[PATCH for-next 2/3] IB/hfi1: Fix sdma.h tx->num_descs off-by-one errors

[Dennis Dalessandro <dennis.dalessandro@xxxxxxxxxxxxxxxxxxxx>]

From: Patrick Kelsey <pat.kelsey@xxxxxxxxxxxxxxxxxxxx>

Signed-off-by: Brendan Cunningham <bcunningham@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Patrick Kelsey <pat.kelsey@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxxxxxxxxxxxxx>
---
 drivers/infiniband/hw/hfi1/sdma.c |    4 ++--
 drivers/infiniband/hw/hfi1/sdma.h |   15 +++++++--------
 2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/sdma.c b/drivers/infiniband/hw/hfi1/sdma.c
index a95b654f5254..8ed20392e9f0 100644
--- a/drivers/infiniband/hw/hfi1/sdma.c
+++ b/drivers/infiniband/hw/hfi1/sdma.c
@@ -3160,8 +3160,7 @@ int _pad_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
 {
 	int rval = 0;
 
-	tx->num_desc++;
-	if ((unlikely(tx->num_desc == tx->desc_limit))) {
+	if ((unlikely(tx->num_desc + 1 == tx->desc_limit))) {
 		rval = _extend_sdma_tx_descs(dd, tx);
 		if (rval) {
 			__sdma_txclean(dd, tx);
@@ -3174,6 +3173,7 @@ int _pad_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
 		SDMA_MAP_NONE,
 		dd->sdma_pad_phys,
 		sizeof(u32) - (tx->packet_len & (sizeof(u32) - 1)));
+	tx->num_desc++;
 	_sdma_close_tx(dd, tx);
 	return rval;
 }
diff --git a/drivers/infiniband/hw/hfi1/sdma.h b/drivers/infiniband/hw/hfi1/sdma.h
index d8170fcbfbdd..b023fc461bd5 100644
--- a/drivers/infiniband/hw/hfi1/sdma.h
+++ b/drivers/infiniband/hw/hfi1/sdma.h
@@ -631,14 +631,13 @@ static inline void sdma_txclean(struct hfi1_devdata *dd, struct sdma_txreq *tx)
 static inline void _sdma_close_tx(struct hfi1_devdata *dd,
 				  struct sdma_txreq *tx)
 {
-	tx->descp[tx->num_desc].qw[0] |=
-		SDMA_DESC0_LAST_DESC_FLAG;
-	tx->descp[tx->num_desc].qw[1] |=
-		dd->default_desc1;
+	u16 last_desc = tx->num_desc - 1;
+
+	tx->descp[last_desc].qw[0] |= SDMA_DESC0_LAST_DESC_FLAG;
+	tx->descp[last_desc].qw[1] |= dd->default_desc1;
 	if (tx->flags & SDMA_TXREQ_F_URGENT)
-		tx->descp[tx->num_desc].qw[1] |=
-			(SDMA_DESC1_HEAD_TO_HOST_FLAG |
-			 SDMA_DESC1_INT_REQ_FLAG);
+		tx->descp[last_desc].qw[1] |= (SDMA_DESC1_HEAD_TO_HOST_FLAG |
+					       SDMA_DESC1_INT_REQ_FLAG);
 }
 
 static inline int _sdma_txadd_daddr(
@@ -655,6 +654,7 @@ static inline int _sdma_txadd_daddr(
 		type,
 		addr, len);
 	WARN_ON(len > tx->tlen);
+	tx->num_desc++;
 	tx->tlen -= len;
 	/* special cases for last */
 	if (!tx->tlen) {
@@ -666,7 +666,6 @@ static inline int _sdma_txadd_daddr(
 			_sdma_close_tx(dd, tx);
 		}
 	}
-	tx->num_desc++;
 	return rval;
 }