From 70790dbe3f6651fb66ad38da0a1e24368778bc16 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 23 Sep 2016 12:39:22 +0100 Subject: 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 --- net/rxrpc/input.c | 102 +++++++++++++++++++++++++++++++++++------------------- 1 file changed, 67 insertions(+), 35 deletions(-) (limited to 'net/rxrpc/input.c') 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"); } /* -- cgit v1.2.3