Patch "tipc: re-enable compensation for socket receive buffer double counting" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

tipc: re-enable compensation for socket receive buffer double counting

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
tipc-re-enable-compensation-for-socket-receive-buffer-double-counting.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jon Paul Maloy <[email protected]>
Date: Mon, 2 May 2016 11:58:45 -0400
Subject: tipc: re-enable compensation for socket receive buffer double counting

From: Jon Paul Maloy <[email protected]>

commit 7c8bcfb1255fe9d929c227d67bdcd84430fd200b upstream.

In the refactoring commit d570d86497ee ("tipc: enqueue arrived buffers in socket in separate function") we did by accident replace the test

if (sk->sk_backlog.len == 0)

     atomic_set(&tsk->dupl_rcvcnt, 0);

with

if (sk->sk_backlog.len)

     atomic_set(&tsk->dupl_rcvcnt, 0);

This effectively disables the compensation we have for the double receive buffer accounting that occurs temporarily when buffers are moved from the backlog to the socket receive queue. Until now, this has gone unnoticed because of the large receive buffer limits we are applying, but becomes indispensable when we reduce this buffer limit later in this series.

We now fix this by inverting the mentioned condition.

---
 net/tipc/socket.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -1755,7 +1755,7 @@ static void tipc_sk_enqueue(struct sk_bu
 
 		/* Try backlog, compensating for double-counted bytes */
 		dcnt = &tipc_sk(sk)->dupl_rcvcnt;
-		if (sk->sk_backlog.len)
+		if (!sk->sk_backlog.len)
 			atomic_set(dcnt, 0);
 		lim = rcvbuf_limit(sk, skb) + atomic_read(dcnt);
 		if (likely(!sk_add_backlog(sk, skb, lim)))

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/tipc-make-sure-ipv6-header-fits-in-skb-headroom.patch queue-4.4/tipc-make-dist-queue-pernet.patch queue-4.4/tipc-correct-error-in-node-fsm.patch queue-4.4/tipc-re-enable-compensation-for-socket-receive-buffer-double-counting.patch