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Commit 09c4854f authored by Kalderon, Michal's avatar Kalderon, Michal Committed by Jason Gunthorpe
Browse files

RDMA/qedr: Fix wmb usage in qedr 



This patch comes as a result of Sinan Kaya's work and the decision that
writel() must be a strong enough barrier for DMA.

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.

Fixes: 561e5d48 ("RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs")
Signed-off-by: default avatarMichal Kalderon <Michal.Kalderon@cavium.com>
Signed-off-by: default avatarAriel Elior <Ariel.Elior@cavium.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent 39e00b6c

drivers/infiniband/hw/qedr/verbs.c

+18 −8
Original line number Diff line number Diff line
@@ -804,8 +804,6 @@ 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);
@@ -1812,8 +1810,7 @@ static int qedr_update_qp_state(struct qedr_dev *dev, 
			 */



			if (rdma_protocol_roce(&dev->ibdev, 1)) {

				wmb();

				writel_relaxed(qp->rq.db_data.raw, qp->rq.db);

				writel(qp->rq.db_data.raw, qp->rq.db);

				/* Make sure write takes effect */

				mmiowb();

			}
@@ -3198,9 +3195,16 @@ int qedr_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, 
	 * vane. However this is not harmful (as long as the producer value is

	 * unchanged). For performance reasons we avoid checking for this

	 * redundant doorbell.

	 *

	 * 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.

	 */

	wmb();

	writel_relaxed(qp->sq.db_data.raw, qp->sq.db);

	smp_wmb();

	writel(qp->sq.db_data.raw, qp->sq.db);



	/* Make sure write sticks */

	mmiowb();
@@ -3286,8 +3290,14 @@ 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++;