Merge pull request #8795 from markdroth/client_channel_init_cleanup

Client channel init cleanup

include/grpc/impl/codegen/grpc_types.h

@@ -206,18 +206,12 @@ typedef struct {
 /** If non-zero, allow the use of SO_REUSEPORT if it's available (default 1) */
 #define GRPC_ARG_ALLOW_REUSEPORT "grpc.so_reuseport"
 /** If non-zero, a pointer to a buffer pool (use grpc_resource_quota_arg_vtable
-   to fetch an appropriate pointer arg vtable */
+   to fetch an appropriate pointer arg vtable) */
 #define GRPC_ARG_RESOURCE_QUOTA "grpc.resource_quota"
-/** Service config data, to be passed to subchannels.
-    Not intended for external use. */
+/** Service config data in JSON form. Not intended for use outside of tests. */
 #define GRPC_ARG_SERVICE_CONFIG "grpc.service_config"
 /** LB policy name. */
 #define GRPC_ARG_LB_POLICY_NAME "grpc.lb_policy_name"
-/** Server name. Not intended for external use. */
-#define GRPC_ARG_SERVER_NAME "grpc.server_name"
-/** Resolved addresses in a form used by the LB policy.
-    Not intended for external use. */
-#define GRPC_ARG_LB_ADDRESSES "grpc.lb_addresses"
 /** The grpc_socket_mutator instance that set the socket options. A pointer. */
 #define GRPC_ARG_SOCKET_MUTATOR "grpc.socket_mutator"
 /** \} */

src/core/ext/census/grpc_filter.c

@@ -167,11 +167,12 @@ static void server_destroy_call_elem(grpc_exec_ctx *exec_ctx,
   /* TODO(hongyu): record rpc server stats and census_tracing_end_op here */
 }
 
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   channel_data *chand = elem->channel_data;
   GPR_ASSERT(chand != NULL);
+  return GRPC_ERROR_NONE;
 }
 
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,

src/core/ext/client_channel/client_channel.c

@@ -44,6 +44,7 @@
 #include <grpc/support/useful.h>
 
 #include "src/core/ext/client_channel/lb_policy_registry.h"
+#include "src/core/ext/client_channel/resolver_registry.h"
 #include "src/core/ext/client_channel/subchannel.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/connected_channel.h"
@@ -499,24 +500,37 @@ static void cc_get_channel_info(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for channel_data */
-static void cc_init_channel_elem(grpc_exec_ctx *exec_ctx,
-                                 grpc_channel_element *elem,
-                                 grpc_channel_element_args *args) {
+static grpc_error *cc_init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                        grpc_channel_element *elem,
+                                        grpc_channel_element_args *args) {
   channel_data *chand = elem->channel_data;
-
   memset(chand, 0, sizeof(*chand));
-
   GPR_ASSERT(args->is_last);
   GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
-
+  // Initialize data members.
   gpr_mu_init(&chand->mu);
+  chand->owning_stack = args->channel_stack;
   grpc_closure_init(&chand->on_resolver_result_changed,
                     on_resolver_result_changed, chand);
-  chand->owning_stack = args->channel_stack;
-
+  chand->interested_parties = grpc_pollset_set_create();
   grpc_connectivity_state_init(&chand->state_tracker, GRPC_CHANNEL_IDLE,
                                "client_channel");
-  chand->interested_parties = grpc_pollset_set_create();
+  // Record client channel factory.
+  const grpc_arg *arg = grpc_channel_args_find(args->channel_args,
+                                               GRPC_ARG_CLIENT_CHANNEL_FACTORY);
+  GPR_ASSERT(arg != NULL);
+  GPR_ASSERT(arg->type == GRPC_ARG_POINTER);
+  grpc_client_channel_factory_ref(arg->value.pointer.p);
+  chand->client_channel_factory = arg->value.pointer.p;
+  // Instantiate resolver.
+  arg = grpc_channel_args_find(args->channel_args, GRPC_ARG_SERVER_URI);
+  GPR_ASSERT(arg != NULL);
+  GPR_ASSERT(arg->type == GRPC_ARG_STRING);
+  chand->resolver = grpc_resolver_create(arg->value.string, args->channel_args);
+  if (chand->resolver == NULL) {
+    return GRPC_ERROR_CREATE("resolver creation failed");
+  }
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for channel_data */
@@ -1135,30 +1149,6 @@ const grpc_channel_filter grpc_client_channel_filter = {
     "client-channel",
 };
 
-void grpc_client_channel_finish_initialization(
-    grpc_exec_ctx *exec_ctx, grpc_channel_stack *channel_stack,
-    grpc_resolver *resolver,
-    grpc_client_channel_factory *client_channel_factory) {
-  /* post construction initialization: set the transport setup pointer */
-  GPR_ASSERT(client_channel_factory != NULL);
-  grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
-  channel_data *chand = elem->channel_data;
-  gpr_mu_lock(&chand->mu);
-  GPR_ASSERT(!chand->resolver);
-  chand->resolver = resolver;
-  GRPC_RESOLVER_REF(resolver, "channel");
-  if (!grpc_closure_list_empty(chand->waiting_for_config_closures) ||
-      chand->exit_idle_when_lb_policy_arrives) {
-    chand->started_resolving = true;
-    GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
-    grpc_resolver_next(exec_ctx, resolver, &chand->resolver_result,
-                       &chand->on_resolver_result_changed);
-  }
-  chand->client_channel_factory = client_channel_factory;
-  grpc_client_channel_factory_ref(client_channel_factory);
-  gpr_mu_unlock(&chand->mu);
-}
-
 grpc_connectivity_state grpc_client_channel_check_connectivity_state(
     grpc_exec_ctx *exec_ctx, grpc_channel_element *elem, int try_to_connect) {
   channel_data *chand = elem->channel_data;

src/core/ext/client_channel/client_channel.h

@@ -38,6 +38,9 @@
 #include "src/core/ext/client_channel/resolver.h"
 #include "src/core/lib/channel/channel_stack.h"
 
+// Channel arg key for server URI string.
+#define GRPC_ARG_SERVER_URI "grpc.server_uri"
+
 /* A client channel is a channel that begins disconnected, and can connect
    to some endpoint on demand. If that endpoint disconnects, it will be
    connected to again later.
@@ -47,13 +50,6 @@
 
 extern const grpc_channel_filter grpc_client_channel_filter;
 
-/* Post-construction initializer to give the client channel its resolver
-   and factory. */
-void grpc_client_channel_finish_initialization(
-    grpc_exec_ctx *exec_ctx, grpc_channel_stack *channel_stack,
-    grpc_resolver *resolver,
-    grpc_client_channel_factory *client_channel_factory);
-
 grpc_connectivity_state grpc_client_channel_check_connectivity_state(
     grpc_exec_ctx *exec_ctx, grpc_channel_element *elem, int try_to_connect);
 

src/core/ext/client_channel/client_channel_factory.c

@@ -55,3 +55,35 @@ grpc_channel* grpc_client_channel_factory_create_channel(
   return factory->vtable->create_client_channel(exec_ctx, factory, target, type,
                                                 args);
 }
+
+static void* factory_arg_copy(void* factory) {
+  grpc_client_channel_factory_ref(factory);
+  return factory;
+}
+
+static void factory_arg_destroy(void* factory) {
+  // TODO(roth): Remove local exec_ctx when
+  // https://github.com/grpc/grpc/pull/8705 is merged.
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_client_channel_factory_unref(&exec_ctx, factory);
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
+static int factory_arg_cmp(void* factory1, void* factory2) {
+  if (factory1 < factory2) return -1;
+  if (factory1 > factory2) return 1;
+  return 0;
+}
+
+static const grpc_arg_pointer_vtable factory_arg_vtable = {
+    factory_arg_copy, factory_arg_destroy, factory_arg_cmp};
+
+grpc_arg grpc_client_channel_factory_create_channel_arg(
+    grpc_client_channel_factory* factory) {
+  grpc_arg arg;
+  arg.type = GRPC_ARG_POINTER;
+  arg.key = GRPC_ARG_CLIENT_CHANNEL_FACTORY;
+  arg.value.pointer.p = factory;
+  arg.value.pointer.vtable = &factory_arg_vtable;
+  return arg;
+}

src/core/ext/client_channel/client_channel_factory.h

@@ -39,6 +39,9 @@
 #include "src/core/ext/client_channel/subchannel.h"
 #include "src/core/lib/channel/channel_stack.h"
 
