[PATCH net-next 0/2] Add additional phydev locks

[PATCH net-next 0/2] Add additional phydev locks

[Andrew Lunn]

The phydev lock should be held when accessing members of phydev, or
calling into the driver. Some of the phy_ethtool_ functions are
missing locks. Add them. To avoid deadlock the marvell driver is
modified since it calls one of the functions which gain locks, which
would result in a deadlock.

The missing locks have not caused noticeable issues, so these patches
are for net-next.

Andrew Lunn (2):
  net: phy: marvell: Use the unlocked genphy_c45_ethtool_get_eee()
  net: phy: Add locks to ethtool functions

 drivers/net/phy/marvell.c |  2 +-
 drivers/net/phy/phy.c     | 84 ++++++++++++++++++++++++++++++---------
 drivers/net/usb/lan78xx.c |  2 -
 3 files changed, 67 insertions(+), 21 deletions(-)

-- 
2.39.1

[=PATCH net-next 1/2] net: phy: marvell: Use the unlocked genphy_c45_ethtool_get_eee()

[Andrew Lunn]

phy_ethtool_get_eee() is about to gain locking of the phydev lock.
This means it cannot be used within a PHY driver without causing a
deadlock. Swap to using genphy_c45_ethtool_get_eee() which assumes the
lock has already been taken.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/phy/marvell.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
index 0d706ee266af..63a3644d86c9 100644
--- a/drivers/net/phy/marvell.c
+++ b/drivers/net/phy/marvell.c
@@ -1467,7 +1467,7 @@ static int m88e1540_set_fld(struct phy_device *phydev, const u8 *msecs)
 	/* According to the Marvell data sheet EEE must be disabled for
 	 * Fast Link Down detection to work properly
 	 */
-	ret = phy_ethtool_get_eee(phydev, &eee);
+	ret = genphy_c45_ethtool_get_eee(phydev, &eee);
 	if (!ret && eee.eee_enabled) {
 		phydev_warn(phydev, "Fast Link Down detection requires EEE to be disabled!\n");
 		return -EBUSY;
-- 
2.39.1

[=PATCH net-next 2/2] net: phy: Add locks to ethtool functions

[Andrew Lunn]

The phydev lock should be held while accessing members of phydev,
or calling into the driver.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/phy/phy.c | 84 +++++++++++++++++++++++++++++++++----------
 1 file changed, 66 insertions(+), 18 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 2f1041a7211e..b33e55a7364e 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -1069,27 +1069,35 @@ EXPORT_SYMBOL(phy_ethtool_ksettings_set);
 int phy_speed_down(struct phy_device *phydev, bool sync)
 {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(adv_tmp);
-	int ret;
+	int ret = 0;
+
+	mutex_lock(&phydev->lock);
 
 	if (phydev->autoneg != AUTONEG_ENABLE)
-		return 0;
+		goto out;
 
 	linkmode_copy(adv_tmp, phydev->advertising);
 
 	ret = phy_speed_down_core(phydev);
 	if (ret)
-		return ret;
+		goto out;
 
 	linkmode_copy(phydev->adv_old, adv_tmp);
 
-	if (linkmode_equal(phydev->advertising, adv_tmp))
-		return 0;
+	if (linkmode_equal(phydev->advertising, adv_tmp)) {
+		ret = 0;
+		goto out;
+	}
 
 	ret = phy_config_aneg(phydev);
 	if (ret)
-		return ret;
+		goto out;
+
+	ret = sync ? phy_poll_aneg_done(phydev) : 0;
+out:
+	mutex_unlock(&phydev->lock);
 
-	return sync ? phy_poll_aneg_done(phydev) : 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(phy_speed_down);
 
@@ -1102,21 +1110,28 @@ EXPORT_SYMBOL_GPL(phy_speed_down);
 int phy_speed_up(struct phy_device *phydev)
 {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(adv_tmp);
+	int ret = 0;
+
+	mutex_lock(&phydev->lock);
 
 	if (phydev->autoneg != AUTONEG_ENABLE)
-		return 0;
+		goto out;
 
 	if (linkmode_empty(phydev->adv_old))
-		return 0;
+		goto out;
 
 	linkmode_copy(adv_tmp, phydev->advertising);
 	linkmode_copy(phydev->advertising, phydev->adv_old);
 	linkmode_zero(phydev->adv_old);
 
 	if (linkmode_equal(phydev->advertising, adv_tmp))
-		return 0;
+		goto out;
+
+	ret = phy_config_aneg(phydev);
+out:
+	mutex_unlock(&phydev->lock);
 
-	return phy_config_aneg(phydev);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(phy_speed_up);
 
@@ -1500,10 +1515,16 @@ EXPORT_SYMBOL(phy_init_eee);
  */
 int phy_get_eee_err(struct phy_device *phydev)
 {
+	int ret;
+
 	if (!phydev->drv)
 		return -EIO;
 
