Commit 4ee4c2f8 authored by David Howells's avatar David Howells Committed by Jakub Kicinski
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rxrpc: Fix request for an ACK when cwnd is minimum 



rxrpc_prepare_data_subpacket() sets the REQUEST-ACK flag on the outgoing
DATA packet under a number of circumstances, including, theoretically, when
the cwnd is at minimum (or less).  However, the minimum in this function is
hard-coded as 2, but the actual minimum is RXRPC_MIN_CWND (which is
currently 4) and so this never occurs.

Without this, we will miss the request of some ACKs, potentially leading to
a transmission stall until a timeout occurs on one side or the other that
leads to an ACK being generated.

Fix the function to use RXRPC_MIN_CWND rather than a hard-coded number.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent b40ef2b8

net/rxrpc/output.c

+1 −1
Original line number Diff line number Diff line
@@ -469,7 +469,7 @@ static size_t rxrpc_prepare_data_subpacket(struct rxrpc_call *call, 
		why = rxrpc_reqack_ack_lost;

	else if (txb->flags & RXRPC_TXBUF_RESENT)

		why = rxrpc_reqack_retrans;

	else if (call->cong_ca_state == RXRPC_CA_SLOW_START && call->cong_cwnd <= 2)

	else if (call->cong_ca_state == RXRPC_CA_SLOW_START && call->cong_cwnd <= RXRPC_MIN_CWND)

		why = rxrpc_reqack_slow_start;

	else if (call->tx_winsize <= 2)

		why = rxrpc_reqack_small_txwin;