From 7389ab8d218fe7b7cf2ebdd232524a1ebd5a0b81 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Thu, 30 Sep 2010 14:09:19 -0400
Subject: [PATCH] runtime: serialize mcache allocation

Fixes racy regex-dna-parallel crashes.

R=r, r2
CC=golang-dev
https://golang.org/cl/2308042
---
 src/pkg/runtime/malloc.goc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/pkg/runtime/malloc.goc b/src/pkg/runtime/malloc.goc
index fa7164ec57a..604290b93b9 100644
--- a/src/pkg/runtime/malloc.goc
+++ b/src/pkg/runtime/malloc.goc
@@ -236,9 +236,11 @@ allocmcache(void)
 {
 	MCache *c;
 
+	lock(&mheap);
 	c = FixAlloc_Alloc(&mheap.cachealloc);
 	mstats.mcache_inuse = mheap.cachealloc.inuse;
 	mstats.mcache_sys = mheap.cachealloc.sys;
+	unlock(&mheap);
 	return c;
 }