OTP-8658 Add missing memory barriers in erts_poll()

Missing memory barriers in erts_poll() could cause the runtime system to
hang indefinitely.

1 files changed, 15 insertions, 5 deletions

diff --git a/erts/include/internal/i386/atomic.h b/erts/include/internal/i386/atomic.h
index 3291ad38e5..90b4c5f773 100644
--- a/erts/include/internal/i386/atomic.h
+++ b/erts/include/internal/i386/atomic.h
@@ -1,19 +1,19 @@
 /*
  * %CopyrightBegin%
- * 
- * Copyright Ericsson AB 2005-2009. All Rights Reserved.
- * 
+ *
+ * Copyright Ericsson AB 2005-2010. All Rights Reserved.
+ *
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
  * compliance with the License. You should have received a copy of the
  * Erlang Public License along with this software. If not, it can be
  * retrieved online at http://www.erlang.org/.
- * 
+ *
  * Software distributed under the License is distributed on an "AS IS"
  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  * the License for the specific language governing rights and limitations
  * under the License.
- * 
+ *
  * %CopyrightEnd%
  */
 
@@ -32,6 +32,16 @@ typedef struct {
     volatile long counter;
 } ethr_native_atomic_t;
 
+#ifdef __x86_64__
+#define ETHR_MEMORY_BARRIER __asm__ __volatile__("mfence" : : : "memory")
+#else
+#define ETHR_MEMORY_BARRIER \
+do { \
+    volatile long x___ = 0; \
+    __asm__ __volatile__("lock; incl %0" : "=m"(x___) : "m"(x___) : "memory"); \
+} while (0)
+#endif
+
 #ifdef ETHR_TRY_INLINE_FUNCS
 
 #ifdef __x86_64__