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rxrpc: Generate a summary of the ACK state for later use
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Generate a summary of the Tx buffer packet state when an ACK is received
for use in a later patch that does congestion management.

Signed-off-by: David Howells <dhowells@redhat.com>
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David Howells committed Sep 24, 2016
1 parent df0562a commit 31a1b98
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Showing 2 changed files with 48 additions and 11 deletions.
14 changes: 14 additions & 0 deletions net/rxrpc/ar-internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -540,6 +540,20 @@ struct rxrpc_call {

/* transmission-phase ACK management */
rxrpc_serial_t acks_latest; /* serial number of latest ACK received */
rxrpc_seq_t acks_lowest_nak; /* Lowest NACK in the buffer (or ==tx_hard_ack) */
};

/*
* Summary of a new ACK and the changes it made.
*/
struct rxrpc_ack_summary {
u8 ack_reason;
u8 nr_acks; /* Number of ACKs in packet */
u8 nr_nacks; /* Number of NACKs in packet */
u8 nr_new_acks; /* Number of new ACKs in packet */
u8 nr_new_nacks; /* Number of new NACKs in packet */
u8 nr_rot_new_acks; /* Number of rotated new ACKs */
bool new_low_nack; /* T if new low NACK found */
};

enum rxrpc_skb_trace {
Expand Down
45 changes: 34 additions & 11 deletions net/rxrpc/input.c
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Original file line number Diff line number Diff line change
Expand Up @@ -56,12 +56,20 @@ static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb,
/*
* Apply a hard ACK by advancing the Tx window.
*/
static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to)
static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
struct rxrpc_ack_summary *summary)
{
struct sk_buff *skb, *list = NULL;
int ix;
u8 annotation;

if (call->acks_lowest_nak == call->tx_hard_ack) {
call->acks_lowest_nak = to;
} else if (before_eq(call->acks_lowest_nak, to)) {
summary->new_low_nack = true;
call->acks_lowest_nak = to;
}

spin_lock(&call->lock);

while (before(call->tx_hard_ack, to)) {
Expand All @@ -77,6 +85,8 @@ static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to)

if (annotation & RXRPC_TX_ANNO_LAST)
set_bit(RXRPC_CALL_TX_LAST, &call->flags);
if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
summary->nr_rot_new_acks++;
}

spin_unlock(&call->lock);
Expand Down Expand Up @@ -147,6 +157,7 @@ static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
*/
static bool rxrpc_receiving_reply(struct rxrpc_call *call)
{
struct rxrpc_ack_summary summary = { 0 };
rxrpc_seq_t top = READ_ONCE(call->tx_top);

if (call->ackr_reason) {
Expand All @@ -159,7 +170,7 @@ static bool rxrpc_receiving_reply(struct rxrpc_call *call)
}

if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags))
rxrpc_rotate_tx_window(call, top);
rxrpc_rotate_tx_window(call, top, &summary);
if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
rxrpc_proto_abort("TXL", call, top);
return false;
Expand Down Expand Up @@ -508,7 +519,8 @@ static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
* the time the ACK was sent.
*/
static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
rxrpc_seq_t seq, int nr_acks)
rxrpc_seq_t seq, int nr_acks,
struct rxrpc_ack_summary *summary)
{
bool resend = false;
int ix;
Expand All @@ -521,14 +533,23 @@ static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
annotation &= ~RXRPC_TX_ANNO_MASK;
switch (*acks++) {
case RXRPC_ACK_TYPE_ACK:
summary->nr_acks++;
if (anno_type == RXRPC_TX_ANNO_ACK)
continue;
summary->nr_new_acks++;
call->rxtx_annotations[ix] =
RXRPC_TX_ANNO_ACK | annotation;
break;
case RXRPC_ACK_TYPE_NACK:
if (!summary->nr_nacks &&
call->acks_lowest_nak != seq) {
call->acks_lowest_nak = seq;
summary->new_low_nack = true;
}
summary->nr_nacks++;
if (anno_type == RXRPC_TX_ANNO_NAK)
continue;
summary->nr_new_nacks++;
if (anno_type == RXRPC_TX_ANNO_RETRANS)
continue;
call->rxtx_annotations[ix] =
Expand Down Expand Up @@ -558,7 +579,7 @@ static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
u16 skew)
{
u8 ack_reason;
struct rxrpc_ack_summary summary = { 0 };
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
union {
struct rxrpc_ackpacket ack;
Expand All @@ -581,18 +602,18 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
first_soft_ack = ntohl(buf.ack.firstPacket);
hard_ack = first_soft_ack - 1;
nr_acks = buf.ack.nAcks;
ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
buf.ack.reason : RXRPC_ACK__INVALID);
summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
buf.ack.reason : RXRPC_ACK__INVALID);

trace_rxrpc_rx_ack(call, first_soft_ack, ack_reason, nr_acks);
trace_rxrpc_rx_ack(call, first_soft_ack, summary.ack_reason, nr_acks);

_proto("Rx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
sp->hdr.serial,
ntohs(buf.ack.maxSkew),
first_soft_ack,
ntohl(buf.ack.previousPacket),
acked_serial,
rxrpc_ack_names[ack_reason],
rxrpc_ack_names[summary.ack_reason],
buf.ack.nAcks);

if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
Expand Down Expand Up @@ -649,12 +670,13 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
return rxrpc_proto_abort("AKN", call, 0);

if (after(hard_ack, call->tx_hard_ack))
rxrpc_rotate_tx_window(call, hard_ack);
rxrpc_rotate_tx_window(call, hard_ack, &summary);

if (nr_acks > 0) {
if (skb_copy_bits(skb, sp->offset, buf.acks, nr_acks) < 0)
return rxrpc_proto_abort("XSA", call, 0);
rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks);
rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
&summary);
}

if (test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
Expand All @@ -669,11 +691,12 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
*/
static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
{
struct rxrpc_ack_summary summary = { 0 };
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);

_proto("Rx ACKALL %%%u", sp->hdr.serial);

rxrpc_rotate_tx_window(call, call->tx_top);
rxrpc_rotate_tx_window(call, call->tx_top, &summary);
if (test_bit(RXRPC_CALL_TX_LAST, &call->flags))
rxrpc_end_tx_phase(call, false, "ETL");
}
Expand Down

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