drivers: Remove explicit invocations of mmiowb()

mmiowb() is now implied by spin_unlock() on architectures that require
it, so there is no reason to call it from driver code. This patch was
generated using coccinelle:

	@mmiowb@
	@@
	- mmiowb();

and invoked as:

$ for d in drivers include/linux/qed sound; do \
spatch --include-headers --sp-file mmiowb.cocci --dir $d --in-place; done

NOTE: mmiowb() has only ever guaranteed ordering in conjunction with
spin_unlock(). However, pairing each mmiowb() removal in this patch with
the corresponding call to spin_unlock() is not at all trivial, so there
is a small chance that this change may regress any drivers incorrectly
relying on mmiowb() to order MMIO writes between CPUs using lock-free
synchronisation. If you've ended up bisecting to this commit, you can
reintroduce the mmiowb() calls using wmb() instead, which should restore
the old behaviour on all architectures other than some esoteric ia64
systems.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 0 insertions, 12 deletions

diff --git a/drivers/infiniband/hw/qedr/verbs.c b/drivers/infiniband/hw/qedr/verbs.c
index 4dab2b5ffb0e..8686a98e113d 100644
--- a/drivers/infiniband/hw/qedr/verbs.c
+++ b/drivers/infiniband/hw/qedr/verbs.c
@@ -773,9 +773,6 @@ static void doorbell_cq(struct qedr_cq *cq, u32 cons, u8 flags)
 	cq->db.data.agg_flags = flags;
 	cq->db.data.value = cpu_to_le32(cons);
 	writeq(cq->db.raw, cq->db_addr);
-
-	/* Make sure write would stick */
-	mmiowb();
 }
 
 int qedr_arm_cq(struct ib_cq *ibcq, enum ib_cq_notify_flags flags)
@@ -2084,8 +2081,6 @@ static int qedr_update_qp_state(struct qedr_dev *dev,
 
 			if (rdma_protocol_roce(&dev->ibdev, 1)) {
 				writel(qp->rq.db_data.raw, qp->rq.db);
-				/* Make sure write takes effect */
-				mmiowb();
 			}
 			break;
 		case QED_ROCE_QP_STATE_ERR:
@@ -3502,9 +3497,6 @@ int qedr_post_send(struct ib_qp *ibqp, const struct ib_send_wr *wr,
 	smp_wmb();
 	writel(qp->sq.db_data.raw, qp->sq.db);
 
-	/* Make sure write sticks */
-	mmiowb();
-
 	spin_unlock_irqrestore(&qp->q_lock, flags);
 
 	return rc;
@@ -3695,12 +3687,8 @@ int qedr_post_recv(struct ib_qp *ibqp, const struct ib_recv_wr *wr,
 
 		writel(qp->rq.db_data.raw, qp->rq.db);
 
-		/* Make sure write sticks */
-		mmiowb();
-
 		if (rdma_protocol_iwarp(&dev->ibdev, 1)) {
 			writel(qp->rq.iwarp_db2_data.raw, qp->rq.iwarp_db2);
-			mmiowb();
 		}
 
 		wr = wr->next;