FAILED: patch "[PATCH] phy: phy_ethtool_ksettings_set: Lock the PHY while changing" failed to apply to 5.4-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From af1a02aa23c37045e6adfcf074cf7dbac167a403 Mon Sep 17 00:00:00 2001
From: Andrew Lunn <andrew@lunn.ch>
Date: Sun, 24 Oct 2021 21:48:05 +0200
Subject: [PATCH] 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@duagon.com>
Suggested-by: Walter Stoll <Walter.Stoll@duagon.com>
Tested-by: Walter Stoll <Walter.Stoll@duagon.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

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);