rxrpc: Pass the last Tx packet marker in the annotation buffer
When the last packet of data to be transmitted on a call is queued, tx_top
is set and then the RXRPC_CALL_TX_LAST flag is set. Unfortunately, this
leaves a race in the ACK processing side of things because the flag affects
the interpretation of tx_top and also allows us to start receiving reply
data before we've finished transmitting.
To fix this, make the following changes:
(1) rxrpc_queue_packet() now sets a marker in the annotation buffer
instead of setting the RXRPC_CALL_TX_LAST flag.
(2) rxrpc_rotate_tx_window() detects the marker and sets the flag in the
same context as the routines that use it.
(3) rxrpc_end_tx_phase() is simplified to just shift the call state.
The Tx window must have been rotated before calling to discard the
last packet.
(4) rxrpc_receiving_reply() is added to handle the arrival of the first
DATA packet of a reply to a client call (which is an implicit ACK of
the Tx phase).
(5) The last part of rxrpc_input_ack() is reordered to perform Tx
rotation, then soft-ACK application and then to end the phase if we've
rotated the last packet. In the event of a terminal ACK, the soft-ACK
application will be skipped as nAcks should be 0.
(6) rxrpc_input_ackall() now has to rotate as well as ending the phase.
In addition:
(7) Alter the transmit tracepoint to log the rotation of the last packet.
(8) Remove the no-longer relevant queue_reqack tracepoint note. The
ACK-REQUESTED packet header flag is now set as needed when we actually
transmit the packet and may vary by retransmission.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c
index 0d425e7..fe64871 100644
--- a/net/rxrpc/misc.c
+++ b/net/rxrpc/misc.c
@@ -155,9 +155,10 @@
const char rxrpc_transmit_traces[rxrpc_transmit__nr_trace][4] = {
[rxrpc_transmit_wait] = "WAI",
[rxrpc_transmit_queue] = "QUE",
- [rxrpc_transmit_queue_reqack] = "QRA",
[rxrpc_transmit_queue_last] = "QLS",
[rxrpc_transmit_rotate] = "ROT",
+ [rxrpc_transmit_rotate_last] = "RLS",
+ [rxrpc_transmit_await_reply] = "AWR",
[rxrpc_transmit_end] = "END",
};