[PATCH for-rc] RDMA/vmw_pvrdma: Report CQ missed events

[Adit Ranadive <aditr-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>]

From: Bryan Tan <bryantan-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>

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 <asarwade-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
Signed-off-by: Bryan Tan <bryantan-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
Signed-off-by: Adit Ranadive <aditr-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
---
 drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c b/drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c
index 69bda61..f4ab5fa 100644
--- a/drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c
+++ b/drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c
@@ -65,12 +65,27 @@ 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;
 
 	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);
 
+	if (notify_flags & IB_CQ_REPORT_MISSED_EVENTS) {
+		unsigned int head;
+
+		if (pvrdma_idx_ring_has_data(&cq->ring_state->rx,
+					     cq->ibcq.cqe, &head)) {
+			spin_unlock_irqrestore(&cq->cq_lock, flags);
+			return 1;
+		}
+	}
+
+	spin_unlock_irqrestore(&cq->cq_lock, flags);
+
 	return 0;
 }
 
-- 
2.7.4

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