From f39a31cda09afeaa11b79ddca1f878b27062767a Mon Sep 17 00:00:00 2001
From: "Tate, Hongliang Tian" <tate.thl@antfin.com>
Date: Wed, 30 Sep 2020 06:03:06 +0000
Subject: [PATCH] Fix a bug in HostEventFd

---
 src/libos/src/events/host_event_fd.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/libos/src/events/host_event_fd.rs b/src/libos/src/events/host_event_fd.rs
index aff80a19..8e44ee17 100644
--- a/src/libos/src/events/host_event_fd.rs
+++ b/src/libos/src/events/host_event_fd.rs
@@ -65,6 +65,10 @@ impl HostEventFd {
     ///
     /// Precondition. The caller must ensure that the host fds are valid.
     pub unsafe fn write_u64_raw_and_batch(host_fds: &[FileDesc], val: u64) {
+        if host_fds.len() == 0 {
+            return;
+        }
+
         ocall_eventfd_write_batch(host_fds, val);
     }