pm24.git/net/tipc/node.h, branch v4.3-rc6

tipc: remove implicit message delivery in node_unlock()

2015-07-31T00:25:14Z

After the most recent changes, all access calls to a link which may entail addition of messages to the link's input queue are postpended by an explicit call to tipc_sk_rcv(), using a reference to the correct queue. This means that the potentially hazardous implicit delivery, using tipc_node_unlock() in combination with a binary flag and a cached queue pointer, now has become redundant. This commit removes this implicit delivery mechanism both for regular data messages and for binding table update messages. Tested-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: move received discovery data evaluation inside node.c

2015-07-31T00:25:14Z

The node lock is currently grabbed and and released in the function tipc_disc_rcv() in the file discover.c. As a preparation for the next commits, we need to move this node lock handling, along with the code area it is covering, to node.c. This commit introduces this change. Tested-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: move link synch and failover to link aggregation level

2015-07-31T00:25:14Z

Link failover and synchronization have until now been handled by the links themselves, forcing them to have knowledge about and to access parallel links in order to make the two algorithms work correctly. In this commit, we move the control part of this functionality to the link aggregation level in node.c, which is the right location for this. As a result, the two algorithms become easier to follow, and the link implementation becomes simpler. Tested-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: extend node FSM

2015-07-31T00:25:13Z

In the next commit, we will move link synch/failover orchestration to the link aggregation level. In order to do this, we first need to extend the node FSM with two more states, NODE_SYNCHING and NODE_FAILINGOVER, plus four new events to enter and leave those states. This commit introduces this change, without yet making use of it. The node FSM now looks as follows: +-----------------------------------------+ | PEER_DOWN_EVT| | | +------------------------+----------------+ | |SELF_DOWN_EVT | | | | | | | | +-----------+ +-----------+ | | |NODE_ | |NODE_ | | | +----------|FAILINGOVER|<---------|SYNCHING |------------+ | | |SELF_ +-----------+ FAILOVER_+-----------+ PEER_ | | | |DOWN_EVT | A BEGIN_EVT A | DOWN_EVT| | | | | | | | | | | | | | | | | | | | |FAILOVER_|FAILOVER_ |SYNCH_ |SYNCH_ | | | | |END_EVT |BEGIN_EVT |BEGIN_EVT|END_EVT | | | | | | | | | | | | | | | | | | | | | +--------------+ | | | | | +------->| SELF_UP_ |<-------+ | | | | +----------------| PEER_UP |------------------+ | | | | |SELF_DOWN_EVT +--------------+ PEER_DOWN_EVT| | | | | | A A | | | | | | | | | | | | | | PEER_UP_EVT| |SELF_UP_EVT | | | | | | | | | | | V V V | | V V V +------------+ +-----------+ +-----------+ +------------+ |SELF_DOWN_ | |SELF_UP_ | |PEER_UP_ | |PEER_DOWN | |PEER_LEAVING|<------|PEER_COMING| |SELF_COMING|------>|SELF_LEAVING| +------------+ SELF_ +-----------+ +-----------+ PEER_ +------------+ | DOWN_EVT A A DOWN_EVT | | | | | | | | | | SELF_UP_EVT| |PEER_UP_EVT | | | | | | | | | |PEER_DOWN_EVT +--------------+ SELF_DOWN_EVT| +------------------->| SELF_DOWN_ |<--------------------+ | PEER_DOWN | +--------------+ Tested-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: move all link_reset() calls to link aggregation level

2015-07-31T00:25:13Z

In line with our effort to let the node level have full control over its links, we want to move all link reset calls from link.c to node.c. Some of the calls can be moved by simply moving the calling function, when this is the right thing to do. For the remaining calls we use the now established technique of returning a TIPC_LINK_DOWN_EVT flag from tipc_link_rcv(), whereafter we perform the reset call when the call returns. This change serves as a preparation for the coming commits. Tested-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: reduce locking scope during packet reception

