From: Andy Pan <panjf2000@gmail.com>
Date: Wed, 9 Aug 2023 13:13:50 +0000 (+0800)
Subject: syscall: avoid setting O_NONBLOCK needlessly by checking flags beforehand
X-Git-Tag: go1.22rc1~1346
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=8ecdc4e593676ff56f8ac273a01f27f0862992a9;p=gostls13.git

syscall: avoid setting O_NONBLOCK needlessly by checking flags beforehand

Change-Id: I097a2941f1d1a7fd98ccf1534940d03f47ac3229
Reviewed-on: https://go-review.googlesource.com/c/go/+/517675
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: Andy Pan <panjf2000@gmail.com>
---

diff --git a/src/syscall/exec_unix.go b/src/syscall/exec_unix.go
index 206c0ab32b..c6a6caaa70 100644
--- a/src/syscall/exec_unix.go
+++ b/src/syscall/exec_unix.go
@@ -107,6 +107,9 @@ 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 {