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authorAllan Stephens <allan.stephens@windriver.com>2011-05-27 17:00:51 +0200
committerPaul Gortmaker <paul.gortmaker@windriver.com>2011-09-18 04:55:03 +0200
commitb4b5610223f17790419b03eaa962b0e3ecf930d7 (patch)
treea8cdae892e3e2eac0ea1e5493cded8394f8a5d6d /net/tipc/node.h
parenttipc: Ensure congested links receive bearer status updates (diff)
downloadlinux-b4b5610223f17790419b03eaa962b0e3ecf930d7.tar.xz
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tipc: Ensure both nodes recognize loss of contact between them
Enhances TIPC to ensure that a node that loses contact with a neighboring node does not allow contact to be re-established until it sees that its peer has also recognized the loss of contact. Previously, nodes that were connected by two or more links could encounter a situation in which node A would lose contact with node B on all of its links, purge its name table of names published by B, and then fail to repopulate those names once contact with B was restored. This would happen because B was able to re-establish one or more links so quickly that it never reached a point where it had no links to A -- meaning that B never saw a loss of contact with A, and consequently didn't re-publish its names to A. This problem is now prevented by enhancing the cleanup done by TIPC following a loss of contact with a neighboring node to ensure that node A ignores all messages sent by B until it receives a LINK_PROTOCOL message that indicates B has lost contact with A, thereby preventing the (re)establishment of links between the nodes. The loss of contact is recognized when a RESET or ACTIVATE message is received that has a "redundant link exists" field of 0, indicating that B's sending link endpoint is in a reset state and that B has no other working links. Additionally, TIPC now suppresses the sending of (most) link protocol messages to a neighboring node while it is cleaning up after an earlier loss of contact with that node. This stops the peer node from prematurely activating its link endpoint, which would prevent TIPC from later activating its own end. TIPC still allows outgoing RESET messages to occur during cleanup, to avoid problems if its own node recognizes the loss of contact first and tries to notify the peer of the situation. Finally, TIPC now recognizes an impending loss of contact with a peer node as soon as it receives a RESET message on a working link that is the peer's only link to the node, and ensures that the link protocol suppression mentioned above goes into effect right away -- that is, even before its own link endpoints have failed. This is necessary to ensure correct operation when there are redundant links between the nodes, since otherwise TIPC would send an ACTIVATE message upon receiving a RESET on its first link and only begin suppressing when a RESET on its second link was received, instead of initiating suppression with the first RESET message as it needs to. Note: The reworked cleanup code also eliminates a check that prevented a link endpoint's discovery object from responding to incoming messages while stale name table entries are being purged. This check is now unnecessary and would have slowed down re-establishment of communication between the nodes in some situations. Signed-off-by: Allan Stephens <allan.stephens@windriver.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Diffstat (limited to 'net/tipc/node.h')
-rw-r--r--net/tipc/node.h10
1 files changed, 8 insertions, 2 deletions
diff --git a/net/tipc/node.h b/net/tipc/node.h
index 5c61afc7a0b9..4f15cb40aaa4 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -42,6 +42,12 @@
#include "net.h"
#include "bearer.h"
+/* Flags used to block (re)establishment of contact with a neighboring node */
+
+#define WAIT_PEER_DOWN 0x0001 /* wait to see that peer's links are down */
+#define WAIT_NAMES_GONE 0x0002 /* wait for peer's publications to be purged */
+#define WAIT_NODE_DOWN 0x0004 /* wait until peer node is declared down */
+
/**
* struct tipc_node - TIPC node structure
* @addr: network address of node
@@ -52,7 +58,7 @@
* @active_links: pointers to active links to node
* @links: pointers to all links to node
* @working_links: number of working links to node (both active and standby)
- * @cleanup_required: non-zero if cleaning up after a prior loss of contact
+ * @block_setup: bit mask of conditions preventing link establishment to node
* @link_cnt: number of links to node
* @permit_changeover: non-zero if node has redundant links to this system
* @bclink: broadcast-related info
@@ -77,7 +83,7 @@ struct tipc_node {
struct link *links[MAX_BEARERS];
int link_cnt;
int working_links;
- int cleanup_required;
+ int block_setup;
int permit_changeover;
struct {
int supported;