From af9d0e6976621eee931c80ac4a784885e5a4b5a7 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Wed, 11 Jan 2012 14:41:33 -0700
Subject: [PATCH] add missing OS X thread-data synchronization

Merge to 5.2.1
---
 src/racket/gc2/vm_osx.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/racket/gc2/vm_osx.c b/src/racket/gc2/vm_osx.c
index 73466e621e..8c63088f88 100644
--- a/src/racket/gc2/vm_osx.c
+++ b/src/racket/gc2/vm_osx.c
@@ -102,6 +102,7 @@ static void unregister_mach_thread() {
   int index = thread_self % OSX_THREAD_TABLE_SIZE;
   OSXThreadData * thread, *prev = NULL;
 
+  pthread_mutex_lock(&osxthreadsmutex);
   thread = osxthreads[index];
   while (thread->thread_port_id != thread_self) {
     prev = thread;
@@ -114,6 +115,7 @@ static void unregister_mach_thread() {
       osxthreads[index] = thread->next;
     free(thread);
   }
+  pthread_mutex_unlock(&osxthreadsmutex);
 }
 
 #endif