Ipoib can miss a change in dgid under some conditions. The problem is
caused when ipoib_neigh->dgid contains a stale address. The fix is to
set ipoib_neigh->dgid to zero in ipoib_neigh_alloc().
Detail description: A systems using bonding on its ipoib interface has
switched it active slave interface from interface A to B and back to A
setting up the situation for this bug. The system that fails will not
correctly processes the 2nd address change.
When an address has changed neighbor->ha is updated with the new address.
Each neighbor has an associated ipoib_neigh. ipoib_neigh->dgid also
holds a copy of the remote node's hardware address. When an address
changes neighbor->ha is updated by the network layer (arp code) with the
new address. Ipoib detects this change in ipoib_start_xmit() by comparing
neighbor->ha with ipoib_neigh->dgid. The bug is that ipoib_neigh->dgid
already contains the new address(A) thus the change from B to A is missed
by ipoib. Here is the sequence of events:
ipoib_neigh->dgid = A neighbor->ha=A
The address is switched to B (the first switch)
neighbor->ha=B
The change is seen in ipoib_start_xmit(). neighbor->ha !=
ipoib_neigh->dgid
The ipoib_neigh is released, and a new one is allocated.
The memory allocation system returned the same chunk of memory that was
just released, therefore ipoib_neigh->dgid still contains A at this point.
ipoib_neigh->dgid should be updated in neigh_add_path(), but if the
following conditions are true dgid is not updated.
1) __path_find() returns a path
2) path->ah is NULL
The remote system now switches from address B to A, neighbor->ha is
updated to A.
Now we have: ipoib_neigh->dgid = A neighbor->ha=A
Since the address are the same ipoib won't process the change in address.
Signed-off-by: David Wilder <[email protected]>
------------------------------------------------------
drivers/infiniband/ulp/ipoib/ipoib_main.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c
b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index 2bf5116..25ef50b 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -884,6 +884,7 @@ struct ipoib_neigh *ipoib_neigh_alloc(struct neighbour
*neighbour,
neigh->neighbour = neighbour;
neigh->dev = dev;
+ memset(&neigh->dgid.raw, 0, sizeof(union ib_gid));
*to_ipoib_neigh(neighbour) = neigh;
skb_queue_head_init(&neigh->queue);
ipoib_cm_set(neigh, NULL);
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