rxrpc: Add tracepoint for ACK proposal

Add a tracepoint to log proposed ACKs, including whether the proposal is
used to update a pending ACK or is discarded in favour of an easlier,
higher priority ACK.

Whilst we're at it, get rid of the rxrpc_acks() function and access the
name array directly.  We do, however, need to validate the ACK reason
number given to trace_rxrpc_rx_ack() to make sure we don't overrun the
array.

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

net/rxrpc/ar-internal.h

@@ -689,8 +689,28 @@ enum rxrpc_timer_trace {
 
 extern const char rxrpc_timer_traces[rxrpc_timer__nr_trace][8];
 
+enum rxrpc_propose_ack_trace {
+	rxrpc_propose_ack_input_data,
+	rxrpc_propose_ack_ping_for_params,
+	rxrpc_propose_ack_respond_to_ack,
+	rxrpc_propose_ack_respond_to_ping,
+	rxrpc_propose_ack_retry_tx,
+	rxrpc_propose_ack_terminal_ack,
+	rxrpc_propose_ack__nr_trace
+};
+
+enum rxrpc_propose_ack_outcome {
+	rxrpc_propose_ack_use,
+	rxrpc_propose_ack_update,
+	rxrpc_propose_ack_subsume,
+	rxrpc_propose_ack__nr_outcomes
+};
+
+extern const char rxrpc_propose_ack_traces[rxrpc_propose_ack__nr_trace][8];
+extern const char *const rxrpc_propose_ack_outcomes[rxrpc_propose_ack__nr_outcomes];
+
 extern const char *const rxrpc_pkts[];
-extern const char *rxrpc_acks(u8 reason);
+extern const char const rxrpc_ack_names[RXRPC_ACK__INVALID + 1][4];
 
 #include <trace/events/rxrpc.h>
 
@@ -719,7 +739,8 @@ int rxrpc_reject_call(struct rxrpc_sock *);
  * call_event.c
  */
 void rxrpc_set_timer(struct rxrpc_call *, enum rxrpc_timer_trace);
-void rxrpc_propose_ACK(struct rxrpc_call *, u8, u16, u32, bool, bool);
+void rxrpc_propose_ACK(struct rxrpc_call *, u8, u16, u32, bool, bool,
+		       enum rxrpc_propose_ack_trace);
 void rxrpc_process_call(struct work_struct *);
 
 /*