[PATCH 5.18 520/879] rxrpc: Dont let ack.previousPacket regress

Greg Kroah-Hartman
2022-06-08T00:38:25Z

From: David Howells <dhowells@redhat.com>

[ Upstream commit 81524b6312535897707f2942695da1d359a5e56b ]

The previousPacket field in the rx ACK packet should never go backwards -
it's now the highest DATA sequence number received, not the last on
received (it used to be used for out of sequence detection).

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/rxrpc/ar-internal.h | 4 ++--
net/rxrpc/input.c | 4 +++-
net/rxrpc/output.c | 2 +-
3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index cc1fe6d00eca..4ba51e6d3d85 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -679,7 +679,7 @@ struct rxrpc_call {
/* 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_seq_t ackr_prev_seq; /* previous sequence number received */
+ rxrpc_seq_t ackr_highest_seq; /* Higest sequence number received */
rxrpc_seq_t ackr_consumed; /* Highest packet shown consumed */
rxrpc_seq_t ackr_seen; /* Highest packet shown seen */

@@ -694,7 +694,7 @@ struct rxrpc_call {
/* 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_prev_seq; /* Highest previousPacket 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 */
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 3da33b5c13b2..680b984ef87f 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -453,7 +453,6 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
!rxrpc_receiving_reply(call))
goto unlock;

- call->ackr_prev_seq = seq0;
hard_ack = READ_ONCE(call->rx_hard_ack);

nr_subpackets = sp->nr_subpackets;
@@ -534,6 +533,9 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
ack_serial = serial;
}

+ if (after(seq0, call->ackr_highest_seq))
+ call->ackr_highest_seq = seq0;
+
/* Queue the packet. We use a couple of memory barriers here as need
* to make sure that rx_top is perceived to be set after the buffer
* pointer and that the buffer pointer is set after the annotation and
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index a45c83f22236..46aae9b7006f 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -89,7 +89,7 @@ static size_t rxrpc_fill_out_ack(struct rxrpc_connection *conn,
pkt->ack.bufferSpace = htons(8);
pkt->ack.maxSkew = htons(0);
pkt->ack.firstPacket = htonl(hard_ack + 1);
- pkt->ack.previousPacket = htonl(call->ackr_prev_seq);
+ pkt->ack.previousPacket = htonl(call->ackr_highest_seq);
pkt->ack.serial = htonl(serial);
pkt->ack.reason = reason;
pkt->ack.nAcks = top - hard_ack;
--
2.35.1