Commit a2ad7c21 authored Jun 17, 2020 by David Howells

rxrpc: Fix handling of rwind from an ACK packet



The handling of the receive window size (rwind) from a received ACK packet
is not correct.  The rxrpc_input_ackinfo() function currently checks the
current Tx window size against the rwind from the ACK to see if it has
changed, but then limits the rwind size before storing it in the tx_winsize
member and, if it increased, wake up the transmitting process.  This means
that if rwind > RXRPC_RXTX_BUFF_SIZE - 1, this path will always be
followed.

Fix this by limiting rwind before we compare it to tx_winsize.

The effect of this can be seen by enabling the rxrpc_rx_rwind_change
tracepoint.

Fixes: 702f2ac8 ("rxrpc: Wake up the transmitter if Rx window size increases on the peer")
Signed-off-by: David Howells <dhowells@redhat.com>

parent aadf9dce

net/rxrpc/input.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -722,13 +722,12 @@ static void rxrpc_input_ackinfo(struct rxrpc_call call, struct sk_buff skb,
		ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
		rwind, ntohl(ackinfo->jumbo_max));

		if (call->tx_winsize != rwind) {
		if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
		rwind = RXRPC_RXTX_BUFF_SIZE - 1;
		if (call->tx_winsize != rwind) {
		if (rwind > call->tx_winsize)
		wake = true;
		trace_rxrpc_rx_rwind_change(call, sp->hdr.serial,
		ntohl(ackinfo->rwind), wake);
		trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
		call->tx_winsize = rwind;
		}

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