From: Joyce Kong <joyce.kong@arm.com>
Date: Tue, 6 Jul 2021 06:54:04 +0000 (-0500)
Subject: net/i40e: replace SMP barrier with thread fence in Rx
X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=8649e2356689a6fdd2d4ae3ebe183f2ecd6046fd;p=dpdk.git

net/i40e: replace SMP barrier with thread fence in Rx

Simply replace the SMP barrier with atomic thread fence for
i40e hw ring scan, if there is no synchronization point.

Signed-off-by: Joyce Kong <joyce.kong@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>
---

diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
index 8489f91f1d..026cda948c 100644
--- a/drivers/net/i40e/i40e_rxtx.c
+++ b/drivers/net/i40e/i40e_rxtx.c
@@ -490,7 +490,8 @@ i40e_rx_scan_hw_ring(struct i40e_rx_queue *rxq)
 					I40E_RXD_QW1_STATUS_SHIFT;
 		}
 
-		rte_smp_rmb();
+		/* This barrier is to order loads of different words in the descriptor */
+		rte_atomic_thread_fence(__ATOMIC_ACQUIRE);
 
 		/* Compute how many status bits were set */
 		for (j = 0, nb_dd = 0; j < I40E_LOOK_AHEAD; j++) {