rxrpc: Move DATA transmission into call processor work item

Move DATA transmission into the call processor work item.  In a future
patch, this will be called from the I/O thread rather than being itsown
work item.

This will allow DATA transmission to be driven directly by incoming ACKs,
pokes and timers as those are processed.

The Tx queue is also split: The queue of packets prepared by sendmsg is now
places in call->tx_sendmsg and the packet dispatcher decants the packets
into call->tx_buffer as space becomes available in the transmission
window.  This allows sendmsg to run ahead of the available space to try and
prevent an underflow in transmission.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

1 files changed, 13 insertions, 70 deletions

diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 76b1e2e89c1e..11af37275d5b 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -22,30 +22,9 @@
  */
 static bool rxrpc_check_tx_space(struct rxrpc_call *call, rxrpc_seq_t *_tx_win)
 {
-	unsigned int win_size;
-	rxrpc_seq_t tx_win = smp_load_acquire(&call->acks_hard_ack);
-
-	/* If we haven't transmitted anything for >1RTT, we should reset the
-	 * congestion management state.
-	 */
-	if (ktime_before(ktime_add_us(call->tx_last_sent,
-				      call->peer->srtt_us >> 3),
-			 ktime_get_real())) {
-		if (RXRPC_TX_SMSS > 2190)
-			win_size = 2;
-		else if (RXRPC_TX_SMSS > 1095)
-			win_size = 3;
-		else
-			win_size = 4;
-		win_size += call->cong_extra;
-	} else {
-		win_size = min_t(unsigned int, call->tx_winsize,
-				 call->cong_cwnd + call->cong_extra);
-	}
-
 	if (_tx_win)
-		*_tx_win = tx_win;
-	return call->tx_top - tx_win < win_size;
+		*_tx_win = call->tx_bottom;
+	return call->tx_prepared - call->tx_bottom < 256;
 }
 
 /*
@@ -66,11 +45,6 @@ static int rxrpc_wait_for_tx_window_intr(struct rxrpc_sock *rx,
 		if (signal_pending(current))
 			return sock_intr_errno(*timeo);
 
-		if (READ_ONCE(call->acks_hard_ack) != call->tx_bottom) {
-			rxrpc_shrink_call_tx_buffer(call);
-			continue;
-		}
-
 		trace_rxrpc_txqueue(call, rxrpc_txqueue_wait);
 		*timeo = schedule_timeout(*timeo);
 	}
@@ -107,11 +81,6 @@ static int rxrpc_wait_for_tx_window_waitall(struct rxrpc_sock *rx,
 		    tx_win == tx_start && signal_pending(current))
 			return -EINTR;
 
-		if (READ_ONCE(call->acks_hard_ack) != call->tx_bottom) {
-			rxrpc_shrink_call_tx_buffer(call);
-			continue;
-		}
-
 		if (tx_win != tx_start) {
 			timeout = rtt;
 			tx_start = tx_win;
@@ -137,11 +106,6 @@ static int rxrpc_wait_for_tx_window_nonintr(struct rxrpc_sock *rx,
 		if (call->state >= RXRPC_CALL_COMPLETE)
 			return call->error;
 
-		if (READ_ONCE(call->acks_hard_ack) != call->tx_bottom) {
-			rxrpc_shrink_call_tx_buffer(call);
-			continue;
-		}
-
 		trace_rxrpc_txqueue(call, rxrpc_txqueue_wait);
 		*timeo = schedule_timeout(*timeo);
 	}
@@ -207,29 +171,27 @@ static void rxrpc_queue_packet(struct rxrpc_sock *rx, struct rxrpc_call *call,
 	unsigned long now;
 	rxrpc_seq_t seq = txb->seq;
 	bool last = test_bit(RXRPC_TXBUF_LAST, &txb->flags);
-	int ret;
 
 	rxrpc_inc_stat(call->rxnet, stat_tx_data);
 
-	ASSERTCMP(seq, ==, call->tx_top + 1);
+	ASSERTCMP(txb->seq, ==, call->tx_prepared + 1);
 
 	/* We have to set the timestamp before queueing as the retransmit
 	 * algorithm can see the packet as soon as we queue it.
 	 */
 	txb->last_sent = ktime_get_real();
 
-	/* Add the packet to the call's output buffer */
-	rxrpc_get_txbuf(txb, rxrpc_txbuf_get_buffer);
-	spin_lock(&call->tx_lock);
-	list_add_tail(&txb->call_link, &call->tx_buffer);
-	call->tx_top = seq;
-	spin_unlock(&call->tx_lock);
-
 	if (last)
 		trace_rxrpc_txqueue(call, rxrpc_txqueue_queue_last);
 	else
 		trace_rxrpc_txqueue(call, rxrpc_txqueue_queue);
 
+	/* Add the packet to the call's output buffer */
+	spin_lock(&call->tx_lock);
+	list_add_tail(&txb->call_link, &call->tx_sendmsg);
+	call->tx_prepared = seq;
+	spin_unlock(&call->tx_lock);
+
 	if (last || call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
 		_debug("________awaiting reply/ACK__________");
 		write_lock_bh(&call->state_lock);
@@ -258,30 +220,11 @@ static void rxrpc_queue_packet(struct rxrpc_sock *rx, struct rxrpc_call *call,
 		write_unlock_bh(&call->state_lock);
 	}
 
-	if (seq == 1 && rxrpc_is_client_call(call))
-		rxrpc_expose_client_call(call);
-
-	ret = rxrpc_send_data_packet(call, txb);
-	if (ret < 0) {
-		switch (ret) {
-		case -ENETUNREACH:
-		case -EHOSTUNREACH:
-		case -ECONNREFUSED:
-			rxrpc_set_call_completion(call, RXRPC_CALL_LOCAL_ERROR,
-						  0, ret);
-			goto out;
-		}
-	} else {
-		unsigned long now = jiffies;
-		unsigned long resend_at = now + call->peer->rto_j;
 
-		WRITE_ONCE(call->resend_at, resend_at);
-		rxrpc_reduce_call_timer(call, resend_at, now,
-					rxrpc_timer_set_for_send);
-	}
-
-out:
-	rxrpc_put_txbuf(txb, rxrpc_txbuf_put_trans);
+	/* Stick the packet on the crypto queue or the transmission queue as
+	 * appropriate.
+	 */
+	rxrpc_queue_call(call, rxrpc_call_queue_tx_data);
 }
 
 /*