From 4cf2ffe28b462b4025a170ddebeb7e721d4f016b Mon Sep 17 00:00:00 2001
From: Argyrios Kyrtzidis <akyrtzi@gmail.com>
Date: Tue, 3 Jul 2012 16:30:52 +0000
Subject: [PATCH] [libclang] Protect against a race condition where a thread
 may be destroying an ASTUnit while cleanupOnDiskMapAtExit is getting called.

rdar://11781241

llvm-svn: 159664
---
 clang/lib/Frontend/ASTUnit.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index d2f63a80fee9..7be25e96b4c3 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -116,7 +116,8 @@ static OnDiskDataMap &getOnDiskDataMap() {
 }
 
 static void cleanupOnDiskMapAtExit(void) {
-  // No mutex required here since we are leaving the program.
+  // Use the mutex because there can be an alive thread destroying an ASTUnit.
+  llvm::MutexGuard Guard(getOnDiskMutex());
   OnDiskDataMap &M = getOnDiskDataMap();
   for (OnDiskDataMap::iterator I = M.begin(), E = M.end(); I != E; ++I) {
     // We don't worry about freeing the memory associated with OnDiskDataMap.
-- 
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