[dpdk-stable] [PATCH v2] stack: fix reload head when pop fails

[Julien Meunier]

The previous commit 18effad9cfa7 ("stack: reload head when pop fails")
only changed C11 implementation, not generic implementation.

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: 3340202f5954 ("stack: add lock-free implementation")
Cc: stable at dpdk.org

Signed-off-by: Julien Meunier <julien.meunier at nokia.com>
---
v2:
* rebase
* update commit log + remove invalid CC email address

lib/stack/rte_stack_lf_generic.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/stack/rte_stack_lf_generic.h b/lib/stack/rte_stack_lf_generic.h
index 4850a05ee7..7fa29cedb2 100644
--- a/lib/stack/rte_stack_lf_generic.h
+++ b/lib/stack/rte_stack_lf_generic.h
@@ -128,8 +128,10 @@ __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;
--
2.17.1