[ofa-general] Re: [RFC][PATCH] last wqe event handler patch

[Roland Dreier]

 > 1. QP100 last WQE reached event, QP100 context is added into flush_list,
 > and then it is put into drain_list, and does post_send of a drain WR.
 > 2. QP200 last WQE reached event, QP200 context is added into flush_list,
 > but not drain_list since only one drain WR will be posted
 > 3. QP300 ...., QP300 context is added into flush_list, but not drain_list
 > 
 > So QP100 is on drain_list, QP200, QP300 are on flush_list
 > 
 > In rcq poll_cq,
 > 1. QP 100 drain WR cqe is polled, it will put QP100 into reap_list then
 > call ipoib_cm_start_rx_drain(), post_send of QP200 drain WR, and QP200,
 > QP300 are both moved from flush_list to drain_list
 > 2. QP 200 drain WR cqe is polled, it will move both QP200 and QP300 from
 > drain_list to reap_list
 > 3. QP300 cqe comes, but QP300 context has been freed, ---> panic.
 > 
 > Does that make sense?

This is a really good explanation (exactly what I would hope to see in a
changelog).  I'm not positive I understand though: is the issue that
when the QP300 last WQE reached event is seen, we are not guaranteed
that we have handled all CQEs for QP300 yet?

 - R.