net: free altname using an RCU callback

We had to add another synchronize_rcu() in recent fix.
Bite the bullet and add an rcu_head to netdev_name_node,
free from RCU.

Note that name_node does not hold any reference on dev
to which it points, but there must be a synchronize_rcu()
on device removal path, so we should be fine.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dev.c b/net/core/dev.c
index cb2dab0feee0abe758479a7a001342bf6613df08..b53b9c94de4008aa7e808d58618675425aff0f4c 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -341,13 +341,22 @@ int netdev_name_node_alt_create(struct net_device *dev, const char *name)
        return 0;
 }
 
-static void __netdev_name_node_alt_destroy(struct netdev_name_node *name_node)
+static void netdev_name_node_alt_free(struct rcu_head *head)
 {
-       list_del(&name_node->list);
+       struct netdev_name_node *name_node =
+               container_of(head, struct netdev_name_node, rcu);
+
        kfree(name_node->name);
        netdev_name_node_free(name_node);
 }
 
+static void __netdev_name_node_alt_destroy(struct netdev_name_node *name_node)
+{
+       netdev_name_node_del(name_node);
+       list_del(&name_node->list);
+       call_rcu(&name_node->rcu, netdev_name_node_alt_free);
+}
+
 int netdev_name_node_alt_destroy(struct net_device *dev, const char *name)
 {
        struct netdev_name_node *name_node;
@@ -362,10 +371,7 @@ int netdev_name_node_alt_destroy(struct net_device *dev, const char *name)
        if (name_node == dev->name_node || name_node->dev != dev)
                return -EINVAL;
 
-       netdev_name_node_del(name_node);
-       synchronize_rcu();
        __netdev_name_node_alt_destroy(name_node);
-
        return 0;
 }
 
@@ -373,8 +379,10 @@ static void netdev_name_node_alt_flush(struct net_device *dev)
 {
        struct netdev_name_node *name_node, *tmp;
 
-       list_for_each_entry_safe(name_node, tmp, &dev->name_node->list, list)
-               __netdev_name_node_alt_destroy(name_node);
+       list_for_each_entry_safe(name_node, tmp, &dev->name_node->list, list) {
+               list_del(&name_node->list);
+               netdev_name_node_alt_free(&name_node->rcu);
+       }
 }
 
 /* Device list insertion */
@@ -11576,11 +11584,8 @@ static void __net_exit default_device_exit_net(struct net *net)
                        snprintf(fb_name, IFNAMSIZ, "dev%%d");
 
                netdev_for_each_altname_safe(dev, name_node, tmp)
-                       if (netdev_name_in_use(&init_net, name_node->name)) {
-                               netdev_name_node_del(name_node);
-                               synchronize_rcu();
+                       if (netdev_name_in_use(&init_net, name_node->name))
                                __netdev_name_node_alt_destroy(name_node);
-                       }
 
                err = dev_change_net_namespace(dev, &init_net, fb_name);
                if (err) {

diff --git a/net/core/dev.h b/net/core/dev.h
index 7480b4c8429808378f7c5ec499c4f479d5a4b285..a43dfe3de50ee75ee0f4b290b385378ed4a6cfdc 100644 (file)
--- a/net/core/dev.h
+++ b/net/core/dev.h
@@ -56,6 +56,7 @@ struct netdev_name_node {
        struct list_head list;
        struct net_device *dev;
        const char *name;
+       struct rcu_head rcu;
 };
 
 int netdev_get_name(struct net *net, char *name, int ifindex);