Re: [PATCH bpf-next v4 2/5] af_unix: add unix_stream_proto for sockmap

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c

@@ -791,17 +791,35 @@ static void unix_close(struct sock *sk, long timeout)
 	 */
 }

-struct proto unix_proto = {
-	.name			= "UNIX",
+static void unix_unhash(struct sock *sk)
+{
+	/* Nothing to do here, unix socket does not need a ->unhash().
+	 * This is merely for sockmap.
+	 */
+}
+
+struct proto unix_dgram_proto = {
+	.name			= "UNIX-DGRAM",
+	.owner			= THIS_MODULE,
+	.obj_size		= sizeof(struct unix_sock),
+	.close			= unix_close,
+#ifdef CONFIG_BPF_SYSCALL
+	.psock_update_sk_prot	= unix_dgram_bpf_update_proto,
+#endif
+};
+
+struct proto unix_stream_proto = {
+	.name			= "UNIX-STREAM",
 	.owner			= THIS_MODULE,
 	.obj_size		= sizeof(struct unix_sock),
 	.close			= unix_close,
+	.unhash			= unix_unhash,
 #ifdef CONFIG_BPF_SYSCALL
-	.psock_update_sk_prot	= unix_bpf_update_proto,
+	.psock_update_sk_prot	= unix_stream_bpf_update_proto,
 #endif
 };

-static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)
+static struct sock *unix_create1(struct net *net, struct socket *sock, int kern, int type)
 {
 	struct sock *sk = NULL;
 	struct unix_sock *u;

@@ -810,7 +828,11 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)
 	if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files())
 		goto out;

-	sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_proto, kern);
+	if (type == SOCK_STREAM)
+		sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_stream_proto, kern);
+	else /*dgram and  seqpacket */
+		sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_dgram_proto, kern);
+
 	if (!sk)
 		goto out;

@@ -872,7 +894,7 @@ static int unix_create(struct net *net, struct socket *sock, int protocol,
 		return -ESOCKTNOSUPPORT;
 	}

-	return unix_create1(net, sock, kern) ? 0 : -ENOMEM;
+	return unix_create1(net, sock, kern, sock->type) ? 0 : -ENOMEM;
 }

 static int unix_release(struct socket *sock)

@@ -1286,7 +1308,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 	err = -ENOMEM;

 	/* create new sock for complete connection */
-	newsk = unix_create1(sock_net(sk), NULL, 0);
+	newsk = unix_create1(sock_net(sk), NULL, 0, sock->type);
 	if (newsk == NULL)
 		goto out;

@@ -2261,7 +2283,7 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, size_t si
 	struct sock *sk = sock->sk;

 #ifdef CONFIG_BPF_SYSCALL
-	if (sk->sk_prot != &unix_proto)
+	if (READ_ONCE(sk->sk_prot) != &unix_dgram_proto)
 		return sk->sk_prot->recvmsg(sk, msg, size, flags & MSG_DONTWAIT,
 					    flags & ~MSG_DONTWAIT, NULL);

 #endif

@@ -2580,6 +2602,20 @@ static int unix_stream_read_actor(struct sk_buff *skb,
 	return ret ?: chunk;
 }

+int __unix_stream_recvmsg(struct sock *sk, struct msghdr *msg,
+			  size_t size, int flags)
+{
+	struct unix_stream_read_state state = {
+		.recv_actor = unix_stream_read_actor,
+		.socket = sk->sk_socket,
+		.msg = msg,
+		.size = size,
+		.flags = flags
+	};
+
+	return unix_stream_read_generic(&state, true);
+}
+
 static int unix_stream_recvmsg(struct socket *sock, struct msghdr *msg,
 			       size_t size, int flags)
 {

@@ -2591,6 +2627,12 @@ static int unix_stream_recvmsg(struct socket *sock, struct msghdr *msg,
 		.flags = flags
 	};

+#ifdef CONFIG_BPF_SYSCALL
+	struct sock *sk = sock->sk;
+	if (sk->sk_prot != &unix_stream_proto)
+		return sk->sk_prot->recvmsg(sk, msg, size, flags & MSG_DONTWAIT,
+					    flags & ~MSG_DONTWAIT, NULL);

+#endif
 	return unix_stream_read_generic(&state, true);
 }

@@ -2652,6 +2694,7 @@ static int unix_shutdown(struct socket *sock, int mode)

 		int peer_mode = 0;

+		other->sk_prot->unhash(other);