linux/net/tipc
Jon Paul Maloy 634696b197 tipc: guarantee peer bearer id exchange after reboot
When a link endpoint is going down locally, e.g., because its interface
is being stopped, it will spontaneously send out a RESET message to
its peer, informing it about this fact. This saves the peer from
detecting the failure via probing, and hence gives both speedier and
less resource consuming failure detection on the peer side.

According to the link FSM, a receiver of a RESET message, ignoring the
reason for it, must now consider the sender ready to come back up, and
starts periodically sending out ACTIVATE messages to the peer in order
to re-establish the link. Also, according to the FSM, the receiver of
an ACTIVATE message can now go directly to state ESTABLISHED and start
sending regular traffic packets. This is a well-proven and robust FSM.

However, in the case of a reboot, there is a small possibilty that link
endpoint on the rebooted node may have been re-created with a new bearer
identity between the moment it sent its (pre-boot) RESET and the moment
it receives the ACTIVATE from the peer. The new bearer identity cannot
be known by the peer according to this scenario, since traffic headers
don't convey such information. This is a problem, because both endpoints
need to know the correct value of the peer's bearer id at any moment in
time in order to be able to produce correct link events for their users.

The only way to guarantee this is to enforce a full setup message
exchange (RESET + ACTIVATE) even after the reboot, since those messages
carry the bearer idientity in their header.

In this commit we do this by introducing and setting a "stopping" bit in
the header of the spontaneously generated RESET messages, informing the
peer that the sender will not be immediately ready to re-establish the
link. A receiver seeing this bit must act as if this were a locally
detected connectivity failure, and hence has to go through a full two-
way setup message exchange before any link can be re-established.

Although never reported, this problem seems to have always been around.

This protocol addition is fully backwards compatible.

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>
2016-04-15 16:09:05 -04:00
..
addr.c tipc: simplify include dependencies 2015-05-14 12:24:45 -04:00
addr.h tipc: simplify include dependencies 2015-05-14 12:24:45 -04:00
bcast.c tipc: remove pre-allocated message header in link struct 2016-03-06 23:01:20 -05:00
bcast.h tipc: remove pre-allocated message header in link struct 2016-03-06 23:01:20 -05:00
bearer.c tipc: stricter filtering of packets in bearer layer 2016-04-07 17:00:13 -04:00
bearer.h tipc: remove remnants of old broadcast code 2016-04-13 17:49:11 -04:00
core.c tipc: create broadcast transmission link at namespace init 2015-10-24 06:56:27 -07:00
core.h tipc: reduce code dependency between binding table and node layer 2015-11-20 14:06:10 -05:00
discover.c tipc: eliminate buffer leak in bearer layer 2016-04-07 17:00:13 -04:00
discover.h tipc: eliminate buffer leak in bearer layer 2016-04-07 17:00:13 -04:00
eth_media.c tipc: make media address offset a common define 2015-02-27 18:18:48 -05:00
ib_media.c tipc: rename media/msg related definitions 2015-02-27 18:18:48 -05:00
Kconfig tipc: add ip/udp media type 2015-03-05 22:08:42 -05:00
link.c tipc: guarantee peer bearer id exchange after reboot 2016-04-15 16:09:05 -04:00
link.h tipc: remove pre-allocated message header in link struct 2016-03-06 23:01:20 -05:00
Makefile tipc: add ip/udp media type 2015-03-05 22:08:42 -05:00
msg.c tipc: let broadcast packet reception use new link receive function 2015-10-24 06:56:37 -07:00
msg.h tipc: guarantee peer bearer id exchange after reboot 2016-04-15 16:09:05 -04:00
name_distr.c tipc: reduce code dependency between binding table and node layer 2015-11-20 14:06:10 -05:00
name_distr.h tipc: reduce code dependency between binding table and node layer 2015-11-20 14:06:10 -05:00
name_table.c tipc: move netlink policies to netlink.c 2016-03-07 14:56:41 -05:00
name_table.h
net.c tipc: move netlink policies to netlink.c 2016-03-07 14:56:41 -05:00
net.h
netlink_compat.c tipc: fix null deref crash in compat config path 2016-02-25 17:04:48 -05:00
netlink.c tipc: move netlink policies to netlink.c 2016-03-07 14:56:41 -05:00
netlink.h tipc: move netlink policies to netlink.c 2016-03-07 14:56:41 -05:00
node.c tipc: move netlink policies to netlink.c 2016-03-07 14:56:41 -05:00
node.h tipc: narrow down interface towards struct tipc_link 2015-11-20 14:06:10 -05:00
server.c tipc: fix a race condition leading to subscriber refcnt bug 2016-04-14 16:46:46 -04:00
server.h tipc: fix a race condition leading to subscriber refcnt bug 2016-04-14 16:46:46 -04:00
socket.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-03-08 12:34:12 -05:00
socket.h tipc: clean up socket layer message reception 2015-07-26 16:31:50 -07:00
subscr.c tipc: fix a race condition leading to subscriber refcnt bug 2016-04-14 16:46:46 -04:00
subscr.h tipc: remove struct tipc_name_seq from struct tipc_subscription 2016-02-06 03:40:43 -05:00
sysctl.c
udp_media.c tipc: make sure IPv6 header fits in skb headroom 2016-03-14 12:23:12 -04:00