can: j1939: extend UAPI to notify about RX status

To be able to create applications with user friendly feedback, we need be
able to provide receive status information.

Typical ETP transfer may take seconds or even hours. To give user some
clue or show a progress bar, the stack should push status updates.
Same as for the TX information, the socket error queue will be used with
following new signals:
- J1939_EE_INFO_RX_RTS - received and accepted request to send signal.
- J1939_EE_INFO_RX_DPO - received data package offset signal
- J1939_EE_INFO_RX_ABORT - RX session was aborted

Instead of completion signal, user will get data package.
To activate this signals, application should set
SOF_TIMESTAMPING_RX_SOFTWARE to the SO_TIMESTAMPING socket option. This
will avoid unpredictable application behavior for the old software.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Oleksij Rempel <[e-mail]>
Signed-off-by: Marc Kleine-Budde <[e-mail]>

include/uapi/linux/can/j1939.h

···
 enum {
 	J1939_NLA_PAD,
 	J1939_NLA_BYTES_ACKED,
+	J1939_NLA_TOTAL_SIZE,
+	J1939_NLA_PGN,
+	J1939_NLA_SRC_NAME,
+	J1939_NLA_DEST_NAME,
+	J1939_NLA_SRC_ADDR,
+	J1939_NLA_DEST_ADDR,
 };
 
 enum {
 	J1939_EE_INFO_NONE,
 	J1939_EE_INFO_TX_ABORT,
+	J1939_EE_INFO_RX_RTS,
+	J1939_EE_INFO_RX_DPO,
+	J1939_EE_INFO_RX_ABORT,
 };
 
 struct j1939_filter {

net/can/j1939/j1939-priv.h

···
 	J1939_ERRQUEUE_TX_ACK,
 	J1939_ERRQUEUE_TX_SCHED,
 	J1939_ERRQUEUE_TX_ABORT,
+	J1939_ERRQUEUE_RX_RTS,
+	J1939_ERRQUEUE_RX_DPO,
+	J1939_ERRQUEUE_RX_ABORT,
 };
 
 /* j1939 devices */
···
 	struct list_head j1939_socks;
 
 	struct kref rx_kref;
+	u32 rx_tskey;
 };
 
 void j1939_ecu_put(struct j1939_ecu *ecu);

net/can/j1939/socket.c

···
 	return NULL;
 }
 
-static size_t j1939_sk_opt_stats_get_size(void)
+static size_t j1939_sk_opt_stats_get_size(enum j1939_sk_errqueue_type type)
 {
-	return
-		nla_total_size(sizeof(u32)) + /* J1939_NLA_BYTES_ACKED */
-		0;
+	switch (type) {
+	case J1939_ERRQUEUE_RX_RTS:
+		return
+			nla_total_size(sizeof(u32)) + /* J1939_NLA_TOTAL_SIZE */
+			nla_total_size(sizeof(u32)) + /* J1939_NLA_PGN */
+			nla_total_size(sizeof(u64)) + /* J1939_NLA_SRC_NAME */
+			nla_total_size(sizeof(u64)) + /* J1939_NLA_DEST_NAME */
+			nla_total_size(sizeof(u8)) +  /* J1939_NLA_SRC_ADDR */
+			nla_total_size(sizeof(u8)) +  /* J1939_NLA_DEST_ADDR */
+			0;
+	default:
+		return
+			nla_total_size(sizeof(u32)) + /* J1939_NLA_BYTES_ACKED */
+			0;
+	}
 }
 
 static struct sk_buff *
-j1939_sk_get_timestamping_opt_stats(struct j1939_session *session)
+j1939_sk_get_timestamping_opt_stats(struct j1939_session *session,
+				    enum j1939_sk_errqueue_type type)
 {
 	struct sk_buff *stats;
 	u32 size;
 
-	stats = alloc_skb(j1939_sk_opt_stats_get_size(), GFP_ATOMIC);
+	stats = alloc_skb(j1939_sk_opt_stats_get_size(type), GFP_ATOMIC);
 	if (!stats)
 		return NULL;
 
