[dpdk-dev] [PATCH v2] raw/ntb: fix write memory barrier issue

[Xiaoyun Li]

All buffers and ring info should be written before tail register update.
This patch relocates the write memory barrier before updating tail register
to avoid potential issues.

Fixes: 11b5c7daf019 ("raw/ntb: add enqueue and dequeue functions")
Cc: stable at dpdk.org

Signed-off-by: Xiaoyun Li <xiaoyun.li at intel.com>
---
v2:
 * Replaced rte_wmb with rte_io_wmb since rte_io_wmb is enough.
---
 drivers/raw/ntb/ntb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/raw/ntb/ntb.c b/drivers/raw/ntb/ntb.c
index ad7f6abfd..c7de86f36 100644
--- a/drivers/raw/ntb/ntb.c
+++ b/drivers/raw/ntb/ntb.c
@@ -683,8 +683,8 @@ ntb_enqueue_bufs(struct rte_rawdev *dev,
 			   sizeof(struct ntb_used) * nb1);
 		rte_memcpy(txq->tx_used_ring, tx_used + nb1,
 			   sizeof(struct ntb_used) * nb2);
+		rte_io_wmb();
 		*txq->used_cnt = txq->last_used;
-		rte_wmb();
 
 		/* update queue stats */
 		hw->ntb_xstats[NTB_TX_BYTES_ID + off] += bytes;
@@ -789,8 +789,8 @@ ntb_dequeue_bufs(struct rte_rawdev *dev,
 			   sizeof(struct ntb_desc) * nb1);
 		rte_memcpy(rxq->rx_desc_ring, rx_desc + nb1,
 			   sizeof(struct ntb_desc) * nb2);
+		rte_io_wmb();
 		*rxq->avail_cnt = rxq->last_avail;
-		rte_wmb();
 
 		/* update queue stats */
 		off = NTB_XSTATS_NUM * ((size_t)context + 1);
-- 
2.17.1