From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuval Shaia Subject: Re: [PATCH v1 for-rc] RDMA/vmw_pvrdma: Report CQ missed events Date: Thu, 10 Aug 2017 23:02:56 +0300 Message-ID: <20170810200256.GA4913@yuvallap> References: <1502391902-5674-1-git-send-email-aditr@vmware.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1502391902-5674-1-git-send-email-aditr-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Adit Ranadive Cc: dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, pv-drivers-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org, Bryan Tan , Jorgen Hansen , Aditya Sarwade List-Id: linux-rdma@vger.kernel.org On Thu, Aug 10, 2017 at 12:05:02PM -0700, Adit Ranadive wrote: > From: Bryan Tan > > There is a chance of a race between arming the CQ and receiving > completions. By reporting CQ missed events any ULPs should poll > again to get the completions. > > Fixes: 29c8d9eba550 ("IB: Add vmw_pvrdma driver") > Acked-by: Aditya Sarwade > Signed-off-by: Bryan Tan > Signed-off-by: Adit Ranadive > --- > v0 -> v1: > - Check for invalid ring index. > --- > drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c | 17 ++++++++++++++++- > 1 file changed, 16 insertions(+), 1 deletion(-) > > diff --git a/drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c b/drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c > index 69bda61..90aa326 100644 > --- a/drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c > +++ b/drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c > @@ -65,13 +65,28 @@ int pvrdma_req_notify_cq(struct ib_cq *ibcq, > struct pvrdma_dev *dev = to_vdev(ibcq->device); > struct pvrdma_cq *cq = to_vcq(ibcq); > u32 val = cq->cq_handle; > + unsigned long flags; > + int has_data = 0; > > val |= (notify_flags & IB_CQ_SOLICITED_MASK) == IB_CQ_SOLICITED ? > PVRDMA_UAR_CQ_ARM_SOL : PVRDMA_UAR_CQ_ARM; > > + spin_lock_irqsave(&cq->cq_lock, flags); > + > pvrdma_write_uar_cq(dev, val); > > - return 0; > + if (notify_flags & IB_CQ_REPORT_MISSED_EVENTS) { > + unsigned int head; > + > + has_data = pvrdma_idx_ring_has_data(&cq->ring_state->rx, > + cq->ibcq.cqe, &head); > + if (unlikely(has_data == PVRDMA_INVALID_IDX)) > + dev_err(&dev->pdev->dev, "CQ ring state invalid\n"); I see the point of checking the return value but per my understanding, and correct me if i'm wrong, this rare case points to a corrupted ring which can happen *only* in case of a bug so it is not "error" by nature. If this is correct then i don't see the point of having this "question" on every call to ib_notify_cq. Do you agree to move this check to pvrdma_idx_ring_has_data and even make the function use BUG_ON? > + } > + > + spin_unlock_irqrestore(&cq->cq_lock, flags); > + > + return has_data; > } > > /** > -- > 2.7.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html