[PATCH 2/2] net: phy: Don't use drv when it is NULL in phy_attached_print

[Romain Perier]

Currently, if this logging function is used prior the phy driver is
binded to the phy device (that is usually done from .ndo_open),
'phydev->drv' might be NULL, resulting in a kernel crash. That is
typically the case in the stmmac driver, info about the phy is displayed
during the registration of the MDIO bus, and then genphy driver is binded
to this phydev when .ndo_open is called.

This commit fixes the issue by using the right genphy driver, when
phydev->drv is NULL.

Fixes: commit fbca164776e4 ("net: stmmac: Use the right logging functi")
Signed-off-by: Romain Perier <romain.perier@xxxxxxxxxxxxx>
---
 drivers/net/phy/phy_device.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 9493fb369682..b38926bc275f 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -877,15 +877,24 @@ EXPORT_SYMBOL(phy_attached_info);
 #define ATTACHED_FMT "attached PHY driver [%s] (mii_bus:phy_addr=%s, irq=%d)"
 void phy_attached_print(struct phy_device *phydev, const char *fmt, ...)
 {
+	struct phy_driver *drv = phydev->drv;
+
+	if (!drv) {
+		if (phydev->is_c45)
+			drv = &genphy_10g_driver;
+		else
+			drv = &genphy_driver;
+	}
+
 	if (!fmt) {
 		dev_info(&phydev->mdio.dev, ATTACHED_FMT "\n",
-			 phydev->drv->name, phydev_name(phydev),
+			 drv->name, phydev_name(phydev),
 			 phydev->irq);
 	} else {
 		va_list ap;
 
 		dev_info(&phydev->mdio.dev, ATTACHED_FMT,
-			 phydev->drv->name, phydev_name(phydev),
+			 drv->name, phydev_name(phydev),
 			 phydev->irq);
 
 		va_start(ap, fmt);
-- 
2.11.0