;
 
-	spin_lock_irqsave(&mdp->lock, flags);
-
-	/* disable tx and rx */
-	sh_eth_rcv_snd_disable(ndev);
-
-	ret = phy_ethtool_ksettings_set(ndev->phydev, cmd);
-	if (ret)
-		goto error_exit;
-
-	if (cmd->base.duplex == DUPLEX_FULL)
-		mdp->duplex = 1;
-	else
-		mdp->duplex = 0;
-
-	if (mdp->cd->set_duplex)
-		mdp->cd->set_duplex(ndev);
-
-error_exit:
-	mdelay(1);
-
-	/* enable tx and rx */
-	sh_eth_rcv_snd_enable(ndev);
-
-	spin_unlock_irqrestore(&mdp->lock, flags);
-
-	return ret;
+	return phy_ethtool_ksettings_set(ndev->phydev, cmd);
 }
 
 /* If it is ever necessary to increase SH_ETH_REG_DUMP_MAX_REGS, the