mctp: Add refcounts to mctp_dev

Currently, we tie the struct mctp_dev lifetime to the underlying struct
net_device, and hold/put that device as a proxy for a separate mctp_dev
refcount. This works because we're not holding any references to the
mctp_dev that are different from the netdev lifetime.

In a future change we'll break that assumption though, as we'll need to
hold mctp_dev references in a workqueue, which might live past the
netdev unregister notification.

In order to support that, this change introduces a refcount on the
mctp_dev, currently taken by the net_device->mctp_ptr reference, and
released on netdev unregister events. We can then use this for future
references that might outlast the net device.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/mctp/neigh.c b/net/mctp/neigh.c
index 90ed2f02d1fb..5cc042121493 100644
--- a/net/mctp/neigh.c
+++ b/net/mctp/neigh.c
@@ -47,7 +47,7 @@ static int mctp_neigh_add(struct mctp_dev *mdev, mctp_eid_t eid,
 	}
 	INIT_LIST_HEAD(&neigh->list);
 	neigh->dev = mdev;
-	dev_hold(neigh->dev->dev);
+	mctp_dev_hold(neigh->dev);
 	neigh->eid = eid;
 	neigh->source = source;
 	memcpy(neigh->ha, lladdr, lladdr_len);
@@ -63,7 +63,7 @@ static void __mctp_neigh_free(struct rcu_head *rcu)
 {
 	struct mctp_neigh *neigh = container_of(rcu, struct mctp_neigh, rcu);
 
-	dev_put(neigh->dev->dev);
+	mctp_dev_put(neigh->dev);
 	kfree(neigh);
 }