rxrpc: Clean up Tx header flags generation handling

Clean up the generation of the header flags when building packet headers
for transmission:

 (1) Assemble the flags in a local variable rather than in the txb->flags.

 (2) Do the flags masking and JUMBO-PACKET setting in one bit of code for
     both the main header and the jumbo headers.

 (3) Generate the REQUEST-ACK flag afresh each time.  There's a possibility
     we might want to do jumbo retransmission packets in future.

 (4) Pass the local flags variable to the rxrpc_tx_data tracepoint rather
     than the combination of the txb flags and the wire header flags (the
     latter belong only to the first subpacket).

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20241204074710.990092-5-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 14 insertions, 10 deletions

diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index 27c23873c881..62064f63d6eb 100644
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -452,7 +452,6 @@
 
 #define rxrpc_req_ack_traces \
 	EM(rxrpc_reqack_ack_lost,		"ACK-LOST  ")	\
-	EM(rxrpc_reqack_already_on,		"ALREADY-ON")	\
 	EM(rxrpc_reqack_more_rtt,		"MORE-RTT  ")	\
 	EM(rxrpc_reqack_no_srv_last,		"NO-SRVLAST")	\
 	EM(rxrpc_reqack_old_rtt,		"OLD-RTT   ")	\
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index d0fd37bdcfe9..fcdfbc1d5aaf 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -110,7 +110,7 @@ struct rxrpc_net {
 	atomic_t		stat_tx_acks[256];
 	atomic_t		stat_rx_acks[256];
 
-	atomic_t		stat_why_req_ack[8];
+	atomic_t		stat_why_req_ack[7];
 
 	atomic_t		stat_io_loop;
 };
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index 85112ea31a39..50d5f2a02458 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -330,6 +330,8 @@ static void rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_t
 	struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
 	enum rxrpc_req_ack_trace why;
 	struct rxrpc_connection *conn = call->conn;
+	bool last;
+	u8 flags;
 
 	_enter("%x,{%d}", txb->seq, txb->len);
 
@@ -339,6 +341,10 @@ static void rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_t
 	    txb->seq == 1)
 		whdr->userStatus = RXRPC_USERSTATUS_SERVICE_UPGRADE;
 
+	txb->flags &= ~RXRPC_REQUEST_ACK;
+	flags = txb->flags & RXRPC_TXBUF_WIRE_FLAGS;
+	last = txb->flags & RXRPC_LAST_PACKET;
+
 	/* If our RTT cache needs working on, request an ACK.  Also request
 	 * ACKs if a DATA packet appears to have been lost.
 	 *
@@ -346,9 +352,7 @@ static void rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_t
 	 * service call, lest OpenAFS incorrectly send us an ACK with some
 	 * soft-ACKs in it and then never follow up with a proper hard ACK.
 	 */
-	if (txb->flags & RXRPC_REQUEST_ACK)
-		why = rxrpc_reqack_already_on;
-	else if ((txb->flags & RXRPC_LAST_PACKET) && rxrpc_sending_to_client(txb))
+	if (last && rxrpc_sending_to_client(txb))
 		why = rxrpc_reqack_no_srv_last;
 	else if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
 		why = rxrpc_reqack_ack_lost;
@@ -367,15 +371,17 @@ static void rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_t
 
 	rxrpc_inc_stat(call->rxnet, stat_why_req_ack[why]);
 	trace_rxrpc_req_ack(call->debug_id, txb->seq, why);
-	if (why != rxrpc_reqack_no_srv_last)
+	if (why != rxrpc_reqack_no_srv_last) {
 		txb->flags |= RXRPC_REQUEST_ACK;
+		flags |= RXRPC_REQUEST_ACK;
+	}
 dont_set_request_ack:
 
-	whdr->flags = txb->flags & RXRPC_TXBUF_WIRE_FLAGS;
+	whdr->flags	= flags;
 	whdr->serial	= htonl(txb->serial);
 	whdr->cksum	= txb->cksum;
 
-	trace_rxrpc_tx_data(call, txb->seq, txb->serial, txb->flags, false);
+	trace_rxrpc_tx_data(call, txb->seq, txb->serial, flags, false);
 }
 
 /*
diff --git a/net/rxrpc/proc.c b/net/rxrpc/proc.c
index 263a2251e3d2..3b7e34dd4385 100644
--- a/net/rxrpc/proc.c
+++ b/net/rxrpc/proc.c
@@ -519,9 +519,8 @@ int rxrpc_stats_show(struct seq_file *seq, void *v)
 		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_DELAY]),
 		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_IDLE]));
 	seq_printf(seq,
-		   "Why-Req-A: acklost=%u already=%u mrtt=%u ortt=%u\n",
+		   "Why-Req-A: acklost=%u mrtt=%u ortt=%u\n",
 		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_ack_lost]),
-		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_already_on]),
 		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_more_rtt]),
 		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_old_rtt]));
 	seq_printf(seq,