rxrpc: Fix overlapping ACK accounting

Fix accidental overlapping of Rx-phase ACK accounting with Tx-phase ACK
accounting through variables shared between the two.  call->acks_* members
refer to ACKs received in the Tx phase and call->ackr_* members to ACKs
sent/to be sent during the Rx phase.

Fixes: 1a2391c3 ("rxrpc: Fix detection of out of order acks")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rxrpc/ar-internal.h

@@ -676,10 +676,9 @@ struct rxrpc_call {
 
 	spinlock_t		input_lock;	/* Lock for packet input to this call */
 
-	/* receive-phase ACK management */
+	/* Receive-phase ACK management (ACKs we send). */
 	u8			ackr_reason;	/* reason to ACK */
 	rxrpc_serial_t		ackr_serial;	/* serial of packet being ACK'd */
-	rxrpc_serial_t		ackr_first_seq;	/* first sequence number received */
 	rxrpc_seq_t		ackr_prev_seq;	/* previous sequence number received */
 	rxrpc_seq_t		ackr_consumed;	/* Highest packet shown consumed */
 	rxrpc_seq_t		ackr_seen;	/* Highest packet shown seen */
@@ -692,8 +691,10 @@ struct rxrpc_call {
 #define RXRPC_CALL_RTT_AVAIL_MASK	0xf
 #define RXRPC_CALL_RTT_PEND_SHIFT	8
 
-	/* transmission-phase ACK management */
+	/* Transmission-phase ACK management (ACKs we've received). */
 	ktime_t			acks_latest_ts;	/* Timestamp of latest ACK received */
+	rxrpc_seq_t		acks_first_seq;	/* first sequence number received */
+	rxrpc_seq_t		acks_prev_seq;	/* previous sequence number received */
 	rxrpc_seq_t		acks_lowest_nak; /* Lowest NACK in the buffer (or ==tx_hard_ack) */
 	rxrpc_seq_t		acks_lost_top;	/* tx_top at the time lost-ack ping sent */
 	rxrpc_serial_t		acks_lost_ping;	/* Serial number of probe ACK */

net/rxrpc/input.c

@@ -812,7 +812,7 @@ static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
 			       rxrpc_seq_t first_pkt, rxrpc_seq_t prev_pkt)
 {
-	rxrpc_seq_t base = READ_ONCE(call->ackr_first_seq);
+	rxrpc_seq_t base = READ_ONCE(call->acks_first_seq);
 
 	if (after(first_pkt, base))
 		return true; /* The window advanced */
@@ -820,7 +820,7 @@ static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
 	if (before(first_pkt, base))
 		return false; /* firstPacket regressed */
 
-	if (after_eq(prev_pkt, call->ackr_prev_seq))
+	if (after_eq(prev_pkt, call->acks_prev_seq))
 		return true; /* previousPacket hasn't regressed. */
 
 	/* Some rx implementations put a serial number in previousPacket. */
@@ -906,8 +906,8 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 	/* Discard any out-of-order or duplicate ACKs (outside lock). */
 	if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 		trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
-					   first_soft_ack, call->ackr_first_seq,
-					   prev_pkt, call->ackr_prev_seq);
+					   first_soft_ack, call->acks_first_seq,
+					   prev_pkt, call->acks_prev_seq);
 		return;
 	}
 
@@ -922,14 +922,14 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 	/* Discard any out-of-order or duplicate ACKs (inside lock). */
 	if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 		trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
-					   first_soft_ack, call->ackr_first_seq,
-					   prev_pkt, call->ackr_prev_seq);
+					   first_soft_ack, call->acks_first_seq,
+					   prev_pkt, call->acks_prev_seq);
 		goto out;
 	}
 	call->acks_latest_ts = skb->tstamp;
 
-	call->ackr_first_seq = first_soft_ack;
-	call->ackr_prev_seq = prev_pkt;
+	call->acks_first_seq = first_soft_ack;
+	call->acks_prev_seq = prev_pkt;
 
 	/* Parse rwind and mtu sizes if provided. */
 	if (buf.info.rxMTU)