mcb: correct error handling in mcb_alloc_bus

[Pan Bian]

There are two issues in the error handling code. First, if ID allocation
fails, the reference count of carrier is decremented, which has
not been incremented yet. Second, if device_add fails, the allocated ID
will not be released. This patches fixes them.

Signed-off-by: Pan Bian <bianpan2016@xxxxxxx>
---
 drivers/mcb/mcb-core.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/mcb/mcb-core.c b/drivers/mcb/mcb-core.c
index bb5c569..b5c6a1b 100644
--- a/drivers/mcb/mcb-core.c
+++ b/drivers/mcb/mcb-core.c
@@ -280,8 +280,8 @@ struct mcb_bus *mcb_alloc_bus(struct device *carrier)
 
 	bus_nr = ida_simple_get(&mcb_ida, 0, 0, GFP_KERNEL);
 	if (bus_nr < 0) {
-		rc = bus_nr;
-		goto err_free;
+		kfree(bus);
+		return ERR_PTR(bus_nr);
 	}
 
 	bus->bus_nr = bus_nr;
@@ -296,12 +296,11 @@ struct mcb_bus *mcb_alloc_bus(struct device *carrier)
 	dev_set_name(&bus->dev, "mcb:%d", bus_nr);
 	rc = device_add(&bus->dev);
 	if (rc)
-		goto err_free;
+		goto err_put;
 
 	return bus;
-err_free:
-	put_device(carrier);
-	kfree(bus);
+err_put:
+	put_device(&bus->dev);
 	return ERR_PTR(rc);
 }
 EXPORT_SYMBOL_GPL(mcb_alloc_bus);
-- 
2.7.4