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Commit c140eb16 authored by LUU Duc Canh's avatar LUU Duc Canh Committed by David S. Miller
Browse files

tipc: fix failover problem 



We see the following scenario:
1) Link endpoint B on node 1 discovers that its peer endpoint is gone.
   Since there is a second working link, failover procedure is started.
2) Link endpoint A on node 1 sends a FAILOVER message to peer endpoint
   A on node 2. The node item 1->2 goes to state FAILINGOVER.
3) Linke endpoint A/2 receives the failover, and is supposed to take
   down its parallell link endpoint B/2, while producing a FAILOVER
   message to send back to A/1.
4) However, B/2 has already been deleted, so no FAILOVER message can
   created.
5) Node 1->2 remains in state FAILINGOVER forever, refusing to receive
   any messages that can bring B/1 up again. We are left with a non-
   redundant link between node 1 and 2.

We fix this with letting endpoint A/2 build a dummy FAILOVER message
to send to back to A/1, so that the situation can be resolved.

Signed-off-by: default avatarLUU Duc Canh <canh.d.luu@dektech.com.au>
Signed-off-by: default avatarJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 418b9a35

net/tipc/link.c

+35 −0
Original line number Diff line number Diff line
@@ -410,6 +410,11 @@ char *tipc_link_name(struct tipc_link *l) 
	return l->name;

}



u32 tipc_link_state(struct tipc_link *l)

{

	return l->state;

}



/**

 * tipc_link_create - create a new link

 * @n: pointer to associated node
@@ -1385,6 +1390,36 @@ static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe, 
	__skb_queue_tail(xmitq, skb);

}



void tipc_link_create_dummy_tnl_msg(struct tipc_link *l,

				    struct sk_buff_head *xmitq)

{

	u32 onode = tipc_own_addr(l->net);

	struct tipc_msg *hdr, *ihdr;

	struct sk_buff_head tnlq;

	struct sk_buff *skb;

	u32 dnode = l->addr;



	skb_queue_head_init(&tnlq);

	skb = tipc_msg_create(TUNNEL_PROTOCOL, FAILOVER_MSG,

			      INT_H_SIZE, BASIC_H_SIZE,

			      dnode, onode, 0, 0, 0);

	if (!skb) {

		pr_warn("%sunable to create tunnel packet\n", link_co_err);

		return;

	}



	hdr = buf_msg(skb);

	msg_set_msgcnt(hdr, 1);

	msg_set_bearer_id(hdr, l->peer_bearer_id);



	ihdr = (struct tipc_msg *)msg_data(hdr);

	tipc_msg_init(onode, ihdr, TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,

		      BASIC_H_SIZE, dnode);

	msg_set_errcode(ihdr, TIPC_ERR_NO_PORT);

	__skb_queue_tail(&tnlq, skb);

	tipc_link_xmit(l, &tnlq, xmitq);

}



/* tipc_link_tnl_prepare(): prepare and return a list of tunnel packets

 * with contents of the link's transmit and backlog queues.

 */

net/tipc/link.h

+3 −0
Original line number Diff line number Diff line
@@ -88,6 +88,8 @@ bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer, 
			 struct tipc_link **link);

void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,

			   int mtyp, struct sk_buff_head *xmitq);

void tipc_link_create_dummy_tnl_msg(struct tipc_link *tnl,

				    struct sk_buff_head *xmitq);

void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq);

int tipc_link_fsm_evt(struct tipc_link *l, int evt);

bool tipc_link_is_up(struct tipc_link *l);
@@ -107,6 +109,7 @@ u16 tipc_link_rcv_nxt(struct tipc_link *l); 
u16 tipc_link_acked(struct tipc_link *l);

u32 tipc_link_id(struct tipc_link *l);

char *tipc_link_name(struct tipc_link *l);

u32 tipc_link_state(struct tipc_link *l);

char tipc_link_plane(struct tipc_link *l);

int tipc_link_prio(struct tipc_link *l);

int tipc_link_window(struct tipc_link *l);

net/tipc/node.c

+11 −0
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ struct tipc_node { 
	int action_flags;

	struct list_head list;

	int state;

	bool failover_sent;

	u16 sync_point;

	int link_cnt;

	u16 working_links;
@@ -680,6 +681,7 @@ static void __tipc_node_link_up(struct tipc_node *n, int bearer_id, 
		*slot0 = bearer_id;

		*slot1 = bearer_id;

		tipc_node_fsm_evt(n, SELF_ESTABL_CONTACT_EVT);

		n->failover_sent = false;

		n->action_flags |= TIPC_NOTIFY_NODE_UP;

		tipc_link_set_active(nl, true);

		tipc_bcast_add_peer(n->net, nl, xmitq);
@@ -1615,6 +1617,15 @@ static bool tipc_node_check_state(struct tipc_node *n, struct sk_buff *skb, 
			tipc_skb_queue_splice_tail_init(tipc_link_inputq(pl),

							tipc_link_inputq(l));

		}

		/* If parallel link was already down, and this happened before

		 * the tunnel link came up, FAILOVER was never sent. Ensure that

		 * FAILOVER is sent to get peer out of NODE_FAILINGOVER state.

		 */

		if (n->state != NODE_FAILINGOVER && !n->failover_sent) {

			tipc_link_create_dummy_tnl_msg(l, xmitq);

			n->failover_sent = true;

		}



		/* If pkts arrive out of order, use lowest calculated syncpt */

		if (less(syncpt, n->sync_point))

			n->sync_point = syncpt;