net: phy: Don't call phy_resume if phy_init_hw failed

[ Upstream commit b394745 ]

After the call to phy_init_hw failed in phy_attach_direct, phy_detach is called
to detach the phy device from its network device. If the attached driver is a
generic phy driver, this also detaches the driver. Subsequently phy_resume
is called, which assumes without checking that a driver is attached to the
device. This will result in a crash such as

Unable to handle kernel paging request for data at address 0xffffffffffffff90
Faulting instruction address: 0xc0000000003a0e18
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP [c0000000003a0e18] .phy_attach_direct+0x68/0x17c
LR [c0000000003a0e6c] .phy_attach_direct+0xbc/0x17c
Call Trace:
[c0000003fc0475d0] [c0000000003a0e6c] .phy_attach_direct+0xbc/0x17c (unreliable)
[c0000003fc047670] [c0000000003a0ff8] .phy_connect_direct+0x28/0x98
[c0000003fc047700] [c0000000003f0074] .of_phy_connect+0x4c/0xa4

Only call phy_resume if phy_init_hw was successful.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/phy/phy_device.c

@@ -613,8 +613,8 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 	err = phy_init_hw(phydev);
 	if (err)
 		phy_detach(phydev);
-
-	phy_resume(phydev);
+	else
+		phy_resume(phydev);
 
 	return err;
 }