[PATCH net v1] net: emac: move setting of netops to fix crash

[Christian Lamparter <chunkeey@gmail.com>]

fixes the following crash on driver initialization:

|BUG: Kernel NULL pointer dereference on read at 0x00000158
|Faulting instruction address: 0xc0566b40
|Oops: Kernel access of bad area, sig: 11 [#1]
|BE PAGE_SIZE=4K  PowerPC 44x Platform
|Modules linked in:
|CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Tainted: GW 7.3.0-rc3+ #1
|Tainted: [W]=WARN
|Hardware name: MyBook Live APM821XX 0x12c41c83 PowerPC 44x Platform
|NIP:  c0566b40 LR: c05648f8 CTR: c04c1e9c
|REGS: c1053a20 TRAP: 0300   Tainted: GW  (7.3.0-rc3+)
|MSR:  0002b000 <CE,EE,FP,ME>  CR: 24008808  XER: 00000000
|DEAR: 00000158 ESR: 00000000
|GPR00: c05648f8 c1053b10 c1063600 c1030000 c5ab3000 00000000 [...]
|GPR08: 00000002 00000000 00000000 c1053b40 84002808 00000000 [...]
|GPR16: cfffd210 00000002 c0beafcc cfffc960 00000000 c1030644 [...]
|GPR24: c0beafbc c1037000 00000000 0000000a 00000000 c1030000 [...]
|NIP [c0566b40] phy_link_topo_add_phy+0x2c/0x1d0
|LR [c05648f8] phy_attach_direct+0x1a4/0x368
|Call Trace:
|[c1053b10] [c0811e04] klist_put+0x54/0xb4 (unreliable)
|[c1053b40] [c05648f8] phy_attach_direct+0x1a4/0x368
|[c1053b70] [c0564ae8] phy_connect_direct+0x2c/0x60
|[c1053b90] [c056c7a8] of_phy_connect+0x50/0x74
|[c1053bc0] [c0572a88] emac_probe+0xd50/0x119c
|[c1053c90] [c04cb770] platform_probe+0x74/0xa4
|[c1053cb0] [c04c8f08] really_probe+0x120/0x2b0
|[c1053cd0] [c04c9254] __driver_probe_device+0x1bc/0x1fc
|[c1053d00] [c04c9334] driver_probe_device+0x38/0xa8
|[c1053d30] [c04c9560] __driver_attach+0xf4/0x10c
|[c1053d50] [c04c6af8] bus_for_each_dev+0x68/0xd0
|[c1053d90] [c04c7c34] bus_add_driver+0xcc/0x1ec
|[c1053dc0] [c04c9f6c] driver_register+0xcc/0x110
|[c1053de0] [c0aa3f40] emac_init+0x1c4/0x200

This bug showed up starting with v7.3-rc1. At the NIP in
phy_link_topo_add_phy() is a netdev_need_ops_lock() check.
This was added by the following
commit ded86da4bbb7 ("net: ethtool: relax ethnl_req_get_phydev() locking assertion")

The bug shows up because at the time of_phy_connect() was called, the
netdev_ops were *not yet* determined. My fix is to move the code that
sets netdev_ops+ethtool_ops further up as emac_init_config() derives
that by looking at the device-tree and sets the required dev->phy_mode
accordingly.

This patch was tested on a WD MyBook Live. the device now works again.

Fixes: ded86da4bbb7 ("net: ethtool: relax ethnl_req_get_phydev() locking assertion")
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
---
 drivers/net/ethernet/ibm/emac/core.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/ibm/emac/core.c b/drivers/net/ethernet/ibm/emac/core.c
index 1d46cf6c2c12..48ece86bcc8e 100644
--- a/drivers/net/ethernet/ibm/emac/core.c
+++ b/drivers/net/ethernet/ibm/emac/core.c
@@ -3044,6 +3044,14 @@ static int emac_probe(struct platform_device *ofdev)
 	if (err)
 		goto err_gone;
 
+	if (emac_phy_supports_gige(dev->phy_mode)) {
+		ndev->netdev_ops = &emac_gige_netdev_ops;
+		dev->commac.ops = &emac_commac_sg_ops;
+	} else {
+		ndev->netdev_ops = &emac_netdev_ops;
+	}
+	ndev->ethtool_ops = &emac_ethtool_ops;
+
 	dev->emacp = devm_platform_ioremap_resource(ofdev, 0);
 	if (IS_ERR(dev->emacp)) {
 		err = PTR_ERR(dev->emacp);
@@ -3144,12 +3152,6 @@ static int emac_probe(struct platform_device *ofdev)
 		ndev->features |= ndev->hw_features | NETIF_F_RXCSUM;
 	}
 	ndev->watchdog_timeo = 5 * HZ;
-	if (emac_phy_supports_gige(dev->phy_mode)) {
-		ndev->netdev_ops = &emac_gige_netdev_ops;
-		dev->commac.ops = &emac_commac_sg_ops;
-	} else
-		ndev->netdev_ops = &emac_netdev_ops;
-	ndev->ethtool_ops = &emac_ethtool_ops;
 
 	/* MTU range: 46 - 1500 or whatever is in OF */
 	ndev->min_mtu = EMAC_MIN_MTU;
-- 
2.55.0