[PATCH] net: dsa: Fix error handling in dsa_port_parse_of

[Ma Ke <make24@iscas.ac.cn>]

When of_find_net_device_by_node() successfully acquires a reference to
a network device but the subsequent call to dsa_port_parse_cpu()
fails, dsa_port_parse_of() returns without releasing the reference
count on the network device.

of_find_net_device_by_node() increments the reference count of the
returned structure, which should be balanced with a corresponding
put_device() when the reference is no longer needed.

Found by code review.

Cc: stable@vger.kernel.org
Fixes: 6ca80638b90c ("net: dsa: Use conduit and user terms")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
 net/dsa/dsa.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 5b01a0e43ebe..632e0d716d62 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -1246,6 +1246,7 @@ static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
 	struct device_node *ethernet = of_parse_phandle(dn, "ethernet", 0);
 	const char *name = of_get_property(dn, "label", NULL);
 	bool link = of_property_read_bool(dn, "link");
+	int err;
 
 	dp->dn = dn;
 
@@ -1259,7 +1260,13 @@ static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
 			return -EPROBE_DEFER;
 
 		user_protocol = of_get_property(dn, "dsa-tag-protocol", NULL);
-		return dsa_port_parse_cpu(dp, conduit, user_protocol);
+		err = dsa_port_parse_cpu(dp, conduit, user_protocol);
+		if (err) {
+			put_device(conduit);
+			return err;
+		}
+
+		return 0;
 	}
 
 	if (link)
-- 
2.17.1