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Commit 5fa85a09 authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

net: core: rcu-ify rtnl af_ops 



rtnl af_ops currently rely on rtnl mutex: unregister (called from module
exit functions) takes the rtnl mutex and all users that do af_ops lookup
also take the rtnl mutex. IOW, parallel rmmod will block until doit()
callback is done.

As none of the af_ops implementation sleep we can use rcu instead.

doit functions that need the af_ops can now use rcu instead of the
rtnl mutex provided the mutex isn't needed for other reasons.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 070cbf5b

net/core/rtnetlink.c

+46 −16
Original line number Diff line number Diff line
@@ -453,7 +453,7 @@ static const struct rtnl_af_ops *rtnl_af_lookup(const int family) 
{

	const struct rtnl_af_ops *ops;



	list_for_each_entry(ops, &rtnl_af_ops, list) {

	list_for_each_entry_rcu(ops, &rtnl_af_ops, list) {

		if (ops->family == family)

			return ops;

	}
@@ -470,7 +470,7 @@ static const struct rtnl_af_ops *rtnl_af_lookup(const int family) 
void rtnl_af_register(struct rtnl_af_ops *ops)

{

	rtnl_lock();

	list_add_tail(&ops->list, &rtnl_af_ops);

	list_add_tail_rcu(&ops->list, &rtnl_af_ops);

	rtnl_unlock();

}

EXPORT_SYMBOL_GPL(rtnl_af_register);
@@ -482,8 +482,10 @@ EXPORT_SYMBOL_GPL(rtnl_af_register); 
void rtnl_af_unregister(struct rtnl_af_ops *ops)

{

	rtnl_lock();

	list_del(&ops->list);

	list_del_rcu(&ops->list);

	rtnl_unlock();



	synchronize_rcu();

}

EXPORT_SYMBOL_GPL(rtnl_af_unregister);
@@ -496,13 +498,15 @@ static size_t rtnl_link_get_af_size(const struct net_device *dev, 
	/* IFLA_AF_SPEC */

	size = nla_total_size(sizeof(struct nlattr));



	list_for_each_entry(af_ops, &rtnl_af_ops, list) {

	rcu_read_lock();

	list_for_each_entry_rcu(af_ops, &rtnl_af_ops, list) {

		if (af_ops->get_link_af_size) {

			/* AF_* + nested data */

			size += nla_total_size(sizeof(struct nlattr)) +

				af_ops->get_link_af_size(dev, ext_filter_mask);

		}

	}

	rcu_read_unlock();



	return size;

}
@@ -1393,7 +1397,7 @@ static int rtnl_fill_link_af(struct sk_buff *skb, 
	if (!af_spec)

		return -EMSGSIZE;



	list_for_each_entry(af_ops, &rtnl_af_ops, list) {

	list_for_each_entry_rcu(af_ops, &rtnl_af_ops, list) {

		struct nlattr *af;

		int err;
@@ -1516,12 +1520,16 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev, 
	    nla_put_s32(skb, IFLA_NEW_NETNSID, *new_nsid) < 0)

		goto nla_put_failure;



	rcu_read_lock();

	if (rtnl_fill_link_af(skb, dev, ext_filter_mask))

		goto nla_put_failure;

		goto nla_put_failure_rcu;

	rcu_read_unlock();



	nlmsg_end(skb, nlh);

	return 0;



nla_put_failure_rcu:

	rcu_read_unlock();

nla_put_failure:

	nlmsg_cancel(skb, nlh);

	return -EMSGSIZE;
@@ -1783,18 +1791,28 @@ static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[]) 
		nla_for_each_nested(af, tb[IFLA_AF_SPEC], rem) {

			const struct rtnl_af_ops *af_ops;



			if (!(af_ops = rtnl_af_lookup(nla_type(af))))

			rcu_read_lock();

			af_ops = rtnl_af_lookup(nla_type(af));

			if (!af_ops) {

				rcu_read_unlock();

				return -EAFNOSUPPORT;

			}



			if (!af_ops->set_link_af)

			if (!af_ops->set_link_af) {

				rcu_read_unlock();

				return -EOPNOTSUPP;

			}



			if (af_ops->validate_link_af) {

				err = af_ops->validate_link_af(dev, af);

				if (err < 0)

				if (err < 0) {

					rcu_read_unlock();

					return err;

				}

			}



			rcu_read_unlock();

		}

	}



	return 0;
@@ -2251,13 +2269,18 @@ static int do_setlink(const struct sk_buff *skb, 
		nla_for_each_nested(af, tb[IFLA_AF_SPEC], rem) {

			const struct rtnl_af_ops *af_ops;



			rcu_read_lock();



			if (!(af_ops = rtnl_af_lookup(nla_type(af))))

				BUG();



			err = af_ops->set_link_af(dev, af);

			if (err < 0)

			if (err < 0) {

				rcu_read_unlock();

				goto errout;

			}



			rcu_read_unlock();

			status |= DO_SETLINK_NOTIFY;

		}

	}
@@ -4004,25 +4027,30 @@ static int rtnl_fill_statsinfo(struct sk_buff *skb, struct net_device *dev, 
		if (!attr)

			goto nla_put_failure;



		list_for_each_entry(af_ops, &rtnl_af_ops, list) {

		rcu_read_lock();

		list_for_each_entry_rcu(af_ops, &rtnl_af_ops, list) {

			if (af_ops->fill_stats_af) {

				struct nlattr *af;

				int err;



				af = nla_nest_start(skb, af_ops->family);

				if (!af)

				if (!af) {

					rcu_read_unlock();

					goto nla_put_failure;



				}

				err = af_ops->fill_stats_af(skb, dev);



				if (err == -ENODATA)

				if (err == -ENODATA) {

					nla_nest_cancel(skb, af);

				else if (err < 0)

				} else if (err < 0) {

					rcu_read_unlock();

					goto nla_put_failure;

				}



				nla_nest_end(skb, af);

			}

		}

		rcu_read_unlock();



		nla_nest_end(skb, attr);
@@ -4091,7 +4119,8 @@ static size_t if_nlmsg_stats_size(const struct net_device *dev, 
		/* for IFLA_STATS_AF_SPEC */

		size += nla_total_size(0);



		list_for_each_entry(af_ops, &rtnl_af_ops, list) {

		rcu_read_lock();

		list_for_each_entry_rcu(af_ops, &rtnl_af_ops, list) {

			if (af_ops->get_stats_af_size) {

				size += nla_total_size(

					af_ops->get_stats_af_size(dev));
@@ -4100,6 +4129,7 @@ static size_t if_nlmsg_stats_size(const struct net_device *dev, 
				size += nla_total_size(0);

			}

		}

		rcu_read_unlock();

	}



	return size;

net/ipv4/devinet.c

+2 −2
Original line number Diff line number Diff line
@@ -1757,7 +1757,7 @@ static int inet_validate_link_af(const struct net_device *dev, 
	struct nlattr *a, *tb[IFLA_INET_MAX+1];

	int err, rem;



	if (dev && !__in_dev_get_rtnl(dev))

	if (dev && !__in_dev_get_rcu(dev))

		return -EAFNOSUPPORT;



	err = nla_parse_nested(tb, IFLA_INET_MAX, nla, inet_af_policy, NULL);
@@ -1781,7 +1781,7 @@ static int inet_validate_link_af(const struct net_device *dev, 


static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla)

{

	struct in_device *in_dev = __in_dev_get_rtnl(dev);

	struct in_device *in_dev = __in_dev_get_rcu(dev);

	struct nlattr *a, *tb[IFLA_INET_MAX+1];

	int rem;