Commit 43f55f23 authored by Jeremy Kerr's avatar Jeremy Kerr Committed by David S. Miller
Browse files

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: default avatarJeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 73c61845

include/net/mctpdevice.h

+5 −0
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 
struct mctp_dev {

	struct net_device	*dev;



	refcount_t		refs;



	unsigned int		net;



	/* Only modified under RTNL. Reads have addrs_lock held */
@@ -32,4 +34,7 @@ struct mctp_dev { 
struct mctp_dev *mctp_dev_get_rtnl(const struct net_device *dev);

struct mctp_dev *__mctp_dev_get(const struct net_device *dev);



void mctp_dev_hold(struct mctp_dev *mdev);

void mctp_dev_put(struct mctp_dev *mdev);



#endif /* __NET_MCTPDEVICE_H */

net/mctp/device.c

+16 −9
Original line number Diff line number Diff line
@@ -35,14 +35,6 @@ struct mctp_dev *mctp_dev_get_rtnl(const struct net_device *dev) 
	return rtnl_dereference(dev->mctp_ptr);

}



static void mctp_dev_destroy(struct mctp_dev *mdev)

{

	struct net_device *dev = mdev->dev;



	dev_put(dev);

	kfree_rcu(mdev, rcu);

}



static int mctp_fill_addrinfo(struct sk_buff *skb, struct netlink_callback *cb,

			      struct mctp_dev *mdev, mctp_eid_t eid)

{
@@ -255,6 +247,19 @@ static int mctp_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh, 
	return 0;

}



void mctp_dev_hold(struct mctp_dev *mdev)

{

	refcount_inc(&mdev->refs);

}



void mctp_dev_put(struct mctp_dev *mdev)

{

	if (refcount_dec_and_test(&mdev->refs)) {

		dev_put(mdev->dev);

		kfree_rcu(mdev, rcu);

	}

}



static struct mctp_dev *mctp_add_dev(struct net_device *dev)

{

	struct mctp_dev *mdev;
@@ -270,7 +275,9 @@ static struct mctp_dev *mctp_add_dev(struct net_device *dev) 
	mdev->net = mctp_default_net(dev_net(dev));



	/* associate to net_device */

	refcount_set(&mdev->refs, 1);

	rcu_assign_pointer(dev->mctp_ptr, mdev);



	dev_hold(dev);

	mdev->dev = dev;
@@ -345,7 +352,7 @@ static void mctp_unregister(struct net_device *dev) 
	mctp_neigh_remove_dev(mdev);

	kfree(mdev->addrs);



	mctp_dev_destroy(mdev);

	mctp_dev_put(mdev);

}



static int mctp_register(struct net_device *dev)

net/mctp/neigh.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

}

net/mctp/route.c

+2 −2
Original line number Diff line number Diff line
@@ -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;