From ac851a6d8123822ac3317627fd633cd4106a71cd Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Mon, 1 Apr 2024 15:26:30 -0400
Subject: [PATCH] fix: in `Fut.await`, upon failure, use `resume`

otherwise a fairly vicious bug happens: the await-er is resumed on the
current runner, not its native one, which can cause deadlocks as it
breaks the executors' dependency DAG. When using `resume` there is no
bug since `resume` is designed to always schedule on the correct runner.
---
 src/core/fut.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/core/fut.ml b/src/core/fut.ml
index 91a95a7f..17afb908 100644
--- a/src/core/fut.ml
+++ b/src/core/fut.ml
@@ -438,7 +438,7 @@ let await (fut : 'a t) : 'a =
                 resume k (Ok ())
               | Error (exn, bt) ->
                 (* fail continuation immediately *)
-                k (Error (exn, bt))));
+                resume k (Error (exn, bt))));
       };
     (* un-suspended: we should have a result! *)
     get_or_fail_exn fut