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From:   "Ivan T. Ivanov" <iivanov@suse.de>
To:     Woojung Huh <woojung.huh@microchip.com>
Cc:     UNGLinuxDriver@microchip.com,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        "Ivan T. Ivanov" <iivanov@suse.de>
Subject: [PATCH] net: usb: lan78xx: don't modify phy_device state concurrently
Date:   Wed,  4 Aug 2021 11:13:39 +0300
Message-Id: <20210804081339.19909-1-iivanov@suse.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Currently phy_device state could be left in inconsistent state shown
by following alert message[1]. This is because phy_read_status could
be called concurrently from lan78xx_delayedwork, phy_state_machine and
__ethtool_get_link. Fix this by making sure that phy_device state is
updated atomically.

[1] lan78xx 1-1.1.1:1.0 eth0: No phy led trigger registered for speed(-1)

Signed-off-by: Ivan T. Ivanov <iivanov@suse.de>
---
 drivers/net/usb/lan78xx.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index b27229d34425..0c964d0bd2d6 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -1154,7 +1154,7 @@ static int lan78xx_link_reset(struct lan78xx_net *dev)
 {
 	struct phy_device *phydev = dev->net->phydev;
 	struct ethtool_link_ksettings ecmd;
-	int ladv, radv, ret;
+	int ladv, radv, ret, link;
 	u32 buf;
 
 	/* clear LAN78xx interrupt status */
@@ -1162,9 +1162,12 @@ static int lan78xx_link_reset(struct lan78xx_net *dev)
 	if (unlikely(ret < 0))
 		return -EIO;
 
+	mutex_lock(&phydev->lock);
 	phy_read_status(phydev);
+	link = phydev->link;
+	mutex_unlock(&phydev->lock);
 
-	if (!phydev->link && dev->link_on) {
+	if (!link && dev->link_on) {
 		dev->link_on = false;
 
 		/* reset MAC */
@@ -1177,7 +1180,7 @@ static int lan78xx_link_reset(struct lan78xx_net *dev)
 			return -EIO;
 
 		del_timer(&dev->stat_monitor);
-	} else if (phydev->link && !dev->link_on) {
+	} else if (link && !dev->link_on) {
 		dev->link_on = true;
 
 		phy_ethtool_ksettings_get(phydev, &ecmd);
@@ -1464,9 +1467,14 @@ static int lan78xx_set_eee(struct net_device *net, struct ethtool_eee *edata)
 
 static u32 lan78xx_get_link(struct net_device *net)
 {
+	u32 link;
+
+	mutex_lock(&net->phydev->lock);
 	phy_read_status(net->phydev);
+	link = net->phydev->link;
+	mutex_unlock(&net->phydev->lock);
 
-	return net->phydev->link;
+	return link;
 }
 
 static void lan78xx_get_drvinfo(struct net_device *net,
-- 
2.32.0