[PATCH 3.16 094/328] IB/IPoIB: Set ah valid flag in multicast send flow

Ben Hutchings
2018-12-09T22:25:59Z

From: Denis Drozdov <denisd@mellanox.com>

commit 75da96067ade4e7854379ec2f7834f3497652b1a upstream.

The change of ipoib_ah data structure with adding "valid" flag and
checks of ah->valid in ipoib_start_xmit affected multicast packet flow.

Since the multicast flow doesn't invoke path_rec_start, "ah->valid" flag
remains unset, so that ipoib_start_xmit end up with neigh_refresh_path
instead of sending the packet using neigh.

"ah->valid" has to be set in multicast send flow. As a result IPoIB
starts sending packets via neigh immediately and eliminates 60sec delay
of neigh keep alive interval.

The typical example of this issue are two sequential arpings:

arping 11.134.208.9 -> got response (mcast_send)
arping 11.134.208.9 -> no response (ah->valid = 0)

Fixes: fa9391dbad4b ("RDMA/ipoib: Update paths on CLIENT_REREG/SM_CHANGE events")
Signed-off-by: Denis Drozdov <denisd@mellanox.com>
Reviewed-by: Erez Shitrit <erezsh@mellanox.com>
Reviewed-by: Feras Daoud <ferasda@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/infiniband/ulp/ipoib/ipoib_multicast.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -734,6 +734,7 @@ out:
if (neigh && list_empty(&neigh->list)) {
kref_get(&mcast->ah->ref);
neigh->ah = mcast->ah;
+ neigh->ah->valid = 1;
list_add_tail(&neigh->list, &mcast->neigh_list);
}
}