[PATCH net-next 04/11] rxrpc: Add a tracepoint to follow the life of a packet in the Tx buffer

[David Howells]

Add a tracepoint to follow the insertion of a packet into the transmit
buffer, its transmission and its rotation out of the buffer.

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

 include/trace/events/rxrpc.h |   26 ++++++++++++++++++++++++++
 net/rxrpc/ar-internal.h      |   12 ++++++++++++
 net/rxrpc/input.c            |    2 ++
 net/rxrpc/misc.c             |    9 +++++++++
 net/rxrpc/sendmsg.c          |    9 ++++++++-
 5 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index c0c496c83f31..ffc74b3e5b76 100644
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -208,6 +208,32 @@ TRACE_EVENT(rxrpc_abort,
                      __entry->abort_code, __entry->error, __entry->why)
            );
 
+TRACE_EVENT(rxrpc_transmit,
+           TP_PROTO(struct rxrpc_call *call, enum rxrpc_transmit_trace why),
+
+           TP_ARGS(call, why),
+
+           TP_STRUCT__entry(
+                   __field(struct rxrpc_call *,        call            )
+                   __field(enum rxrpc_transmit_trace,  why             )
+                   __field(rxrpc_seq_t,                tx_hard_ack     )
+                   __field(rxrpc_seq_t,                tx_top          )
+                            ),
+
+           TP_fast_assign(
+                   __entry->call = call;
+                   __entry->why = why;
+                   __entry->tx_hard_ack = call->tx_hard_ack;
+                   __entry->tx_top = call->tx_top;
+                          ),
+
+           TP_printk("c=%p %s f=%08x n=%u",
+                     __entry->call,
+                     rxrpc_transmit_traces[__entry->why],
+                     __entry->tx_hard_ack + 1,
+                     __entry->tx_top - __entry->tx_hard_ack)
+           );
+
 #endif /* _TRACE_RXRPC_H */
 
 /* This part must be outside protection */
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 6ca40eea3022..afa5dcc05fe0 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -593,6 +593,18 @@ enum rxrpc_call_trace {
 
 extern const char rxrpc_call_traces[rxrpc_call__nr_trace][4];
 
+enum rxrpc_transmit_trace {
+       rxrpc_transmit_wait,
+       rxrpc_transmit_queue,
+       rxrpc_transmit_queue_reqack,
+       rxrpc_transmit_queue_last,
+       rxrpc_transmit_rotate,
+       rxrpc_transmit_end,
+       rxrpc_transmit__nr_trace
+};
+
+extern const char rxrpc_transmit_traces[rxrpc_transmit__nr_trace][4];
+
 extern const char *const rxrpc_pkts[];
 extern const char *rxrpc_acks(u8 reason);
 
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index c1f83d22f9b7..c7eb5104e91a 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -59,6 +59,7 @@ static void rxrpc_rotate_tx_window(struct rxrpc_call *call, 
rxrpc_seq_t to)
 
        spin_unlock(&call->lock);
 
+       trace_rxrpc_transmit(call, rxrpc_transmit_rotate);
        wake_up(&call->waitq);
 
        while (list) {
@@ -107,6 +108,7 @@ static bool rxrpc_end_tx_phase(struct rxrpc_call *call, 
const char *abort_why)
        }
 
        write_unlock(&call->state_lock);
+       trace_rxrpc_transmit(call, rxrpc_transmit_end);
        _leave(" = ok");
        return true;
 }
diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c
index 598064d3bdd2..dca89995f03e 100644
--- a/net/rxrpc/misc.c
+++ b/net/rxrpc/misc.c
@@ -132,3 +132,12 @@ const char rxrpc_client_traces[rxrpc_client__nr_trace][7] 
= {
        [rxrpc_client_to_waiting]       = "->Wait",
        [rxrpc_client_uncount]          = "Uncoun",
 };
+
+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_end]            = "END",
+};
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 8bfddf4e338c..28d8f73cf11d 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -56,6 +56,7 @@ static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
                        break;
                }
 
+               trace_rxrpc_transmit(call, rxrpc_transmit_wait);
                release_sock(&rx->sk);
                *timeo = schedule_timeout(*timeo);
                lock_sock(&rx->sk);
@@ -104,8 +105,14 @@ static void rxrpc_queue_packet(struct rxrpc_call *call, 
struct sk_buff *skb,
        smp_wmb();
        call->rxtx_buffer[ix] = skb;
        call->tx_top = seq;
-       if (last)
+       if (last) {
                set_bit(RXRPC_CALL_TX_LAST, &call->flags);
+               trace_rxrpc_transmit(call, rxrpc_transmit_queue_last);
+       } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
+               trace_rxrpc_transmit(call, rxrpc_transmit_queue_reqack);
+       } else {
+               trace_rxrpc_transmit(call, rxrpc_transmit_queue);
+       }
 
        if (last || call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
                _debug("________awaiting reply/ACK__________");