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: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index a49cad2..20b550d 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -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;
@@ -1783,17 +1791,27 @@ 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();
}
}
@@ -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;