+// Channel arg key for client channel factory.
+#define GRPC_ARG_CLIENT_CHANNEL_FACTORY "grpc.client_channel_factory"
+
 typedef struct grpc_client_channel_factory grpc_client_channel_factory;
 typedef struct grpc_client_channel_factory_vtable
     grpc_client_channel_factory_vtable;
@@ -83,4 +86,7 @@ grpc_channel *grpc_client_channel_factory_create_channel(
     const char *target, grpc_client_channel_type type,
     const grpc_channel_args *args);
 
+grpc_arg grpc_client_channel_factory_create_channel_arg(
+    grpc_client_channel_factory *factory);
+
 #endif /* GRPC_CORE_EXT_CLIENT_CHANNEL_CLIENT_CHANNEL_FACTORY_H */

src/core/ext/client_channel/http_connect_handshaker.c

@@ -40,6 +40,8 @@
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
 
+#include "src/core/ext/client_channel/client_channel.h"
+#include "src/core/ext/client_channel/resolver_registry.h"
 #include "src/core/ext/client_channel/uri_parser.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/http/format_request.h"
@@ -51,7 +53,6 @@ typedef struct http_connect_handshaker {
   grpc_handshaker base;
 
   char* proxy_server;
-  char* server_name;
 
   gpr_refcount refcount;
   gpr_mu mu;
@@ -86,7 +87,6 @@ static void http_connect_handshaker_unref(grpc_exec_ctx* exec_ctx,
       gpr_free(handshaker->read_buffer_to_destroy);
     }
     gpr_free(handshaker->proxy_server);
-    gpr_free(handshaker->server_name);
     grpc_slice_buffer_destroy(&handshaker->write_buffer);
     grpc_http_parser_destroy(&handshaker->http_parser);
     grpc_http_response_destroy(&handshaker->http_response);
@@ -265,18 +265,27 @@ static void http_connect_handshaker_do_handshake(
     grpc_tcp_server_acceptor* acceptor, grpc_closure* on_handshake_done,
     grpc_handshaker_args* args) {
   http_connect_handshaker* handshaker = (http_connect_handshaker*)handshaker_in;
-  gpr_mu_lock(&handshaker->mu);
+  // Get server name from channel args.
+  const grpc_arg* arg = grpc_channel_args_find(args->args, GRPC_ARG_SERVER_URI);
+  GPR_ASSERT(arg != NULL);
+  GPR_ASSERT(arg->type == GRPC_ARG_STRING);
+  char* canonical_uri =
+      grpc_resolver_factory_add_default_prefix_if_needed(arg->value.string);
+  grpc_uri* uri = grpc_uri_parse(canonical_uri, 1);
+  char* server_name = uri->path;
+  if (server_name[0] == '/') ++server_name;
   // Save state in the handshaker object.
+  gpr_mu_lock(&handshaker->mu);
   handshaker->args = args;
   handshaker->on_handshake_done = on_handshake_done;
   // Send HTTP CONNECT request.
-  gpr_log(GPR_INFO, "Connecting to server %s via HTTP proxy %s",
-          handshaker->server_name, handshaker->proxy_server);
+  gpr_log(GPR_INFO, "Connecting to server %s via HTTP proxy %s", server_name,
+          handshaker->proxy_server);
   grpc_httpcli_request request;
   memset(&request, 0, sizeof(request));
-  request.host = handshaker->proxy_server;
+  request.host = server_name;
   request.http.method = "CONNECT";
-  request.http.path = handshaker->server_name;
+  request.http.path = server_name;
   request.handshaker = &grpc_httpcli_plaintext;
   grpc_slice request_slice = grpc_httpcli_format_connect_request(&request);
   grpc_slice_buffer_add(&handshaker->write_buffer, request_slice);
@@ -285,23 +294,23 @@ static void http_connect_handshaker_do_handshake(
   grpc_endpoint_write(exec_ctx, args->endpoint, &handshaker->write_buffer,
                       &handshaker->request_done_closure);
   gpr_mu_unlock(&handshaker->mu);
+  // Clean up.
+  gpr_free(canonical_uri);
+  grpc_uri_destroy(uri);
 }
 
 static const grpc_handshaker_vtable http_connect_handshaker_vtable = {
     http_connect_handshaker_destroy, http_connect_handshaker_shutdown,
     http_connect_handshaker_do_handshake};
 
-grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server,
-                                                     const char* server_name) {
+grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server) {
   GPR_ASSERT(proxy_server != NULL);
-  GPR_ASSERT(server_name != NULL);
   http_connect_handshaker* handshaker = gpr_malloc(sizeof(*handshaker));
   memset(handshaker, 0, sizeof(*handshaker));
   grpc_handshaker_init(&http_connect_handshaker_vtable, &handshaker->base);
   gpr_mu_init(&handshaker->mu);
   gpr_ref_init(&handshaker->refcount, 1);
   handshaker->proxy_server = gpr_strdup(proxy_server);
-  handshaker->server_name = gpr_strdup(server_name);
   grpc_slice_buffer_init(&handshaker->write_buffer);
   grpc_closure_init(&handshaker->request_done_closure, on_write_done,
                     handshaker);

src/core/ext/client_channel/http_connect_handshaker.h

@@ -36,9 +36,8 @@
 
 #include "src/core/lib/channel/handshaker.h"
 
-/// Does NOT take ownership of \a proxy_server or \a server_name.
-grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server,
-                                                     const char* server_name);
+/// Does NOT take ownership of \a proxy_server.
+grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server);
 
 /// Returns the name of the proxy to use, or NULL if no proxy is configured.
 /// Caller takes ownership of result.

src/core/ext/client_channel/lb_policy_factory.h

@@ -40,6 +40,9 @@
 #include "src/core/lib/iomgr/exec_ctx.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 
+// Channel arg key for grpc_lb_addresses.
+#define GRPC_ARG_LB_ADDRESSES "grpc.lb_addresses"
+
 typedef struct grpc_lb_policy_factory grpc_lb_policy_factory;
 typedef struct grpc_lb_policy_factory_vtable grpc_lb_policy_factory_vtable;
 

src/core/ext/client_channel/resolver_registry.c

@@ -109,8 +109,8 @@ static grpc_resolver_factory *lookup_factory_by_uri(grpc_uri *uri) {
 }
 
 static grpc_resolver_factory *resolve_factory(const char *target,
-                                              grpc_uri **uri) {
-  char *tmp;
+                                              grpc_uri **uri,
+                                              char **canonical_target) {
   grpc_resolver_factory *factory = NULL;
 
   GPR_ASSERT(uri != NULL);
@@ -118,15 +118,15 @@ static grpc_resolver_factory *resolve_factory(const char *target,
   factory = lookup_factory_by_uri(*uri);
   if (factory == NULL) {
     grpc_uri_destroy(*uri);
-    gpr_asprintf(&tmp, "%s%s", g_default_resolver_prefix, target);
-    *uri = grpc_uri_parse(tmp, 1);
+    gpr_asprintf(canonical_target, "%s%s", g_default_resolver_prefix, target);
+    *uri = grpc_uri_parse(*canonical_target, 1);
     factory = lookup_factory_by_uri(*uri);
     if (factory == NULL) {
       grpc_uri_destroy(grpc_uri_parse(target, 0));
-      grpc_uri_destroy(grpc_uri_parse(tmp, 0));
-      gpr_log(GPR_ERROR, "don't know how to resolve '%s' or '%s'", target, tmp);
+      grpc_uri_destroy(grpc_uri_parse(*canonical_target, 0));
+      gpr_log(GPR_ERROR, "don't know how to resolve '%s' or '%s'", target,
+              *canonical_target);
     }
-    gpr_free(tmp);
   }
   return factory;
 }
@@ -134,7 +134,9 @@ static grpc_resolver_factory *resolve_factory(const char *target,
 grpc_resolver *grpc_resolver_create(const char *target,
                                     const grpc_channel_args *args) {
   grpc_uri *uri = NULL;
-  grpc_resolver_factory *factory = resolve_factory(target, &uri);
+  char *canonical_target = NULL;
+  grpc_resolver_factory *factory =
+      resolve_factory(target, &uri, &canonical_target);
   grpc_resolver *resolver;
   grpc_resolver_args resolver_args;
   memset(&resolver_args, 0, sizeof(resolver_args));
@@ -142,13 +144,25 @@ grpc_resolver *grpc_resolver_create(const char *target,
   resolver_args.args = args;
   resolver = grpc_resolver_factory_create_resolver(factory, &resolver_args);
   grpc_uri_destroy(uri);
+  gpr_free(canonical_target);
   return resolver;
 }
 
 char *grpc_get_default_authority(const char *target) {
   grpc_uri *uri = NULL;
-  grpc_resolver_factory *factory = resolve_factory(target, &uri);
+  char *canonical_target = NULL;
+  grpc_resolver_factory *factory =
+      resolve_factory(target, &uri, &canonical_target);
   char *authority = grpc_resolver_factory_get_default_authority(factory, uri);
   grpc_uri_destroy(uri);
+  gpr_free(canonical_target);
   return authority;
 }
+
+char *grpc_resolver_factory_add_default_prefix_if_needed(const char *target) {
+  grpc_uri *uri = NULL;
+  char *canonical_target = NULL;
+  resolve_factory(target, &uri, &canonical_target);
+  grpc_uri_destroy(uri);
+  return canonical_target == NULL ? gpr_strdup(target) : canonical_target;
+}

src/core/ext/client_channel/resolver_registry.h

@@ -71,4 +71,8 @@ grpc_resolver_factory *grpc_resolver_factory_lookup(const char *name);
     representing the default authority to pass from a client. */
 char *grpc_get_default_authority(const char *target);
 
