[PATCH 5.4 22/61] net: usb: lan78xx: don't modify phy_device state concurrently

Sasha Levin
2021-08-24T17:16:02Z

From: "Ivan T. Ivanov" <iivanov@suse.de>

[ Upstream commit 6b67d4d63edece1033972214704c04f36c5be89a ]

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 71cc5b63d8ce..92d9d3407b79 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/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,
--
2.30.2