fix a deadlock in cancel call

src/core/surface/call.c

@@ -246,6 +246,10 @@ static int fill_send_ops(grpc_call *call, grpc_transport_op *op);
 static void execute_op(grpc_call *call, grpc_transport_op *op);
 static void recv_metadata(grpc_call *call, grpc_metadata_batch *metadata);
 static void finish_read_ops(grpc_call *call);
+static grpc_call_error grpc_call_cancel_with_status_internal(grpc_call *c,
+                                             grpc_status_code status,
+                                             const char *description,
+                                             gpr_uint8 locked);
 
 grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
                             const void *server_transport_data,
@@ -627,7 +631,7 @@ static int begin_message(grpc_call *call, grpc_begin_message msg) {
     gpr_asprintf(
         &message, "Message terminated early; read %d bytes, expected %d",
         (int)call->incoming_message.length, (int)call->incoming_message_length);
-    grpc_call_cancel_with_status(call, GRPC_STATUS_INVALID_ARGUMENT, message);
+    grpc_call_cancel_with_status_internal(call, GRPC_STATUS_INVALID_ARGUMENT, message, 1);
     gpr_free(message);
     return 0;
   }
@@ -638,7 +642,7 @@ static int begin_message(grpc_call *call, grpc_begin_message msg) {
         &message,
         "Maximum message length of %d exceeded by a message of length %d",
         grpc_channel_get_max_message_length(call->channel), msg.length);
-    grpc_call_cancel_with_status(call, GRPC_STATUS_INVALID_ARGUMENT, message);
+    grpc_call_cancel_with_status_internal(call, GRPC_STATUS_INVALID_ARGUMENT, message, 1);
     gpr_free(message);
     return 0;
   } else if (msg.length > 0) {
@@ -658,9 +662,9 @@ static int add_slice_to_message(grpc_call *call, gpr_slice slice) {
   }
   /* we have to be reading a message to know what to do here */
   if (!call->reading_message) {
-    grpc_call_cancel_with_status(
+    grpc_call_cancel_with_status_internal(
         call, GRPC_STATUS_INVALID_ARGUMENT,
-        "Received payload data while not reading a message");
+        "Received payload data while not reading a message", 1);
     return 0;
   }
   /* append the slice to the incoming buffer */
@@ -671,7 +675,7 @@ static int add_slice_to_message(grpc_call *call, gpr_slice slice) {
     gpr_asprintf(
         &message, "Receiving message overflow; read %d bytes, expected %d",
         (int)call->incoming_message.length, (int)call->incoming_message_length);
-    grpc_call_cancel_with_status(call, GRPC_STATUS_INVALID_ARGUMENT, message);
+    grpc_call_cancel_with_status_internal(call, GRPC_STATUS_INVALID_ARGUMENT, message, 1);
     gpr_free(message);
     return 0;
   } else if (call->incoming_message.length == call->incoming_message_length) {
@@ -996,6 +1000,13 @@ grpc_call_error grpc_call_cancel(grpc_call *call) {
 grpc_call_error grpc_call_cancel_with_status(grpc_call *c,
                                              grpc_status_code status,
                                              const char *description) {
+  return grpc_call_cancel_with_status_internal(c, status, description, 0);
+}
+
+static grpc_call_error grpc_call_cancel_with_status_internal(grpc_call *c,
+                                             grpc_status_code status,
+                                             const char *description,
+                                             gpr_uint8 locked) {
   grpc_transport_op op;
   grpc_mdstr *details =
       description ? grpc_mdstr_from_string(c->metadata_context, description)
@@ -1003,10 +1014,14 @@ grpc_call_error grpc_call_cancel_with_status(grpc_call *c,
   memset(&op, 0, sizeof(op));
   op.cancel_with_status = status;
 
-  lock(c);
+  if (locked == 0) {
+    lock(c);
+  }
   set_status_code(c, STATUS_FROM_API_OVERRIDE, status);
   set_status_details(c, STATUS_FROM_API_OVERRIDE, details);
-  unlock(c);
+  if (locked == 0) {
+    unlock(c);
+  }
 
   execute_op(c, &op);
 
@@ -1027,8 +1042,8 @@ static void call_alarm(void *arg, int success) {
   grpc_call *call = arg;
   if (success) {
     if (call->is_client) {
-      grpc_call_cancel_with_status(call, GRPC_STATUS_DEADLINE_EXCEEDED,
+      grpc_call_cancel_with_status_internal(call, GRPC_STATUS_DEADLINE_EXCEEDED,
-                                   "Deadline Exceeded");
+                                   "Deadline Exceeded", 0);
     } else {
       grpc_call_cancel(call);
     }