[dpdk-dev] [PATCH v2 2/5] lib/stack: remove push acquire fence

[Steven Lariau <steven.lariau@arm.com>]

An acquire fence is used to make sure loads after the fence can observe
all store operations before a specific store-release.
But push doesn't read any data, except for the head which is part of a
CAS operation (the items on the list are not read).
So there is no need for the acquire barrier.

Signed-off-by: Steven Lariau <steven.lariau@arm.com>
Reviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Gage Eads <gage.eads@intel.com>
---
 lib/librte_stack/rte_stack_lf_c11.h | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/lib/librte_stack/rte_stack_lf_c11.h b/lib/librte_stack/rte_stack_lf_c11.h
index 1e0ea0bef..82b7287f1 100644
--- a/lib/librte_stack/rte_stack_lf_c11.h
+++ b/lib/librte_stack/rte_stack_lf_c11.h
@@ -44,12 +44,6 @@ __rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
 	do {
 		struct rte_stack_lf_head new_head;
 
-		/* Use an acquire fence to establish a synchronized-with
-		 * relationship between the list->head load and store-release
-		 * operations (as part of the rte_atomic128_cmp_exchange()).
-		 */
-		__atomic_thread_fence(__ATOMIC_ACQUIRE);
-
 		/* Swing the top pointer to the first element in the list and
 		 * make the last element point to the old top.
 		 */
-- 
2.17.1