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tipc: eliminate the dummy packet in link synching 

When preparing tunnel packets for the link failover or synchronization,
as for the safe algorithm, we added a dummy packet on the pair link but
never sent it out. In the case of failover, the pair link will be reset
anyway. But for link synching, it will always result in retransmission
of the dummy packet after that.
We have also observed that such the retransmission at the early stage
when a new node comes in a large cluster will take some time and hard
to be done, leading to the repeated retransmit failures and the link is
reset.

Since in commit 4929a932be ("tipc: optimize link synching mechanism")
we have already built a dummy 'TUNNEL_PROTOCOL' message on the new link
for the synchronization, there's no need for the dummy on the pair one,
this commit will skip it when the new mechanism takes in place. In case
nothing exists in the pair link's transmq, the link synching will just
start and stop shortly on the peer side.

The patch is backward compatible.

Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Tested-by: Hoang Le <hoang.h.le@dektech.com.au>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tuong Lien 2019-11-06 18:12:17 +07:00 committed by David S. Miller
parent 3924f72a3a
commit d0d605c5e1
1 changed files with 14 additions and 15 deletions
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29
net/tipc/link.c
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@ -1731,21 +1731,6 @@ void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
return;
__skb_queue_head_init(&tnlq);
__skb_queue_head_init(&tmpxq);
__skb_queue_head_init(&frags);
/* At least one packet required for safe algorithm => add dummy */
skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
0, 0, TIPC_ERR_NO_PORT);
if (!skb) {
pr_warn("%sunable to create tunnel packet\n", link_co_err);
return;
}
__skb_queue_tail(&tnlq, skb);
tipc_link_xmit(l, &tnlq, &tmpxq);
__skb_queue_purge(&tmpxq);
/* Link Synching:
* From now on, send only one single ("dummy") SYNCH message
* to peer. The SYNCH message does not contain any data, just
@ -1771,6 +1756,20 @@ void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
return;
}
__skb_queue_head_init(&tmpxq);
__skb_queue_head_init(&frags);
/* At least one packet required for safe algorithm => add dummy */
skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
0, 0, TIPC_ERR_NO_PORT);
if (!skb) {
pr_warn("%sunable to create tunnel packet\n", link_co_err);
return;
}
__skb_queue_tail(&tnlq, skb);
tipc_link_xmit(l, &tnlq, &tmpxq);
__skb_queue_purge(&tmpxq);
/* Initialize reusable tunnel packet header */
tipc_msg_init(tipc_own_addr(l->net), &tnlhdr, TUNNEL_PROTOCOL,
mtyp, INT_H_SIZE, l->addr);