net: dsa: Fix legacy probing

After commit 6d3c8c0dd88a ("net: dsa: Remove master_netdev and
use dst->cpu_dp->netdev") and a29342e73911 ("net: dsa: Associate
slave network device with CPU port") we would be seeing NULL pointer
dereferences when accessing dst->cpu_dp->netdev too early. In the legacy
code, we actually know early in advance the master network device, so
pass it down to the relevant functions.

Fixes: 6d3c8c0dd88a ("net: dsa: Remove master_netdev and use dst->cpu_dp->netdev")
Fixes: a29342e73911 ("net: dsa: Associate slave network device with CPU port")
Reported-by: Jason Cobham <jcobham@questertangent.com>
Tested-by: Jason Cobham <jcobham@questertangent.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dsa/legacy.c b/net/dsa/legacy.c
index e60906125375eaca0768e89157c53557f7589887..1d7a3282f2a7c20e5d21e2ce57bd56e39785d1bc 100644 (file)
--- a/net/dsa/legacy.c
+++ b/net/dsa/legacy.c
@@ -95,18 +95,16 @@ static int dsa_cpu_dsa_setups(struct dsa_switch *ds, struct device *dev)
        return 0;
 }
 
-static int dsa_switch_setup_one(struct dsa_switch *ds, struct device *parent)
+static int dsa_switch_setup_one(struct dsa_switch *ds, struct net_device *master,
+                               struct device *parent)
 {
        const struct dsa_switch_ops *ops = ds->ops;
        struct dsa_switch_tree *dst = ds->dst;
        struct dsa_chip_data *cd = ds->cd;
        bool valid_name_found = false;
-       struct net_device *master;
        int index = ds->index;
        int i, ret;
 
-       master = dst->cpu_dp->netdev;
-
        /*
         * Validate supplied switch configuration.
         */
@@ -124,12 +122,12 @@ static int dsa_switch_setup_one(struct dsa_switch *ds, struct device *parent)
                                return -EINVAL;
                        }
                        dst->cpu_dp = &ds->ports[i];
+                       dst->cpu_dp->netdev = master;
                        ds->cpu_port_mask |= 1 << i;
                } else if (!strcmp(name, "dsa")) {
                        ds->dsa_port_mask |= 1 << i;
                } else {
                        ds->enabled_port_mask |= 1 << i;
-                       ds->ports[i].cpu_dp = dst->cpu_dp;
                }
                valid_name_found = true;
        }
@@ -193,6 +191,7 @@ static int dsa_switch_setup_one(struct dsa_switch *ds, struct device *parent)
         */
        for (i = 0; i < ds->num_ports; i++) {
                ds->ports[i].dn = cd->port_dn[i];
+               ds->ports[i].cpu_dp = dst->cpu_dp;
 
                if (!(ds->enabled_port_mask & (1 << i)))
                        continue;
@@ -217,11 +216,10 @@ static int dsa_switch_setup_one(struct dsa_switch *ds, struct device *parent)
 }
 
 static struct dsa_switch *
-dsa_switch_setup(struct dsa_switch_tree *dst, int index,
-                struct device *parent, struct device *host_dev)
+dsa_switch_setup(struct dsa_switch_tree *dst, struct net_device *master,
+                int index, struct device *parent, struct device *host_dev)
 {
        struct dsa_chip_data *cd = dst->pd->chip + index;
-       struct net_device *master = dst->cpu_dp->netdev;
        const struct dsa_switch_ops *ops;
        struct dsa_switch *ds;
        int ret;
@@ -254,7 +252,7 @@ dsa_switch_setup(struct dsa_switch_tree *dst, int index,
        ds->ops = ops;
        ds->priv = priv;
 
-       ret = dsa_switch_setup_one(ds, parent);
+       ret = dsa_switch_setup_one(ds, master, parent);
        if (ret)
                return ERR_PTR(ret);
 
@@ -580,12 +578,11 @@ static int dsa_setup_dst(struct dsa_switch_tree *dst, struct net_device *dev,
        unsigned configured = 0;
 
        dst->pd = pd;
-       dst->cpu_dp->netdev = dev;
 
        for (i = 0; i < pd->nr_chips; i++) {
                struct dsa_switch *ds;
 
-               ds = dsa_switch_setup(dst, i, parent, pd->chip[i].host_dev);
+               ds = dsa_switch_setup(dst, dev, i, parent, pd->chip[i].host_dev);
                if (IS_ERR(ds)) {
                        netdev_err(dev, "[%d]: couldn't create dsa switch instance (error %ld)\n",
                                   i, PTR_ERR(ds));