[PATCH] RDMA/qedr: Fix wmb usage in qedr

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This patch comes as a result of Sinan Kaya's patch:
https://patchwork.kernel.org/patch/10301863/

wmb usages in qedr driver have either been removed
where they were there only to order DMA accesses,
and replaced with smp_wmb and comments for the places
that the barrier was there for SMP reasons.

Signed-off-by: Michal Kalderon <Michal.Kalderon@xxxxxxxxxx>
Signed-off-by: Ariel Elior <Ariel.Elior@xxxxxxxxxx>
---
 drivers/infiniband/hw/qedr/verbs.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/hw/qedr/verbs.c b/drivers/infiniband/hw/qedr/verbs.c
index 875b172..3868bf0 100644
--- a/drivers/infiniband/hw/qedr/verbs.c
+++ b/drivers/infiniband/hw/qedr/verbs.c
@@ -856,8 +856,6 @@ static inline void qedr_init_cq_params(struct qedr_cq *cq,
 
 static void doorbell_cq(struct qedr_cq *cq, u32 cons, u8 flags)
 {
-	/* Flush data before signalling doorbell */
-	wmb();
 	cq->db.data.agg_flags = flags;
 	cq->db.data.value = cpu_to_le32(cons);
 	writeq(cq->db.raw, cq->db_addr);
@@ -1869,7 +1867,6 @@ static int qedr_update_qp_state(struct qedr_dev *dev,
 			 */
 
 			if (rdma_protocol_roce(&dev->ibdev, 1)) {
-				wmb();
 				writel(qp->rq.db_data.raw, qp->rq.db);
 				/* Make sure write takes effect */
 				mmiowb();
@@ -3256,7 +3253,8 @@ int qedr_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 	 * unchanged). For performance reasons we avoid checking for this
 	 * redundant doorbell.
 	 */
-	wmb();
+	/* qp->wqe_wr_id must be updated before completion process */
+	smp_wmb();
 	writel(qp->sq.db_data.raw, qp->sq.db);
 
 	/* Make sure write sticks */
@@ -3343,8 +3341,8 @@ int qedr_post_recv(struct ib_qp *ibqp, struct ib_recv_wr *wr,
 
 		qedr_inc_sw_prod(&qp->rq);
 
-		/* Flush all the writes before signalling doorbell */
-		wmb();
+		/* qp->rqe_wr_id must be updated before completion process */
+		smp_wmb();
 
 		qp->rq.db_data.data.value++;
 
-- 
2.9.5

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