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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From 7c8bcfb1255fe9d929c227d67bdcd84430fd200b Mon Sep 17 00:00:00 2001
From: Jon Paul Maloy <jon.maloy@ericsson.com>
Date: Mon, 2 May 2016 11:58:45 -0400
Subject: tipc: re-enable compensation for socket receive buffer double counting

From: Jon Paul Maloy <jon.maloy@ericsson.com>

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.

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -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 jon.maloy@ericsson.com 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