+/** Returns a newly allocated string containing \a target, adding the
+    default prefix if needed. */
+char *grpc_resolver_factory_add_default_prefix_if_needed(const char *target);
+
 #endif /* GRPC_CORE_EXT_CLIENT_CHANNEL_RESOLVER_REGISTRY_H */

src/core/ext/client_channel/subchannel.c

@@ -604,14 +604,20 @@ static void publish_transport_locked(grpc_exec_ctx *exec_ctx,
   grpc_channel_stack_builder_set_transport(builder,
                                            c->connecting_result.transport);
 
-  if (grpc_channel_init_create_stack(exec_ctx, builder,
-                                     GRPC_CLIENT_SUBCHANNEL)) {
-    con = grpc_channel_stack_builder_finish(exec_ctx, builder, 0, 1,
-                                            connection_destroy, NULL);
-  } else {
+  if (!grpc_channel_init_create_stack(exec_ctx, builder,
+                                      GRPC_CLIENT_SUBCHANNEL)) {
     grpc_channel_stack_builder_destroy(builder);
     abort(); /* TODO(ctiller): what to do here (previously we just crashed) */
   }
+  grpc_error *error = grpc_channel_stack_builder_finish(
+      exec_ctx, builder, 0, 1, connection_destroy, NULL, (void **)&con);
+  if (error != GRPC_ERROR_NONE) {
+    const char *msg = grpc_error_string(error);
+    gpr_log(GPR_ERROR, "error initializing subchannel stack: %s", msg);
+    grpc_error_free_string(msg);
+    GRPC_ERROR_UNREF(error);
+    abort(); /* TODO(ctiller): what to do here? */
+  }
   stk = CHANNEL_STACK_FROM_CONNECTION(con);
   memset(&c->connecting_result, 0, sizeof(c->connecting_result));
 

src/core/ext/client_channel/subchannel.h

@@ -164,8 +164,6 @@ struct grpc_subchannel_args {
   size_t filter_count;
   /** Channel arguments to be supplied to the newly created channel */
   const grpc_channel_args *args;
-  /** Server name */
-  const char *server_name;
   /** Address to connect to */
   grpc_resolved_address *addr;
 };

src/core/ext/client_channel/subchannel_index.c

@@ -86,7 +86,6 @@ static grpc_subchannel_key *create_key(
   } else {
     k->args.filters = NULL;
   }
-  k->args.server_name = gpr_strdup(args->server_name);
   k->args.addr = gpr_malloc(sizeof(grpc_resolved_address));
   k->args.addr->len = args->addr->len;
   if (k->args.addr->len > 0) {
@@ -113,8 +112,6 @@ static int subchannel_key_compare(grpc_subchannel_key *a,
   if (c != 0) return c;
   c = GPR_ICMP(a->args.filter_count, b->args.filter_count);
   if (c != 0) return c;
-  c = strcmp(a->args.server_name, b->args.server_name);
-  if (c != 0) return c;
   if (a->args.addr->len) {
     c = memcmp(a->args.addr->addr, b->args.addr->addr, a->args.addr->len);
     if (c != 0) return c;
@@ -132,7 +129,6 @@ void grpc_subchannel_key_destroy(grpc_exec_ctx *exec_ctx,
   grpc_connector_unref(exec_ctx, k->connector);
   gpr_free((grpc_channel_args *)k->args.filters);
   grpc_channel_args_destroy((grpc_channel_args *)k->args.args);
-  gpr_free((void *)k->args.server_name);
   gpr_free(k->args.addr);
   gpr_free(k);
 }

src/core/ext/lb_policy/grpclb/grpclb.c

@@ -106,6 +106,7 @@
 #include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 
+#include "src/core/ext/client_channel/client_channel.h"
 #include "src/core/ext/client_channel/client_channel_factory.h"
 #include "src/core/ext/client_channel/lb_policy_factory.h"
 #include "src/core/ext/client_channel/lb_policy_registry.h"
@@ -743,12 +744,6 @@ static void glb_rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
 static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
                                   grpc_lb_policy_factory *factory,
                                   grpc_lb_policy_args *args) {
-  /* Get server name. */
-  const grpc_arg *arg =
-      grpc_channel_args_find(args->args, GRPC_ARG_SERVER_NAME);
-  const char *server_name =
-      arg != NULL && arg->type == GRPC_ARG_STRING ? arg->value.string : NULL;
-
   /* Count the number of gRPC-LB addresses. There must be at least one.
    * TODO(roth): For now, we ignore non-balancer addresses, but in the
    * future, we may change the behavior such that we fall back to using
@@ -756,7 +751,8 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
    * time, this should be changed to allow a list with no balancer addresses,
    * since the resolver might fail to return a balancer address even when
    * this is the right LB policy to use. */
-  arg = grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
+  const grpc_arg *arg =
+      grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
   GPR_ASSERT(arg != NULL && arg->type == GRPC_ARG_POINTER);
   grpc_lb_addresses *addresses = arg->value.pointer.p;
   size_t num_grpclb_addrs = 0;
@@ -768,13 +764,19 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
   glb_lb_policy *glb_policy = gpr_malloc(sizeof(*glb_policy));
   memset(glb_policy, 0, sizeof(*glb_policy));
 
+  /* Get server name. */
+  arg = grpc_channel_args_find(args->args, GRPC_ARG_SERVER_URI);
+  GPR_ASSERT(arg != NULL);
+  GPR_ASSERT(arg->type == GRPC_ARG_STRING);
+  grpc_uri *uri = grpc_uri_parse(arg->value.string, 1);
+  glb_policy->server_name = gpr_strdup(uri->path);
+  grpc_uri_destroy(uri);
+
   /* All input addresses in addresses come from a resolver that claims
    * they are LB services. It's the resolver's responsibility to make sure
-   * this
-   * policy is only instantiated and used in that case.
+   * this policy is only instantiated and used in that case.
    *
    * Create a client channel over them to communicate with a LB service */
-  glb_policy->server_name = gpr_strdup(server_name);
   glb_policy->cc_factory = args->client_channel_factory;
   glb_policy->args = grpc_channel_args_copy(args->args);
   GPR_ASSERT(glb_policy->cc_factory != NULL);
@@ -818,9 +820,14 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
    * We need the LB channel to return addresses with is_balancer=false
    * so that it does not wind up recursively using the grpclb LB policy,
    * as per the special case logic in client_channel.c.
+   *
+   * Finally, we also strip out the channel arg for the server URI,
+   * since that will be different for the LB channel than for the parent
+   * channel.  (The client channel factory will re-add this arg with
+   * the right value.)
    */
-  static const char *keys_to_remove[] = {GRPC_ARG_LB_POLICY_NAME,
-                                         GRPC_ARG_LB_ADDRESSES};
+  static const char *keys_to_remove[] = {
+      GRPC_ARG_LB_POLICY_NAME, GRPC_ARG_LB_ADDRESSES, GRPC_ARG_SERVER_URI};
   grpc_channel_args *new_args = grpc_channel_args_copy_and_remove(
       args->args, keys_to_remove, GPR_ARRAY_SIZE(keys_to_remove));
   glb_policy->lb_channel = grpc_client_channel_factory_create_channel(

src/core/ext/lb_policy/pick_first/pick_first.c

@@ -438,15 +438,10 @@ static grpc_lb_policy *create_pick_first(grpc_exec_ctx *exec_ctx,
                                          grpc_lb_policy_args *args) {
   GPR_ASSERT(args->client_channel_factory != NULL);
 
