From: Phil Yang <phil.yang@arm.com>
Date: Tue, 13 Oct 2020 16:25:36 +0000 (-0500)
Subject: ethdev: replace full barrier with relaxed barrier
X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=8dd4b2afc7b3aabcd364f9638cc7f476d48096ff;p=dpdk.git

ethdev: replace full barrier with relaxed barrier

While registering the call back functions full write barrier
can be replaced with one-way write barrier.

Signed-off-by: Phil Yang <phil.yang@arm.com>
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
---

diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index 7817224c4f..2198548663 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -26,7 +26,6 @@
 #include <rte_eal.h>
 #include <rte_per_lcore.h>
 #include <rte_lcore.h>
-#include <rte_atomic.h>
 #include <rte_branch_prediction.h>
 #include <rte_common.h>
 #include <rte_mempool.h>
@@ -4651,8 +4650,12 @@ rte_eth_add_first_rx_callback(uint16_t port_id, uint16_t queue_id,
 	rte_spinlock_lock(&rte_eth_rx_cb_lock);
 	/* Add the callbacks at first position */
 	cb->next = rte_eth_devices[port_id].post_rx_burst_cbs[queue_id];
-	rte_smp_wmb();
-	rte_eth_devices[port_id].post_rx_burst_cbs[queue_id] = cb;
+	/* Stores to cb->fn, cb->param and cb->next should complete before
+	 * cb is visible to data plane threads.
+	 */
+	__atomic_store_n(
+		&rte_eth_devices[port_id].post_rx_burst_cbs[queue_id],
+		cb, __ATOMIC_RELEASE);
 	rte_spinlock_unlock(&rte_eth_rx_cb_lock);
 
 	return cb;