linux-stable/net/tipc
Jon Paul Maloy 2be80c2d87 tipc: fix stale link problem during synchronization
Recent changes to the link synchronization means that we can now just
drop packets arriving on the synchronizing link before the synch point
is reached. This has lead to significant simplifications to the
implementation, but also turns out to have a flip side that we need
to consider.

Under unlucky circumstances, the two endpoints may end up
repeatedly dropping each other's packets, while immediately
asking for retransmission of the same packets, just to drop
them once more. This pattern will eventually be broken when
the synch point is reached on the other link, but before that,
the endpoints may have arrived at the retransmission limit
(stale counter) that indicates that the link should be broken.
We see this happen at rare occasions.

The fix for this is to not ask for retransmissions when a link is in
state LINK_SYNCHING. The fact that the link has reached this state
means that it has already received the first SYNCH packet, and that it
knows the synch point. Hence, it doesn't need any more packets until the
other link has reached the synch point, whereafter it can go ahead and
ask for the missing packets.

However, because of the reduced traffic on the synching link that
follows this change, it may now take longer to discover that the
synch point has been reached. We compensate for this by letting all
packets, on any of the links, trig a check for synchronization
termination. This is possible because the packets themselves don't
contain any information that is needed for discovering this condition.

Reviewed-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>
2015-08-23 16:14:45 -07:00
..
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: reduce locking scope during packet reception 2015-07-20 20:41:16 -07:00
bcast.h tipc: reduce locking scope during packet reception 2015-07-20 20:41:16 -07:00
bearer.c tipc: move all link_reset() calls to link aggregation level 2015-07-30 17:25:13 -07:00
bearer.h tipc: make media xmit call outside node spinlock context 2015-07-20 20:41:15 -07:00
core.c tipc: rename functions defined in subscr.c 2015-05-04 15:04:00 -04:00
core.h tipc: clean up link creation 2015-07-30 17:25:15 -07:00
discover.c tipc: move received discovery data evaluation inside node.c 2015-07-30 17:25:14 -07:00
discover.h tipc: involve namespace infrastructure 2015-01-12 16:24:32 -05:00
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: fix stale link problem during synchronization 2015-08-23 16:14:45 -07:00
link.h tipc: clean up link creation 2015-07-30 17:25:15 -07:00
Makefile tipc: add ip/udp media type 2015-03-05 22:08:42 -05:00
msg.c tipc: clean up socket layer message reception 2015-07-26 16:31:50 -07:00
msg.h tipc: remove implicit message delivery in node_unlock() 2015-07-30 17:25:14 -07:00
name_distr.c tipc: make media xmit call outside node spinlock context 2015-07-20 20:41:15 -07:00
name_distr.h tipc: resolve race problem at unicast message reception 2015-02-05 16:00:02 -08:00
name_table.c tipc: rename functions defined in subscr.c 2015-05-04 15:04:00 -04:00
name_table.h tipc: convert legacy nl name table dump to nl compat 2015-02-09 13:20:48 -08:00
net.c tipc: simplify include dependencies 2015-05-14 12:24:45 -04:00
net.h tipc: make tipc node table aware of net namespace 2015-01-12 16:24:32 -05:00
netlink.c tipc: move and rename the legacy nl api to "nl compat" 2015-02-09 13:20:47 -08:00
netlink.h tipc: move and rename the legacy nl api to "nl compat" 2015-02-09 13:20:47 -08:00
netlink_compat.c tipc: don't sanity check non-existing TLV (NL compat) 2015-08-17 10:39:54 -07:00
node.c tipc: fix stale link problem during synchronization 2015-08-23 16:14:45 -07:00
node.h tipc: remove implicit message delivery in node_unlock() 2015-07-30 17:25:14 -07:00
server.c tipc: use sock_create_kern interface to create kernel socket 2015-05-14 13:39:33 -04:00
server.h tipc: make subscriber server support net namespace 2015-01-12 16:24:33 -05:00
socket.c tipc: clean up socket layer message reception 2015-07-26 16:31:50 -07:00
socket.h tipc: clean up socket layer message reception 2015-07-26 16:31:50 -07:00
subscr.c tipc: adjust locking policy of subscription 2015-05-04 15:04:01 -04:00
subscr.h tipc: rename functions defined in subscr.c 2015-05-04 15:04:00 -04:00
sysctl.c tipc: add name distributor resiliency queue 2014-09-01 17:51:48 -07:00
udp_media.c ipv6: change ipv6_stub_impl.ipv6_dst_lookup to take net argument 2015-07-31 15:21:30 -07:00