On 25/02/2013 19:46, Roland Dreier wrote:
If IPoIB fails to look up a path record (eg if it tries during an SM
failover when one SM is dead but the new one hasn't taken over yet), the
driver ends up with a neighbour structure but no address handle (AH).
There's no mechanism to recover from this: any further packets sent to
this destination will be silently dumped in ipoib_start_xmit().
Looking on the flow of sending ARP probes, I see that in
unicast_arp_send, if there's no AH for the path, a path query is initiated,
if (path->ah) {
ipoib_dbg(priv, "Send unicast ARP to %04x\n",
be16_to_cpu(path->pathrec.dlid));
spin_unlock_irqrestore(&priv->lock, flags);
ipoib_send(dev, skb, path->ah, IPOIB_QPN(cb->hwaddr));
return;
} else if ((path->query || !path_rec_start(dev, path)) &&
skb_queue_len(&path->queue) <
IPOIB_MAX_PATH_REC_QUEUE) {
__skb_queue_tail(&path->queue, skb);
} else {
++dev->stats.tx_dropped;
dev_kfree_skb_any(skb);
}
so eventually the traffic should resume once the ND state machine sends
a probe, agree? did you only wanted to make that faster?
Or.
Fix this by freeing the neighbour structures when a path rec query fails, so
that the next packet queued to be sent will trigger a new path record query.
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