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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, David Howells <dhowells@redhat.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.16 095/272] rxrpc: Fix Tx ring annotation after initial Tx failure
Date:   Mon, 28 May 2018 12:02:08 +0200
Message-Id: <20180528100249.152143582@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

[ Upstream commit 03877bf6a30cca7d4bc3ffabd3c3e9464a7a1a19 ]

rxrpc calls have a ring of packets that are awaiting ACK or retransmission
and a parallel ring of annotations that tracks the state of those packets.
If the initial transmission of a packet on the underlying UDP socket fails
then the packet annotation is marked for resend - but the setting of this
mark accidentally erases the last-packet mark also stored in the same
annotation slot.  If this happens, a call won't switch out of the Tx phase
when all the packets have been transmitted.

Fix this by retaining the last-packet mark and only altering the packet
state.

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/rxrpc/sendmsg.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -130,7 +130,9 @@ static inline void rxrpc_instant_resend(
 	spin_lock_bh(&call->lock);
 
 	if (call->state < RXRPC_CALL_COMPLETE) {
-		call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS;
+		call->rxtx_annotations[ix] =
+			(call->rxtx_annotations[ix] & RXRPC_TX_ANNO_LAST) |
+			RXRPC_TX_ANNO_RETRANS;
 		if (!test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 			rxrpc_queue_call(call);
 	}