1 files changed, 21 insertions, 5 deletions

diff --git a/net/socket.c b/net/socket.c
index 3ca2fd9e3720..c1663c0ff3d3 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -156,7 +156,7 @@ static const struct file_operations socket_file_ops = {
  */
 
 static DEFINE_SPINLOCK(net_family_lock);
-static const struct net_proto_family *net_families[NPROTO] __read_mostly;
+static const struct net_proto_family __rcu *net_families[NPROTO] __read_mostly;
 
 /*
  *	Statistics counters of the socket lists
@@ -732,6 +732,21 @@ static int sock_recvmsg_nosec(struct socket *sock, struct msghdr *msg,
 	return ret;
 }
 
+/**
+ * kernel_recvmsg - Receive a message from a socket (kernel space)
+ * @sock:       The socket to receive the message from
+ * @msg:        Received message
+ * @vec:        Input s/g array for message data
+ * @num:        Size of input s/g array
+ * @size:       Number of bytes to read
+ * @flags:      Message flags (MSG_DONTWAIT, etc...)
+ *
+ * On return the msg structure contains the scatter/gather array passed in the
+ * vec argument. The array is modified so that it consists of the unfilled
+ * portion of the original array.
+ *
+ * The returned value is the total number of bytes received, or an error.
+ */
 int kernel_recvmsg(struct socket *sock, struct msghdr *msg,
 		   struct kvec *vec, size_t num, size_t size, int flags)
 {
@@ -1200,7 +1215,7 @@ int __sock_create(struct net *net, int family, int type, int protocol,
 	 * requested real, full-featured networking support upon configuration.
 	 * Otherwise module support will break!
 	 */
-	if (net_families[family] == NULL)
+	if (rcu_access_pointer(net_families[family]) == NULL)
 		request_module("net-pf-%d", family);
 #endif
 
@@ -2332,10 +2347,11 @@ int sock_register(const struct net_proto_family *ops)
 	}
 
 	spin_lock(&net_family_lock);
-	if (net_families[ops->family])
+	if (rcu_dereference_protected(net_families[ops->family],
+				      lockdep_is_held(&net_family_lock)))
 		err = -EEXIST;
 	else {
-		net_families[ops->family] = ops;
+		rcu_assign_pointer(net_families[ops->family], ops);
 		err = 0;
 	}
 	spin_unlock(&net_family_lock);
@@ -2363,7 +2379,7 @@ void sock_unregister(int family)
 	BUG_ON(family < 0 || family >= NPROTO);
 
 	spin_lock(&net_family_lock);
-	net_families[family] = NULL;
+	rcu_assign_pointer(net_families[family], NULL);
 	spin_unlock(&net_family_lock);
 
 	synchronize_rcu();