From f6e6f543c0da8f0eef17bdda7d4f3614c0112d93 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Sun, 30 Aug 2020 13:40:52 +0200
Subject: [PATCH] Only need to do syscall if something was submitted

---
 .../io/netty/channel/uring/IOUringSubmissionQueue.java   | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/transport-native-io_uring/src/main/java/io/netty/channel/uring/IOUringSubmissionQueue.java b/transport-native-io_uring/src/main/java/io/netty/channel/uring/IOUringSubmissionQueue.java
index f6966a4407..4d1d9411aa 100644
--- a/transport-native-io_uring/src/main/java/io/netty/channel/uring/IOUringSubmissionQueue.java
+++ b/transport-native-io_uring/src/main/java/io/netty/channel/uring/IOUringSubmissionQueue.java
@@ -288,10 +288,11 @@ final class IOUringSubmissionQueue {
     public void submit() {
         int submitted = flushSqe();
         logger.trace("Submitted: {}", submitted);
-
-        int ret = Native.ioUringEnter(ringFd, submitted, 0, 0);
-        if (ret < 0) {
-            throw new RuntimeException("ioUringEnter syscall");
+        if (submitted > 0) {
+            int ret = Native.ioUringEnter(ringFd, submitted, 0, 0);
+            if (ret < 0) {
+                throw new RuntimeException("ioUringEnter syscall");
+            }
         }
     }