2015-07-21T03:41:16Z

We convert packet/message reception according to the same principle we have been using for message sending and timeout handling: We move the function tipc_rcv() to node.c, hence handling the initial packet reception at the link aggregation level. The function grabs the node lock, selects the receiving link, and accesses it via a new call tipc_link_rcv(). This function appends buffers to the input queue for delivery upwards, but it may also append outgoing packets to the xmit queue, just as we do during regular message sending. The latter will happen when buffers are forwarded from the link backlog, or when retransmission is requested. Upon return of this function, and after having released the node lock, tipc_rcv() delivers/tranmsits the contents of those queues, but it may also perform actions such as link activation or reset, as indicated by the return flags from the link. This reduces the number of cpu cycles spent inside the node spinlock, and reduces contention on that lock. Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: introduce node contact FSM

2015-07-21T03:41:16Z

The logics for determining when a node is permitted to establish and maintain contact with its peer node becomes non-trivial in the presence of multiple parallel links that may come and go independently. A known failure scenario is that one endpoint registers both its links to the peer lost, cleans up it binding table, and prepares for a table update once contact is re-establihed, while the other endpoint may see its links reset and re-established one by one, hence seeing no need to re-synchronize the binding table. To avoid this, a node must not allow re-establishing contact until it has confirmation that even the peer has lost both links. Currently, the mechanism for handling this consists of setting and resetting two state flags from different locations in the code. This solution is hard to understand and maintain. A closer analysis even reveals that it is not completely safe. In this commit we do instead introduce an FSM that keeps track of the conditions for when the node can establish and maintain links. It has six states and four events, and is strictly based on explicit knowledge about the own node's and the peer node's contact states. Only events leading to state change are shown as edges in the figure below. +--------------+ | SELF_UP/ | +---------------->| PEER_COMING |-----------------+ SELF_ | +--------------+ |PEER_ ESTBL_ | | |ESTBL_ CONTACT| SELF_LOST_CONTACT | |CONTACT | v | | +--------------+ | | PEER_ | SELF_DOWN/ | SELF_ | | LOST_ +--| PEER_LEAVING |<--+ LOST_ v +-------------+ CONTACT | +--------------+ | CONTACT +-----------+ | SELF_DOWN/ |<----------+ +----------| SELF_UP/ | | PEER_DOWN |<----------+ +----------| PEER_UP | +-------------+ SELF_ | +--------------+ | PEER_ +-----------+ | LOST_ +--| SELF_LEAVING/|<--+ LOST_ A | CONTACT | PEER_DOWN | CONTACT | | +--------------+ | | A | PEER_ | PEER_LOST_CONTACT | |SELF_ ESTBL_ | | |ESTBL_ CONTACT| +--------------+ |CONTACT +---------------->| PEER_UP/ |-----------------+ | SELF_COMING | +--------------+ Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: move link supervision timer to node level

2015-07-21T03:41:16Z

In our effort to move control of the links to the link aggregation layer, we move the perodic link supervision timer to struct tipc_node. The new timer is shared between all links belonging to the node, thus saving resources, while still kicking the FSM on both its pertaining links at each expiration. The current link timer and corresponding functions are removed. Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: make media xmit call outside node spinlock context

2015-07-21T03:41:15Z

Currently, message sending is performed through a deep call chain, where the node spinlock is grabbed and held during a significant part of the transmission time. This is clearly detrimental to overall throughput performance; it would be better if we could send the message after the spinlock has been released. In this commit, we do instead let the call revert on the stack after the buffer chain has been added to the transmission queue, whereafter clones of the buffers are transmitted to the device layer outside the spinlock scope. As a further step in our effort to separate the roles of the node and link entities we also move the function tipc_link_xmit() to node.c, and rename it to tipc_node_xmit(). Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: use bearer index when looking up active links

2015-07-21T03:41:14Z

struct tipc_node currently holds two arrays of link pointers; one, indexed by bearer identity, which contains all links irrespective of current state, and one two-slot array for the currently active link or links. The latter array contains direct pointers into the elements of the former. This has the effect that we cannot know the bearer id of a link when accessing it via the "active_links[]" array without actually dereferencing the pointer, something we want to avoid in some cases. In this commit, we do instead store the bearer identity in the "active_links" array, and use this as an index to find the right element in the overall link entry array. This change should be seen as a preparation for the later commits in this series. Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller