net: usb: lan78xx: don't modify phy_device state concurrently

stable inclusion
from stable-5.10.61
commit 8849a8c7058e697d7fe5864b84a1bd58c58963bd
bugzilla: 177029 https://gitee.com/openeuler/kernel/issues/I4EAXD

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8849a8c7058e697d7fe5864b84a1bd58c58963bd

--------------------------------

[ Upstream commit 6b67d4d6 ]

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: NIvan T. Ivanov <iivanov@suse.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/net/usb/lan78xx.c

@@ -1159,7 +1159,7 @@ 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 */
@@ -1167,9 +1167,12 @@ 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 */
@@ -1182,7 +1185,7 @@ 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);
@@ -1471,9 +1474,14 @@ 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,