user/sven/linux.git/net/tipc/link.c, branch v4.14

tipc: don't reset stale broadcast send link

2017-08-21T20:37:45Z

When the broadcast send link after 100 attempts has failed to transfer a packet to all peers, we consider it stale, and reset it. Thereafter it needs to re-synchronize with the peers, something currently done by just resetting and re-establishing all links to all peers. This has turned out to be overkill, with potentially unwanted consequences for the remaining cluster. A closer analysis reveals that this can be done much simpler. When this kind of failure happens, for reasons that may lie outside the TIPC protocol, it is typically only one peer which is failing to receive and acknowledge packets. It is hence sufficient to identify and reset the links only to that peer to resolve the situation, without having to reset the broadcast link at all. This solution entails a much lower risk of negative consequences for the own node as well as for the overall cluster. We implement this change in this commit. Reviewed-by: Parthasarathy Bhuvaragan Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

netlink: pass extended ACK struct to parsing functions

2017-04-13T17:58:22Z

Pass the new extended ACK reporting struct to all of the generic netlink parsing functions. For now, pass NULL in almost all callers (except for some in the core.) Signed-off-by: Johannes Berg Signed-off-by: David S. Miller

tipc: make replicast a user selectable option

2017-01-20T17:10:17Z

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

2017-01-20T17:10:17Z

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

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2017-01-17T20:19:37Z

tipc: allocate user memory with GFP_KERNEL flag

2017-01-16T18:31:53Z

Until now, we allocate memory always with GFP_ATOMIC flag. When the system is under memory pressure and a user tries to send, the send fails due to low memory. However, the user application can wait for free memory if we allocate it using GFP_KERNEL flag. In this commit, we use allocate memory with GFP_KERNEL for all user allocation. Reported-by: Rune Torgersen Acked-by: Jon Maloy Signed-off-by: Parthasarathy Bhuvaragan Signed-off-by: David S. Miller

tipc: reduce risk of user starvation during link congestion

2017-01-03T16:13:05Z

The socket code currently handles link congestion by either blocking and trying to send again when the congestion has abated, or just returning to the user with -EAGAIN and let him re-try later. This mechanism is prone to starvation, because the wakeup algorithm is non-atomic. During the time the link issues a wakeup signal, until the socket wakes up and re-attempts sending, other senders may have come in between and occupied the free buffer space in the link. This in turn may lead to a socket having to make many send attempts before it is successful. In extremely loaded systems we have observed latency times of several seconds before a low-priority socket is able to send out a message. In this commit, we simplify this mechanism and reduce the risk of the described scenario happening. When a message is attempted sent via a congested link, we now let it be added to the link's backlog queue anyway, thus permitting an oversubscription of one message per source socket. We still create a wakeup item and return an error code, hence instructing the sender to block or stop sending. Only when enough space has been freed up in the link's backlog queue do we issue a wakeup event that allows the sender to continue with the next message, if any. The fact that a socket now can consider a message sent even when the link returns a congestion code means that the sending socket code can be simplified. Also, since this is a good opportunity to get rid of the obsolete 'mtu change' condition in the three socket send functions, we now choose to refactor those functions completely. Signed-off-by: Parthasarathy Bhuvaragan Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: fix link statistics counter errors

2016-11-28T01:35:55Z

In commit e4bf4f76962b ("tipc: simplify packet sequence number handling") we changed the internal representation of the packet sequence number counters from u32 to u16, reflecting what is really sent over the wire. Since then some link statistics counters have been displaying incorrect values, partially because the counters meant to be used as sequence number snapshots are now used as direct counters, stored as u32, and partially because some counter updates are just missing in the code. In this commit we correct this in two ways. First, we base the displayed packet sent/received values on direct counters instead of as previously a calculated difference between current sequence number and a snapshot. Second, we add the missing updates of the counters. This change is compatible with the current netlink API, and requires no changes to the user space tools. Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: fix compatibility bug in link monitoring

2016-11-26T01:06:18Z

commit 817298102b0b ("tipc: fix link priority propagation") introduced a compatibility problem between TIPC versions newer than Linux 4.6 and those older than Linux 4.4. In versions later than 4.4, link STATE messages only contain a non-zero link priority value when the sender wants the receiver to change its priority. This has the effect that the receiver resets itself in order to apply the new priority. This works well, and is consistent with the said commit. However, in versions older than 4.4 a valid link priority is present in all sent link STATE messages, leading to cyclic link establishment and reset on the 4.6+ node. We fix this by adding a test that the received value should not only be valid, but also differ from the current value in order to cause the receiving link endpoint to reset. Reported-by: Amar Nv Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: fix broadcast link synchronization problem

2016-10-29T21:21:09Z

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