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From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
To: dev@dpdk.org, honnappa.nagarahalli@arm.com, ruifeng.wang@arm.com,
	matan@nvidia.com, shahafs@nvidia.com, viacheslavo@nvidia.com
Cc: nd@arm.com, matan@mellanox.com, stable@dpdk.org
Subject: [PATCH v2] net/mlx5: use just sufficient barrier for Arm platforms
Date: Tue, 30 Aug 2022 15:00:38 -0500	[thread overview]
Message-ID: <20220830200038.1694160-1-honnappa.nagarahalli@arm.com> (raw)
In-Reply-To: <20210606164948.35997-1-honnappa.nagarahalli@arm.com>

cqe->op_own indicates if the CQE is owned by the NIC. The rest of
the fields in CQE should be read only after op_own is read. On Arm
platforms using "dmb ishld" is sufficient to enforce this.

Fixes: 88c0733535d6 ("net/mlx5: extend Rx completion with error handling")
Cc: matan@mellanox.com
Cc: stable@dpdk.org

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
---
 drivers/common/mlx5/mlx5_common.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/common/mlx5/mlx5_common.h b/drivers/common/mlx5/mlx5_common.h
index 5028a05b49..ac2e85b15f 100644
--- a/drivers/common/mlx5/mlx5_common.h
+++ b/drivers/common/mlx5/mlx5_common.h
@@ -195,7 +195,11 @@ check_cqe(volatile struct mlx5_cqe *cqe, const uint16_t cqes_n,
 
 	if (unlikely((op_owner != (!!(idx))) || (op_code == MLX5_CQE_INVALID)))
 		return MLX5_CQE_STATUS_HW_OWN;
-	rte_io_rmb();
+	/* Prevent speculative reading of other fields in CQE until
+	 * CQE is valid.
+	 */
+	rte_atomic_thread_fence(__ATOMIC_ACQUIRE);
+
 	if (unlikely(op_code == MLX5_CQE_RESP_ERR ||
 		     op_code == MLX5_CQE_REQ_ERR))
 		return MLX5_CQE_STATUS_ERR;
-- 
2.17.1


  parent reply	other threads:[~2022-08-30 20:00 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-06 16:49 [dpdk-stable] [PATCH] net/mlx5: remove unwanted barrier Honnappa Nagarahalli
2021-07-01 12:52 ` Slava Ovsiienko
2021-07-02 21:51   ` Honnappa Nagarahalli
2022-08-30 20:00 ` Honnappa Nagarahalli [this message]
2022-09-27  6:34   ` [PATCH v2] net/mlx5: use just sufficient barrier for Arm platforms Slava Ovsiienko
2022-09-27 21:03     ` Honnappa Nagarahalli
2022-11-15  1:45       ` Honnappa Nagarahalli
2023-03-07 16:07         ` Slava Ovsiienko
2023-03-09  2:42           ` Honnappa Nagarahalli
2022-09-27 21:06     ` Honnappa Nagarahalli
2023-03-09  2:32   ` [PATCH v3] net/mlx5: use just sufficient barrier for ARM platforms Honnappa Nagarahalli
2023-03-09 15:44     ` Slava Ovsiienko
2023-03-19 13:32     ` Raslan Darawsheh

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