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From: "Steve Wise" <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
To: 'Sagi Grimberg' <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: RE: possible core cq bug
Date: Sun, 3 Dec 2017 09:24:15 -0600	[thread overview]
Message-ID: <006c01d36c4a$c79cfb50$56d6f1f0$@opengridcomputing.com> (raw)
In-Reply-To: <be658098-28a6-e5a8-cebf-5865096f99ce-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>

> 
> > If an application creates its cq for DIRECT poll mode using ib_create_cq()
> > instead of ib_alloc_cq(),  and then uses ib_drain_qp() to drain its qp,
> > ib_drain_sq/rq() will always hang forever because cq->wc is NULL.  IE
> > ib_create_cq() doesn't allocate cq->wc, and ib_alloc_cq() does.  Yet the
> > __ib_process_cq() requires cq->wc to actually complete any completions
> and
> > calling the cqe_done function.
> >
> > Is this a bug in the CQ core code or the application?
> 
> Take a look in __ib_drain_rq/__ib_drain_sq for
> cq->poll_ctx == IB_POLL_DIRECT. The drain routine polls
> the completion queue from time to time...

Yes, but it ends up calling __ib_process_cq() which doesn't actually poll the CQ because cq->wc is NULL. 

Steve.

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  parent reply	other threads:[~2017-12-03 15:24 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-02 19:19 possible core cq bug Steve Wise
2017-12-03 11:51 ` Sagi Grimberg
     [not found]   ` <be658098-28a6-e5a8-cebf-5865096f99ce-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
2017-12-03 15:24     ` Steve Wise [this message]
2017-12-03 16:53       ` Sagi Grimberg
     [not found]         ` <e7782921-b55a-a628-02d4-874d88049ec5-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
2017-12-03 17:17           ` Steve Wise
2017-12-04 18:41             ` Sagi Grimberg
     [not found]               ` <456aef15-a5a7-6dc8-478b-9fc7f75ff1fb-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
2017-12-07 16:00                 ` Steve Wise

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