stack: reload head when pop fails

List head must be loaded right before continue (when failed to
find the new head).
Without this, one thread might keep trying and failing to pop items
without ever loading the new correct head.

Fixes: 7e6e609939a8 ("stack: add C11 atomic implementation")
Cc: gage.eads@intel.com
Cc: stable@dpdk.org
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>

diff --git a/lib/librte_stack/rte_stack_lf_c11.h b/lib/librte_stack/rte_stack_lf_c11.h
index 2bc6394..adb9f59 100644 (file)
--- a/lib/librte_stack/rte_stack_lf_c11.h
+++ b/lib/librte_stack/rte_stack_lf_c11.h
@@ -133,8 +133,10 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
                /* If NULL was encountered, the list was modified while
                 * traversing it. Retry.
                 */
-               if (i != num)
+               if (i != num) {
+                       old_head = list->head;
                        continue;
+               }
 
                new_head.top = tmp;
                new_head.cnt = old_head.cnt + 1;