rxrpc: Perform terminal call ACK/ABORT retransmission from conn processor

Perform terminal call ACK/ABORT retransmission in the connection processor
rather than in the call processor.  With this change, once last_call is
set, no more incoming packets will be routed to the corresponding call or
any earlier calls on that channel (call IDs must only increase on a channel
on a connection).

Further, if a packet's callNumber is before the last_call ID or a packet is
aimed at successfully completed service call then that packet is discarded
and ignored.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 113 insertions, 0 deletions

diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c
index c631d92..c1c6b7f 100644
--- a/net/rxrpc/conn_event.c
+++ b/net/rxrpc/conn_event.c
@@ -25,6 +25,113 @@
 #include "ar-internal.h"
 
 /*
+ * Retransmit terminal ACK or ABORT of the previous call.
+ */
+static void rxrpc_conn_retransmit(struct rxrpc_connection *conn,
+				  struct sk_buff *skb)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	struct rxrpc_channel *chan;
+	struct msghdr msg;
+	struct kvec iov;
+	struct {
+		struct rxrpc_wire_header whdr;
+		union {
+			struct {
+				__be32 code;
+			} abort;
+			struct {
+				struct rxrpc_ackpacket ack;
+				struct rxrpc_ackinfo info;
+			};
+		};
+	} __attribute__((packed)) pkt;
+	size_t len;
+	u32 serial, mtu, call_id;
+
+	_enter("%d", conn->debug_id);
+
+	chan = &conn->channels[sp->hdr.cid & RXRPC_CHANNELMASK];
+
+	/* If the last call got moved on whilst we were waiting to run, just
+	 * ignore this packet.
+	 */
+	call_id = READ_ONCE(chan->last_call);
+	/* Sync with __rxrpc_disconnect_call() */
+	smp_rmb();
+	if (call_id != sp->hdr.callNumber)
+		return;
+
+	msg.msg_name	= &conn->params.peer->srx.transport;
+	msg.msg_namelen	= conn->params.peer->srx.transport_len;
+	msg.msg_control	= NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags	= 0;
+
+	pkt.whdr.epoch		= htonl(sp->hdr.epoch);
+	pkt.whdr.cid		= htonl(sp->hdr.cid);
+	pkt.whdr.callNumber	= htonl(sp->hdr.callNumber);
+	pkt.whdr.seq		= 0;
+	pkt.whdr.type		= chan->last_type;
+	pkt.whdr.flags		= conn->out_clientflag;
+	pkt.whdr.userStatus	= 0;
+	pkt.whdr.securityIndex	= conn->security_ix;
+	pkt.whdr._rsvd		= 0;
+	pkt.whdr.serviceId	= htons(chan->last_service_id);
+
+	len = sizeof(pkt.whdr);
+	switch (chan->last_type) {
+	case RXRPC_PACKET_TYPE_ABORT:
+		pkt.abort.code	= htonl(chan->last_abort);
+		len += sizeof(pkt.abort);
+		break;
+
+	case RXRPC_PACKET_TYPE_ACK:
+		mtu = conn->params.peer->if_mtu;
+		mtu -= conn->params.peer->hdrsize;
+		pkt.ack.bufferSpace	= 0;
+		pkt.ack.maxSkew		= htons(skb->priority);
+		pkt.ack.firstPacket	= htonl(chan->last_seq);
+		pkt.ack.previousPacket	= htonl(chan->last_seq - 1);
+		pkt.ack.serial		= htonl(sp->hdr.serial);
+		pkt.ack.reason		= RXRPC_ACK_DUPLICATE;
+		pkt.ack.nAcks		= 0;
+		pkt.info.rxMTU		= htonl(rxrpc_rx_mtu);
+		pkt.info.maxMTU		= htonl(mtu);
+		pkt.info.rwind		= htonl(rxrpc_rx_window_size);
+		pkt.info.jumbo_max	= htonl(rxrpc_rx_jumbo_max);
+		len += sizeof(pkt.ack) + sizeof(pkt.info);
+		break;
+	}
+
+	/* Resync with __rxrpc_disconnect_call() and check that the last call
+	 * didn't get advanced whilst we were filling out the packets.
+	 */
+	smp_rmb();
+	if (READ_ONCE(chan->last_call) != call_id)
+		return;
+
+	iov.iov_base	= &pkt;
+	iov.iov_len	= len;
+
+	serial = atomic_inc_return(&conn->serial);
+	pkt.whdr.serial = htonl(serial);
+
+	switch (chan->last_type) {
+	case RXRPC_PACKET_TYPE_ABORT:
+		_proto("Tx ABORT %%%u { %d } [re]", serial, conn->local_abort);
+		break;
+	case RXRPC_PACKET_TYPE_ACK:
+		_proto("Tx ACK %%%u [re]", serial);
+		break;
+	}
+
+	kernel_sendmsg(conn->params.local->socket, &msg, &iov, 1, len);
+	_leave("");
+	return;
+}
+
+/*
  * pass a connection-level abort onto all calls on that connection
  */
 static void rxrpc_abort_calls(struct rxrpc_connection *conn, int state,
@@ -166,6 +273,12 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
 	_enter("{%d},{%u,%%%u},", conn->debug_id, sp->hdr.type, sp->hdr.serial);
 
 	switch (sp->hdr.type) {
+	case RXRPC_PACKET_TYPE_DATA:
+	case RXRPC_PACKET_TYPE_ACK:
+		rxrpc_conn_retransmit(conn, skb);
+		rxrpc_free_skb(skb);
+		return 0;
+
 	case RXRPC_PACKET_TYPE_ABORT:
 		if (skb_copy_bits(skb, 0, &wtmp, sizeof(wtmp)) < 0)
 			return -EPROTO;