net: ibm: emac: fix regression caused by emac_dt_phy_probe()

Julian Margetson reported a panic on his SAM460EX with Kernel 4.11-rc1:
| Unable to handle kernel paging request for data at address 0x00000014
| Oops: Kernel access of bad area, sig: 11 [#1]
| PREEMPT
| Canyonlands
| Modules linked in:
| CPU: 0 PID: 1 Comm: swapper Not tainted [...]
| task: ea838000 task.stack: ea836000
| NIP: c0599f5c LR: c0599dd8 CTR: 00000000
| REGS: ea837c80 TRAP: 0300   Not tainted [...]
| MSR: 00029000 <CE,EE,ME>
|  CR: 24371242  XER: 20000000
| DEAR: 00000014 ESR: 00000000
| GPR00: c0599ce8 ea837d30 ea838000 c0e52dcc c0d56ffb [...]
| NIP [c0599f5c] emac_probe+0xfb4/0x1304
| LR [c0599dd8] emac_probe+0xe30/0x1304
| Call Trace:
| [ea837d30] [c0599ce8] emac_probe+0xd40/0x1304 (unreliable)
| [ea837d80] [c0533504] platform_drv_probe+0x48/0x90
| [ea837da0] [c0531c14] driver_probe_device+0x15c/0x2c4
| [ea837dd0] [c0531e04] __driver_attach+0x88/0xb0
| ---[ end trace ... ]---

The problem is caused by emac_dt_phy_probe() returing success (0)
for existing device-trees configurations that do not specify a
"phy-handle" property. This caused the code to skip the existing
phy probe and setup. Which led to essential phy related
data-structures being uninitialized.

This patch also removes the unused variable in emac_dt_phy_connect().

Fixes: a577ca6badb5261d ("net: emac: add support for device-tree based PHY discovery and setup")
Reported-by: Julian Margetson <runaway@candw.ms>
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/ibm/emac/core.c b/drivers/net/ethernet/ibm/emac/core.c
index 275c2e2349ad92de224df1939769238d83ea5f3b..c44036d5761a4cbec301afb63393d49b47bac867 100644 (file)
--- a/drivers/net/ethernet/ibm/emac/core.c
+++ b/drivers/net/ethernet/ibm/emac/core.c
@@ -2589,8 +2589,6 @@ static int emac_dt_mdio_probe(struct emac_instance *dev)
 static int emac_dt_phy_connect(struct emac_instance *dev,
                               struct device_node *phy_handle)
 {
-       int res;
-
        dev->phy.def = devm_kzalloc(&dev->ofdev->dev, sizeof(*dev->phy.def),
                                    GFP_KERNEL);
        if (!dev->phy.def)
@@ -2617,7 +2615,7 @@ static int emac_dt_phy_probe(struct emac_instance *dev)
 {
        struct device_node *np = dev->ofdev->dev.of_node;
        struct device_node *phy_handle;
-       int res = 0;
+       int res = 1;
 
        phy_handle = of_parse_phandle(np, "phy-handle", 0);
 
@@ -2714,13 +2712,24 @@ static int emac_init_phy(struct emac_instance *dev)
        if (emac_has_feature(dev, EMAC_FTR_HAS_RGMII)) {
                int res = emac_dt_phy_probe(dev);
 
-               mutex_unlock(&emac_phy_map_lock);
-               if (!res)
+               switch (res) {
+               case 1:
+                       /* No phy-handle property configured.
+                        * Continue with the existing phy probe
+                        * and setup code.
+                        */
+                       break;
+
+               case 0:
+                       mutex_unlock(&emac_phy_map_lock);
                        goto init_phy;
 
-               dev_err(&dev->ofdev->dev, "failed to attach dt phy (%d).\n",
-                       res);
-               return res;
+               default:
+                       mutex_unlock(&emac_phy_map_lock);
+                       dev_err(&dev->ofdev->dev, "failed to attach dt phy (%d).\n",
+                               res);
+                       return res;
+               }
        }
 
        if (dev->phy_address != 0xffffffff)