From 552c4e81921bc15a070c372bf28ce91e7122c706 Mon Sep 17 00:00:00 2001
From: Andy Pan <panjf2000@gmail.com>
Date: Wed, 9 Aug 2023 21:43:21 +0800
Subject: [PATCH] unix: avoid setting O_NONBLOCK needlessly by checking flags
 beforehand

Change-Id: I227118221df469a677f3ff140ca7b94acb7f9571
Reviewed-on: https://go-review.googlesource.com/c/sys/+/517576
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Andy Pan <panjf2000@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
---
 unix/syscall_unix.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/unix/syscall_unix.go b/unix/syscall_unix.go
index 8bb30e7ce..f6eda2705 100644
--- a/unix/syscall_unix.go
+++ b/unix/syscall_unix.go
@@ -549,6 +549,9 @@ func SetNonblock(fd int, nonblocking bool) (err error) {
 	if err != nil {
 		return err
 	}
+	if (flag&O_NONBLOCK != 0) == nonblocking {
+		return nil
+	}
 	if nonblocking {
 		flag |= O_NONBLOCK
 	} else {