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  1. 12 7月, 2016 1 次提交
    • J
      tipc: extend broadcast link initialization criteria · 2d18ac4b
      由 Jon Paul Maloy 提交于 
      At first contact between two nodes, an endpoint might sometimes have
time to send out a LINK_PROTOCOL/STATE packet before it has received
the broadcast initialization packet from the peer, i.e., before it has
received a valid broadcast packet number to add to the 'bc_ack' field
of the protocol message.

This means that the peer endpoint will receive a protocol packet with an
invalid broadcast acknowledge value of 0. Under unlucky circumstances
this may lead to the original, already received acknowledge value being
overwritten, so that the whole broadcast link goes stale after a while.

We fix this by delaying the setting of the link field 'bc_peer_is_up'
until we know that the peer really has received our own broadcast
initialization message. The latter is always sent out as the first
unicast message on a link, and always with seqeunce number 1. Because
of this, we only need to look for a non-zero unicast acknowledge value
in the arriving STATE messages, and once that is confirmed we know we
are safe and can set the mentioned field. Before this moment, we must
ignore all broadcast acknowledges from the peer.
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      2d18ac4b
  3. 16 6月, 2016 1 次提交
  5. 25 4月, 2016 1 次提交
  7. 16 4月, 2016 4 次提交
    • J
      tipc: let first message on link be a state message · 34b9cd64
      由 Jon Paul Maloy 提交于 
      According to the link FSM, a received traffic packet can take a link
from state ESTABLISHING to ESTABLISHED, but the link can still not be
fully set up in one atomic operation. This means that even if the the
very first packet on the link is a traffic packet with sequence number
1 (one), it has to be dropped and retransmitted.

This can be avoided if we let the mentioned packet be preceded by a
LINK_PROTOCOL/STATE message, which takes up the endpoint before the
arrival of the traffic.

We add this small feature in this commit.

This is a fully compatible change.
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      34b9cd64
    • J
      tipc: refactor function tipc_link_timeout() · 42b18f60
      由 Jon Paul Maloy 提交于 
      The function tipc_link_timeout() is unnecessary complex, and can
easily be made more readable.

We do that with this commit. The only functional change is that we
remove a redundant test for whether the broadcast link is up or not.
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      42b18f60
    • J
      tipc: reduce transmission rate of reset messages when link is down · 88e8ac70
      由 Jon Paul Maloy 提交于 
      When a link is down, it will continuously try to re-establish contact
with the peer by sending out a RESET or an ACTIVATE message at each
timeout interval. The default value for this interval is currently
375 ms. This is wasteful, and may become a problem in very large
clusters with dozens or hundreds of nodes being down simultaneously.

We now introduce a simple backoff algorithm for these cases. The
first five messages are sent at default rate; thereafter a message
is sent only each 16th timer interval.

This will cover the vast majority of link recycling cases, since the
endpoint starting last will transmit at the higher speed, and the link
should normally be established well be before the rate needs to be
reduced.

The only case where we will see a degradation of link re-establishment
times is when the endpoints remain intact, and a glitch in the
transmission media is causing the link reset. We will then experience
a worst-case re-establishing time of 6 seconds, something we deem
acceptable.
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      88e8ac70
    • J
      tipc: guarantee peer bearer id exchange after reboot · 634696b1
      由 Jon Paul Maloy 提交于 
      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: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      634696b1
  9. 08 3月, 2016 1 次提交
  11. 07 3月, 2016 1 次提交
  13. 20 2月, 2016 1 次提交
  15. 17 2月, 2016 1 次提交
  17. 06 2月, 2016 2 次提交
  19. 21 11月, 2015 7 次提交
    • J
      tipc: correct settings of broadcast link state · 9a650838
      由 Jon Paul Maloy 提交于 
      Since commit 52666986 ("tipc: let broadcast packet
reception use new link receive function") the broadcast send
link state was meant to always be set to LINK_ESTABLISHED, since
we don't need this link to follow the regular link FSM rules. It
was also the intention that this state anyway shouldn't impact
the run-time working state of the link, since the latter in
reality is controlled by the number of registered peers.

We have now discovered that this assumption is not quite correct.
If the broadcast link is reset because of too many retransmissions,
its state will inadvertently go to LINK_RESETTING, and never go
back to LINK_ESTABLISHED, because the LINK_FAILURE event was not
anticipated. This will work well once, but if it happens a second
time, the reset on a link in LINK_RESETTING has has no effect, and
neither the broadcast link nor the unicast links will go down as
they should.

