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> --- Changes from v1: - Modified the smp_wmb usage comment to be clearer --- drivers/infiniband/hw/qedr/verbs.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/drivers/infiniband/hw/qedr/verbs.c b/drivers/infiniband/hw/qedr/verbs.c index 875b172..450344f 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 +3253,14 @@ 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 is accessed during qedr_poll_cq, as + * soon as we give the doorbell, we could get a completion + * for this wr, therefore we need to make sure that the + * memory is updated before giving the doorbell. + * During qedr_poll_cq, rmb is called before accessing the + * cqe. This covers for the smp_rmb as well. + */ + smp_wmb(); writel(qp->sq.db_data.raw, qp->sq.db); /* Make sure write sticks */ @@ -3343,8 +3347,14 @@ 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 is accessed during qedr_poll_cq, as + * soon as we give the doorbell, we could get a completion + * for this wr, therefore we need to make sure that the + * memory is update before giving the doorbell. + * During qedr_poll_cq, rmb is called before accessing the + * cqe. This covers for the smp_rmb as well. + */ + smp_wmb(); qp->rq.db_data.data.value++; -- 2.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
