From f4919e4a824372c70af64a80e16db4de995bdc3c Mon Sep 17 00:00:00 2001
From: Richard Henderson <rth@redhat.com>
Date: Wed, 28 Nov 2012 13:01:26 -0800
Subject: [PATCH] re PR libgcc/48076 (Unsafe double checked locking in
__emutls_get_address)
PR libgcc/48076
* emutls.c (__emutls_get_address): Avoid race condition between
obj->loc.offset read and emutls_key initialization.
From-SVN: r193907
---
libgcc/ChangeLog | 6 ++++++
libgcc/emutls.c | 4 ++--
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index c547dcb06c6d..6506e85e89fa 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,9 @@
+2012-11-28 Richard Henderson <rth@redhat.com>
+
+ PR libgcc/48076
+ * emutls.c (__emutls_get_address): Avoid race condition between
+ obj->loc.offset read and emutls_key initialization.
+
2012-11-22 Georg-Johann Lay <avr@gjlay.de>
Adjust decimal point of signed accum mode to GCC default.
diff --git a/libgcc/emutls.c b/libgcc/emutls.c
index 22ea4403edbd..f1b653b7d542 100644
--- a/libgcc/emutls.c
+++ b/libgcc/emutls.c
@@ -136,7 +136,7 @@ __emutls_get_address (struct __emutls_object *obj)
#ifndef __GTHREADS
abort ();
#else
- pointer offset = obj->loc.offset;
+ pointer offset = __atomic_load_n (&obj->loc.offset, __ATOMIC_ACQUIRE);
if (__builtin_expect (offset == 0, 0))
{
@@ -147,7 +147,7 @@ __emutls_get_address (struct __emutls_object *obj)
if (offset == 0)
{
offset = ++emutls_size;
- obj->loc.offset = offset;
+ __atomic_store_n (&obj->loc.offset, offset, __ATOMIC_RELEASE);
}
__gthread_mutex_unlock (&emutls_mutex);
}
--
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