4 files changed, 50 insertions, 5 deletions

diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index 8a9eaa8b6a..3ee5e976f8 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
@@ -168,7 +168,7 @@ static void destruct_transport(grpc_exec_ctx *exec_ctx,
   grpc_chttp2_stream_map_destroy(&t->stream_map);
   grpc_connectivity_state_destroy(exec_ctx, &t->channel_callback.state_tracker);
 
-  grpc_combiner_destroy(exec_ctx, t->combiner);
+  GRPC_COMBINER_UNREF(exec_ctx, t->combiner, "chttp2_transport");
 
   cancel_pings(exec_ctx, t, GRPC_ERROR_CREATE("Transport destroyed"));
 
diff --git a/src/core/lib/iomgr/combiner.c b/src/core/lib/iomgr/combiner.c
index ba6c7087a9..fa9966c3a6 100644
--- a/src/core/lib/iomgr/combiner.c
+++ b/src/core/lib/iomgr/combiner.c
@@ -72,6 +72,7 @@ struct grpc_combiner {
   bool final_list_covered_by_poller;
   grpc_closure_list final_list;
   grpc_closure offload;
+  gpr_refcount refs;
 };
 
 static void combiner_exec_uncovered(grpc_exec_ctx *exec_ctx,
@@ -126,6 +127,7 @@ static bool is_covered_by_poller(grpc_combiner *lock) {
 
 grpc_combiner *grpc_combiner_create(grpc_workqueue *optional_workqueue) {
   grpc_combiner *lock = gpr_malloc(sizeof(*lock));
+  gpr_ref_init(&lock->refs, 1);
   lock->next_combiner_on_this_exec_ctx = NULL;
   lock->time_to_execute_final_list = false;
   lock->optional_workqueue = optional_workqueue;
@@ -152,7 +154,7 @@ static void really_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
   gpr_free(lock);
 }
 
-void grpc_combiner_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
+static void start_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
   gpr_atm old_state = gpr_atm_full_fetch_add(&lock->state, -STATE_UNORPHANED);
   GRPC_COMBINER_TRACE(gpr_log(
       GPR_DEBUG, "C:%p really_destroy old_state=%" PRIdPTR, lock, old_state));
@@ -161,6 +163,30 @@ void grpc_combiner_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
   }
 }
 
+#ifdef GRPC_COMBINER_REFCOUNT_DEBUG
+#define GRPC_COMBINER_DEBUG_SPAM(op, delta)                               \
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,                             \
+          "combiner[%p] %s %" PRIdPTR " --> %" PRIdPTR " %s", lock, (op), \
+          gpr_atm_no_barrier_load(&lock->refs.count),                     \
+          gpr_atm_no_barrier_load(&lock->refs.count) + (delta), reason);
+#else
+#define GRPC_COMBINER_DEBUG_SPAM(op, delta)
+#endif
+
+void grpc_combiner_unref(grpc_exec_ctx *exec_ctx,
+                         grpc_combiner *lock GRPC_COMBINER_DEBUG_ARGS) {
+  GRPC_COMBINER_DEBUG_SPAM("UNREF", -1);
+  if (gpr_unref(&lock->refs)) {
+    start_destroy(exec_ctx, lock);
+  }
+}
+
+grpc_combiner *grpc_combiner_ref(grpc_combiner *lock GRPC_COMBINER_DEBUG_ARGS) {
+  GRPC_COMBINER_DEBUG_SPAM("  REF", 1);
+  gpr_ref(&lock->refs);
+  return lock;
+}
+
 static void push_last_on_exec_ctx(grpc_exec_ctx *exec_ctx,
                                   grpc_combiner *lock) {
   lock->next_combiner_on_this_exec_ctx = NULL;
diff --git a/src/core/lib/iomgr/combiner.h b/src/core/lib/iomgr/combiner.h
index 81dff85d40..75dcb0b70a 100644
--- a/src/core/lib/iomgr/combiner.h
+++ b/src/core/lib/iomgr/combiner.h
@@ -48,8 +48,27 @@
 // Initialize the lock, with an optional workqueue to shift load to when
 // necessary
 grpc_combiner *grpc_combiner_create(grpc_workqueue *optional_workqueue);
-// Destroy the lock
-void grpc_combiner_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock);
+
+//#define GRPC_COMBINER_REFCOUNT_DEBUG
+#ifdef GRPC_COMBINER_REFCOUNT_DEBUG
+#define GRPC_COMBINER_DEBUG_ARGS \
+  , const char *file, int line, const char *reason
+#define GRPC_COMBINER_REF(combiner, reason) \
+  grpc_combiner_ref((combiner), __FILE__, __LINE__, (reason))
+#define GRPC_COMBINER_UNREF(exec_ctx, combiner, reason) \
+  grpc_combiner_unref((exec_ctx), (combiner), __FILE__, __LINE__, (reason))
+#else
+#define GRPC_COMBINER_DEBUG_ARGS
+#define GRPC_COMBINER_REF(combiner, reason) grpc_combiner_ref((combiner))
+#define GRPC_COMBINER_UNREF(exec_ctx, combiner, reason) \
+  grpc_combiner_unref((exec_ctx), (combiner))
+#endif
+
+// Ref/unref the lock, for when we're sharing the lock ownership
+// Prefer to use the macros above
+grpc_combiner *grpc_combiner_ref(grpc_combiner *lock GRPC_COMBINER_DEBUG_ARGS);
+void grpc_combiner_unref(grpc_exec_ctx *exec_ctx,
+                         grpc_combiner *lock GRPC_COMBINER_DEBUG_ARGS);
 // Fetch a scheduler to schedule closures against
 grpc_closure_scheduler *grpc_combiner_scheduler(grpc_combiner *lock,
                                                 bool covered_by_poller);
diff --git a/src/core/lib/iomgr/resource_quota.c b/src/core/lib/iomgr/resource_quota.c
index 2cc979467f..511ffdcdf1 100644
--- a/src/core/lib/iomgr/resource_quota.c
+++ b/src/core/lib/iomgr/resource_quota.c
@@ -599,7 +599,7 @@ grpc_resource_quota *grpc_resource_quota_create(const char *name) {
 void grpc_resource_quota_unref_internal(grpc_exec_ctx *exec_ctx,
                                         grpc_resource_quota *resource_quota) {
   if (gpr_unref(&resource_quota->refs)) {
-    grpc_combiner_destroy(exec_ctx, resource_quota->combiner);
+    GRPC_COMBINER_UNREF(exec_ctx, resource_quota->combiner, "resource_quota");
     gpr_free(resource_quota->name);
     gpr_free(resource_quota);
   }