drivers/infiniband: Remove now-redundant smp_read_barrier_depends()

The smp_read_barrier_depends() does nothing at all except on DEC Alpha,
and no current DEC Alpha systems use Infiniband:

	lkml.kernel.org/r/20171023085921.jwbntptn6ictbnvj@tower

This commit therefore makes Infiniband depend on !ALPHA and removes
the now-ineffective invocations of smp_read_barrier_depends() from
the InfiniBand driver.

Please note that this patch should not be construed as my saying that
InfiniBand's memory ordering is correct, but rather that this patch does
not in any way affect InfiniBand's correctness.  In other words, the
result of applying this patch is bug-for-bug compatible with the original.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Cree <mcree@orcon.net.nz>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: <linux-rdma@vger.kernel.org>
Cc: <linux-alpha@vger.kernel.org>
[ paulmck: Removed drivers/dma/ioat/dma.c per Jason Gunthorpe's feedback. ]
Acked-by: Jason Gunthorpe <jgg@mellanox.com>

4 files changed, 0 insertions, 8 deletions

diff --git a/drivers/infiniband/hw/qib/qib_rc.c b/drivers/infiniband/hw/qib/qib_rc.c
index 8f5754fb8579..1a785c37ad0a 100644
--- a/drivers/infiniband/hw/qib/qib_rc.c
+++ b/drivers/infiniband/hw/qib/qib_rc.c
@@ -246,7 +246,6 @@ int qib_make_rc_req(struct rvt_qp *qp, unsigned long *flags)
 		if (!(ib_rvt_state_ops[qp->state] & RVT_FLUSH_SEND))
 			goto bail;
 		/* We are in the error state, flush the work request. */
-		smp_read_barrier_depends(); /* see post_one_send() */
 		if (qp->s_last == READ_ONCE(qp->s_head))
 			goto bail;
 		/* If DMAs are in progress, we can't flush immediately. */
@@ -293,7 +292,6 @@ int qib_make_rc_req(struct rvt_qp *qp, unsigned long *flags)
 		newreq = 0;
 		if (qp->s_cur == qp->s_tail) {
 			/* Check if send work queue is empty. */
-			smp_read_barrier_depends(); /* see post_one_send() */
 			if (qp->s_tail == READ_ONCE(qp->s_head))
 				goto bail;
 			/*
@@ -1340,7 +1338,6 @@ static void qib_rc_rcv_resp(struct qib_ibport *ibp,
 		goto ack_done;
 
 	/* Ignore invalid responses. */
-	smp_read_barrier_depends(); /* see post_one_send */
 	if (qib_cmp24(psn, READ_ONCE(qp->s_next_psn)) >= 0)
 		goto ack_done;
 
diff --git a/drivers/infiniband/hw/qib/qib_ruc.c b/drivers/infiniband/hw/qib/qib_ruc.c
index 9a37e844d4c8..4662cc7bde92 100644
--- a/drivers/infiniband/hw/qib/qib_ruc.c
+++ b/drivers/infiniband/hw/qib/qib_ruc.c
@@ -367,7 +367,6 @@ static void qib_ruc_loopback(struct rvt_qp *sqp)
 	sqp->s_flags |= RVT_S_BUSY;
 
 again:
-	smp_read_barrier_depends(); /* see post_one_send() */
 	if (sqp->s_last == READ_ONCE(sqp->s_head))
 		goto clr_busy;
 	wqe = rvt_get_swqe_ptr(sqp, sqp->s_last);
diff --git a/drivers/infiniband/hw/qib/qib_uc.c b/drivers/infiniband/hw/qib/qib_uc.c
index bddcc37ace44..70c58b88192c 100644
--- a/drivers/infiniband/hw/qib/qib_uc.c
+++ b/drivers/infiniband/hw/qib/qib_uc.c
@@ -60,7 +60,6 @@ int qib_make_uc_req(struct rvt_qp *qp, unsigned long *flags)
 		if (!(ib_rvt_state_ops[qp->state] & RVT_FLUSH_SEND))
 			goto bail;
 		/* We are in the error state, flush the work request. */
-		smp_read_barrier_depends(); /* see post_one_send() */
 		if (qp->s_last == READ_ONCE(qp->s_head))
 			goto bail;
 		/* If DMAs are in progress, we can't flush immediately. */
@@ -90,7 +89,6 @@ int qib_make_uc_req(struct rvt_qp *qp, unsigned long *flags)
 		    RVT_PROCESS_NEXT_SEND_OK))
 			goto bail;
 		/* Check if send work queue is empty. */
-		smp_read_barrier_depends(); /* see post_one_send() */
 		if (qp->s_cur == READ_ONCE(qp->s_head))
 			goto bail;
 		/*
diff --git a/drivers/infiniband/hw/qib/qib_ud.c b/drivers/infiniband/hw/qib/qib_ud.c
index 15962ed193ce..386c3c4da0c7 100644
--- a/drivers/infiniband/hw/qib/qib_ud.c
+++ b/drivers/infiniband/hw/qib/qib_ud.c
@@ -252,7 +252,6 @@ int qib_make_ud_req(struct rvt_qp *qp, unsigned long *flags)
 		if (!(ib_rvt_state_ops[qp->state] & RVT_FLUSH_SEND))
 			goto bail;
 		/* We are in the error state, flush the work request. */
-		smp_read_barrier_depends(); /* see post_one_send */
 		if (qp->s_last == READ_ONCE(qp->s_head))
 			goto bail;
 		/* If DMAs are in progress, we can't flush immediately. */
@@ -266,7 +265,6 @@ int qib_make_ud_req(struct rvt_qp *qp, unsigned long *flags)
 	}
 
 	/* see post_one_send() */
-	smp_read_barrier_depends();
 	if (qp->s_cur == READ_ONCE(qp->s_head))
 		goto bail;