netdev - [PATCH net 4/4] phy: phy_ethtool_ksettings_set: Lock the PHY while changing settings

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Message-Id: <20211024194805.2762333-5-andrew@lunn.ch>
Date:   Sun, 24 Oct 2021 21:48:05 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>, Walter.Stoll@...gon.com,
        Russell King <rmk+kernel@...linux.org.uk>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Andrew Lunn <andrew@...n.ch>
Subject: [PATCH net 4/4] phy: phy_ethtool_ksettings_set: Lock the PHY while changing settings

There is a race condition where the PHY state machine can change
members of the phydev structure at the same time userspace requests a
change via ethtool. To prevent this, have phy_ethtool_ksettings_set
take the PHY lock.

Fixes: 2d55173e71b0 ("phy: add generic function to support ksetting support")
Reported-by: Walter Stoll <Walter.Stoll@...gon.com>
Suggested-by: Walter Stoll <Walter.Stoll@...gon.com>
Tested-by: Walter Stoll <Walter.Stoll@...gon.com>
Signed-off-by: Andrew Lunn <andrew@...n.ch>
---
 drivers/net/phy/phy.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index d845afab1af7..a3bfb156c83d 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -798,6 +798,7 @@ int phy_ethtool_ksettings_set(struct phy_device *phydev,
 	      duplex != DUPLEX_FULL)))
 		return -EINVAL;
 
+	mutex_lock(&phydev->lock);
 	phydev->autoneg = autoneg;
 
 	if (autoneg == AUTONEG_DISABLE) {
@@ -814,8 +815,9 @@ int phy_ethtool_ksettings_set(struct phy_device *phydev,
 	phydev->mdix_ctrl = cmd->base.eth_tp_mdix_ctrl;
 
 	/* Restart the PHY */
-	phy_start_aneg(phydev);
+	_phy_start_aneg(phydev);
 
+	mutex_unlock(&phydev->lock);
 	return 0;
 }
 EXPORT_SYMBOL(phy_ethtool_ksettings_set);
-- 
2.33.0