lwn.git/net/tipc/bcast.h, branch v5.0-rc5

tipc: make replicast a user selectable option

2017-01-20T17:10:17+00:00

If the bearer carrying multicast messages supports broadcast, those messages will be sent to all cluster nodes, irrespective of whether these nodes host any actual destinations socket or not. This is clearly wasteful if the cluster is large and there are only a few real destinations for the message being sent. In this commit we extend the eligibility of the newly introduced "replicast" transmit option. We now make it possible for a user to select which method he wants to be used, either as a mandatory setting via setsockopt(), or as a relative setting where we let the broadcast layer decide which method to use based on the ratio between cluster size and the message's actual number of destination nodes. In the latter case, a sending socket must stick to a previously selected method until it enters an idle period of at least 5 seconds. This eliminates the risk of message reordering caused by method change, i.e., when changes to cluster size or number of destinations would otherwise mandate a new method to be used. Reviewed-by: Parthasarathy Bhuvaragan Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: introduce replicast as transport option for multicast

2017-01-20T17:10:17+00:00

TIPC multicast messages are currently carried over a reliable 'broadcast link', making use of the underlying media's ability to transport packets as L2 broadcast or IP multicast to all nodes in the cluster. When the used bearer is lacking that ability, we can instead emulate the broadcast service by replicating and sending the packets over as many unicast links as needed to reach all identified destinations. We now introduce a new TIPC link-level 'replicast' service that does this. Reviewed-by: Parthasarathy Bhuvaragan Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: add functionality to lookup multicast destination nodes

2017-01-20T17:10:16+00:00

As a further preparation for the upcoming 'replicast' functionality, we add some necessary structs and functions for looking up and returning a list of all nodes that host destinations for a given multicast message. Reviewed-by: Parthasarathy Bhuvaragan Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: fix broadcast link synchronization problem

2016-10-29T21:21:09+00:00

In commit 2d18ac4ba745 ("tipc: extend broadcast link initialization criteria") we tried to fix a problem with the initial synchronization of broadcast link acknowledge values. Unfortunately that solution is not sufficient to solve the issue. We have seen it happen that LINK_PROTOCOL/STATE packets with a valid non-zero unicast acknowledge number may bypass BCAST_PROTOCOL initialization, NAME_DISTRIBUTOR and other STATE packets with invalid broadcast acknowledge numbers, leading to premature opening of the broadcast link. When the bypassed packets finally arrive, they are inadvertently accepted, and the already correctly initialized acknowledge number in the broadcast receive link is overwritten by the invalid (zero) value of the said packets. After this the broadcast link goes stale. We now fix this by marking the packets where we know the acknowledge value is or may be invalid, and then ignoring the acks from those. To this purpose, we claim an unused bit in the header to indicate that the value is invalid. We set the bit to 1 in the initial BCAST_PROTOCOL synchronization packet and all initial ("bulk") NAME_DISTRIBUTOR packets, plus those LINK_PROTOCOL packets sent out before the broadcast links are fully synchronized. This minor protocol update is fully backwards compatible. Reported-by: John Thompson Tested-by: John Thompson Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: transfer broadcast nacks in link state messages

2016-09-03T00:10:24+00:00

When we send broadcasts in clusters of more 70-80 nodes, we sometimes see the broadcast link resetting because of an excessive number of retransmissions. This is caused by a combination of two factors: 1) A 'NACK crunch", where loss of broadcast packets is discovered and NACK'ed by several nodes simultaneously, leading to multiple redundant broadcast retransmissions. 2) The fact that the NACKS as such also are sent as broadcast, leading to excessive load and packet loss on the transmitting switch/bridge. This commit deals with the latter problem, by moving sending of broadcast nacks from the dedicated BCAST_PROTOCOL/NACK message type to regular unicast LINK_PROTOCOL/STATE messages. We allocate 10 unused bits in word 8 of the said message for this purpose, and introduce a new capability bit, TIPC_BCAST_STATE_NACK in order to keep the change backwards compatible. Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: remove pre-allocated message header in link struct

2016-03-07T04:01:20+00:00

Until now, we have kept a pre-allocated protocol message header aggregated into struct tipc_link. Apart from adding unnecessary footprint to the link instances, this requires extra code both to initialize and re-initialize it. We now remove this sub-optimization. This change also makes it possible to clean up the function tipc_build_proto_msg() and remove a couple of small functions that were accessing the mentioned header. In particular, we can replace all occurrences of the local function call link_own_addr(link) with the generic tipc_own_addr(net). Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: narrow down exposure of struct tipc_node

2015-11-20T19:06:10+00:00

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: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: clean up unused code and structures

2015-10-24T13:56:47+00:00

After the previous changes in this series, we can now remove some unused code and structures, both in the broadcast, link aggregation and link code. There are no functional changes in this commit. Signed-off-by: Jon Maloy Reviewed-by: Ying Xue Signed-off-by: David S. Miller

tipc: introduce jumbo frame support for broadcast

2015-10-24T13:56:40+00:00

Until now, we have only been supporting a fix MTU size of 1500 bytes for all broadcast media, irrespective of their actual capability. We now make the broadcast MTU adaptable to the carrying media, i.e., we use the smallest MTU supported by any of the interfaces attached to TIPC. Signed-off-by: Jon Maloy Reviewed-by: Ying Xue Signed-off-by: David S. Miller

tipc: simplify bearer level broadcast

2015-10-24T13:56:39+00:00

Until now, we have been keeping track of the exact set of broadcast destinations though the help structure tipc_node_map. This leads us to have to maintain a whole infrastructure for supporting this, including a pseudo-bearer and a number of functions to manipulate both the bearers and the node map correctly. Apart from the complexity, this approach is also limiting, as struct tipc_node_map only can support cluster local broadcast if we want to avoid it becoming excessively large. We want to eliminate this limitation, in order to enable introduction of scoped multicast in the future. A closer analysis reveals that it is unnecessary maintaining this "full set" overview; it is sufficient to keep a counter per bearer, indicating how many nodes can be reached via this bearer at the moment. The protocol is now robust enough to handle transitional discrepancies between the nominal number of reachable destinations, as expected by the broadcast protocol itself, and the number which is actually reachable at the moment. The initial broadcast synchronization, in conjunction with the retransmission mechanism, ensures that all packets will eventually be acknowledged by the correct set of destinations. This commit introduces these changes. Signed-off-by: Jon Maloy Reviewed-by: Ying Xue Signed-off-by: David S. Miller