Furthermore, it is confusing that the management tool shows that
this link is in UP state when that obviously isn't the case.

We now ensure that this state strictly follows the true working
state of the link. The state is set to LINK_ESTABLISHED when
the number of peers is non-zero, and to LINK_RESET otherwise.
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9a650838
    • J
      tipc: eliminate remnants of hungarian notation · 1a90632d
      由 Jon Paul Maloy 提交于 
      The number of variables with Hungarian notation (l_ptr, n_ptr etc.)
has been significantly reduced over the last couple of years.

We now root out the last traces of this practice.
There are no functional changes in this commit.
Reviewed-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1a90632d
    • J
      tipc: narrow down interface towards struct tipc_link · 38206d59
      由 Jon Paul Maloy 提交于 
      We move the definition of struct tipc_link from link.h to link.c in
order to minimize its exposure to the rest of the code.

When needed, we define new functions to make it possible for external
entities to access and set data in the link.

Apart from the above, there are no functional changes.
Reviewed-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      38206d59
    • J
      tipc: narrow down exposure of struct tipc_node · 5be9c086
      由 Jon Paul Maloy 提交于 
      In our effort to have less code and include dependencies between
entities such as node, link and bearer, we try to narrow down
the exposed interface towards the node as much as possible.

In this commit, we move the definition of struct tipc_node, along
with many of its associated function declarations, from node.h to
node.c. We also move some function definitions from link.c and
name_distr.c to node.c, since they access fields in struct tipc_node
that should not be externally visible. The moved functions are renamed
according to new location, and made static whenever possible.

There are no functional changes in this commit.
Reviewed-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5be9c086
    • J
      tipc: convert node lock to rwlock · 5405ff6e
      由 Jon Paul Maloy 提交于 
      According to the node FSM a node in state SELF_UP_PEER_UP cannot
change state inside a lock context, except when a TUNNEL_PROTOCOL
(SYNCH or FAILOVER) packet arrives. However, the node's individual
links may still change state.

Since each link now is protected by its own spinlock, we finally have
the conditions in place to convert the node spinlock to an rwlock_t.
If the node state and arriving packet type are rigth, we can let the
link directly receive the packet under protection of its own spinlock
and the node lock in read mode. In all other cases we use the node
lock in write mode. This enables full concurrent execution between
parallel links during steady-state traffic situations, i.e., 99+ %
of the time.

This commit implements this change.
Reviewed-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5405ff6e
    • J
      tipc: introduce per-link spinlock · 2312bf61
      由 Jon Paul Maloy 提交于 
      As a preparation to allow parallel links to work more independently
from each other we introduce a per-link spinlock, to be stored in the
struct nodes's link entry area. Since the node lock still is a regular
spinlock there is no increase in parallellism at this stage.
Reviewed-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      2312bf61
    • J
      tipc: move linearization of buffers to generic code · c7cad0d6
      由 Jon Paul Maloy 提交于 
      In commit 5cbb28a4 ("tipc: linearize arriving NAME_DISTR
and LINK_PROTO buffers") we added linearization of NAME_DISTRIBUTOR,
LINK_PROTOCOL/RESET and LINK_PROTOCOL/ACTIVATE to the function
tipc_udp_recv(). The location of the change was selected in order
to make the commit easily appliable to 'net' and 'stable'.

We now move this linearization to where it should be done, in the
functions tipc_named_rcv() and tipc_link_proto_rcv() respectively.
Reviewed-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c7cad0d6
  21. 25 10月, 2015 1 次提交
  23. 24 10月, 2015 10 次提交
  25. 16 10月, 2015 7 次提交
    • J
      tipc: update node FSM when peer RESET message is received · c8199300
      由 Jon Paul Maloy 提交于 
      The change made in the previous commit revealed a small flaw in the way
the node FSM is updated. When the function tipc_node_link_down() is
called for the last link to a node, we should check whether this was
caused by a local reset or by a received RESET message from the peer.
In the latter case, we can directly issue a PEER_LOST_CONTACT_EVT to
the node FSM, so that it is ready to re-establish contact. If this is
not done, the peer node will sometimes have to go through a second
establish cycle before the link becomes stable.

