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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: LUU Duc Canh <canh.d.luu@dektech.com.au>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
LUU Duc Canh 2018-09-26 21:00:54 +02:00 committed by David S. Miller
parent 418b9a353a
commit c140eb166d
3 changed files with 49 additions and 0 deletions
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35
net/tipc/link.c
View File

@ -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.
*/

3
net/tipc/link.h
View File

@ -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);

11
net/tipc/node.c
View File

@ -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;