-  /* Get server name. */
-  const grpc_arg *arg =
-      grpc_channel_args_find(args->args, GRPC_ARG_SERVER_NAME);
-  const char *server_name =
-      arg != NULL && arg->type == GRPC_ARG_STRING ? arg->value.string : NULL;
-
   /* Find the number of backend addresses. We ignore balancer
    * addresses, since we don't know how to handle them. */
-  arg = grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
+  const grpc_arg *arg =
+      grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
   GPR_ASSERT(arg != NULL && arg->type == GRPC_ARG_POINTER);
   grpc_lb_addresses *addresses = arg->value.pointer.p;
   size_t num_addrs = 0;
@@ -472,9 +467,6 @@ static grpc_lb_policy *create_pick_first(grpc_exec_ctx *exec_ctx,
     }
 
     memset(&sc_args, 0, sizeof(grpc_subchannel_args));
-    /* server_name will be copied as part of the subchannel creation. This makes
-     * the copying of server_name (a borrowed pointer) OK. */
-    sc_args.server_name = server_name;
     sc_args.addr = &addresses->addresses[i].address;
     sc_args.args = args->args;
 

src/core/ext/lb_policy/round_robin/round_robin.c

@@ -703,15 +703,10 @@ static grpc_lb_policy *round_robin_create(grpc_exec_ctx *exec_ctx,
                                           grpc_lb_policy_args *args) {
   GPR_ASSERT(args->client_channel_factory != NULL);
 
-  /* Get server name. */
-  const grpc_arg *arg =
-      grpc_channel_args_find(args->args, GRPC_ARG_SERVER_NAME);
-  const char *server_name =
-      arg != NULL && arg->type == GRPC_ARG_STRING ? arg->value.string : NULL;
-
   /* Find the number of backend addresses. We ignore balancer
    * addresses, since we don't know how to handle them. */
-  arg = grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
+  const grpc_arg *arg =
+      grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
   GPR_ASSERT(arg != NULL && arg->type == GRPC_ARG_POINTER);
   grpc_lb_addresses *addresses = arg->value.pointer.p;
   size_t num_addrs = 0;
@@ -734,9 +729,6 @@ static grpc_lb_policy *round_robin_create(grpc_exec_ctx *exec_ctx,
     if (addresses->addresses[i].is_balancer) continue;
 
     memset(&sc_args, 0, sizeof(grpc_subchannel_args));
-    /* server_name will be copied as part of the subchannel creation. This makes
-     * the copying of server_name (a borrowed pointer) OK. */
-    sc_args.server_name = server_name;
     sc_args.addr = &addresses->addresses[i].address;
     sc_args.args = args->args;
 

src/core/ext/load_reporting/load_reporting_filter.c

@@ -152,9 +152,9 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   GPR_ASSERT(!args->is_last);
 
   channel_data *chand = elem->channel_data;
@@ -171,6 +171,8 @@ static void init_channel_elem(grpc_exec_ctx *exec_ctx,
                                                 NULL,
                                                 NULL};
                                                 */
+
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for channel data */

src/core/ext/resolver/dns/native/dns_resolver.c

@@ -264,12 +264,7 @@ static grpc_resolver *dns_create(grpc_resolver_args *args,
   grpc_resolver_init(&r->base, &dns_resolver_vtable);
   r->name_to_resolve = proxy_name == NULL ? gpr_strdup(path) : proxy_name;
   r->default_port = gpr_strdup(default_port);
-  grpc_arg server_name_arg;
-  server_name_arg.type = GRPC_ARG_STRING;
-  server_name_arg.key = GRPC_ARG_SERVER_NAME;
-  server_name_arg.value.string = (char *)path;
-  r->channel_args =
-      grpc_channel_args_copy_and_add(args->args, &server_name_arg, 1);
+  r->channel_args = grpc_channel_args_copy(args->args);
   gpr_backoff_init(&r->backoff_state, GRPC_DNS_INITIAL_CONNECT_BACKOFF_SECONDS,
                    GRPC_DNS_RECONNECT_BACKOFF_MULTIPLIER,
                    GRPC_DNS_RECONNECT_JITTER,

src/core/ext/resolver/sockaddr/sockaddr_resolver.c

@@ -198,12 +198,7 @@ static grpc_resolver *sockaddr_create(grpc_resolver_args *args,
   sockaddr_resolver *r = gpr_malloc(sizeof(sockaddr_resolver));
   memset(r, 0, sizeof(*r));
   r->addresses = addresses;
-  grpc_arg server_name_arg;
-  server_name_arg.type = GRPC_ARG_STRING;
-  server_name_arg.key = GRPC_ARG_SERVER_NAME;
-  server_name_arg.value.string = args->uri->path;
-  r->channel_args =
-      grpc_channel_args_copy_and_add(args->args, &server_name_arg, 1);
+  r->channel_args = grpc_channel_args_copy(args->args);
   gpr_mu_init(&r->mu);
   grpc_resolver_init(&r->base, &sockaddr_resolver_vtable);
   return &r->base;

src/core/ext/transport/chttp2/client/chttp2_connector.c

@@ -58,7 +58,6 @@ typedef struct {
   bool shutdown;
   bool connecting;
 
-  char *server_name;
   grpc_chttp2_add_handshakers_func add_handshakers;
   void *add_handshakers_user_data;
 
@@ -89,7 +88,6 @@ static void chttp2_connector_unref(grpc_exec_ctx *exec_ctx,
     // If handshaking is not yet in progress, destroy the endpoint.
     // Otherwise, the handshaker will do this for us.
     if (c->endpoint != NULL) grpc_endpoint_destroy(exec_ctx, c->endpoint);
-    gpr_free(c->server_name);
     gpr_free(c);
   }
 }
@@ -155,9 +153,8 @@ static void start_handshake_locked(grpc_exec_ctx *exec_ctx,
   c->handshake_mgr = grpc_handshake_manager_create();
   char *proxy_name = grpc_get_http_proxy_server();
   if (proxy_name != NULL) {
-    grpc_handshake_manager_add(
-        c->handshake_mgr,
-        grpc_http_connect_handshaker_create(proxy_name, c->server_name));
+    grpc_handshake_manager_add(c->handshake_mgr,
+                               grpc_http_connect_handshaker_create(proxy_name));
     gpr_free(proxy_name);
   }
   if (c->add_handshakers != NULL) {
@@ -254,15 +251,13 @@ static const grpc_connector_vtable chttp2_connector_vtable = {
     chttp2_connector_connect};
 
 grpc_connector *grpc_chttp2_connector_create(
-    grpc_exec_ctx *exec_ctx, const char *server_name,
-    grpc_chttp2_add_handshakers_func add_handshakers,
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_add_handshakers_func add_handshakers,
     void *add_handshakers_user_data) {
   chttp2_connector *c = gpr_malloc(sizeof(*c));
   memset(c, 0, sizeof(*c));
   c->base.vtable = &chttp2_connector_vtable;
   gpr_mu_init(&c->mu);
   gpr_ref_init(&c->refs, 1);
-  c->server_name = gpr_strdup(server_name);
   c->add_handshakers = add_handshakers;
   c->add_handshakers_user_data = add_handshakers_user_data;
   return &c->base;

src/core/ext/transport/chttp2/client/chttp2_connector.h

@@ -45,8 +45,7 @@ typedef void (*grpc_chttp2_add_handshakers_func)(
 /// If \a add_handshakers is non-NULL, it will be called with
 /// \a add_handshakers_user_data to add handshakers.
 grpc_connector* grpc_chttp2_connector_create(
-    grpc_exec_ctx* exec_ctx, const char* server_name,
-    grpc_chttp2_add_handshakers_func add_handshakers,
+    grpc_exec_ctx* exec_ctx, grpc_chttp2_add_handshakers_func add_handshakers,
     void* add_handshakers_user_data);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_CLIENT_CHTTP2_CONNECTOR_H */

src/core/ext/transport/chttp2/client/insecure/channel_create.c

@@ -39,8 +39,8 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/client_channel/client_channel.h"
-#include "src/core/ext/client_channel/resolver_registry.h"
 #include "src/core/ext/transport/chttp2/client/chttp2_connector.h"
+#include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/channel.h"
 
