netdev - [PATCH v2 09/14] ravb: fix invalid context bug while changing link options by ethtool

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Date:   Wed, 4 Jul 2018 11:14:51 +0300
From:   Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        "David S . Miller" <davem@...emloft.net>
CC:     Andrew Lunn <andrew@...n.ch>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        <netdev@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>
Subject: [PATCH v2 09/14] ravb: 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 35b5f6b1a82b ("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 ravb_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.

Fixes: a0d2f20650e8 ("Renesas Ethernet AVB PTP clock driver")
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
---
 drivers/net/ethernet/renesas/ravb_main.c | 49 ++++++++----------------
 1 file changed, 15 insertions(+), 34 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index e7d6d1b6e7d6..40266fe01186 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -980,6 +980,13 @@ static void ravb_adjust_link(struct net_device *ndev)
 	struct ravb_private *priv = netdev_priv(ndev);
 	struct phy_device *phydev = ndev->phydev;
 	bool new_state = false;
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	/* Disable TX and RX right over here, if E-MAC change is ignored */
+	if (priv->no_avb_link)
+		ravb_rcv_snd_disable(ndev);
 
 	if (phydev->link) {
 		if (phydev->duplex != priv->duplex) {
@@ -997,18 +1004,21 @@ static void ravb_adjust_link(struct net_device *ndev)
 			ravb_modify(ndev, ECMR, ECMR_TXF, 0);
 			new_state = true;
 			priv->link = phydev->link;
-			if (priv->no_avb_link)
-				ravb_rcv_snd_enable(ndev);
 		}
 	} else if (priv->link) {
 		new_state = true;
 		priv->link = 0;
 		priv->speed = 0;
 		priv->duplex = -1;
-		if (priv->no_avb_link)
-			ravb_rcv_snd_disable(ndev);
 	}
 
+	/* Enable TX and RX right over here, if E-MAC change is ignored */
+	if (priv->no_avb_link && phydev->link)
+		ravb_rcv_snd_enable(ndev);
+
+	mmiowb();
+	spin_unlock_irqrestore(&priv->lock, flags);
+
 	if (new_state && netif_msg_link(priv))
 		phy_print_status(phydev);
 }
@@ -1115,39 +1125,10 @@ static int ravb_get_link_ksettings(struct net_device *ndev,
 static int ravb_set_link_ksettings(struct net_device *ndev,
 				   const struct ethtool_link_ksettings *cmd)
 {
-	struct ravb_private *priv = netdev_priv(ndev);
-	unsigned long flags;
-	int error;
-
 	if (!ndev->phydev)
 		return -ENODEV;
 
-	spin_lock_irqsave(&priv->lock, flags);
-
-	/* Disable TX and RX */
-	ravb_rcv_snd_disable(ndev);
-
-	error = phy_ethtool_ksettings_set(ndev->phydev, cmd);
-	if (error)
-		goto error_exit;
-
-	if (cmd->base.duplex == DUPLEX_FULL)
-		priv->duplex = 1;
-	else
-		priv->duplex = 0;
-
-	ravb_set_duplex(ndev);
-
-error_exit:
-	mdelay(1);
-
-	/* Enable TX and RX */
-	ravb_rcv_snd_enable(ndev);
-
-	mmiowb();
-	spin_unlock_irqrestore(&priv->lock, flags);
-
-	return error;
+	return phy_ethtool_ksettings_set(ndev->phydev, cmd);
 }
 
 static int ravb_nway_reset(struct net_device *ndev)
-- 
2.17.1