[PATCH net-next v3 10/21] rxrpc: Split up the DATA packet transmission function

David Howells
2024-03-06T00:07:27Z

Split (sub)packet preparation and timestamping out of the DATA packet
transmission function to make it easier to glue multiple txbufs together
into a jumbo DATA packet. This will require preparation and timestamping
of all the subpackets in a txbuf, and these functions provide convenient
points to place the required iteration.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
---
net/rxrpc/ar-internal.h | 1 -
net/rxrpc/output.c | 98 +++++++++++++++++++++++++++++------------
2 files changed, 69 insertions(+), 30 deletions(-)

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index c6731f43a2d5..54550ab62adc 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -1166,7 +1166,6 @@ static inline struct rxrpc_net *rxrpc_net(struct net *net)
*/
int rxrpc_send_ack_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb);
int rxrpc_send_abort_packet(struct rxrpc_call *);
-int rxrpc_send_data_packet(struct rxrpc_call *, struct rxrpc_txbuf *);
void rxrpc_send_conn_abort(struct rxrpc_connection *conn);
void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb);
void rxrpc_send_keepalive(struct rxrpc_peer *);
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index f2b10c3e4cc2..25b8fc9aef97 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -313,37 +313,23 @@ int rxrpc_send_abort_packet(struct rxrpc_call *call)
}

/*
- * send a packet through the transport endpoint
+ * Prepare a (sub)packet for transmission.
*/
-int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
+static void rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_txbuf *txb,
+ rxrpc_serial_t serial)
{
- struct rxrpc_connection *conn = call->conn;
+ struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
enum rxrpc_req_ack_trace why;
- enum rxrpc_tx_point frag;
- struct msghdr msg;
- size_t len;
- int ret, rtt_slot = -1;
+ struct rxrpc_connection *conn = call->conn;

_enter("%x,{%d}", txb->seq, txb->len);

- /* Each transmission of a Tx packet+ needs a new serial number */
- txb->serial = rxrpc_get_next_serial(conn);
- txb->wire.serial = htonl(txb->serial);
- txb->wire.cksum = txb->cksum;
+ txb->serial = serial;

if (test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags) &&
txb->seq == 1)
txb->wire.userStatus = RXRPC_USERSTATUS_SERVICE_UPGRADE;

- len = txb->kvec[0].iov_len;
- iov_iter_kvec(&msg.msg_iter, WRITE, txb->kvec, txb->nr_kvec, len);
-
- msg.msg_name = &call->peer->srx.transport;
- msg.msg_namelen = call->peer->srx.transport_len;
- msg.msg_control = NULL;
- msg.msg_controllen = 0;
- msg.msg_flags = 0;
-
/* If our RTT cache needs working on, request an ACK. Also request
* ACKs if a DATA packet appears to have been lost.
*
@@ -376,6 +362,59 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
txb->flags |= RXRPC_REQUEST_ACK;
dont_set_request_ack:

+ whdr->flags = txb->flags & RXRPC_TXBUF_WIRE_FLAGS;
+ whdr->serial = htonl(txb->serial);
+ whdr->cksum = txb->cksum;
+
+ trace_rxrpc_tx_data(call, txb->seq, txb->serial, txb->flags, false);
+}
+
+/*
+ * Prepare a packet for transmission.
+ */
+static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
+{
+ rxrpc_serial_t serial;
+
+ /* Each transmission of a Tx packet needs a new serial number */
+ serial = rxrpc_get_next_serial(call->conn);
+
+ rxrpc_prepare_data_subpacket(call, txb, serial);
+
+ return txb->len;
+}
+
+/*
+ * Set the times on a packet before transmission
+ */
+static int rxrpc_tstamp_data_packets(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
+{
+ ktime_t tstamp = ktime_get_real();
+ int rtt_slot = -1;
+
+ txb->last_sent = tstamp;
+ if (txb->flags & RXRPC_REQUEST_ACK)
+ rtt_slot = rxrpc_begin_rtt_probe(call, txb->serial, rxrpc_rtt_tx_data);
+
+ return rtt_slot;
+}
+
+/*
+ * send a packet through the transport endpoint
+ */
+static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
+{
+ struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
+ struct rxrpc_connection *conn = call->conn;
+ enum rxrpc_tx_point frag;
+ struct msghdr msg;
+ size_t len;
+ int ret, rtt_slot = -1;
+
+ _enter("%x,{%d}", txb->seq, txb->len);
+
+ len = rxrpc_prepare_data_packet(call, txb);
+
if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
static int lose;
if ((lose++ & 7) == 7) {
@@ -386,7 +425,13 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
}
}

- trace_rxrpc_tx_data(call, txb->seq, txb->serial, txb->flags, false);
+ iov_iter_kvec(&msg.msg_iter, WRITE, txb->kvec, txb->nr_kvec, len);
+
+ msg.msg_name = &call->peer->srx.transport;
+ msg.msg_namelen = call->peer->srx.transport_len;
+ msg.msg_control = NULL;
+ msg.msg_controllen = 0;
+ msg.msg_flags = 0;

/* Track what we've attempted to transmit at least once so that the
* retransmission algorithm doesn't try to resend what we haven't sent
@@ -405,11 +450,8 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
frag = rxrpc_tx_point_call_data_nofrag;
}

- txb->wire.flags = txb->flags & RXRPC_TXBUF_WIRE_FLAGS;
retry:
- txb->last_sent = ktime_get_real();
- if (txb->flags & RXRPC_REQUEST_ACK)
- rtt_slot = rxrpc_begin_rtt_probe(call, txb->serial, rxrpc_rtt_tx_data);
+ rtt_slot = rxrpc_tstamp_data_packets(call, txb);

/* send the packet by UDP
* - returns -EMSGSIZE if UDP would have to fragment the packet
@@ -424,11 +466,9 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
if (ret < 0) {
rxrpc_inc_stat(call->rxnet, stat_tx_data_send_fail);
rxrpc_cancel_rtt_probe(call, txb->serial, rtt_slot);
- trace_rxrpc_tx_fail(call->debug_id, txb->serial, ret,
- rxrpc_tx_point_call_data_nofrag);
+ trace_rxrpc_tx_fail(call->debug_id, txb->serial, ret, frag);
} else {
- trace_rxrpc_tx_packet(call->debug_id, &txb->wire,
- rxrpc_tx_point_call_data_nofrag);
+ trace_rxrpc_tx_packet(call->debug_id, whdr, frag);
}

rxrpc_tx_backoff(call, ret);