[PATCH net-next v2 35/39] rxrpc: Add a reason indicator to the tx_data tracepoint

[David Howells <dhowells@redhat.com>]

Add an indicator to the rxrpc_tx_data tracepoint to indicate what triggered
the transmission of a particular packet.  At this point, it's only normal
transmission and retransmission, plus the tracepoint is also used to record
loss injection, but in a future patch, TLP-induced (re-)transmission will
also be a thing.

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
---
 include/trace/events/rxrpc.h | 21 ++++++++++++++-------
 net/rxrpc/ar-internal.h      |  1 +
 net/rxrpc/call_event.c       | 12 ++++++++----
 net/rxrpc/output.c           |  6 +++---
 4 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index 326a4c257aea..d79623fff746 100644
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -302,6 +302,11 @@
 	EM(rxrpc_txqueue_rotate_last,		"RLS") \
 	E_(rxrpc_txqueue_wait,			"WAI")
 
+#define rxrpc_txdata_traces \
+	EM(rxrpc_txdata_inject_loss,		" *INJ-LOSS*") \
+	EM(rxrpc_txdata_new_data,		" ") \
+	E_(rxrpc_txdata_retransmit,		" *RETRANS*")
+
 #define rxrpc_receive_traces \
 	EM(rxrpc_receive_end,			"END") \
 	EM(rxrpc_receive_front,			"FRN") \
@@ -534,6 +539,7 @@ enum rxrpc_timer_trace		{ rxrpc_timer_traces } __mode(byte);
 enum rxrpc_tq_trace		{ rxrpc_tq_traces } __mode(byte);
 enum rxrpc_tx_point		{ rxrpc_tx_points } __mode(byte);
 enum rxrpc_txbuf_trace		{ rxrpc_txbuf_traces } __mode(byte);
+enum rxrpc_txdata_trace		{ rxrpc_txdata_traces } __mode(byte);
 enum rxrpc_txqueue_trace	{ rxrpc_txqueue_traces } __mode(byte);
 
 #endif /* end __RXRPC_DECLARE_TRACE_ENUMS_ONCE_ONLY */
@@ -572,6 +578,7 @@ rxrpc_timer_traces;
 rxrpc_tq_traces;
 rxrpc_tx_points;
 rxrpc_txbuf_traces;
+rxrpc_txdata_traces;
 rxrpc_txqueue_traces;
 
 /*
@@ -1222,9 +1229,10 @@ TRACE_EVENT(rxrpc_tx_packet,
 
 TRACE_EVENT(rxrpc_tx_data,
 	    TP_PROTO(struct rxrpc_call *call, rxrpc_seq_t seq,
-		     rxrpc_serial_t serial, unsigned int flags, bool lose),
+		     rxrpc_serial_t serial, unsigned int flags,
+		     enum rxrpc_txdata_trace trace),
 
-	    TP_ARGS(call, seq, serial, flags, lose),
+	    TP_ARGS(call, seq, serial, flags, trace),
 
 	    TP_STRUCT__entry(
 		    __field(unsigned int,	call)
@@ -1233,7 +1241,7 @@ TRACE_EVENT(rxrpc_tx_data,
 		    __field(u32,		cid)
 		    __field(u32,		call_id)
 		    __field(u16,		flags)
-		    __field(bool,		lose)
+		    __field(enum rxrpc_txdata_trace, trace)
 			     ),
 
 	    TP_fast_assign(
@@ -1243,18 +1251,17 @@ TRACE_EVENT(rxrpc_tx_data,
 		    __entry->seq = seq;
 		    __entry->serial = serial;
 		    __entry->flags = flags;
-		    __entry->lose = lose;
+		    __entry->trace = trace;
 			   ),
 
-	    TP_printk("c=%08x DATA %08x:%08x %08x q=%08x fl=%02x%s%s",
+	    TP_printk("c=%08x DATA %08x:%08x %08x q=%08x fl=%02x%s",
 		      __entry->call,
 		      __entry->cid,
 		      __entry->call_id,
 		      __entry->serial,
 		      __entry->seq,
 		      __entry->flags & RXRPC_TXBUF_WIRE_FLAGS,
-		      __entry->flags & RXRPC_TXBUF_RESENT ? " *RETRANS*" : "",
-		      __entry->lose ? " *LOSE*" : "")
+		      __print_symbolic(__entry->trace, rxrpc_txdata_traces))
 	    );
 
