@@ -172,7 +172,8 @@ void rtnl_link_unregister(struct rtnl_link_ops *ops);
/**
* struct rtnl_af_ops - rtnetlink address family operations
*
- * @list: Used internally
+ * @list: Used internally, protected by RTNL and SRCU
+ * @srcu: Used internally
* @family: Address family
* @fill_link_af: Function to fill IFLA_AF_SPEC with address family
* specific netlink attributes.
@@ -185,6 +186,8 @@ void rtnl_link_unregister(struct rtnl_link_ops *ops);
*/
struct rtnl_af_ops {
struct list_head list;
+ struct srcu_struct srcu;
+
int family;
int (*fill_link_af)(struct sk_buff *skb,
@@ -666,18 +666,31 @@ static size_t rtnl_link_get_size(const struct net_device *dev)
static LIST_HEAD(rtnl_af_ops);
-static const struct rtnl_af_ops *rtnl_af_lookup(const int family)
+static struct rtnl_af_ops *rtnl_af_lookup(const int family, int *srcu_index)
{
- const struct rtnl_af_ops *ops;
+ struct rtnl_af_ops *ops;
ASSERT_RTNL();
- list_for_each_entry(ops, &rtnl_af_ops, list) {
- if (ops->family == family)
- return ops;
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(ops, &rtnl_af_ops, list) {
+ if (ops->family == family) {
+ *srcu_index = srcu_read_lock(&ops->srcu);
+ goto unlock;
+ }
}
- return NULL;
+ ops = NULL;
+unlock:
+ rcu_read_unlock();
+
+ return ops;
+}
+
+static void rtnl_af_put(struct rtnl_af_ops *ops, int srcu_index)
+{
+ srcu_read_unlock(&ops->srcu, srcu_index);
}
/**
@@ -688,6 +701,11 @@ static const struct rtnl_af_ops *rtnl_af_lookup(const int family)
*/
int rtnl_af_register(struct rtnl_af_ops *ops)
{
+ int err = init_srcu_struct(&ops->srcu);
+
+ if (err)
+ return err;
+
rtnl_lock();
list_add_tail_rcu(&ops->list, &rtnl_af_ops);
rtnl_unlock();
@@ -707,6 +725,8 @@ void rtnl_af_unregister(struct rtnl_af_ops *ops)
rtnl_unlock();
synchronize_rcu();
+ synchronize_srcu(&ops->srcu);
+ cleanup_srcu_struct(&ops->srcu);
}
EXPORT_SYMBOL_GPL(rtnl_af_unregister);
@@ -2579,20 +2599,24 @@ static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[],
int rem, err;
nla_for_each_nested(af, tb[IFLA_AF_SPEC], rem) {
- const struct rtnl_af_ops *af_ops;
+ struct rtnl_af_ops *af_ops;
+ int af_ops_srcu_index;
- af_ops = rtnl_af_lookup(nla_type(af));
+ af_ops = rtnl_af_lookup(nla_type(af), &af_ops_srcu_index);
if (!af_ops)
return -EAFNOSUPPORT;
if (!af_ops->set_link_af)
- return -EOPNOTSUPP;
-
- if (af_ops->validate_link_af) {
+ err = -EOPNOTSUPP;
+ else if (af_ops->validate_link_af)
err = af_ops->validate_link_af(dev, af, extack);
- if (err < 0)
- return err;
- }
+ else
+ err = 0;
+
+ rtnl_af_put(af_ops, af_ops_srcu_index);
+
+ if (err < 0)
+ return err;
}
}
@@ -3172,11 +3196,18 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev,
int rem;
nla_for_each_nested(af, tb[IFLA_AF_SPEC], rem) {
- const struct rtnl_af_ops *af_ops;
+ struct rtnl_af_ops *af_ops;
+ int af_ops_srcu_index;
- BUG_ON(!(af_ops = rtnl_af_lookup(nla_type(af))));
+ af_ops = rtnl_af_lookup(nla_type(af), &af_ops_srcu_index);
+ if (!af_ops) {
+ err = -EAFNOSUPPORT;
+ goto errout;
+ }
err = af_ops->set_link_af(dev, af, extack);
+ rtnl_af_put(af_ops, af_ops_srcu_index);
+
if (err < 0)
goto errout;
Once RTNL is replaced with rtnl_net_lock(), we need a mechanism to guarantee that rtnl_af_ops is alive during inflight RTM_SETLINK even when its module is being unloaded. Let's use SRCU to protect ops. rtnl_af_lookup() now iterates rtnl_af_ops under RCU and returns SRCU-protected ops pointer. The caller must call rtnl_af_put() to release the pointer after the use. Also, rtnl_af_unregister() unlinks the ops first and calls synchronize_srcu() to wait for inflight RTM_SETLINK requests to complete. Note that rtnl_af_ops needs to be protected by its dedicated lock when RTNL is removed. Note also that BUG_ON() in do_setlink() is changed to the normal error handling as a different af_ops might be found after validate_linkmsg(). Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> --- v2: * Handle error of init_srcu_struct(). * Call cleanup_srcu_struct() after synchronize_srcu(). --- include/net/rtnetlink.h | 5 +++- net/core/rtnetlink.c | 63 ++++++++++++++++++++++++++++++----------- 2 files changed, 51 insertions(+), 17 deletions(-)