Bluetooth: ISO: add TX timestamping

Add BT_SCM_ERROR socket CMSG type.

Support TX timestamping in ISO sockets.

Support MSG_ERRQUEUE in ISO recvmsg.

If a packet from sendmsg() is fragmented, only the first ACL fragment is
timestamped.

Signed-off-by: Pauli Virtanen <[e-mail]>
Reviewed-by: Willem de Bruijn <[e-mail]>
Signed-off-by: Luiz Augusto von Dentz <[e-mail]>

include/net/bluetooth/bluetooth.h

···
 #define BT_PKT_STATUS           16
 
 #define BT_SCM_PKT_STATUS	0x03
+#define BT_SCM_ERROR		0x04
 
 #define BT_ISO_QOS		17
 

net/bluetooth/iso.c

···
 	return &iso_pi(sk)->qos;
 }
 
-static int iso_send_frame(struct sock *sk, struct sk_buff *skb)
+static int iso_send_frame(struct sock *sk, struct sk_buff *skb,
+			  const struct sockcm_cookie *sockc)
 {
 	struct iso_conn *conn = iso_pi(sk)->conn;
 	struct bt_iso_qos *qos = iso_sock_get_qos(sk);
···
 	hdr->slen = cpu_to_le16(hci_iso_data_len_pack(len,
 						      HCI_ISO_STATUS_VALID));
 
-	if (sk->sk_state == BT_CONNECTED)
+	if (sk->sk_state == BT_CONNECTED) {
+		hci_setup_tx_timestamp(skb, 1, sockc);
 		hci_send_iso(conn->hcon, skb);
-	else
+	} else {
 		len = -ENOTCONN;
+	}
 
 	return len;
 }
···
 {
 	struct sock *sk = sock->sk;
 	struct sk_buff *skb, **frag;
+	struct sockcm_cookie sockc;
 	size_t mtu;
 	int err;
 
···
 
 	if (msg->msg_flags & MSG_OOB)
 		return -EOPNOTSUPP;
+
+	hci_sockcm_init(&sockc, sk);
+
+	if (msg->msg_controllen) {
+		err = sock_cmsg_send(sk, msg, &sockc);
+		if (err)
+			return err;
+	}
 
 	lock_sock(sk);
 
···
 	lock_sock(sk);
 
 	if (sk->sk_state == BT_CONNECTED)
-		err = iso_send_frame(sk, skb);
+		err = iso_send_frame(sk, skb, &sockc);
 	else
 		err = -ENOTCONN;
 
···
 	int err = 0;
 
 	BT_DBG("sk %p", sk);
+
+	if (unlikely(flags & MSG_ERRQUEUE))
+		return sock_recv_errqueue(sk, msg, len, SOL_BLUETOOTH,
+					  BT_SCM_ERROR);
 
 	if (test_and_clear_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags)) {
 		sock_hold(sk);