Patch "tipc: fix random link resets while adding a second bearer" has been added to the 4.4-stable tree

Patch "tipc: fix random link resets while adding a second bearer" 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: fix random link resets while adding a second bearer

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-fix-random-link-resets-while-adding-a-second-bearer.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 d2f394dc4816b7bd1b44981d83509f18f19c53f0 Mon Sep 17 00:00:00 2001
From: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Date: Thu, 1 Sep 2016 16:22:16 +0200
Subject: tipc: fix random link resets while adding a second bearer

From: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>

commit d2f394dc4816b7bd1b44981d83509f18f19c53f0 upstream.

In a dual bearer configuration, if the second tipc link becomes
active while the first link still has pending nametable "bulk"
updates, it randomly leads to reset of the second link.

When a link is established, the function named_distribute(),
fills the skb based on node mtu (allows room for TUNNEL_PROTOCOL)
with NAME_DISTRIBUTOR message for each PUBLICATION.
However, the function named_distribute() allocates the buffer by
increasing the node mtu by INT_H_SIZE (to insert NAME_DISTRIBUTOR).
This consumes the space allocated for TUNNEL_PROTOCOL.

When establishing the second link, the link shall tunnel all the
messages in the first link queue including the "bulk" update.
As size of the NAME_DISTRIBUTOR messages while tunnelling, exceeds
the link mtu the transmission fails (-EMSGSIZE).

Thus, the synch point based on the message count of the tunnel
packets is never reached leading to link timeout.

In this commit, we adjust the size of name distributor message so that
they can be tunnelled.

Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/tipc/name_distr.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/net/tipc/name_distr.c
+++ b/net/tipc/name_distr.c
@@ -62,6 +62,8 @@ static void publ_to_item(struct distr_it
 
 /**
  * named_prepare_buf - allocate & initialize a publication message
+ *
+ * The buffer returned is of size INT_H_SIZE + payload size
  */
 static struct sk_buff *named_prepare_buf(struct net *net, u32 type, u32 size,
 					 u32 dest)
@@ -166,9 +168,9 @@ static void named_distribute(struct net
 	struct publication *publ;
 	struct sk_buff *skb = NULL;
 	struct distr_item *item = NULL;
-	uint msg_dsz = (tipc_node_get_mtu(net, dnode, 0) / ITEM_SIZE) *
-			ITEM_SIZE;
-	uint msg_rem = msg_dsz;
+	u32 msg_dsz = ((tipc_node_get_mtu(net, dnode, 0) - INT_H_SIZE) /
+			ITEM_SIZE) * ITEM_SIZE;
+	u32 msg_rem = msg_dsz;
 
 	list_for_each_entry(publ, pls, local_list) {
 		/* Prepare next buffer: */


Patches currently in stable-queue which might be from parthasarathy.bhuvaragan@ericsson.com are

queue-4.4/tipc-fix-random-link-resets-while-adding-a-second-bearer.patch