Bluetooth: L2CAP: add TX timestamping

Support TX timestamping in L2CAP sockets.

Support MSG_ERRQUEUE recvmsg.

For other than SOCK_STREAM L2CAP sockets, if a packet from sendmsg() is
fragmented, only the first ACL fragment is timestamped.

For SOCK_STREAM L2CAP sockets, use the bytestream convention and
timestamp the last fragment and count bytes in tskey.

Timestamps are not generated in the Enhanced Retransmission mode, as
meaning of COMPLETION stamp is unclear if L2CAP layer retransmits.

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/l2cap.h

···
 int l2cap_chan_connect(struct l2cap_chan *chan, __le16 psm, u16 cid,
 		       bdaddr_t *dst, u8 dst_type, u16 timeout);
 int l2cap_chan_reconfigure(struct l2cap_chan *chan, __u16 mtu);
-int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len);
+int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len,
+		    const struct sockcm_cookie *sockc);
 void l2cap_chan_busy(struct l2cap_chan *chan, int busy);
 void l2cap_chan_rx_avail(struct l2cap_chan *chan, ssize_t rx_avail);
 int l2cap_chan_check_security(struct l2cap_chan *chan, bool initiator);

net/bluetooth/6lowpan.c

···
 	memset(&msg, 0, sizeof(msg));
 	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iv, 1, skb->len);
 
-	err = l2cap_chan_send(chan, &msg, skb->len);
+	err = l2cap_chan_send(chan, &msg, skb->len, NULL);
 	if (err > 0) {
 		netdev->stats.tx_bytes += err;
 		netdev->stats.tx_packets++;

net/bluetooth/l2cap_core.c

···
 	       skb_queue_len(&chan->tx_q));
 }
 
-int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len)
+static void l2cap_tx_timestamp(struct sk_buff *skb,
+			       const struct sockcm_cookie *sockc,
+			       size_t len)
+{
+	struct sock *sk = skb ? skb->sk : NULL;
+
+	if (sk && sk->sk_type == SOCK_STREAM)
+		hci_setup_tx_timestamp(skb, len, sockc);
+	else
+		hci_setup_tx_timestamp(skb, 1, sockc);
+}
+
+static void l2cap_tx_timestamp_seg(struct sk_buff_head *queue,
+				   const struct sockcm_cookie *sockc,
+				   size_t len)
+{
+	struct sk_buff *skb = skb_peek(queue);
+	struct sock *sk = skb ? skb->sk : NULL;
+
+	if (sk && sk->sk_type == SOCK_STREAM)
+		l2cap_tx_timestamp(skb_peek_tail(queue), sockc, len);
+	else
+		l2cap_tx_timestamp(skb, sockc, len);
+}
+
+int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len,
+		    const struct sockcm_cookie *sockc)
 {
 	struct sk_buff *skb;
 	int err;
···
 		skb = l2cap_create_connless_pdu(chan, msg, len);
 		if (IS_ERR(skb))
 			return PTR_ERR(skb);
+
+		l2cap_tx_timestamp(skb, sockc, len);
 
 		l2cap_do_send(chan, skb);
 		return len;
···
 		if (err)
 			return err;
 
+		l2cap_tx_timestamp_seg(&seg_queue, sockc, len);
+
 		skb_queue_splice_tail_init(&seg_queue, &chan->tx_q);
 
 		l2cap_le_flowctl_send(chan);
···
 		skb = l2cap_create_basic_pdu(chan, msg, len);
 		if (IS_ERR(skb))
 			return PTR_ERR(skb);
+
+		l2cap_tx_timestamp(skb, sockc, len);
 
 		l2cap_do_send(chan, skb);
 		err = len;
···
 		if (err)
 			break;
 
-		if (chan->mode == L2CAP_MODE_ERTM)
+		if (chan->mode == L2CAP_MODE_ERTM) {
+			/* TODO: ERTM mode timestamping */
 			l2cap_tx(chan, NULL, &seg_queue, L2CAP_EV_DATA_REQUEST);
-		else
+		} else {
+			l2cap_tx_timestamp_seg(&seg_queue, sockc, len);
 			l2cap_streaming_send(chan, &seg_queue);
+		}
 
 		err = len;
 

net/bluetooth/l2cap_sock.c

···
 {
 	struct sock *sk = sock->sk;
 	struct l2cap_chan *chan = l2cap_pi(sk)->chan;
+	struct sockcm_cookie sockc;
 	int err;
 
 	BT_DBG("sock %p, sk %p", sock, sk);
···
 	if (sk->sk_state != BT_CONNECTED)
 		return -ENOTCONN;
 
+	hci_sockcm_init(&sockc, sk);
+
+	if (msg->msg_controllen) {
+		err = sock_cmsg_send(sk, msg, &sockc);
+		if (err)
+			return err;
+	}
+
 	lock_sock(sk);
 	err = bt_sock_wait_ready(sk, msg->msg_flags);
 	release_sock(sk);
···
 		return err;
 
 	l2cap_chan_lock(chan);
-	err = l2cap_chan_send(chan, msg, len);
+	err = l2cap_chan_send(chan, msg, len, &sockc);
 	l2cap_chan_unlock(chan);
 
 	return err;
···
 	struct sock *sk = sock->sk;
 	struct l2cap_pinfo *pi = l2cap_pi(sk);
 	int err;
+
+	if (unlikely(flags & MSG_ERRQUEUE))
+		return sock_recv_errqueue(sk, msg, len, SOL_BLUETOOTH,
+					  BT_SCM_ERROR);
 
 	lock_sock(sk);
 

net/bluetooth/smp.c

···
 
 	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, iv, 2, 1 + len);
 
-	l2cap_chan_send(chan, &msg, 1 + len);
+	l2cap_chan_send(chan, &msg, 1 + len, NULL);
 
 	if (!chan->data)
 		return;