[PATCH net] net: phy: clear phydev->devlink when the link is deleted

[Wei Fang <wei.fang@nxp.com>]

The phydev->devlink is not cleared when the link is deleted, so calling
phy_detach() again will cause a crash. For example, the link is deleted
when the network interface is set to down, then re-enable the network
interface and phy_attach_direct() will be called, but an error occurs
and jump to the error path, so phy_detach() is called again and cause a
crash, the crash log is as follows.

[   24.702421] Call trace:
[   24.704856]  device_link_put_kref+0x20/0x120
[   24.709124]  device_link_del+0x30/0x48
[   24.712864]  phy_detach+0x24/0x168
[   24.716261]  phy_attach_direct+0x168/0x3a4
[   24.720352]  phylink_fwnode_phy_connect+0xc8/0x14c
[   24.725140]  phylink_of_phy_connect+0x1c/0x34

Fixes: bc66fa87d4fd ("net: phy: Add link between phy dev and mac dev")
Signed-off-by: Wei Fang <wei.fang@nxp.com>
---
 drivers/net/phy/phy_device.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index cc1bfd22fb81..7d5e76a3db0e 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1727,8 +1727,10 @@ void phy_detach(struct phy_device *phydev)
 	struct module *ndev_owner = NULL;
 	struct mii_bus *bus;
 
-	if (phydev->devlink)
+	if (phydev->devlink) {
 		device_link_del(phydev->devlink);
+		phydev->devlink = NULL;
+	}
 
 	if (phydev->sysfs_links) {
 		if (dev)
-- 
2.34.1