[PATCH net-next 09/15] rxrpc: Pass the last Tx packet marker in the annotation buffer
From: David Howells
Date: Fri Sep 23 2016 - 11:16:29 EST
When the last packet of data to be transmitted on a call is queued, tx_top
is set and then the RXRPC_CALL_TX_LAST flag is set. Unfortunately, this
leaves a race in the ACK processing side of things because the flag affects
the interpretation of tx_top and also allows us to start receiving reply
data before we've finished transmitting.
To fix this, make the following changes:
(1) rxrpc_queue_packet() now sets a marker in the annotation buffer
instead of setting the RXRPC_CALL_TX_LAST flag.
(2) rxrpc_rotate_tx_window() detects the marker and sets the flag in the
same context as the routines that use it.
(3) rxrpc_end_tx_phase() is simplified to just shift the call state.
The Tx window must have been rotated before calling to discard the
last packet.
(4) rxrpc_receiving_reply() is added to handle the arrival of the first
DATA packet of a reply to a client call (which is an implicit ACK of
the Tx phase).
(5) The last part of rxrpc_input_ack() is reordered to perform Tx
rotation, then soft-ACK application and then to end the phase if we've
rotated the last packet. In the event of a terminal ACK, the soft-ACK
application will be skipped as nAcks should be 0.
(6) rxrpc_input_ackall() now has to rotate as well as ending the phase.
In addition:
(7) Alter the transmit tracepoint to log the rotation of the last packet.
(8) Remove the no-longer relevant queue_reqack tracepoint note. The
ACK-REQUESTED packet header flag is now set as needed when we actually
transmit the packet and may vary by retransmission.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
net/rxrpc/ar-internal.h | 7 ++-
net/rxrpc/input.c | 102 +++++++++++++++++++++++++++++++----------------
net/rxrpc/misc.c | 3 +
net/rxrpc/sendmsg.c | 14 +++---
4 files changed, 81 insertions(+), 45 deletions(-)
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 9e3ba4dc9578..a494d56eb236 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -508,7 +508,9 @@ struct rxrpc_call {
#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_TX_ANNO_LAST 0x04
+#define RXRPC_TX_ANNO_RESENT 0x08
+
#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 */
@@ -621,9 +623,10 @@ extern const char rxrpc_call_traces[rxrpc_call__nr_trace][4];
enum rxrpc_transmit_trace {
rxrpc_transmit_wait,
rxrpc_transmit_queue,
- rxrpc_transmit_queue_reqack,
rxrpc_transmit_queue_last,
rxrpc_transmit_rotate,
+ rxrpc_transmit_rotate_last,
+ rxrpc_transmit_await_reply,
rxrpc_transmit_end,
rxrpc_transmit__nr_trace
};
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index d3d69ab1f0a1..fb3e2f6afa3b 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -59,6 +59,7 @@ static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to)
{
struct sk_buff *skb, *list = NULL;
int ix;
+ u8 annotation;
spin_lock(&call->lock);
@@ -66,16 +67,22 @@ static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to)
call->tx_hard_ack++;
ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
skb = call->rxtx_buffer[ix];
+ annotation = call->rxtx_annotations[ix];
rxrpc_see_skb(skb, rxrpc_skb_tx_rotated);
call->rxtx_buffer[ix] = NULL;
call->rxtx_annotations[ix] = 0;
skb->next = list;
list = skb;
+
+ if (annotation & RXRPC_TX_ANNO_LAST)
+ set_bit(RXRPC_CALL_TX_LAST, &call->flags);
}
spin_unlock(&call->lock);
- trace_rxrpc_transmit(call, rxrpc_transmit_rotate);
+ trace_rxrpc_transmit(call, (test_bit(RXRPC_CALL_TX_LAST, &call->flags) ?
+ rxrpc_transmit_rotate_last :
+ rxrpc_transmit_rotate));
wake_up(&call->waitq);
while (list) {
@@ -92,42 +99,65 @@ static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to)
* This occurs when we get an ACKALL packet, the first DATA packet of a reply,
* or a final ACK packet.
*/
-static bool rxrpc_end_tx_phase(struct rxrpc_call *call, const char *abort_why)
+static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
+ const char *abort_why)
{
- _enter("");
-
- switch (call->state) {
- case RXRPC_CALL_CLIENT_RECV_REPLY:
- return true;
- case RXRPC_CALL_CLIENT_AWAIT_REPLY:
- case RXRPC_CALL_SERVER_AWAIT_ACK:
- break;
- default:
- rxrpc_proto_abort(abort_why, call, call->tx_top);
- return false;
- }
- rxrpc_rotate_tx_window(call, call->tx_top);
+ ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
write_lock(&call->state_lock);
switch (call->state) {
- default:
- break;
+ case RXRPC_CALL_CLIENT_SEND_REQUEST:
case RXRPC_CALL_CLIENT_AWAIT_REPLY:
- call->tx_phase = false;
- call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
+ if (reply_begun)
+ call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
+ else
+ call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
break;
+
case RXRPC_CALL_SERVER_AWAIT_ACK:
__rxrpc_call_completed(call);
rxrpc_notify_socket(call);
break;
+
+ default:
+ goto bad_state;
}
write_unlock(&call->state_lock);
- trace_rxrpc_transmit(call, rxrpc_transmit_end);
+ if (call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY) {
+ trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
+ } else {
+ trace_rxrpc_transmit(call, rxrpc_transmit_end);
+ }
_leave(" = ok");
return true;
+
+bad_state:
+ write_unlock(&call->state_lock);
+ kdebug("end_tx %s", rxrpc_call_states[call->state]);
+ rxrpc_proto_abort(abort_why, call, call->tx_top);
+ return false;
+}
+
+/*
+ * Begin the reply reception phase of a call.