We fix this in this commit by conditionally issuing the mentioned
event in the function tipc_node_link_down(). We also move LINK_RESET
FSM even away from the link_reset() function and into the caller
function, partially because it is easier to follow the code when state
changes are gathered at a limited number of locations, partially
because there will be cases in future commits where we don't want the
link to go RESET mode when link_reset() is called.
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c8199300
    • J
      tipc: send out RESET immediately when link goes down · 282b3a05
      由 Jon Paul Maloy 提交于 
      When a link is taken down because of a node local event, such as
disabling of a bearer or an interface, we currently leave it to the
peer node to discover the broken communication. The default time for
such failure discovery is 1.5-2 seconds.

If we instead allow the terminating link endpoint to send out a RESET
message at the moment it is reset, we can achieve the impression that
both endpoints are going down instantly. Since this is a very common
scenario, we find it worthwhile to make this small modification.

Apart from letting the link produce the said message, we also have to
ensure that the interface is able to transmit it before TIPC is
detached. We do this by performing the disabling of a bearer in three
steps:

1) Disable reception of TIPC packets from the interface in question.
2) Take down the links, while allowing them so send out a RESET message.
3) Disable transmission of TIPC packets on the interface.

Apart from this, we now have to react on the NETDEV_GOING_DOWN event,
instead of as currently the NEDEV_DOWN event, to ensure that such
transmission is possible during the teardown phase.
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      282b3a05
    • J
      tipc: delay ESTABLISH state event when link is established · 73f646ce
      由 Jon Paul Maloy 提交于 
      Link establishing, just like link teardown, is a non-atomic action, in
the sense that discovering that conditions are right to establish a link,
and the actual adding of the link to one of the node's send slots is done
in two different lock contexts. The link FSM is designed to help bridging
the gap between the two contexts in a safe manner.

We have now discovered a weakness in the implementaton of this FSM.
Because we directly let the link go from state LINK_ESTABLISHING to
state LINK_ESTABLISHED already in the first lock context, we are unable
to distinguish between a fully established link, i.e., a link that has
been added to its slot, and a link that has not yet reached the second
lock context. It may hence happen that a manual intervention, e.g., when
disabling an interface, causes the function tipc_node_link_down() to try
removing the link from the node slots, decrementing its active link
counter etc, although the link was never added there in the first place.

We solve this by delaying the actual state change until we reach the
second lock context, inside the function tipc_node_link_up(). This
makes it possible for potentail callers of __tipc_node_link_down() to
know if they should proceed or not, and the problem is solved.

Unforunately, the situation described above also has a second problem.
Since there by necessity is a tipc_node_link_up() call pending once
the node lock has been released, we must defuse that call by setting
the link back from LINK_ESTABLISHING to LINK_RESET state. This forces
us to make a slight modification to the link FSM, which will now look
as follows.

 +------------------------------------+
 |RESET_EVT                           |
 |                                    |
 |                             +--------------+
 |           +-----------------|   SYNCHING   |-----------------+
 |           |FAILURE_EVT      +--------------+   PEER_RESET_EVT|
 |           |                  A            |                  |
 |           |                  |            |                  |
 |           |                  |            |                  |
 |           |                  |SYNCH_      |SYNCH_            |
 |           |                  |BEGIN_EVT   |END_EVT           |
 |           |                  |            |                  |
 |           V                  |            V                  V
 |    +-------------+          +--------------+          +------------+
 |    |  RESETTING  |<---------|  ESTABLISHED |--------->| PEER_RESET |
 |    +-------------+ FAILURE_ +--------------+ PEER_    +------------+
 |           |        EVT        |    A         RESET_EVT       |
 |           |                   |    |                         |
 |           |  +----------------+    |                         |
 |  RESET_EVT|  |RESET_EVT            |                         |
 |           |  |                     |                         |
 |           |  |                     |ESTABLISH_EVT            |
 |           |  |  +-------------+    |                         |
 |           |  |  | RESET_EVT   |    |                         |
 |           |  |  |             |    |                         |
 |           V  V  V             |    |                         |
 |    +-------------+          +--------------+        RESET_EVT|
 +--->|    RESET    |--------->| ESTABLISHING |<----------------+
      +-------------+ PEER_    +--------------+
       |           A  RESET_EVT       |
       |           |                  |
       |           |                  |
       |FAILOVER_  |FAILOVER_         |FAILOVER_
       |BEGIN_EVT  |END_EVT           |BEGIN_EVT
       |           |                  |
       V           |                  |
      +-------------+                 |
      | FAILINGOVER |<----------------+
      +-------------+
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      73f646ce
    • J
      tipc: disallow packet duplicates in link deferred queue · 8306f99a
      由 Jon Paul Maloy 提交于 
      After the previous commits, we are guaranteed that no packets
of type LINK_PROTOCOL or with illegal sequence numbers will be
attempted added to the link deferred queue. This makes it possible to
make some simplifications to the sorting algorithm in the function
tipc_skb_queue_sorted().

