3 files changed, 34 insertions, 18 deletions

diff --git a/src/core/lib/iomgr/ev_epollsig_linux.c b/src/core/lib/iomgr/ev_epollsig_linux.c
index e50000dcc9..aba83a6da9 100644
--- a/src/core/lib/iomgr/ev_epollsig_linux.c
+++ b/src/core/lib/iomgr/ev_epollsig_linux.c
@@ -64,9 +64,9 @@
 
 #define GRPC_POLLSET_KICK_BROADCAST ((grpc_pollset_worker *)1)
 
-#define GRPC_POLLING_TRACE(fmt, ...)        \
+#define GRPC_POLLING_TRACE(...)             \
   if (GRPC_TRACER_ON(grpc_polling_trace)) { \
-    gpr_log(GPR_INFO, (fmt), __VA_ARGS__);  \
+    gpr_log(GPR_INFO, __VA_ARGS__);         \
   }
 
 /* Uncomment the following to enable extra checks on poll_object operations */
diff --git a/src/core/lib/iomgr/executor.c b/src/core/lib/iomgr/executor.c
index 513248ca57..a5b698ae0a 100644
--- a/src/core/lib/iomgr/executor.c
+++ b/src/core/lib/iomgr/executor.c
@@ -114,6 +114,10 @@ void grpc_executor_set_threading(grpc_exec_ctx *exec_ctx, bool threading) {
       gpr_cv_signal(&g_thread_state[i].cv);
       gpr_mu_unlock(&g_thread_state[i].mu);
     }
+    /* ensure no thread is adding a new thread... once this is past, then
+       no thread will try to add a new one either (since shutdown is true) */
+    gpr_spinlock_lock(&g_adding_thread_lock);
+    gpr_spinlock_unlock(&g_adding_thread_lock);
     for (gpr_atm i = 0; i < g_cur_threads; i++) {
       gpr_thd_join(g_thread_state[i].id);
     }
@@ -182,10 +186,10 @@ static void executor_push(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
   }
   grpc_closure_list_append(&ts->elems, closure, error);
   ts->depth++;
-  bool try_new_thread =
-      ts->depth > MAX_DEPTH && cur_thread_count < g_max_threads;
-  gpr_mu_unlock(&ts->mu);
+  bool try_new_thread = ts->depth > MAX_DEPTH &&
+                        cur_thread_count < g_max_threads && !ts->shutdown;
   if (try_new_thread && gpr_spinlock_trylock(&g_adding_thread_lock)) {
+    gpr_mu_unlock(&ts->mu);
     cur_thread_count = (size_t)gpr_atm_no_barrier_load(&g_cur_threads);
     if (cur_thread_count < g_max_threads) {
       gpr_atm_no_barrier_store(&g_cur_threads, cur_thread_count + 1);
@@ -196,6 +200,8 @@ static void executor_push(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
                   &g_thread_state[cur_thread_count], &opt);
     }
     gpr_spinlock_unlock(&g_adding_thread_lock);
+  } else {
+    gpr_mu_unlock(&ts->mu);
   }
 }
 
diff --git a/src/core/lib/security/transport/client_auth_filter.c b/src/core/lib/security/transport/client_auth_filter.c
index dff05633ec..ac1cce722f 100644
--- a/src/core/lib/security/transport/client_auth_filter.c
+++ b/src/core/lib/security/transport/client_auth_filter.c
@@ -65,7 +65,8 @@ typedef struct {
   */
   grpc_polling_entity *pollent;
   grpc_transport_stream_op_batch op;
-  uint8_t security_context_set;
+  gpr_atm security_context_set;
+  gpr_mu security_context_mu;
   grpc_linked_mdelem md_links[MAX_CREDENTIALS_METADATA_COUNT];
   grpc_auth_metadata_context auth_md_context;
 } call_data;
@@ -253,19 +254,26 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
   grpc_linked_mdelem *l;
   grpc_client_security_context *sec_ctx = NULL;
 
-  if (!op->cancel_stream && calld->security_context_set == 0) {
-    calld->security_context_set = 1;
-    GPR_ASSERT(op->payload->context != NULL);
-    if (op->payload->context[GRPC_CONTEXT_SECURITY].value == NULL) {
-      op->payload->context[GRPC_CONTEXT_SECURITY].value =
-          grpc_client_security_context_create();
-      op->payload->context[GRPC_CONTEXT_SECURITY].destroy =
-          grpc_client_security_context_destroy;
+  if (!op->cancel_stream) {
+    /* double checked lock over security context to ensure it's set once */
+    if (gpr_atm_acq_load(&calld->security_context_set) == 0) {
+      gpr_mu_lock(&calld->security_context_mu);
+      if (gpr_atm_acq_load(&calld->security_context_set) == 0) {
+        GPR_ASSERT(op->payload->context != NULL);
+        if (op->payload->context[GRPC_CONTEXT_SECURITY].value == NULL) {
+          op->payload->context[GRPC_CONTEXT_SECURITY].value =
+              grpc_client_security_context_create();
+          op->payload->context[GRPC_CONTEXT_SECURITY].destroy =
+              grpc_client_security_context_destroy;
+        }
+        sec_ctx = op->payload->context[GRPC_CONTEXT_SECURITY].value;
+        GRPC_AUTH_CONTEXT_UNREF(sec_ctx->auth_context, "client auth filter");
+        sec_ctx->auth_context =
+            GRPC_AUTH_CONTEXT_REF(chand->auth_context, "client_auth_filter");
+        gpr_atm_rel_store(&calld->security_context_set, 1);
+      }
+      gpr_mu_unlock(&calld->security_context_mu);
     }
-    sec_ctx = op->payload->context[GRPC_CONTEXT_SECURITY].value;
-    GRPC_AUTH_CONTEXT_UNREF(sec_ctx->auth_context, "client auth filter");
-    sec_ctx->auth_context =
-        GRPC_AUTH_CONTEXT_REF(chand->auth_context, "client_auth_filter");
   }
 
   if (op->send_initial_metadata) {
@@ -312,6 +320,7 @@ static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   const grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   memset(calld, 0, sizeof(*calld));
+  gpr_mu_init(&calld->security_context_mu);
   return GRPC_ERROR_NONE;
 }
 
@@ -335,6 +344,7 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
     grpc_slice_unref_internal(exec_ctx, calld->method);
   }
   reset_auth_metadata_context(&calld->auth_md_context);
+  gpr_mu_destroy(&calld->security_context_mu);
 }
 
 /* Constructor for channel_data */