···
 		size = min(session->pkt.tx_acked * 7,
 			   session->total_message_size);
 
-	nla_put_u32(stats, J1939_NLA_BYTES_ACKED, size);
+	switch (type) {
+	case J1939_ERRQUEUE_RX_RTS:
+		nla_put_u32(stats, J1939_NLA_TOTAL_SIZE,
+			    session->total_message_size);
+		nla_put_u32(stats, J1939_NLA_PGN,
+			    session->skcb.addr.pgn);
+		nla_put_u64_64bit(stats, J1939_NLA_SRC_NAME,
+				  session->skcb.addr.src_name, J1939_NLA_PAD);
+		nla_put_u64_64bit(stats, J1939_NLA_DEST_NAME,
+				  session->skcb.addr.dst_name, J1939_NLA_PAD);
+		nla_put_u8(stats, J1939_NLA_SRC_ADDR,
+			   session->skcb.addr.sa);
+		nla_put_u8(stats, J1939_NLA_DEST_ADDR,
+			   session->skcb.addr.da);
+		break;
+	default:
+		nla_put_u32(stats, J1939_NLA_BYTES_ACKED, size);
+	}
 
 	return stats;
 }
 
-void j1939_sk_errqueue(struct j1939_session *session,
-		       enum j1939_sk_errqueue_type type)
+static void __j1939_sk_errqueue(struct j1939_session *session, struct sock *sk,
+				enum j1939_sk_errqueue_type type)
 {
 	struct j1939_priv *priv = session->priv;
-	struct sock *sk = session->sk;
 	struct j1939_sock *jsk;
 	struct sock_exterr_skb *serr;
 	struct sk_buff *skb;
 	char *state = "UNK";
 	int err;
 
-	/* currently we have no sk for the RX session */
-	if (!sk)
-		return;
-
 	jsk = j1939_sk(sk);
 
 	if (!(jsk->state & J1939_SOCK_ERRQUEUE))
 		return;
 
-	skb = j1939_sk_get_timestamping_opt_stats(session);
+	switch (type) {
+	case J1939_ERRQUEUE_TX_ACK:
+		if (!(sk->sk_tsflags & SOF_TIMESTAMPING_TX_ACK))
+			return;
+		break;
+	case J1939_ERRQUEUE_TX_SCHED:
+		if (!(sk->sk_tsflags & SOF_TIMESTAMPING_TX_SCHED))
+			return;
+		break;
+	case J1939_ERRQUEUE_TX_ABORT:
+		break;
+	case J1939_ERRQUEUE_RX_RTS:
+		fallthrough;
+	case J1939_ERRQUEUE_RX_DPO:
+		fallthrough;
+	case J1939_ERRQUEUE_RX_ABORT:
+		if (!(sk->sk_tsflags & SOF_TIMESTAMPING_RX_SOFTWARE))
+			return;
+		break;
+	default:
+		netdev_err(priv->ndev, "Unknown errqueue type %i\n", type);
+	}
+
+	skb = j1939_sk_get_timestamping_opt_stats(session, type);
 	if (!skb)
 		return;
 
