[dpdk-dev] [PATCH RFC v1 3/6] net/mlx5: add missing barrier

[Gavin Hu <gavin.hu@arm.com>]

To keep order of the modification of RX queue descriptor(rxq->cq_db) and
the CQ doorbell register, a rte_cio_wmb barrier is required.

The situation was rescued by the stronger than required barrier in the
mlx5_uar_write64, it becomes a must when the barrier is relaxed.

Fixes: 6bf10ab69be0 ("net/mlx5: support 32-bit systems")
Cc: stable@dpdk.org

Suggested-by: Phil Yang <phil.yang@arm.com>
Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
---
 drivers/net/mlx5/mlx5_rxq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index dc0fd8211..2d1b153a3 100644
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -856,7 +856,8 @@ mlx5_arm_cq(struct mlx5_rxq_data *rxq, int sq_n_rxq)
 	doorbell = (uint64_t)doorbell_hi << 32;
 	doorbell |=  rxq->cqn;
 	rxq->cq_db[MLX5_CQ_ARM_DB] = rte_cpu_to_be_32(doorbell_hi);
-	mlx5_uar_write64(rte_cpu_to_be_64(doorbell),
+	rte_cio_wmb();
+	mlx5_uar_write64_relaxed(rte_cpu_to_be_64(doorbell),
 			 cq_db_reg, rxq->uar_lock_cq);
 }
 
-- 
2.17.1