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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/mctp/route.c b/net/mctp/route.c
index b2243b150e71..37aa67847a5a 100644
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -455,7 +455,7 @@ static int mctp_route_output(struct mctp_route *route, struct sk_buff *skb)
 static void mctp_route_release(struct mctp_route *rt)
 {
 	if (refcount_dec_and_test(&rt->refs)) {
-		dev_put(rt->dev->dev);
+		mctp_dev_put(rt->dev);
 		kfree_rcu(rt, rcu);
 	}
 }
@@ -815,7 +815,7 @@ static int mctp_route_add(struct mctp_dev *mdev, mctp_eid_t daddr_start,
 	rt->max = daddr_start + daddr_extent;
 	rt->mtu = mtu;
 	rt->dev = mdev;
-	dev_hold(rt->dev->dev);
+	mctp_dev_hold(rt->dev);
 	rt->type = type;
 	rt->output = rtfn;