1 files changed, 50 insertions, 0 deletions

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 9f900b56b15b..ee4428a892fa 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -429,6 +429,52 @@ static void xsk_unbind_dev(struct xdp_sock *xs)
 	dev_put(dev);
 }
 
+static struct xsk_map *xsk_get_map_list_entry(struct xdp_sock *xs,
+					      struct xdp_sock ***map_entry)
+{
+	struct xsk_map *map = NULL;
+	struct xsk_map_node *node;
+
+	*map_entry = NULL;
+
+	spin_lock_bh(&xs->map_list_lock);
+	node = list_first_entry_or_null(&xs->map_list, struct xsk_map_node,
+					node);
+	if (node) {
+		WARN_ON(xsk_map_inc(node->map));
+		map = node->map;
+		*map_entry = node->map_entry;
+	}
+	spin_unlock_bh(&xs->map_list_lock);
+	return map;
+}
+
+static void xsk_delete_from_maps(struct xdp_sock *xs)
+{
+	/* This function removes the current XDP socket from all the
+	 * maps it resides in. We need to take extra care here, due to
+	 * the two locks involved. Each map has a lock synchronizing
+	 * updates to the entries, and each socket has a lock that
+	 * synchronizes access to the list of maps (map_list). For
+	 * deadlock avoidance the locks need to be taken in the order
+	 * "map lock"->"socket map list lock". We start off by
+	 * accessing the socket map list, and take a reference to the
+	 * map to guarantee existence between the
+	 * xsk_get_map_list_entry() and xsk_map_try_sock_delete()
+	 * calls. Then we ask the map to remove the socket, which
+	 * tries to remove the socket from the map. Note that there
+	 * might be updates to the map between
+	 * xsk_get_map_list_entry() and xsk_map_try_sock_delete().
+	 */
+	struct xdp_sock **map_entry = NULL;
+	struct xsk_map *map;
+
+	while ((map = xsk_get_map_list_entry(xs, &map_entry))) {
+		xsk_map_try_sock_delete(map, xs, map_entry);
+		xsk_map_put(map);
+	}
+}
+
 static int xsk_release(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
@@ -448,6 +494,7 @@ static int xsk_release(struct socket *sock)
 	sock_prot_inuse_add(net, sk->sk_prot, -1);
 	local_bh_enable();
 
+	xsk_delete_from_maps(xs);
 	xsk_unbind_dev(xs);
 
 	xskq_destroy(xs->rx);
@@ -964,6 +1011,9 @@ static int xsk_create(struct net *net, struct socket *sock, int protocol,
 	spin_lock_init(&xs->rx_lock);
 	spin_lock_init(&xs->tx_completion_lock);
 
+	INIT_LIST_HEAD(&xs->map_list);
+	spin_lock_init(&xs->map_list_lock);
+
 	mutex_lock(&net->xdp.lock);
 	sk_add_node_rcu(sk, &net->xdp.list);
 	mutex_unlock(&net->xdp.lock);