From 902911bcff91127cd8c5c7e10d200eb97f0c1893 Mon Sep 17 00:00:00 2001
From: Dmitriy Vyukov <dvyukov@google.com>
Date: Mon, 25 Jun 2012 11:08:09 +0400
Subject: [PATCH] runtime: fix potential GC deadlock The issue seems to not be
 triggered right now, but I've seen the deadlock after some other legal
 modifications to runtime. So I think we are safer this way.

R=rsc, r
CC=golang-dev
https://golang.org/cl/6339051
---
 src/pkg/runtime/mgc0.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/pkg/runtime/mgc0.c b/src/pkg/runtime/mgc0.c
index 5f1bff2c46..70d0a0f2e2 100644
--- a/src/pkg/runtime/mgc0.c
+++ b/src/pkg/runtime/mgc0.c
@@ -905,12 +905,14 @@ runtime·gc(int32 force)
 	work.debugmarkdone = 0;
 	work.nproc = runtime·gcprocs();
 	addroots();
+	m->locks++;	// disable gc during mallocs in parforalloc
 	if(work.markfor == nil)
 		work.markfor = runtime·parforalloc(MaxGcproc);
 	runtime·parforsetup(work.markfor, work.nproc, work.nroot, nil, false, markroot);
 	if(work.sweepfor == nil)
 		work.sweepfor = runtime·parforalloc(MaxGcproc);
 	runtime·parforsetup(work.sweepfor, work.nproc, runtime·mheap.nspan, nil, true, sweepspan);
+	m->locks--;
 	if(work.nproc > 1) {
 		runtime·noteclear(&work.alldone);
 		runtime·helpgc(work.nproc);
-- 
2.48.1