 TRACE_EVENT(rxrpc_tx_ack,
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index aa240b4b4bec..139575032ae2 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -883,6 +883,7 @@ struct rxrpc_send_data_req {
 	rxrpc_seq_t		seq;		/* Sequence of first data */
 	int			n;		/* Number of DATA packets to glue into jumbo */
 	bool			did_send;	/* T if did actually send */
+	int /* enum rxrpc_txdata_trace */ trace;
 };
 
 #include <trace/events/rxrpc.h>
diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index 39772459426b..99d9502564cc 100644
--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -101,6 +101,7 @@ void rxrpc_resend(struct rxrpc_call *call, rxrpc_serial_t ack_serial, bool ping_
 {
 	struct rxrpc_send_data_req req = {
 		.now	= ktime_get_real(),
+		.trace	= rxrpc_txdata_retransmit,
 	};
 	struct rxrpc_txqueue *tq = call->tx_queue;
 	ktime_t lowest_xmit_ts = KTIME_MAX;
@@ -269,7 +270,8 @@ static unsigned int rxrpc_tx_window_space(struct rxrpc_call *call)
 /*
  * Transmit some as-yet untransmitted data.
  */
-static void rxrpc_transmit_fresh_data(struct rxrpc_call *call)
+static void rxrpc_transmit_fresh_data(struct rxrpc_call *call,
+				      enum rxrpc_txdata_trace trace)
 {
 	int space = rxrpc_tx_window_space(call);
 
@@ -284,6 +286,7 @@ static void rxrpc_transmit_fresh_data(struct rxrpc_call *call)
 			.now	= ktime_get_real(),
 			.seq	= call->tx_transmitted + 1,
 			.n	= 0,
+			.trace	= trace,
 		};
 		struct rxrpc_txqueue *tq;
 		struct rxrpc_txbuf *txb;
@@ -332,7 +335,8 @@ static void rxrpc_transmit_fresh_data(struct rxrpc_call *call)
 	}
 }
 
-static void rxrpc_transmit_some_data(struct rxrpc_call *call)
+static void rxrpc_transmit_some_data(struct rxrpc_call *call,
+				     enum rxrpc_txdata_trace trace)
 {
 	switch (__rxrpc_call_state(call)) {
 	case RXRPC_CALL_SERVER_ACK_REQUEST:
@@ -349,7 +353,7 @@ static void rxrpc_transmit_some_data(struct rxrpc_call *call)
 			rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);
 			return;
 		}
-		rxrpc_transmit_fresh_data(call);
+		rxrpc_transmit_fresh_data(call, trace);
 		break;
 	default:
 		return;
@@ -463,7 +467,7 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
 		resend = true;
 	}
 
-	rxrpc_transmit_some_data(call);
+	rxrpc_transmit_some_data(call, rxrpc_txdata_new_data);
 
 	now = ktime_get_real();
 	t = ktime_sub(call->keepalive_at, now);
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index a7de8a02f419..2633f955d1d0 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -511,7 +511,7 @@ static size_t rxrpc_prepare_data_subpacket(struct rxrpc_call *call,
 		len += sizeof(*jumbo);
 	}
 
-	trace_rxrpc_tx_data(call, txb->seq, txb->serial, txb->flags | flags, false);
+	trace_rxrpc_tx_data(call, txb->seq, txb->serial, flags, req->trace);
 	kv->iov_len = len;
 	return len;
 }
@@ -655,8 +655,8 @@ void rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_send_data_req
 
 		if ((lose++ & 7) == 7) {
 			ret = 0;
-			trace_rxrpc_tx_data(call, txb->seq, txb->serial,
-					    txb->flags, true);
+			trace_rxrpc_tx_data(call, txb->seq, txb->serial, txb->flags,
+					    rxrpc_txdata_inject_loss);
 			conn->peer->last_tx_at = ktime_get_seconds();
 			goto done;
 		}