[ofa-general] [PATCH 15/28] IB/ipath - add barrier before updating WC head in shared memory

[Arthur Jones]

From: Ralph Campbell <ralph.campbell at qlogic.com>

Add a barrier to make sure the CPU doesn't reorder writes
to memory since user programs can be polling on the head index
update and the entry should be written before that.

Signed-off-by: Ralph Campbell <ralph.campbell at qlogic.com>
---

 drivers/infiniband/hw/ipath/ipath_cq.c    |    3 ++-
 drivers/infiniband/hw/ipath/ipath_ruc.c   |    1 +
 drivers/infiniband/hw/ipath/ipath_srq.c   |    1 +
 drivers/infiniband/hw/ipath/ipath_ud.c    |    1 +
 drivers/infiniband/hw/ipath/ipath_verbs.c |    1 +
 5 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/drivers/infiniband/hw/ipath/ipath_cq.c b/drivers/infiniband/hw/ipath/ipath_cq.c
index 3e9241b..8a2a774 100644
--- a/drivers/infiniband/hw/ipath/ipath_cq.c
+++ b/drivers/infiniband/hw/ipath/ipath_cq.c
@@ -90,6 +90,7 @@ void ipath_cq_enter(struct ipath_cq *cq, struct ib_wc *entry, int solicited)
 	wc->queue[head].sl = entry->sl;
 	wc->queue[head].dlid_path_bits = entry->dlid_path_bits;
 	wc->queue[head].port_num = entry->port_num;
+	wmb();
 	wc->head = next;
 
 	if (cq->notify == IB_CQ_NEXT_COMP ||
@@ -139,7 +140,7 @@ int ipath_poll_cq(struct ib_cq *ibcq, int num_entries, struct ib_wc *entry)
 
 		if (tail == wc->head)
 			break;
-
+		rmb();
 		qp = ipath_lookup_qpn(&to_idev(cq->ibcq.device)->qp_table,
 				      wc->queue[tail].qp_num);
 		entry->qp = &qp->ibqp;
diff --git a/drivers/infiniband/hw/ipath/ipath_ruc.c b/drivers/infiniband/hw/ipath/ipath_ruc.c
index 8c5d20a..103dea0 100644
--- a/drivers/infiniband/hw/ipath/ipath_ruc.c
+++ b/drivers/infiniband/hw/ipath/ipath_ruc.c
@@ -194,6 +194,7 @@ int ipath_get_rwqe(struct ipath_qp *qp, int wr_id_only)
 			ret = 0;
 			goto bail;
 		}
+		rmb();
 		wqe = get_rwqe_ptr(rq, tail);
 		if (++tail >= rq->size)
 			tail = 0;
diff --git a/drivers/infiniband/hw/ipath/ipath_srq.c b/drivers/infiniband/hw/ipath/ipath_srq.c
index 03acae6..4b4214e 100644
--- a/drivers/infiniband/hw/ipath/ipath_srq.c
+++ b/drivers/infiniband/hw/ipath/ipath_srq.c
@@ -80,6 +80,7 @@ int ipath_post_srq_receive(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
 		wqe->num_sge = wr->num_sge;
 		for (i = 0; i < wr->num_sge; i++)
 			wqe->sg_list[i] = wr->sg_list[i];
+		wmb();
 		wq->head = next;
 		spin_unlock_irqrestore(&srq->rq.lock, flags);
 	}
diff --git a/drivers/infiniband/hw/ipath/ipath_ud.c b/drivers/infiniband/hw/ipath/ipath_ud.c
index a518f7c..eee54c7 100644
--- a/drivers/infiniband/hw/ipath/ipath_ud.c
+++ b/drivers/infiniband/hw/ipath/ipath_ud.c
@@ -176,6 +176,7 @@ static void ipath_ud_loopback(struct ipath_qp *sqp,
 			dev->n_pkt_drops++;
 			goto bail_sge;
 		}
+		rmb();
 		wqe = get_rwqe_ptr(rq, tail);
 		if (++tail >= rq->size)
 			tail = 0;
diff --git a/drivers/infiniband/hw/ipath/ipath_verbs.c b/drivers/infiniband/hw/ipath/ipath_verbs.c
index 04294ca..b92006a 100644
--- a/drivers/infiniband/hw/ipath/ipath_verbs.c
+++ b/drivers/infiniband/hw/ipath/ipath_verbs.c
@@ -323,6 +323,7 @@ static int ipath_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr,
 		wqe->num_sge = wr->num_sge;
 		for (i = 0; i < wr->num_sge; i++)
 			wqe->sg_list[i] = wr->sg_list[i];
+		wmb();
 		wq->head = next;
 		spin_unlock_irqrestore(&qp->r_rq.lock, flags);
 	}