+ */
+static bool rxrpc_receiving_reply(struct rxrpc_call *call)
+{
+ rxrpc_seq_t top = READ_ONCE(call->tx_top);
+
+ if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags))
+ rxrpc_rotate_tx_window(call, top);
+ if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
+ rxrpc_proto_abort("TXL", call, top);
+ return false;
+ }
+ if (!rxrpc_end_tx_phase(call, true, "ETD"))
+ return false;
+ call->tx_phase = false;
+ return true;
}
/*
@@ -226,8 +256,9 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb,
/* Received data implicitly ACKs all of the request packets we sent
* when we're acting as a client.
*/
- if (call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY &&
- !rxrpc_end_tx_phase(call, "ETD"))
+ if ((call->state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
+ call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
+ !rxrpc_receiving_reply(call))
return;
call->ackr_prev_seq = seq;
@@ -587,27 +618,26 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
}
call->acks_latest = sp->hdr.serial;
- if (test_bit(RXRPC_CALL_TX_LAST, &call->flags) &&
- hard_ack == call->tx_top) {
- rxrpc_end_tx_phase(call, "ETA");
- return;
- }
-
if (before(hard_ack, call->tx_hard_ack) ||
after(hard_ack, call->tx_top))
return rxrpc_proto_abort("AKW", call, 0);
+ if (nr_acks > call->tx_top - hard_ack)
+ return rxrpc_proto_abort("AKN", call, 0);
if (after(hard_ack, call->tx_hard_ack))
rxrpc_rotate_tx_window(call, hard_ack);
- if (after(first_soft_ack, call->tx_top))
+ 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);
+ }
+
+ if (test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
+ rxrpc_end_tx_phase(call, false, "ETA");
return;
+ }
- if (nr_acks > call->tx_top - first_soft_ack + 1)
- nr_acks = first_soft_ack - call->tx_top + 1;
- 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);
}
/*
@@ -619,7 +649,9 @@ static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
_proto("Rx ACKALL %%%u", sp->hdr.serial);
- rxrpc_end_tx_phase(call, "ETL");
+ rxrpc_rotate_tx_window(call, call->tx_top);
+ if (test_bit(RXRPC_CALL_TX_LAST, &call->flags))
+ rxrpc_end_tx_phase(call, false, "ETL");
}
/*
diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c
index 0d425e707f22..fe648711c2f7 100644
--- a/net/rxrpc/misc.c
+++ b/net/rxrpc/misc.c
@@ -155,9 +155,10 @@ const char rxrpc_client_traces[rxrpc_client__nr_trace][7] = {
const char rxrpc_transmit_traces[rxrpc_transmit__nr_trace][4] = {
[rxrpc_transmit_wait] = "WAI",
[rxrpc_transmit_queue] = "QUE",
- [rxrpc_transmit_queue_reqack] = "QRA",
[rxrpc_transmit_queue_last] = "QLS",
[rxrpc_transmit_rotate] = "ROT",
+ [rxrpc_transmit_rotate_last] = "RLS",
+ [rxrpc_transmit_await_reply] = "AWR",
[rxrpc_transmit_end] = "END",
};
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 7cb34b2dfba9..93e6584cd751 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -94,11 +94,15 @@ static void rxrpc_queue_packet(struct rxrpc_call *call, struct sk_buff *skb,
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
rxrpc_seq_t seq = sp->hdr.seq;
int ret, ix;
+ u8 annotation = RXRPC_TX_ANNO_UNACK;
_net("queue skb %p [%d]", skb, seq);
ASSERTCMP(seq, ==, call->tx_top + 1);
+ if (last)
+ annotation |= RXRPC_TX_ANNO_LAST;
+
/* We have to set the timestamp before queueing as the retransmit
* algorithm can see the packet as soon as we queue it.
*/
@@ -106,18 +110,14 @@ static void rxrpc_queue_packet(struct rxrpc_call *call, struct sk_buff *skb,
ix = seq & RXRPC_RXTX_BUFF_MASK;
rxrpc_get_skb(skb, rxrpc_skb_tx_got);
- call->rxtx_annotations[ix] = RXRPC_TX_ANNO_UNACK;
+ call->rxtx_annotations[ix] = annotation;
smp_wmb();
call->rxtx_buffer[ix] = skb;
call->tx_top = seq;
- if (last) {
- set_bit(RXRPC_CALL_TX_LAST, &call->flags);
+ if (last)
trace_rxrpc_transmit(call, rxrpc_transmit_queue_last);
- } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
- trace_rxrpc_transmit(call, rxrpc_transmit_queue_reqack);
- } else {
+ else
trace_rxrpc_transmit(call, rxrpc_transmit_queue);
- }
if (last || call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
_debug("________awaiting reply/ACK__________");