We also alter the function so that it will drop packets if one with
the same seqeunce number is already present in the queue. This is
necessary because we have identified weird packet sequences, involving
duplicate packets, where a legitimate in-sequence packet may advance to
the head of the queue without being detected and de-queued.

Finally, we make this function outline, since it will now be called only
in exceptional cases.
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      8306f99a
    • J
      tipc: improve sequence number checking · 81204c49
      由 Jon Paul Maloy 提交于 
      The sequence number of an incoming packet is currently only checked
for less than, equality to, or bigger than the next expected number,
meaning that the receive window in practice becomes one half sequence
number cycle, or U16_MAX/2. This does not make sense, and may not even
be safe if there are extreme delays in the network. Any packet sent by
the peer during the ongoing cycle must belong inside his current send
window, or should otherwise be dropped if possible.

Since a link endpoint cannot know its peer's current send window, it
has to base this sanity check on a worst-case assumption, i.e., that
the peer is using a maximum sized window of 8191 packets. Using this
assumption, we now add a check that the sequence number is not bigger
than next_expected + TIPC_MAX_LINK_WIN. We also re-order the checks
done, so that the receive window test is performed before the gap test.
This way, we are guaranteed that no packet with illegal sequence numbers
are ever added to the deferred queue.
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      81204c49
    • J
      tipc: simplify tipc_link_rcv() reception loop · f9aa358a
      由 Jon Paul Maloy 提交于 
      Currently, all packets received in tipc_link_rcv() are unconditionally
added to the packet deferred queue, whereafter that queue is walked and
all its buffers evaluated for delivery. This is both non-optimal and
and makes the queue sorting function unnecessary complex.

This commit changes the loop so that an arrived packet is evaluated
first, and added to the deferred queue only when a sequence number gap
is discovered. A non-empty deferred queue is walked until it is empty
or until its head's sequence number doesn't fit.
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      f9aa358a
    • J
      tipc: limit usage of temporary skb list during packet reception · 9945e804
      由 Jon Paul Maloy 提交于 
      During packet reception, the function tipc_link_rcv() adds its accepted
packets to a temporary buffer queue, before finally splicing this queue
into the lock protected input queue that will be delivered up to the
socket layer. The purpose is to reduce potential contention on the input
queue lock. However, since the vast majority of packets arrive in
sequence, they will anyway be added one by one to the input queue, and
the use of the temporary queue becomes a sub-optimization.

The only case where this queue makes sense is when unpacking buffers
from a bundle packet; here we want to avoid dozens of small buffers
to be added individually to the lock-protected input queue in a tight
loop.

In this commit, we remove the general usage of the temporary queue,
and keep it only for the packet unbundling case.
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Acked-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9945e804
  27. 24 8月, 2015 2 次提交
    • J
      tipc: fix stale link problem during synchronization · 2be80c2d
      由 Jon Paul Maloy 提交于 
      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: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      2be80c2d
    • J
      tipc: interrupt link synchronization when a link goes down · 5ae2f8e6
      由 Jon Paul Maloy 提交于 
      When we introduced the new link failover/synch mechanism
in commit 6e498158
("tipc: move link synch and failover to link aggregation level"),
we missed the case when the non-tunnel link goes down during the link
synchronization period. In this case the tunnel link will remain in
state LINK_SYNCHING, something leading to unpredictable behavior when
the failover procedure is initiated.

In this commit, we ensure that the node and remaining link goes
back to regular communication state (SELF_UP_PEER_UP/LINK_ESTABLISHED)
when one of the parallel links goes down. We also ensure that we don't
re-enter synch mode if subsequent SYNCH packets arrive on the remaining
link.
Reviewed-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5ae2f8e6