···
 	memset(serr, 0, sizeof(*serr));
 	switch (type) {
 	case J1939_ERRQUEUE_TX_ACK:
-		if (!(sk->sk_tsflags & SOF_TIMESTAMPING_TX_ACK)) {
-			kfree_skb(skb);
-			return;
-		}
-
 		serr->ee.ee_errno = ENOMSG;
 		serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
 		serr->ee.ee_info = SCM_TSTAMP_ACK;
-		state = "ACK";
+		state = "TX ACK";
 		break;
 	case J1939_ERRQUEUE_TX_SCHED:
-		if (!(sk->sk_tsflags & SOF_TIMESTAMPING_TX_SCHED)) {
-			kfree_skb(skb);
-			return;
-		}
-
 		serr->ee.ee_errno = ENOMSG;
 		serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
 		serr->ee.ee_info = SCM_TSTAMP_SCHED;
-		state = "SCH";
+		state = "TX SCH";
 		break;
 	case J1939_ERRQUEUE_TX_ABORT:
 		serr->ee.ee_errno = session->err;
 		serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
 		serr->ee.ee_info = J1939_EE_INFO_TX_ABORT;
-		state = "ABT";
+		state = "TX ABT";
 		break;
-	default:
-		netdev_err(priv->ndev, "Unknown errqueue type %i\n", type);
+	case J1939_ERRQUEUE_RX_RTS:
+		serr->ee.ee_errno = ENOMSG;
+		serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
+		serr->ee.ee_info = J1939_EE_INFO_RX_RTS;
+		state = "RX RTS";
+		break;
+	case J1939_ERRQUEUE_RX_DPO:
+		serr->ee.ee_errno = ENOMSG;
+		serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
+		serr->ee.ee_info = J1939_EE_INFO_RX_DPO;
+		state = "RX DPO";
+		break;
+	case J1939_ERRQUEUE_RX_ABORT:
+		serr->ee.ee_errno = session->err;
+		serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
+		serr->ee.ee_info = J1939_EE_INFO_RX_ABORT;
+		state = "RX ABT";
+		break;
 	}
 
 	serr->opt_stats = true;
···
 
 	if (err)
 		kfree_skb(skb);
+};
+
+void j1939_sk_errqueue(struct j1939_session *session,
+		       enum j1939_sk_errqueue_type type)
+{
+	struct j1939_priv *priv = session->priv;
+	struct j1939_sock *jsk;
+
+	if (session->sk) {
+		/* send TX notifications to the socket of origin  */
+		__j1939_sk_errqueue(session, session->sk, type);
+		return;
+	}
+
+	/* spread RX notifications to all sockets subscribed to this session */
+	spin_lock_bh(&priv->j1939_socks_lock);
+	list_for_each_entry(jsk, &priv->j1939_socks, list) {
+		if (j1939_sk_recv_match_one(jsk, &session->skcb))
+			__j1939_sk_errqueue(session, &jsk->sk, type);
+	}
+	spin_unlock_bh(&priv->j1939_socks_lock);
 };
 
 void j1939_sk_send_loop_abort(struct sock *sk, int err)

net/can/j1939/transport.c

···
 
 static void j1939_session_destroy(struct j1939_session *session)
 {
-	if (session->err)
-		j1939_sk_errqueue(session, J1939_ERRQUEUE_TX_ABORT);
-	else
-		j1939_sk_errqueue(session, J1939_ERRQUEUE_TX_ACK);
+	if (session->transmission) {
+		if (session->err)
+			j1939_sk_errqueue(session, J1939_ERRQUEUE_TX_ABORT);
+		else
+			j1939_sk_errqueue(session, J1939_ERRQUEUE_TX_ACK);
+	} else if (session->err) {
+			j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT);
+	}
 
 	netdev_dbg(session->priv->ndev, "%s: 0x%p\n", __func__, session);
 
···
 
 	if (session->sk)
 		j1939_sk_send_loop_abort(session->sk, session->err);
+	else
+		j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT);
 }
 
 static void j1939_session_cancel(struct j1939_session *session,
···
 	session->err = j1939_xtp_abort_to_errno(priv, abort);
 	if (session->sk)
 		j1939_sk_send_loop_abort(session->sk, session->err);
+	else
+		j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT);
 	j1939_session_deactivate_activate_next(session);
 
 abort_put:
···
 	session->pkt.rx = 0;
 	session->pkt.tx = 0;
 
+	session->tskey = priv->rx_tskey++;
+	j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_RTS);
+
 	WARN_ON_ONCE(j1939_session_activate(session));
 
 	return session;
···
 	session->pkt.dpo = j1939_etp_ctl_to_packet(skb->data);
 	session->last_cmd = dat[0];
 	j1939_tp_set_rxtimeout(session, 750);
+
+	if (!session->transmission)
+		j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_DPO);
 }
 
 static void j1939_xtp_rx_dpo(struct j1939_priv *priv, struct sk_buff *skb,