From 4501d9ad44510a07e5f07439275b39198268cf47 Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <ian@gcc.gnu.org>
Date: Wed, 24 Feb 2016 15:03:04 +0000
Subject: [PATCH] runtime: lock M during cgo call

    cgo should lock the M.


    See also https://golang.org/cl/18882 .

    Reviewed-on: https://go-review.googlesource.com/18883

From-SVN: r233670
---
 gcc/go/gofrontend/MERGE | 2 +-
 libgo/runtime/go-cgo.c  | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 038e4346660a..9bebd30c431f 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-1c3747d20789c73447ff71cbc739f7423c4bdf67
+156f5f0152797ac2afe5f23803aeb3c7b8f8418e
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/libgo/runtime/go-cgo.c b/libgo/runtime/go-cgo.c
index a36eac92704e..610bcf5ec4e8 100644
--- a/libgo/runtime/go-cgo.c
+++ b/libgo/runtime/go-cgo.c
@@ -41,6 +41,8 @@ syscall_cgocall ()
   if (runtime_needextram && runtime_cas (&runtime_needextram, 1, 0))
     runtime_newextram ();
 
+  runtime_lockOSThread();
+
   m = runtime_m ();
   ++m->ncgocall;
   g = runtime_g ();
@@ -70,6 +72,8 @@ syscall_cgocalldone ()
      _cgo_panic will already have exited syscall mode.  */
   if (g->status == Gsyscall)
     runtime_exitsyscall ();
+
+  runtime_unlockOSThread();
 }
 
 /* Call back from C/C++ code to Go code.  */