tipc: remove 'has_redundant_link' flag from STATE link protocol messages (b9d4c339) · Commits · 戴 / test

The flag 'has_redundant_link' is defined only in RESET and ACTIVATE protocol messages. Due to an ambiguity in the protocol specification it is currently also transferred in STATE messages. Its value is used to initialize a link state variable, 'permit_changeover', which is used to inhibit futile link failover attempts when it is known that the peer node has no working links at the moment, although the local node may still think it has one. The fact that 'has_redundant_link' incorrectly is read from STATE messages has the effect that 'permit_changeover' sometimes gets a wrong value, and permanently blocks any links from being re-established. Such failures can only occur in in dual-link systems, and are extremely rare. This bug seems to have always been present in the code. Furthermore, since commit ("tipc: Ensure both nodes recognize loss of contact between them"), the 'permit_changeover' field serves no purpose any more. The task of enforcing 'lost contact' cycles at both peer endpoints is now taken by a new mechanism, using the flags WAIT_NODE_DOWN and WAIT_PEER_DOWN in struct tipc_node to abort unnecessary failover attempts. We therefore remove the 'has_redundant_link' flag from STATE messages, as well as the now redundant 'permit_changeover' variable. Signed-off-by:

Jon Maloy <jon.maloy@ericsson.com> Reviewed-by:

Ying Xue <ying.xue@windriver.com> Reviewed-by:

Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/tipc/link.c

+1 −9

Original line number	Diff line number	Diff line
		@@ -438,8 +438,7 @@ void tipc_link_reset(struct tipc_link *l_ptr)
		tipc_node_link_down(l_ptr->owner, l_ptr);
		tipc_bearer_remove_dest(l_ptr->b_ptr, l_ptr->addr);

		if (was_active_link && tipc_node_active_links(l_ptr->owner) &&
		l_ptr->owner->permit_changeover) {
		if (was_active_link && tipc_node_active_links(l_ptr->owner)) {
		l_ptr->reset_checkpoint = checkpoint;
		l_ptr->exp_msg_count = START_CHANGEOVER;
		}
		@@ -1838,8 +1837,6 @@ static void link_recv_proto_msg(struct tipc_link l_ptr, struct sk_buff buf)
		if (tipc_own_addr > msg_prevnode(msg))
		l_ptr->b_ptr->net_plane = msg_net_plane(msg);

		l_ptr->owner->permit_changeover = msg_redundant_link(msg);

		switch (msg_type(msg)) {

		case RESET_MSG:
		@@ -2001,11 +1998,6 @@ void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
		if (!tunnel)
		return;

		if (!l_ptr->owner->permit_changeover) {
		pr_warn("%speer did not permit changeover\n", link_co_err);
		return;
		}

		tipc_msg_init(&tunnel_hdr, CHANGEOVER_PROTOCOL,
		ORIGINAL_MSG, INT_H_SIZE, l_ptr->addr);
		msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);

net/tipc/node.h

+0 −2

Original line number	Diff line number	Diff line
		@@ -64,7 +64,6 @@
		* @working_links: number of working links to node (both active and standby)
		* @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
		* @signature: node instance identifier
		* @bclink: broadcast-related info
		* @acked: sequence # of last outbound b'cast message acknowledged by node
		@@ -89,7 +88,6 @@ struct tipc_node {
		int link_cnt;
		int working_links;
		int block_setup;
		int permit_changeover;
		u32 signature;
		struct {
		u32 acked;

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