linux/net/tipc/msg.h, branch v4.1

tipc: eliminate delayed link deletion at link failover

2015-04-02T20:27:12Z

When a bearer is disabled manually, all its links have to be reset and deleted. However, if there is a remaining, parallel link ready to take over a deleted link's traffic, we currently delay the delete of the removed link until the failover procedure is finished. This is because the remaining link needs to access state from the reset link, such as the last received packet number, and any partially reassembled buffer, in order to perform a successful failover. In this commit, we do instead move the state data over to the new link, so that it can fulfill the procedure autonomously, without accessing any data on the old link. This means that we can now proceed and delete all pertaining links immediately when a bearer is disabled. This saves us from some unnecessary complexity in such situations. We also choose to change the confusing definitions CHANGEOVER_PROTOCOL, ORIGINAL_MSG and DUPLICATE_MSG to the more descriptive TUNNEL_PROTOCOL, FAILOVER_MSG and SYNCH_MSG respectively. Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: eliminate race condition at dual link establishment

2015-03-25T18:05:56Z

Despite recent improvements, the establishment of dual parallel links still has a small glitch where messages can bypass each other. When the second link in a dual-link configuration is established, part of the first link's traffic will be steered over to the new link. Although we do have a mechanism to ensure that packets sent before and after the establishment of the new link arrive in sequence to the destination node, this is not enough. The arriving messages will still be delivered upwards in different threads, something entailing a risk of message disordering during the transition phase. To fix this, we introduce a synchronization mechanism between the two parallel links, so that traffic arriving on the new link cannot be added to its input queue until we are guaranteed that all pre-establishment messages have been delivered on the old, parallel link. This problem seems to always have been around, but its occurrence is so rare that it has not been noticed until recent intensive testing. Reviewed-by: Ying Xue Reviewed-by: Erik Hugne Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: clean up handling of link congestion

2015-03-25T18:05:56Z

After the recent changes in message importance handling it becomes possible to simplify handling of messages and sockets when we encounter link congestion. We merge the function tipc_link_cong() into link_schedule_user(), and simplify the code of the latter. The code should now be easier to follow, especially regarding return codes and handling of the message that caused the situation. In case the scheduling function is unable to pre-allocate a wakeup message buffer, it now returns -ENOBUFS, which is a more correct code than the previously used -EHOSTUNREACH. Reviewed-by: Ying Xue Reviewed-by: Erik Hugne Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: clean up handling of message priorities

2015-03-14T18:38:32Z

Messages transferred by TIPC are assigned an "importance priority", -an integer value indicating how to treat the message when there is link or destination socket congestion. There is no separate header field for this value. Instead, the message user values have been chosen in ascending order according to perceived importance, so that the message user field can be used for this. This is not a good solution. First, we have many more users than the needed priority levels, so we end up with treating more priority levels than necessary. Second, the user field cannot always accurately reflect the priority of the message. E.g., a message fragment packet should really have the priority of the enveloped user data message, and not the priority of the MSG_FRAGMENTER user. Until now, we have been working around this problem in different ways, but it is now time to implement a consistent way of handling such priorities, although still within the constraint that we cannot allocate any more bits in the regular data message header for this. In this commit, we define a new priority level, TIPC_SYSTEM_IMPORTANCE, that will be the only one used apart from the four (lower) user data levels. All non-data messages map down to this priority. Furthermore, we take some free bits from the MSG_FRAGMENTER header and allocate them to store the priority of the enveloped message. We then adjust the functions msg_importance()/msg_set_importance() so that they read/set the correct header fields depending on user type. This small protocol change is fully compatible, because the code at the receiving end of a link currently reads the importance level only from user data messages, where there is no change. Reviewed-by: Erik Hugne Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: split link outqueue

2015-03-14T18:38:32Z

struct tipc_link contains one single queue for outgoing packets, where both transmitted and waiting packets are queued. This infrastructure is hard to maintain, because we need to keep a number of fields to keep track of which packets are sent or unsent, and the number of packets in each category. A lot of code becomes simpler if we split this queue into a transmission queue, where sent/unacknowledged packets are kept, and a backlog queue, where we keep the not yet sent packets. In this commit we do this separation. Reviewed-by: Erik Hugne Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: move message validation function to msg.c

2015-03-14T18:38:32Z

The function link_buf_validate() is in reality re-entrant and context independent, and will in later commits be called from several locations. Therefore, we move it to msg.c, make it outline and rename the it to tipc_msg_validate(). We also redesign the function to make proper use of pskb_may_pull() Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: add framework for node capabilities exchange

2015-03-14T18:38:32Z

The TIPC protocol spec has defined a 13 bit capability bitmap in the neighbor discovery header, as a means to maintain compatibility between different code and protocol generations. Until now this field has been unused. We now introduce the basic framework for exchanging capabilities between nodes at first contact. After exchange, a peer node's capabilities are stored as a 16 bit bitmap in struct tipc_node. Reviewed-by: Erik Hugne Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: add ip/udp media type

2015-03-06T03:08:42Z

The ip/udp bearer can be configured in a point-to-point mode by specifying both local and remote ip/hostname, or it can be enabled in multicast mode, where links are established to all tipc nodes that have joined the same multicast group. The multicast IP address is generated based on the TIPC network ID, but can be overridden by using another multicast address as remote ip. Signed-off-by: Erik Hugne Reviewed-by: Jon Maloy Reviewed-by: Ying Xue Signed-off-by: David S. Miller

tipc: rename media/msg related definitions

2015-02-27T23:18:48Z

The TIPC_MEDIA_ADDR_SIZE and TIPC_MEDIA_ADDR_OFFSET names are misleading, as they actually define the size and offset of the whole media info field and not the address part. This patch does not have any functional changes. Signed-off-by: Erik Hugne Signed-off-by: David S. Miller

tipc: eliminate race condition at multicast reception

2015-02-06T00:00:03Z

In a previous commit in this series we resolved a race problem during unicast message reception. Here, we resolve the same problem at multicast reception. We apply the same technique: an input queue serializing the delivery of arriving buffers. The main difference is that here we do it in two steps. First, the broadcast link feeds arriving buffers into the tail of an arrival queue, which head is consumed at the socket level, and where destination lookup is performed. Second, if the lookup is successful, the resulting buffer clones are fed into a second queue, the input queue. This queue is consumed at reception in the socket just like in the unicast case. Both queues are protected by the same lock, -the one of the input queue. Reviewed-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller