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Diffstat (limited to 'net')
-rw-r--r--net/rxrpc/input.c30
1 files changed, 26 insertions, 4 deletions
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 2f22f082a66c..3be4177baf70 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -803,6 +803,30 @@ static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
}
/*
+ * Return true if the ACK is valid - ie. it doesn't appear to have regressed
+ * with respect to the ack state conveyed by preceding 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);
+
+ if (after(first_pkt, base))
+ return true; /* The window advanced */
+
+ if (before(first_pkt, base))
+ return false; /* firstPacket regressed */
+
+ if (after_eq(prev_pkt, call->ackr_prev_seq))
+ return true; /* previousPacket hasn't regressed. */
+
+ /* Some rx implementations put a serial number in previousPacket. */
+ if (after_eq(prev_pkt, base + call->tx_winsize))
+ return false;
+ return true;
+}
+
+/*
* Process an ACK packet.
*
* ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
@@ -865,8 +889,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
}
/* Discard any out-of-order or duplicate ACKs (outside lock). */
- if (before(first_soft_ack, call->ackr_first_seq) ||
- before(prev_pkt, call->ackr_prev_seq)) {
+ if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
trace_rxrpc_rx_discard_ack(call->debug_id, sp->hdr.serial,
first_soft_ack, call->ackr_first_seq,
prev_pkt, call->ackr_prev_seq);
@@ -882,8 +905,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
spin_lock(&call->input_lock);
/* Discard any out-of-order or duplicate ACKs (inside lock). */
- if (before(first_soft_ack, call->ackr_first_seq) ||
- before(prev_pkt, call->ackr_prev_seq)) {
+ if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
trace_rxrpc_rx_discard_ack(call->debug_id, sp->hdr.serial,
first_soft_ack, call->ackr_first_seq,
prev_pkt, call->ackr_prev_seq);