2 files changed, 7 insertions, 4 deletions
diff --git a/src/core/support/stack_lockfree.c b/src/core/support/stack_lockfree.c
index 9497efbfb5..2844330379 100644
--- a/src/core/support/stack_lockfree.c
+++ b/src/core/support/stack_lockfree.c
@@ -65,8 +65,9 @@ typedef union lockfree_node {
 } lockfree_node;
 
 #define ENTRY_ALIGNMENT_BITS 3 /* make sure that entries aligned to 8-bytes */
-#define INVALID_ENTRY_INDEX ((1 << 16) - 1) /* reserve this entry as invalid \
-                                               */
+#define INVALID_ENTRY_INDEX                        \
+  ((1 << 16) - 1) /* reserve this entry as invalid \
+                       */
 
 struct gpr_stack_lockfree {
   lockfree_node *entries;
@@ -96,7 +97,7 @@ void gpr_stack_lockfree_destroy(gpr_stack_lockfree *stack) {
   gpr_free(stack);
 }
 
-void gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) {
+int gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) {
   lockfree_node head;
   lockfree_node newhead;
 
@@ -112,6 +113,7 @@ void gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) {
     stack->entries[entry].contents.index = head.contents.index;
   } while (!gpr_atm_rel_cas(&(stack->head.atm), head.atm, newhead.atm));
   /* Use rel_cas above to make sure that entry index is set properly */
+  return head.contents.index == INVALID_ENTRY_INDEX;
 }
 
 int gpr_stack_lockfree_pop(gpr_stack_lockfree *stack) {
diff --git a/src/core/support/stack_lockfree.h b/src/core/support/stack_lockfree.h
index 0bcf73635d..eec960fbb0 100644
--- a/src/core/support/stack_lockfree.h
+++ b/src/core/support/stack_lockfree.h
@@ -42,7 +42,8 @@ gpr_stack_lockfree* gpr_stack_lockfree_create(int entries);
 void gpr_stack_lockfree_destroy(gpr_stack_lockfree* stack);
 
 /* Pass in a valid entry number for the next stack entry */
-void gpr_stack_lockfree_push(gpr_stack_lockfree* stack, int entry);
+/* Returns 1 if this is the first element on the stack, 0 otherwise */
+int gpr_stack_lockfree_push(gpr_stack_lockfree*, int entry);
 
 /* Returns -1 on empty or the actual entry number */
 int gpr_stack_lockfree_pop(gpr_stack_lockfree* stack);