[PATCH net] net: dsa: Keep a reference count on ethernet_dev

[Florian Fainelli]

of_find_net_device_by_node() just returns a reference to a net_device but does
not increment its reference count, which means that the master network device
can just vanish under our feet.

Fixes: 83c0afaec7b7 ("net: dsa: Add new binding implementation")
Signed-off-by: Florian Fainelli <f.faine...@gmail.com>
---
 net/dsa/dsa2.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index da3862124545..4adb9b11c22c 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -440,6 +440,8 @@ static void dsa_dst_unapply(struct dsa_switch_tree *dst)
 
        pr_info("DSA: tree %d unapplied\n", dst->tree);
        dst->applied = false;
+
+       dev_put(dst->master_netdev);
 }
 
 static int dsa_cpu_parse(struct device_node *port, u32 index,
@@ -458,6 +460,8 @@ static int dsa_cpu_parse(struct device_node *port, u32 
index,
        if (!ethernet_dev)
                return -EPROBE_DEFER;
 
+       dev_hold(ethernet_dev);
+
        if (!ds->master_netdev)
                ds->master_netdev = ethernet_dev;
 
@@ -473,6 +477,7 @@ static int dsa_cpu_parse(struct device_node *port, u32 
index,
        dst->tag_ops = dsa_resolve_tag_protocol(tag_protocol);
        if (IS_ERR(dst->tag_ops)) {
                dev_warn(ds->dev, "No tagger for this switch\n");
+               dev_put(ethernet_dev);
                return PTR_ERR(dst->tag_ops);
        }
 
-- 
2.9.3