@@ -54,8 +54,7 @@ static grpc_subchannel *client_channel_factory_create_subchannel(
     grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory,
     const grpc_subchannel_args *args) {
   grpc_connector *connector = grpc_chttp2_connector_create(
-      exec_ctx, args->server_name, NULL /* add_handshakers */,
-      NULL /* user_data */);
+      exec_ctx, NULL /* add_handshakers */, NULL /* user_data */);
   grpc_subchannel *s = grpc_subchannel_create(exec_ctx, connector, args);
   grpc_connector_unref(exec_ctx, connector);
   return s;
@@ -65,17 +64,15 @@ static grpc_channel *client_channel_factory_create_channel(
     grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory,
     const char *target, grpc_client_channel_type type,
     const grpc_channel_args *args) {
-  grpc_channel *channel =
-      grpc_channel_create(exec_ctx, target, args, GRPC_CLIENT_CHANNEL, NULL);
-  grpc_resolver *resolver = grpc_resolver_create(target, args);
-  if (resolver == NULL) {
-    GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, channel,
-                                "client_channel_factory_create_channel");
-    return NULL;
-  }
-  grpc_client_channel_finish_initialization(
-      exec_ctx, grpc_channel_get_channel_stack(channel), resolver, cc_factory);
-  GRPC_RESOLVER_UNREF(exec_ctx, resolver, "create_channel");
+  // Add channel arg containing the server URI.
+  grpc_arg arg;
+  arg.type = GRPC_ARG_STRING;
+  arg.key = GRPC_ARG_SERVER_URI;
+  arg.value.string = (char *)target;
+  grpc_channel_args *new_args = grpc_channel_args_copy_and_add(args, &arg, 1);
+  grpc_channel *channel = grpc_channel_create(exec_ctx, target, new_args,
+                                              GRPC_CLIENT_CHANNEL, NULL);
+  grpc_channel_args_destroy(new_args);
   return channel;
 }
 
@@ -101,8 +98,14 @@ grpc_channel *grpc_insecure_channel_create(const char *target,
   GPR_ASSERT(reserved == NULL);
   grpc_client_channel_factory *factory =
       (grpc_client_channel_factory *)&client_channel_factory;
+  // Add channel arg containing the client channel factory.
+  grpc_arg arg = grpc_client_channel_factory_create_channel_arg(factory);
+  grpc_channel_args *new_args = grpc_channel_args_copy_and_add(args, &arg, 1);
+  // Create channel.
   grpc_channel *channel = client_channel_factory_create_channel(
-      &exec_ctx, factory, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, args);
+      &exec_ctx, factory, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, new_args);
+  // Clean up.
+  grpc_channel_args_destroy(new_args);
   grpc_client_channel_factory_unref(&exec_ctx, factory);
   grpc_exec_ctx_finish(&exec_ctx);
   return channel != NULL ? channel : grpc_lame_client_channel_create(

src/core/ext/transport/chttp2/client/secure/secure_channel_create.c

@@ -39,7 +39,6 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/client_channel/client_channel.h"
-#include "src/core/ext/client_channel/resolver_registry.h"
 #include "src/core/ext/transport/chttp2/client/chttp2_connector.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/security/credentials/credentials.h"
@@ -80,7 +79,7 @@ static grpc_subchannel *client_channel_factory_create_subchannel(
     const grpc_subchannel_args *args) {
   client_channel_factory *f = (client_channel_factory *)cc_factory;
   grpc_connector *connector = grpc_chttp2_connector_create(
-      exec_ctx, args->server_name, add_handshakers, f->security_connector);
+      exec_ctx, add_handshakers, f->security_connector);
   grpc_subchannel *s = grpc_subchannel_create(exec_ctx, connector, args);
   grpc_connector_unref(exec_ctx, connector);
   return s;
@@ -90,18 +89,15 @@ static grpc_channel *client_channel_factory_create_channel(
     grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory,
     const char *target, grpc_client_channel_type type,
     const grpc_channel_args *args) {
-  client_channel_factory *f = (client_channel_factory *)cc_factory;
-  grpc_channel *channel =
-      grpc_channel_create(exec_ctx, target, args, GRPC_CLIENT_CHANNEL, NULL);
-  grpc_resolver *resolver = grpc_resolver_create(target, args);
-  if (resolver == NULL) {
-    GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, channel,
-                                "client_channel_factory_create_channel");
-    return NULL;
-  }
-  grpc_client_channel_finish_initialization(
-      exec_ctx, grpc_channel_get_channel_stack(channel), resolver, &f->base);
-  GRPC_RESOLVER_UNREF(exec_ctx, resolver, "create_channel");
+  // Add channel arg containing the server URI.
+  grpc_arg arg;
+  arg.type = GRPC_ARG_STRING;
+  arg.key = GRPC_ARG_SERVER_URI;
+  arg.value.string = (char *)target;
+  grpc_channel_args *new_args = grpc_channel_args_copy_and_add(args, &arg, 1);
+  grpc_channel *channel = grpc_channel_create(exec_ctx, target, new_args,
+                                              GRPC_CLIENT_CHANNEL, NULL);
+  grpc_channel_args_destroy(new_args);
   return channel;
 }
 
@@ -142,14 +138,6 @@ grpc_channel *grpc_secure_channel_create(grpc_channel_credentials *creds,
     return grpc_lame_client_channel_create(
         target, GRPC_STATUS_INTERNAL, "Failed to create security connector.");
   }
-  grpc_arg connector_arg =
-      grpc_security_connector_to_arg(&security_connector->base);
-  grpc_channel_args *new_args = grpc_channel_args_copy_and_add(
-      new_args_from_connector != NULL ? new_args_from_connector : args,
-      &connector_arg, 1);
-  if (new_args_from_connector != NULL) {
-    grpc_channel_args_destroy(new_args_from_connector);
-  }
   // Create client channel factory.
   client_channel_factory *f = gpr_malloc(sizeof(*f));
   memset(f, 0, sizeof(*f));
@@ -158,13 +146,24 @@ grpc_channel *grpc_secure_channel_create(grpc_channel_credentials *creds,
   GRPC_SECURITY_CONNECTOR_REF(&security_connector->base,
                               "grpc_secure_channel_create");
   f->security_connector = security_connector;
+  // Add channel args containing the client channel factory and security
+  // connector.
+  grpc_arg new_args[2];
+  new_args[0] = grpc_client_channel_factory_create_channel_arg(&f->base);
+  new_args[1] = grpc_security_connector_to_arg(&security_connector->base);
+  grpc_channel_args *args_copy = grpc_channel_args_copy_and_add(
+      new_args_from_connector != NULL ? new_args_from_connector : args,
+      new_args, GPR_ARRAY_SIZE(new_args));
+  if (new_args_from_connector != NULL) {
+    grpc_channel_args_destroy(new_args_from_connector);
+  }
   // Create channel.
   grpc_channel *channel = client_channel_factory_create_channel(
-      &exec_ctx, &f->base, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, new_args);
+      &exec_ctx, &f->base, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, args_copy);
   // Clean up.
   GRPC_SECURITY_CONNECTOR_UNREF(&f->security_connector->base,
                                 "secure_client_channel_factory_create_channel");
-  grpc_channel_args_destroy(new_args);
+  grpc_channel_args_destroy(args_copy);
   grpc_client_channel_factory_unref(&exec_ctx, &f->base);
   grpc_exec_ctx_finish(&exec_ctx);
   return channel; /* may be NULL */

src/core/lib/channel/channel_stack.c

@@ -102,13 +102,11 @@ grpc_call_element *grpc_call_stack_element(grpc_call_stack *call_stack,
   return CALL_ELEMS_FROM_STACK(call_stack) + index;
 }
 
-void grpc_channel_stack_init(grpc_exec_ctx *exec_ctx, int initial_refs,
-                             grpc_iomgr_cb_func destroy, void *destroy_arg,
-                             const grpc_channel_filter **filters,
-                             size_t filter_count,
-                             const grpc_channel_args *channel_args,
-                             grpc_transport *optional_transport,
-                             const char *name, grpc_channel_stack *stack) {
+grpc_error *grpc_channel_stack_init(
+    grpc_exec_ctx *exec_ctx, int initial_refs, grpc_iomgr_cb_func destroy,
+    void *destroy_arg, const grpc_channel_filter **filters, size_t filter_count,
+    const grpc_channel_args *channel_args, grpc_transport *optional_transport,
+    const char *name, grpc_channel_stack *stack) {
   size_t call_size =
       ROUND_UP_TO_ALIGNMENT_SIZE(sizeof(grpc_call_stack)) +
       ROUND_UP_TO_ALIGNMENT_SIZE(filter_count * sizeof(grpc_call_element));
@@ -126,6 +124,7 @@ void grpc_channel_stack_init(grpc_exec_ctx *exec_ctx, int initial_refs,
       ROUND_UP_TO_ALIGNMENT_SIZE(filter_count * sizeof(grpc_channel_element));
 
