[PATCH net-next 2/9] rxrpc: Add re-sent Tx annotation

David Howells
2016-09-22T00:39:29Z

Add a Tx-phase annotation for packet buffers to indicate that a buffer has
already been retransmitted. This will be used by future congestion
management. Re-retransmissions of a packet don't affect the congestion
window managment in the same way as initial retransmissions.

Signed-off-by: David Howells <dhowells@redhat.com>
---

net/rxrpc/ar-internal.h | 2 ++
net/rxrpc/call_event.c | 28 +++++++++++++++++++---------
net/rxrpc/input.c | 14 +++++++++++---
3 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index f021df4a6a22..dcf54e3fb478 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -505,6 +505,8 @@ struct rxrpc_call {
#define RXRPC_TX_ANNO_UNACK 1
#define RXRPC_TX_ANNO_NAK 2
#define RXRPC_TX_ANNO_RETRANS 3
+#define RXRPC_TX_ANNO_MASK 0x03
+#define RXRPC_TX_ANNO_RESENT 0x04
#define RXRPC_RX_ANNO_JUMBO 0x3f /* Jumbo subpacket number + 1 if not zero */
#define RXRPC_RX_ANNO_JLAST 0x40 /* Set if last element of a jumbo packet */
#define RXRPC_RX_ANNO_VERIFIED 0x80 /* Set if verified and decrypted */
diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index 6247ce25eb21..34ad967f2d81 100644
--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -144,7 +144,7 @@ static void rxrpc_resend(struct rxrpc_call *call)
rxrpc_seq_t cursor, seq, top;
unsigned long resend_at, now;
int ix;
- u8 annotation;
+ u8 annotation, anno_type;

_enter("{%d,%d}", call->tx_hard_ack, call->tx_top);

@@ -165,14 +165,16 @@ static void rxrpc_resend(struct rxrpc_call *call)
for (seq = cursor + 1; before_eq(seq, top); seq++) {
ix = seq & RXRPC_RXTX_BUFF_MASK;
annotation = call->rxtx_annotations[ix];
- if (annotation == RXRPC_TX_ANNO_ACK)
+ anno_type = annotation & RXRPC_TX_ANNO_MASK;
+ annotation &= ~RXRPC_TX_ANNO_MASK;
+ if (anno_type == RXRPC_TX_ANNO_ACK)
continue;

skb = call->rxtx_buffer[ix];
rxrpc_see_skb(skb, rxrpc_skb_tx_seen);
sp = rxrpc_skb(skb);

- if (annotation == RXRPC_TX_ANNO_UNACK) {
+ if (anno_type == RXRPC_TX_ANNO_UNACK) {
if (time_after(sp->resend_at, now)) {
if (time_before(sp->resend_at, resend_at))
resend_at = sp->resend_at;
@@ -181,7 +183,7 @@ static void rxrpc_resend(struct rxrpc_call *call)
}

/* Okay, we need to retransmit a packet. */
- call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS;
+ call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
}

call->resend_at = resend_at;
@@ -194,7 +196,8 @@ static void rxrpc_resend(struct rxrpc_call *call)
for (seq = cursor + 1; before_eq(seq, top); seq++) {
ix = seq & RXRPC_RXTX_BUFF_MASK;
annotation = call->rxtx_annotations[ix];
- if (annotation != RXRPC_TX_ANNO_RETRANS)
+ anno_type = annotation & RXRPC_TX_ANNO_MASK;
+ if (anno_type != RXRPC_TX_ANNO_RETRANS)
continue;

skb = call->rxtx_buffer[ix];
@@ -220,10 +223,17 @@ static void rxrpc_resend(struct rxrpc_call *call)
* received and the packet might have been hard-ACK'd (in which
* case it will no longer be in the buffer).
*/
- if (after(seq, call->tx_hard_ack) &&
- (call->rxtx_annotations[ix] == RXRPC_TX_ANNO_RETRANS ||
- call->rxtx_annotations[ix] == RXRPC_TX_ANNO_NAK))
- call->rxtx_annotations[ix] = RXRPC_TX_ANNO_UNACK;
+ if (after(seq, call->tx_hard_ack)) {
+ annotation = call->rxtx_annotations[ix];
+ anno_type = annotation & RXRPC_TX_ANNO_MASK;
+ if (anno_type == RXRPC_TX_ANNO_RETRANS ||
+ anno_type == RXRPC_TX_ANNO_NAK) {
+ annotation &= ~RXRPC_TX_ANNO_MASK;
+ annotation |= RXRPC_TX_ANNO_UNACK;
+ }
+ annotation |= RXRPC_TX_ANNO_RESENT;
+ call->rxtx_annotations[ix] = annotation;
+ }

if (after(call->tx_hard_ack, seq))
seq = call->tx_hard_ack;
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 7ac1edf3aac7..aa261df9fc9e 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -388,17 +388,25 @@ static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
{
bool resend = false;
int ix;
+ u8 annotation, anno_type;

for (; nr_acks > 0; nr_acks--, seq++) {
ix = seq & RXRPC_RXTX_BUFF_MASK;
+ annotation = call->rxtx_annotations[ix];
+ anno_type = annotation & RXRPC_TX_ANNO_MASK;
+ annotation &= ~RXRPC_TX_ANNO_MASK;
switch (*acks++) {
case RXRPC_ACK_TYPE_ACK:
- call->rxtx_annotations[ix] = RXRPC_TX_ANNO_ACK;
+ if (anno_type == RXRPC_TX_ANNO_ACK)
+ continue;
+ call->rxtx_annotations[ix] =
+ RXRPC_TX_ANNO_ACK | annotation;
break;
case RXRPC_ACK_TYPE_NACK:
- if (call->rxtx_annotations[ix] == RXRPC_TX_ANNO_NAK)
+ if (anno_type == RXRPC_TX_ANNO_NAK)
continue;
- call->rxtx_annotations[ix] = RXRPC_TX_ANNO_NAK;
+ call->rxtx_annotations[ix] =
+ RXRPC_TX_ANNO_NAK | annotation;
resend = true;
break;