Thanks for testing on ehca...
> While using IPoIB over EHCA (rc6 bits), unregister_netdev hangs with
I don't think you're actually using rc6 bits, since in your patch you have:
> -poll_more:
and I think that is only in Dave's net-2.6.24 tree now, right?
> The problem is that the poll handler does netif_rx_complete (which
> does a dev_put) followed by netif_rx_reschedule() to schedule for
> more receives (which again does a dev_put). This reduces refcount to
> < 0 (depending on how many times netif_rx_complete followed by
> netif_rx_reschedule was called).
Dave, the real problem seems to be that netif_rx_recschedule() calls
__napi_schedule() rather than __netif_rx_schedule(), so it misses the
call to dev_hold() that is needed to balance the dev_put() in
netif_rx_complete(). The current netif_rx_reschedule() looks like it
really should be napi_reschedule(), and we need a new function that
takes a netdev too. Or am I misunderstanding the refcounting?
I'll send a patch once I've had some breakfast and had a chance to at
least compile it...
Krishna, unfortunately your proposed fix has a race:
> - netif_rx_complete(dev, napi);
> - if (unlikely(ib_req_notify_cq(priv->cq,
> - IB_CQ_NEXT_COMP |
> - IB_CQ_REPORT_MISSED_EVENTS)) &&
> - netif_rx_reschedule(napi))
> - goto poll_more;
> + if (likely(!ib_req_notify_cq(priv->cq,
> + IB_CQ_NEXT_COMP |
> + IB_CQ_REPORT_MISSED_EVENTS)))
It is possible for an interrupt to happen immediately right here,
before the netif_rx_complete(), so that netif_rx_schedule() gets
called while we are still on the poll list.
> + netif_rx_complete(dev, napi);
- R.
-
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