ralphc> There is a race in IPoIB where it rearms the CQ by calling
ralphc> ib_req_notify_cq() followed by ib_poll_cq(). The loop can
ralphc> call ib_poll_cq() multiple times if new packets arrive but
ralphc> then fail to rearm the CQ properly.
I don't understand the race you're trying to fix. Right now, the CQ
polling code is:
ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
do {
n = ib_poll_cq(cq, IPOIB_NUM_WC, priv->ibwc);
for (i = 0; i < n; ++i)
ipoib_ib_handle_wc(dev, priv->ibwc + i);
} while (n == IPOIB_NUM_WC);
The call to ib_req_notify_cq() will result in an event if any entries
are added to the CQ after the call, so I don't see any way that IPoIB
can miss a CQ event. New entries can indeed arrive and be polled
during the do { } while() loop, but the effect of that is just an
extra CQ event, which might lead to an extra interrupt and polling an
empty CQ once.
Can you give a little more detail about the problem you're fixing?
- R.
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