From: David Howells <dhowells@redhat.com>
Date: Sat, 17 Sep 2016 09:49:13 +0000 (+0100)
Subject: rxrpc: Don't transmit an ACK if there's no reason set
X-Git-Tag: v4.9-rc1~127^2~153^2~2
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=27d0fc431c6b4847231c1490fa541bc3f5a7a351;p=karo-tx-linux.git

rxrpc: Don't transmit an ACK if there's no reason set

Don't transmit an ACK if call->ackr_reason in unset.  There's the
possibility of a race between recvmsg() sending an ACK and the background
processing thread trying to send the same one.

Signed-off-by: David Howells <dhowells@redhat.com>
---

diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index 06a9aca739d1..aa0507214b31 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -137,6 +137,11 @@ int rxrpc_send_call_packet(struct rxrpc_call *call, u8 type)
 	switch (type) {
 	case RXRPC_PACKET_TYPE_ACK:
 		spin_lock_bh(&call->lock);
+		if (!call->ackr_reason) {
+			spin_unlock_bh(&call->lock);
+			ret = 0;
+			goto out;
+		}
 		n = rxrpc_fill_out_ack(call, pkt);
 		call->ackr_reason = 0;