-	return phy_read_mmd(phydev, MDIO_MMD_PCS, MDIO_PCS_EEE_WK_ERR);
+	mutex_lock(&phydev->lock);
+	ret = phy_read_mmd(phydev, MDIO_MMD_PCS, MDIO_PCS_EEE_WK_ERR);
+	mutex_unlock(&phydev->lock);
+
+	return ret;
 }
 EXPORT_SYMBOL(phy_get_eee_err);
 
@@ -1517,10 +1538,16 @@ EXPORT_SYMBOL(phy_get_eee_err);
  */
 int phy_ethtool_get_eee(struct phy_device *phydev, struct ethtool_eee *data)
 {
+	int ret;
+
 	if (!phydev->drv)
 		return -EIO;
 
-	return genphy_c45_ethtool_get_eee(phydev, data);
+	mutex_lock(&phydev->lock);
+	ret = genphy_c45_ethtool_get_eee(phydev, data);
+	mutex_unlock(&phydev->lock);
+
+	return ret;
 }
 EXPORT_SYMBOL(phy_ethtool_get_eee);
 
@@ -1533,10 +1560,16 @@ EXPORT_SYMBOL(phy_ethtool_get_eee);
  */
 int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
 {
+	int ret;
+
 	if (!phydev->drv)
 		return -EIO;
 
-	return genphy_c45_ethtool_set_eee(phydev, data);
+	mutex_lock(&phydev->lock);
+	ret = genphy_c45_ethtool_set_eee(phydev, data);
+	mutex_unlock(&phydev->lock);
+
+	return ret;
 }
 EXPORT_SYMBOL(phy_ethtool_set_eee);
 
@@ -1548,8 +1581,15 @@ EXPORT_SYMBOL(phy_ethtool_set_eee);
  */
 int phy_ethtool_set_wol(struct phy_device *phydev, struct ethtool_wolinfo *wol)
 {
-	if (phydev->drv && phydev->drv->set_wol)
-		return phydev->drv->set_wol(phydev, wol);
+	int ret;
+
+	if (phydev->drv && phydev->drv->set_wol) {
+		mutex_lock(&phydev->lock);
+		ret = phydev->drv->set_wol(phydev, wol);
+		mutex_unlock(&phydev->lock);
+
+		return ret;
+	}
 
 	return -EOPNOTSUPP;
 }
@@ -1563,8 +1603,11 @@ EXPORT_SYMBOL(phy_ethtool_set_wol);
  */
 void phy_ethtool_get_wol(struct phy_device *phydev, struct ethtool_wolinfo *wol)
 {
-	if (phydev->drv && phydev->drv->get_wol)
+	if (phydev->drv && phydev->drv->get_wol) {
+		mutex_lock(&phydev->lock);
 		phydev->drv->get_wol(phydev, wol);
+		mutex_unlock(&phydev->lock);
+	}
 }
 EXPORT_SYMBOL(phy_ethtool_get_wol);
 
@@ -1601,6 +1644,7 @@ EXPORT_SYMBOL(phy_ethtool_set_link_ksettings);
 int phy_ethtool_nway_reset(struct net_device *ndev)
 {
 	struct phy_device *phydev = ndev->phydev;
+	int ret;
 
 	if (!phydev)
 		return -ENODEV;
@@ -1608,6 +1652,10 @@ int phy_ethtool_nway_reset(struct net_device *ndev)
 	if (!phydev->drv)
 		return -EIO;
 
-	return phy_restart_aneg(phydev);
+	mutex_lock(&phydev->lock);
+	ret = phy_restart_aneg(phydev);
+	mutex_unlock(&phydev->lock);
+
+	return ret;
 }
 EXPORT_SYMBOL(phy_ethtool_nway_reset);
-- 
2.39.1

Re: [PATCH net-next 0/2] Add additional phydev locks

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:

On Fri, 17 Feb 2023 04:07:12 +0100 you wrote:
> The phydev lock should be held when accessing members of phydev, or
> calling into the driver. Some of the phy_ethtool_ functions are
> missing locks. Add them. To avoid deadlock the marvell driver is
> modified since it calls one of the functions which gain locks, which
> would result in a deadlock.
> 
> The missing locks have not caused noticeable issues, so these patches
> are for net-next.
> 
> [...]

Here is the summary with links:
  - [=PATCH,net-next,1/2] net: phy: marvell: Use the unlocked genphy_c45_ethtool_get_eee()
    https://git.kernel.org/netdev/net-next/c/3365777a6a22
  - [=PATCH,net-next,2/2] net: phy: Add locks to ethtool functions
    https://git.kernel.org/netdev/net-next/c/2f987d486610

You are awesome, thank you!
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