   /* init per-filter data */
+  grpc_error *first_error = GRPC_ERROR_NONE;
   for (i = 0; i < filter_count; i++) {
     args.channel_stack = stack;
     args.channel_args = channel_args;
@@ -134,7 +133,15 @@ void grpc_channel_stack_init(grpc_exec_ctx *exec_ctx, int initial_refs,
     args.is_last = i == (filter_count - 1);
     elems[i].filter = filters[i];
     elems[i].channel_data = user_data;
-    elems[i].filter->init_channel_elem(exec_ctx, &elems[i], &args);
+    grpc_error *error =
+        elems[i].filter->init_channel_elem(exec_ctx, &elems[i], &args);
+    if (error != GRPC_ERROR_NONE) {
+      if (first_error == GRPC_ERROR_NONE) {
+        first_error = error;
+      } else {
+        GRPC_ERROR_UNREF(error);
+      }
+    }
     user_data += ROUND_UP_TO_ALIGNMENT_SIZE(filters[i]->sizeof_channel_data);
     call_size += ROUND_UP_TO_ALIGNMENT_SIZE(filters[i]->sizeof_call_data);
   }
@@ -144,6 +151,7 @@ void grpc_channel_stack_init(grpc_exec_ctx *exec_ctx, int initial_refs,
              grpc_channel_stack_size(filters, filter_count));
 
   stack->call_stack_size = call_size;
+  return first_error;
 }
 
 void grpc_channel_stack_destroy(grpc_exec_ctx *exec_ctx,

src/core/lib/channel/channel_stack.h

@@ -146,8 +146,9 @@ typedef struct {
      is_first, is_last designate this elements position in the stack, and are
      useful for asserting correct configuration by upper layer code.
      The filter does not need to do any chaining */
-  void (*init_channel_elem)(grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
-                            grpc_channel_element_args *args);
+  grpc_error *(*init_channel_elem)(grpc_exec_ctx *exec_ctx,
+                                   grpc_channel_element *elem,
+                                   grpc_channel_element_args *args);
   /* Destroy per channel data.
      The filter does not need to do any chaining */
   void (*destroy_channel_elem)(grpc_exec_ctx *exec_ctx,
@@ -214,12 +215,11 @@ grpc_call_element *grpc_call_stack_element(grpc_call_stack *stack, size_t i);
 size_t grpc_channel_stack_size(const grpc_channel_filter **filters,
                                size_t filter_count);
 /* Initialize a channel stack given some filters */
-void grpc_channel_stack_init(grpc_exec_ctx *exec_ctx, int initial_refs,
-                             grpc_iomgr_cb_func destroy, void *destroy_arg,
-                             const grpc_channel_filter **filters,
-                             size_t filter_count, const grpc_channel_args *args,
-                             grpc_transport *optional_transport,
-                             const char *name, grpc_channel_stack *stack);
+grpc_error *grpc_channel_stack_init(
+    grpc_exec_ctx *exec_ctx, int initial_refs, grpc_iomgr_cb_func destroy,
+    void *destroy_arg, const grpc_channel_filter **filters, size_t filter_count,
+    const grpc_channel_args *args, grpc_transport *optional_transport,
+    const char *name, grpc_channel_stack *stack);
 /* Destroy a channel stack */
 void grpc_channel_stack_destroy(grpc_exec_ctx *exec_ctx,
                                 grpc_channel_stack *stack);

src/core/lib/channel/channel_stack_builder.c

@@ -227,11 +227,10 @@ void grpc_channel_stack_builder_destroy(grpc_channel_stack_builder *builder) {
   gpr_free(builder);
 }
 
-void *grpc_channel_stack_builder_finish(grpc_exec_ctx *exec_ctx,
-                                        grpc_channel_stack_builder *builder,
-                                        size_t prefix_bytes, int initial_refs,
-                                        grpc_iomgr_cb_func destroy,
-                                        void *destroy_arg) {
+grpc_error *grpc_channel_stack_builder_finish(
+    grpc_exec_ctx *exec_ctx, grpc_channel_stack_builder *builder,
+    size_t prefix_bytes, int initial_refs, grpc_iomgr_cb_func destroy,
+    void *destroy_arg, void **result) {
   // count the number of filters
   size_t num_filters = 0;
   for (filter_node *p = builder->begin.next; p != &builder->end; p = p->next) {
@@ -250,28 +249,35 @@ void *grpc_channel_stack_builder_finish(grpc_exec_ctx *exec_ctx,
   size_t channel_stack_size = grpc_channel_stack_size(filters, num_filters);
 
   // allocate memory, with prefix_bytes followed by channel_stack_size
-  char *result = gpr_malloc(prefix_bytes + channel_stack_size);
+  *result = gpr_malloc(prefix_bytes + channel_stack_size);
   // fetch a pointer to the channel stack
   grpc_channel_stack *channel_stack =
-      (grpc_channel_stack *)(result + prefix_bytes);
+      (grpc_channel_stack *)((char *)(*result) + prefix_bytes);
   // and initialize it
-  grpc_channel_stack_init(exec_ctx, initial_refs, destroy,
-                          destroy_arg == NULL ? result : destroy_arg, filters,
-                          num_filters, builder->args, builder->transport,
-                          builder->name, channel_stack);
-
-  // run post-initialization functions
-  i = 0;
-  for (filter_node *p = builder->begin.next; p != &builder->end; p = p->next) {
-    if (p->init != NULL) {
-      p->init(channel_stack, grpc_channel_stack_element(channel_stack, i),
-              p->init_arg);
+  grpc_error *error = grpc_channel_stack_init(
+      exec_ctx, initial_refs, destroy,
+      destroy_arg == NULL ? *result : destroy_arg, filters, num_filters,
+      builder->args, builder->transport, builder->name, channel_stack);
+
+  if (error != GRPC_ERROR_NONE) {
+    grpc_channel_stack_destroy(exec_ctx, channel_stack);
+    gpr_free(*result);
+    *result = NULL;
+  } else {
+    // run post-initialization functions
+    i = 0;
+    for (filter_node *p = builder->begin.next; p != &builder->end;
+         p = p->next) {
+      if (p->init != NULL) {
+        p->init(channel_stack, grpc_channel_stack_element(channel_stack, i),
+                p->init_arg);
+      }
+      i++;
     }
-    i++;
   }
 
   grpc_channel_stack_builder_destroy(builder);
   gpr_free((grpc_channel_filter **)filters);
 
-  return result;
+  return error;
 }

src/core/lib/channel/channel_stack_builder.h

@@ -146,16 +146,15 @@ bool grpc_channel_stack_builder_append_filter(
 void grpc_channel_stack_builder_iterator_destroy(
     grpc_channel_stack_builder_iterator *iterator);
 
-/// Destroy the builder, return the freshly minted channel stack
+/// Destroy the builder, return the freshly minted channel stack in \a result.
 /// Allocates \a prefix_bytes bytes before the channel stack
 /// Returns the base pointer of the allocated block
 /// \a initial_refs, \a destroy, \a destroy_arg are as per
 /// grpc_channel_stack_init
-void *grpc_channel_stack_builder_finish(grpc_exec_ctx *exec_ctx,
-                                        grpc_channel_stack_builder *builder,
-                                        size_t prefix_bytes, int initial_refs,
-                                        grpc_iomgr_cb_func destroy,
-                                        void *destroy_arg);
+grpc_error *grpc_channel_stack_builder_finish(
+    grpc_exec_ctx *exec_ctx, grpc_channel_stack_builder *builder,
+    size_t prefix_bytes, int initial_refs, grpc_iomgr_cb_func destroy,
+    void *destroy_arg, void **result);
 
 /// Destroy the builder without creating a channel stack
 void grpc_channel_stack_builder_destroy(grpc_channel_stack_builder *builder);

src/core/lib/channel/compress_filter.c

@@ -285,9 +285,9 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   channel_data *channeld = elem->channel_data;
 
   channeld->enabled_algorithms_bitset =
@@ -315,6 +315,7 @@ static void init_channel_elem(grpc_exec_ctx *exec_ctx,
   }
 
   GPR_ASSERT(!args->is_last);
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for channel data */

src/core/lib/channel/connected_channel.c

@@ -114,12 +114,13 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   channel_data *cd = (channel_data *)elem->channel_data;
   GPR_ASSERT(args->is_last);
   cd->transport = NULL;
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for channel_data */

src/core/lib/channel/deadline_filter.c

@@ -207,10 +207,11 @@ void grpc_deadline_state_client_start_transport_stream_op(
 //
 
 // Constructor for channel_data.  Used for both client and server filters.
-static void init_channel_elem(grpc_exec_ctx* exec_ctx,
-                              grpc_channel_element* elem,
-                              grpc_channel_element_args* args) {
+static grpc_error* init_channel_elem(grpc_exec_ctx* exec_ctx,
+                                     grpc_channel_element* elem,
+                                     grpc_channel_element_args* args) {
   GPR_ASSERT(!args->is_last);
+  return GRPC_ERROR_NONE;
 }
 
 // Destructor for channel_data.  Used for both client and server filters.

