From 69c4c6f192271918d1bf64a84d3f8a41d1e943ac Mon Sep 17 00:00:00 2001
From: David Chisnall <theraven@theravensnest.org>
Date: Tue, 28 Feb 2012 15:56:07 +0000
Subject: Fix a potential race in guard logic.

---
 src/guard.cc | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'src')

diff --git a/src/guard.cc b/src/guard.cc
index f236053..1cbeb58 100644
--- a/src/guard.cc
+++ b/src/guard.cc
@@ -103,6 +103,10 @@ extern "C" int __cxa_guard_acquire(volatile int64_t *guard_object)
 	// the lock at the same time.
 	while (!__sync_bool_compare_and_swap_4(lock, 0, 1))
 	{
+		if (1 == ((*guard_object) >> 56))
+		{
+			break;
+		}
 		sched_yield();
 	}
 	// We have to test the guard again, in case another thread has performed
-- 
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