[tip:core/rcu] drivers/dma/ioat: Remove now-redundant smp_read_barrier_depends()

[tip:core/rcu] drivers/dma/ioat: Remove now-redundant smp_read_barrier_depends()

[tip-bot for Borislav Petkov]

Commit-ID:  98c1ec7cefaadbf65680d116c3d8612b93a841a0
Gitweb:     https://git.kernel.org/tip/98c1ec7cefaadbf65680d116c3d8612b93a841a0
Author:     Paul E. McKenney <paulmck@linux.vnet.ibm.com>
AuthorDate: Fri, 1 Dec 2017 17:04:39 -0800
Committer:  Paul E. McKenney <paulmck@linux.vnet.ibm.com>
CommitDate: Tue, 5 Dec 2017 11:57:53 -0800

drivers/dma/ioat: Remove now-redundant smp_read_barrier_depends()

Now that READ_ONCE() implies smp_read_barrier_depends(), the
__cleanup() and ioat_abort_descs() functions no longer need their
smp_read_barrier_depends() calls, which this commit removes.
It is actually not entirely clear why this driver ever included
smp_read_barrier_depends() given that it appears to be x86-only and
given that smp_read_barrier_depends() has no effect whatsoever except
on DEC Alpha.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: <dmaengine@vger.kernel.org>
---
 drivers/dma/ioat/dma.c | 2 --
 1 file changed, 2 deletions(-)

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diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c
index 58d4ccd..8b5b23a 100644
--- a/drivers/dma/ioat/dma.c
+++ b/drivers/dma/ioat/dma.c
@@ -597,7 +597,6 @@ static void __cleanup(struct ioatdma_chan *ioat_chan, dma_addr_t phys_complete)
 	for (i = 0; i < active && !seen_current; i++) {
 		struct dma_async_tx_descriptor *tx;
 
-		smp_read_barrier_depends();
 		prefetch(ioat_get_ring_ent(ioat_chan, idx + i + 1));
 		desc = ioat_get_ring_ent(ioat_chan, idx + i);
 		dump_desc_dbg(ioat_chan, desc);
@@ -715,7 +714,6 @@ static void ioat_abort_descs(struct ioatdma_chan *ioat_chan)
 	for (i = 1; i < active; i++) {
 		struct dma_async_tx_descriptor *tx;
 
-		smp_read_barrier_depends();
 		prefetch(ioat_get_ring_ent(ioat_chan, idx + i + 1));
 		desc = ioat_get_ring_ent(ioat_chan, idx + i);