From fec66b410067b9af48b8c4a141b51528cd6b0da2 Mon Sep 17 00:00:00 2001
From: Josh Bleecher Snyder <josh@tailscale.com>
Date: Thu, 3 Jun 2021 15:55:27 -0700
Subject: [PATCH] make it easy to toggle uring on/off

---
 net/tstun/wrap.go | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/tstun/wrap.go b/net/tstun/wrap.go
index 0574fc9e7..d412b76d8 100644
--- a/net/tstun/wrap.go
+++ b/net/tstun/wrap.go
@@ -568,7 +568,12 @@ func (t *Wrapper) write(buf []byte, offset int) (int, error) {
 func (t *Wrapper) read(buf []byte, offset int) (n int, err error) {
 	// TODO: upstream has graceful shutdown error handling here.
 	buff := buf[offset-4:]
-	n, err = t.ring.Read(buff[:])
+	const useIOUring = false
+	if useIOUring {
+		n, err = t.ring.Read(buff[:])
+	} else {
+		n, err = t.tdev.(*wgtun.NativeTun).File().Read(buff[:])
+	}
 	if errors.Is(err, syscall.EBADFD) {
 		err = os.ErrClosed
 	}