src/core/lib/channel/http_client_filter.c

@@ -457,9 +457,9 @@ static grpc_mdstr *user_agent_from_args(const grpc_channel_args *args,
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   channel_data *chand = elem->channel_data;
   GPR_ASSERT(!args->is_last);
   GPR_ASSERT(args->optional_transport != NULL);
@@ -470,6 +470,7 @@ static void init_channel_elem(grpc_exec_ctx *exec_ctx,
       GRPC_MDSTR_USER_AGENT,
       user_agent_from_args(args->channel_args,
                            args->optional_transport->vtable->name));
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for channel data */

src/core/lib/channel/http_server_filter.c

@@ -350,10 +350,11 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   GPR_ASSERT(!args->is_last);
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for channel data */

src/core/lib/channel/message_size_filter.c

@@ -192,9 +192,9 @@ static void destroy_call_elem(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
                               void* ignored) {}
 
 // Constructor for channel_data.
-static void init_channel_elem(grpc_exec_ctx* exec_ctx,
-                              grpc_channel_element* elem,
-                              grpc_channel_element_args* args) {
+static grpc_error* init_channel_elem(grpc_exec_ctx* exec_ctx,
+                                     grpc_channel_element* elem,
+                                     grpc_channel_element_args* args) {
   GPR_ASSERT(!args->is_last);
   channel_data* chand = elem->channel_data;
   memset(chand, 0, sizeof(*chand));
@@ -231,6 +231,7 @@ static void init_channel_elem(grpc_exec_ctx* exec_ctx,
       grpc_service_config_destroy(service_config);
     }
   }
+  return GRPC_ERROR_NONE;
 }
 
 // Destructor for channel_data.

src/core/lib/security/transport/client_auth_filter.c

@@ -303,9 +303,9 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   grpc_security_connector *sc =
       grpc_find_security_connector_in_args(args->channel_args);
   grpc_auth_context *auth_context =
@@ -327,6 +327,7 @@ static void init_channel_elem(grpc_exec_ctx *exec_ctx,
           sc, "client_auth_filter");
   chand->auth_context =
       GRPC_AUTH_CONTEXT_REF(auth_context, "client_auth_filter");
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for channel data */

src/core/lib/security/transport/server_auth_filter.c

@@ -238,9 +238,9 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                               void *ignored) {}
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   grpc_auth_context *auth_context =
       grpc_find_auth_context_in_args(args->channel_args);
   grpc_server_credentials *creds =
@@ -256,6 +256,7 @@ static void init_channel_elem(grpc_exec_ctx *exec_ctx,
   chand->auth_context =
       GRPC_AUTH_CONTEXT_REF(auth_context, "server_auth_filter");
   chand->creds = grpc_server_credentials_ref(creds);
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for channel data */

src/core/lib/surface/channel.c

@@ -86,87 +86,90 @@ grpc_channel *grpc_channel_create(grpc_exec_ctx *exec_ctx, const char *target,
                                   const grpc_channel_args *input_args,
                                   grpc_channel_stack_type channel_stack_type,
                                   grpc_transport *optional_transport) {
-  bool is_client = grpc_channel_stack_type_is_client(channel_stack_type);
-
   grpc_channel_stack_builder *builder = grpc_channel_stack_builder_create();
   grpc_channel_stack_builder_set_channel_arguments(builder, input_args);
   grpc_channel_stack_builder_set_target(builder, target);
   grpc_channel_stack_builder_set_transport(builder, optional_transport);
-  grpc_channel *channel;
-  grpc_channel_args *args;
   if (!grpc_channel_init_create_stack(exec_ctx, builder, channel_stack_type)) {
     grpc_channel_stack_builder_destroy(builder);
     return NULL;
-  } else {
-    args = grpc_channel_args_copy(
-        grpc_channel_stack_builder_get_channel_arguments(builder));
-    channel = grpc_channel_stack_builder_finish(
-        exec_ctx, builder, sizeof(grpc_channel), 1, destroy_channel, NULL);
+  }
+  grpc_channel_args *args = grpc_channel_args_copy(
+      grpc_channel_stack_builder_get_channel_arguments(builder));
+  grpc_channel *channel;
+  grpc_error *error = grpc_channel_stack_builder_finish(
+      exec_ctx, builder, sizeof(grpc_channel), 1, destroy_channel, NULL,
+      (void **)&channel);
+  if (error != GRPC_ERROR_NONE) {
+    const char *msg = grpc_error_string(error);
+    gpr_log(GPR_ERROR, "channel stack builder failed: %s", msg);
+    grpc_error_free_string(msg);
+    GRPC_ERROR_UNREF(error);
+    goto done;
   }
 
   memset(channel, 0, sizeof(*channel));
   channel->target = gpr_strdup(target);
-  channel->is_client = is_client;
+  channel->is_client = grpc_channel_stack_type_is_client(channel_stack_type);
   gpr_mu_init(&channel->registered_call_mu);
   channel->registered_calls = NULL;
 
   grpc_compression_options_init(&channel->compression_options);
-  if (args) {
-    for (size_t i = 0; i < args->num_args; i++) {
-      if (0 == strcmp(args->args[i].key, GRPC_ARG_DEFAULT_AUTHORITY)) {
-        if (args->args[i].type != GRPC_ARG_STRING) {
-          gpr_log(GPR_ERROR, "%s ignored: it must be a string",
-                  GRPC_ARG_DEFAULT_AUTHORITY);
-        } else {
-          if (channel->default_authority) {
-            /* setting this takes precedence over anything else */
-            GRPC_MDELEM_UNREF(channel->default_authority);
-          }
-          channel->default_authority = grpc_mdelem_from_strings(
-              ":authority", args->args[i].value.string);
+
+  for (size_t i = 0; i < args->num_args; i++) {
+    if (0 == strcmp(args->args[i].key, GRPC_ARG_DEFAULT_AUTHORITY)) {
+      if (args->args[i].type != GRPC_ARG_STRING) {
+        gpr_log(GPR_ERROR, "%s ignored: it must be a string",
+                GRPC_ARG_DEFAULT_AUTHORITY);
+      } else {
+        if (channel->default_authority) {
+          /* setting this takes precedence over anything else */
+          GRPC_MDELEM_UNREF(channel->default_authority);
         }
-      } else if (0 ==
-                 strcmp(args->args[i].key, GRPC_SSL_TARGET_NAME_OVERRIDE_ARG)) {
-        if (args->args[i].type != GRPC_ARG_STRING) {
-          gpr_log(GPR_ERROR, "%s ignored: it must be a string",
+        channel->default_authority =
+            grpc_mdelem_from_strings(":authority", args->args[i].value.string);
+      }
+    } else if (0 ==
+               strcmp(args->args[i].key, GRPC_SSL_TARGET_NAME_OVERRIDE_ARG)) {
+      if (args->args[i].type != GRPC_ARG_STRING) {
+        gpr_log(GPR_ERROR, "%s ignored: it must be a string",
+                GRPC_SSL_TARGET_NAME_OVERRIDE_ARG);
+      } else {
+        if (channel->default_authority) {
+          /* other ways of setting this (notably ssl) take precedence */
+          gpr_log(GPR_ERROR,
+                  "%s ignored: default host already set some other way",
                   GRPC_SSL_TARGET_NAME_OVERRIDE_ARG);
         } else {
-          if (channel->default_authority) {
-            /* other ways of setting this (notably ssl) take precedence */
-            gpr_log(GPR_ERROR,
-                    "%s ignored: default host already set some other way",
-                    GRPC_SSL_TARGET_NAME_OVERRIDE_ARG);
-          } else {
-            channel->default_authority = grpc_mdelem_from_strings(
-                ":authority", args->args[i].value.string);
-          }
+          channel->default_authority = grpc_mdelem_from_strings(
+              ":authority", args->args[i].value.string);
         }
-      } else if (0 == strcmp(args->args[i].key,
-                             GRPC_COMPRESSION_CHANNEL_DEFAULT_LEVEL)) {
-        channel->compression_options.default_level.is_set = true;
-        GPR_ASSERT(args->args[i].value.integer >= 0 &&
-                   args->args[i].value.integer < GRPC_COMPRESS_LEVEL_COUNT);
-        channel->compression_options.default_level.level =
-            (grpc_compression_level)args->args[i].value.integer;
-      } else if (0 == strcmp(args->args[i].key,
-                             GRPC_COMPRESSION_CHANNEL_DEFAULT_ALGORITHM)) {
-        channel->compression_options.default_algorithm.is_set = true;
-        GPR_ASSERT(args->args[i].value.integer >= 0 &&
-                   args->args[i].value.integer <
-                       GRPC_COMPRESS_ALGORITHMS_COUNT);
-        channel->compression_options.default_algorithm.algorithm =
-            (grpc_compression_algorithm)args->args[i].value.integer;
-      } else if (0 ==
-                 strcmp(args->args[i].key,
-                        GRPC_COMPRESSION_CHANNEL_ENABLED_ALGORITHMS_BITSET)) {
-        channel->compression_options.enabled_algorithms_bitset =
-            (uint32_t)args->args[i].value.integer |
-            0x1; /* always support no compression */
       }
+    } else if (0 == strcmp(args->args[i].key,
+                           GRPC_COMPRESSION_CHANNEL_DEFAULT_LEVEL)) {
+      channel->compression_options.default_level.is_set = true;
+      GPR_ASSERT(args->args[i].value.integer >= 0 &&
+                 args->args[i].value.integer < GRPC_COMPRESS_LEVEL_COUNT);
+      channel->compression_options.default_level.level =
+          (grpc_compression_level)args->args[i].value.integer;
+    } else if (0 == strcmp(args->args[i].key,
+                           GRPC_COMPRESSION_CHANNEL_DEFAULT_ALGORITHM)) {
+      channel->compression_options.default_algorithm.is_set = true;
+      GPR_ASSERT(args->args[i].value.integer >= 0 &&
+                 args->args[i].value.integer < GRPC_COMPRESS_ALGORITHMS_COUNT);
+      channel->compression_options.default_algorithm.algorithm =
+          (grpc_compression_algorithm)args->args[i].value.integer;
+    } else if (0 ==
+               strcmp(args->args[i].key,
+                      GRPC_COMPRESSION_CHANNEL_ENABLED_ALGORITHMS_BITSET)) {
+      channel->compression_options.enabled_algorithms_bitset =
+          (uint32_t)args->args[i].value.integer |
+          0x1; /* always support no compression */
     }
-    grpc_channel_args_destroy(args);
   }
 
