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authorDavid Howells <dhowells@redhat.com>2016-09-23 12:39:22 +0100
committerDavid Howells <dhowells@redhat.com>2016-09-23 15:49:19 +0100
commit70790dbe3f6651fb66ad38da0a1e24368778bc16 (patch)
treebaa3dd1cf168385d24f7b631a6a75763f6b82cd4 /net/rxrpc/input.c
parent01a88f7f6bd4514de9551c3fc9a6fd9e65cbf79d (diff)
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rxrpc: Pass the last Tx packet marker in the annotation buffer
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@redhat.com>
Diffstat (limited to 'net/rxrpc/input.c')
-rw-r--r--net/rxrpc/input.c102
1 files changed, 67 insertions, 35 deletions
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");
}
/*