Fix segfault

The server transport started reading fractionally too early, leading to
the accept callback not being ready in some cases.

src/core/security/server_secure_chttp2.c

@@ -99,9 +99,10 @@ static void on_secure_transport_setup_done(void *statep,
     if (!state->is_shutdown) {
       mdctx = grpc_mdctx_create();
       transport = grpc_create_chttp2_transport(
-          grpc_server_get_channel_args(state->server), secure_endpoint, NULL, 0,
+          grpc_server_get_channel_args(state->server), secure_endpoint, mdctx,
-          mdctx, 0);
+          0);
       setup_transport(state, transport, mdctx);
+      grpc_chttp2_transport_start_reading(transport, NULL, 0);
     } else {
       /* We need to consume this here, because the server may already have gone
        * away. */

src/core/surface/channel_create.c

@@ -72,7 +72,8 @@ static void connected(void *arg, grpc_endpoint *tcp) {
   grpc_iomgr_closure *notify;
   if (tcp != NULL) {
     c->result->transport = grpc_create_chttp2_transport(
-        c->args.channel_args, tcp, NULL, 0, c->args.metadata_context, 1);
+        c->args.channel_args, tcp, c->args.metadata_context, 1);
+    grpc_chttp2_transport_start_reading(c->result->transport, NULL, 0);
     GPR_ASSERT(c->result->transport);
     c->result->filters = gpr_malloc(sizeof(grpc_channel_filter *));
     c->result->filters[0] = &grpc_http_client_filter;

src/core/surface/secure_channel_create.c

@@ -82,9 +82,9 @@ static void on_secure_transport_setup_done(void *arg,
     gpr_log(GPR_ERROR, "Secure transport setup failed with error %d.", status);
     memset(c->result, 0, sizeof(*c->result));
   } else {
-    c->result->transport =
+    c->result->transport = grpc_create_chttp2_transport(
-        grpc_create_chttp2_transport(c->args.channel_args, secure_endpoint,
+        c->args.channel_args, secure_endpoint, c->args.metadata_context, 1);
-                                     NULL, 0, c->args.metadata_context, 1);
+    grpc_chttp2_transport_start_reading(c->result->transport, NULL, 0);
     c->result->filters = gpr_malloc(sizeof(grpc_channel_filter *) * 2);
     c->result->filters[0] = &grpc_client_auth_filter;
     c->result->filters[1] = &grpc_http_client_filter;

src/core/surface/server_chttp2.c

@@ -61,8 +61,9 @@ static void new_transport(void *server, grpc_endpoint *tcp) {
    */
   grpc_mdctx *mdctx = grpc_mdctx_create();
   grpc_transport *transport = grpc_create_chttp2_transport(
-      grpc_server_get_channel_args(server), tcp, NULL, 0, mdctx, 0);
+      grpc_server_get_channel_args(server), tcp, mdctx, 0);
   setup_transport(server, transport, mdctx);
+  grpc_chttp2_transport_start_reading(transport, NULL, 0);
 }
 
 /* Server callback: start listening on our ports */

src/core/transport/chttp2_transport.c

@@ -201,8 +201,8 @@ static void ref_transport(grpc_chttp2_transport *t) { gpr_ref(&t->refs); }
 
 static void init_transport(grpc_chttp2_transport *t,
                            const grpc_channel_args *channel_args,
-                           grpc_endpoint *ep, gpr_slice *slices, size_t nslices,
+                           grpc_endpoint *ep, grpc_mdctx *mdctx,
-                           grpc_mdctx *mdctx, int is_client) {
+                           int is_client) {
   size_t i;
   int j;
 
@@ -311,9 +311,6 @@ static void init_transport(grpc_chttp2_transport *t,
       }
     }
   }
-
-  REF_TRANSPORT(t, "recv_data"); /* matches unref inside recv_data */
-  recv_data(t, slices, nslices, GRPC_ENDPOINT_CB_OK);
 }
 
 static void destroy_transport(grpc_transport *gt) {
@@ -1043,9 +1040,16 @@ static const grpc_transport_vtable vtable = {
     perform_transport_op,       destroy_stream, destroy_transport};
 
 grpc_transport *grpc_create_chttp2_transport(
-    const grpc_channel_args *channel_args, grpc_endpoint *ep, gpr_slice *slices,
+    const grpc_channel_args *channel_args, grpc_endpoint *ep, grpc_mdctx *mdctx,
-    size_t nslices, grpc_mdctx *mdctx, int is_client) {
+    int is_client) {
   grpc_chttp2_transport *t = gpr_malloc(sizeof(grpc_chttp2_transport));
-  init_transport(t, channel_args, ep, slices, nslices, mdctx, is_client);
+  init_transport(t, channel_args, ep, mdctx, is_client);
   return &t->base;
 }
+
+void grpc_chttp2_transport_start_reading(grpc_transport *transport,
+                                         gpr_slice *slices, size_t nslices) {
+  grpc_chttp2_transport *t = (grpc_chttp2_transport *)transport;
+  REF_TRANSPORT(t, "recv_data"); /* matches unref inside recv_data */
+  recv_data(t, slices, nslices, GRPC_ENDPOINT_CB_OK);
+}

src/core/transport/chttp2_transport.h

@@ -41,7 +41,10 @@ extern int grpc_http_trace;
 extern int grpc_flowctl_trace;
 
 grpc_transport *grpc_create_chttp2_transport(
-    const grpc_channel_args *channel_args, grpc_endpoint *ep, gpr_slice *slices,
+    const grpc_channel_args *channel_args, grpc_endpoint *ep,
-    size_t nslices, grpc_mdctx *metadata_context, int is_client);
+    grpc_mdctx *metadata_context, int is_client);
+
+void grpc_chttp2_transport_start_reading(grpc_transport *transport,
+                                         gpr_slice *slices, size_t nslices);
 
 #endif /* GRPC_INTERNAL_CORE_TRANSPORT_CHTTP2_TRANSPORT_H */