+done:
+  grpc_channel_args_destroy(args);
   return channel;
 }
 

src/core/lib/surface/lame_client.c

@@ -123,11 +123,12 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   gpr_free(and_free_memory);
 }
 
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   GPR_ASSERT(args->is_first);
   GPR_ASSERT(args->is_last);
+  return GRPC_ERROR_NONE;
 }
 
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,

src/core/lib/surface/server.c

@@ -914,9 +914,9 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   server_unref(exec_ctx, chand->server);
 }
 
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   channel_data *chand = elem->channel_data;
   GPR_ASSERT(args->is_first);
   GPR_ASSERT(!args->is_last);
@@ -927,6 +927,7 @@ static void init_channel_elem(grpc_exec_ctx *exec_ctx,
   chand->connectivity_state = GRPC_CHANNEL_IDLE;
   grpc_closure_init(&chand->channel_connectivity_changed,
                     channel_connectivity_changed, chand);
+  return GRPC_ERROR_NONE;
 }
 
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,

src/cpp/common/channel_filter.h

@@ -220,6 +220,9 @@ class ChannelData {
     if (peer_) gpr_free((void *)peer_);
   }
 
+  /// Initializes the call data.
+  virtual grpc_error *Init() { return GRPC_ERROR_NONE; }
+
   /// Caller does NOT take ownership of result.
   const char *peer() const { return peer_; }
 
@@ -276,15 +279,17 @@ class ChannelFilter final {
  public:
   static const size_t channel_data_size = sizeof(ChannelDataType);
 
-  static void InitChannelElement(grpc_exec_ctx *exec_ctx,
-                                 grpc_channel_element *elem,
-                                 grpc_channel_element_args *args) {
+  static grpc_error *InitChannelElement(grpc_exec_ctx *exec_ctx,
+                                        grpc_channel_element *elem,
+                                        grpc_channel_element_args *args) {
     const char *peer =
         args->optional_transport
             ? grpc_transport_get_peer(exec_ctx, args->optional_transport)
             : nullptr;
     // Construct the object in the already-allocated memory.
-    new (elem->channel_data) ChannelDataType(*args->channel_args, peer);
+    ChannelDataType *channel_data =
+        new (elem->channel_data) ChannelDataType(*args->channel_args, peer);
+    return channel_data->Init();
   }
 
   static void DestroyChannelElement(grpc_exec_ctx *exec_ctx,

test/core/channel/channel_stack_test.c

@@ -41,9 +41,9 @@
 
 #include "test/core/util/test_config.h"
 
-static void channel_init_func(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {
+static grpc_error *channel_init_func(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
   GPR_ASSERT(args->channel_args->num_args == 1);
   GPR_ASSERT(args->channel_args->args[0].type == GRPC_ARG_INTEGER);
   GPR_ASSERT(0 == strcmp(args->channel_args->args[0].key, "test_key"));
@@ -51,6 +51,7 @@ static void channel_init_func(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(args->is_first);
   GPR_ASSERT(args->is_last);
   *(int *)(elem->channel_data) = 0;
+  return GRPC_ERROR_NONE;
 }
 
 static grpc_error *call_init_func(grpc_exec_ctx *exec_ctx,

test/core/client_channel/resolvers/sockaddr_resolver_test.c

@@ -49,11 +49,6 @@ typedef struct on_resolution_arg {
 
 void on_resolution_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
   on_resolution_arg *res = arg;
-  const grpc_arg *channel_arg =
-      grpc_channel_args_find(res->resolver_result, GRPC_ARG_SERVER_NAME);
-  GPR_ASSERT(channel_arg != NULL);
-  GPR_ASSERT(channel_arg->type == GRPC_ARG_STRING);
-  GPR_ASSERT(strcmp(res->expected_server_name, channel_arg->value.string) == 0);
   grpc_channel_args_destroy(res->resolver_result);
 }
 

test/core/end2end/fake_resolver.c

@@ -181,12 +181,7 @@ static grpc_resolver* fake_resolver_create(grpc_resolver_factory* factory,
   // Instantiate resolver.
   fake_resolver* r = gpr_malloc(sizeof(fake_resolver));
   memset(r, 0, sizeof(*r));
-  grpc_arg server_name_arg;
-  server_name_arg.type = GRPC_ARG_STRING;
-  server_name_arg.key = GRPC_ARG_SERVER_NAME;
-  server_name_arg.value.string = args->uri->path;
-  r->channel_args =
-      grpc_channel_args_copy_and_add(args->args, &server_name_arg, 1);
+  r->channel_args = grpc_channel_args_copy(args->args);
   r->addresses = addresses;
   gpr_mu_init(&r->mu);
   grpc_resolver_init(&r->base, &fake_resolver_vtable);

test/core/end2end/tests/filter_call_init_fails.c

@@ -216,9 +216,11 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                               const grpc_call_final_info *final_info,
                               void *and_free_memory) {}
 
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {}
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
+  return GRPC_ERROR_NONE;
+}
 
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {}

test/core/end2end/tests/filter_causes_close.c

@@ -243,9 +243,11 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                               const grpc_call_final_info *final_info,
                               void *and_free_memory) {}
 
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {}
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
+  return GRPC_ERROR_NONE;
+}
 
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {}

test/core/end2end/tests/filter_latency.c

@@ -281,9 +281,11 @@ static void server_destroy_call_elem(grpc_exec_ctx *exec_ctx,
   gpr_mu_unlock(&g_mu);
 }
 
-static void init_channel_elem(grpc_exec_ctx *exec_ctx,
-                              grpc_channel_element *elem,
-                              grpc_channel_element_args *args) {}
+static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
+                                     grpc_channel_element *elem,
+                                     grpc_channel_element_args *args) {
+  return GRPC_ERROR_NONE;
+}
 
 static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                  grpc_channel_element *elem) {}

test/core/surface/channel_create_test.c

@@ -31,9 +31,14 @@
  *
  */
 
+#include <string.h>
+
 #include <grpc/grpc.h>
 #include <grpc/support/log.h>
+
 #include "src/core/ext/client_channel/resolver_registry.h"
+#include "src/core/lib/channel/channel_stack.h"
+#include "src/core/lib/surface/channel.h"
 #include "test/core/util/test_config.h"
 
 void test_unknown_scheme_target(void) {
@@ -44,6 +49,13 @@ void test_unknown_scheme_target(void) {
 
   chan = grpc_insecure_channel_create("blah://blah", NULL, NULL);
   GPR_ASSERT(chan != NULL);
+
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_channel_element *elem =
+      grpc_channel_stack_element(grpc_channel_get_channel_stack(chan), 0);
+  GPR_ASSERT(0 == strcmp(elem->filter->name, "lame-client"));
+  grpc_exec_ctx_finish(&exec_ctx);
+
   grpc_channel_destroy(chan);
 }