From b53f8a67649a371a38dc6d97b0dfe52111236a3e Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Tue, 1 Jun 2010 13:50:50 +0000
Subject: OTP-8658 Add missing memory barriers in erts_poll()

Missing memory barriers in erts_poll() could cause the runtime system to
hang indefinitely.
---
 erts/include/internal/ethread.h        | 22 +++++++++++++++++-----
 erts/include/internal/i386/atomic.h    | 20 +++++++++++++++-----
 erts/include/internal/ppc32/atomic.h   | 11 ++++++-----
 erts/include/internal/sparc32/atomic.h | 14 +++++++++-----
 erts/include/internal/tile/atomic.h    |  2 ++
 5 files changed, 49 insertions(+), 20 deletions(-)

(limited to 'erts/include/internal')

diff --git a/erts/include/internal/ethread.h b/erts/include/internal/ethread.h
index 934a79c6f9..564f8f057c 100644
--- a/erts/include/internal/ethread.h
+++ b/erts/include/internal/ethread.h
@@ -1,19 +1,19 @@
 /*
  * %CopyrightBegin%
- * 
- * Copyright Ericsson AB 2004-2009. All Rights Reserved.
- * 
+ *
+ * Copyright Ericsson AB 2004-2010. 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%
  */
 
@@ -375,6 +375,12 @@ ETHR_INLINE_FUNC_NAME_(ethr_mutex_unlock)(ethr_mutex *mtx)
 #define ETHR_HAVE_OPTIMIZED_ATOMIC_OPS 1
 #define ETHR_HAVE_OPTIMIZED_LOCKS 1
 
+#define ETHR_MEMORY_BARRIER \
+do { \
+    volatile LONG x___ = 0; \
+    (void) _InterlockedCompareExchange(&x___, (LONG) 1, (LONG) 0); \
+} while (0)
+
 typedef struct {
     volatile LONG value;
 } ethr_atomic_t;
@@ -1124,6 +1130,12 @@ ETHR_INLINE_FUNC_NAME_(ethr_write_lock)(ethr_rwlock_t *lock)
  */
 #ifndef ETHR_HAVE_OPTIMIZED_ATOMIC_OPS
 
+/*
+ * ETHR_MEMORY_BARRIER orders between locked and atomic accesses only,
+ * i.e. when this atomic fallback is used a noop is sufficient.
+ */
+#define ETHR_MEMORY_BARRIER
+
 #define ETHR_ATOMIC_ADDR_BITS 4
 #define ETHR_ATOMIC_ADDR_SHIFT 3
 
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__
diff --git a/erts/include/internal/ppc32/atomic.h b/erts/include/internal/ppc32/atomic.h
index fa701c6a92..105d874995 100644
--- a/erts/include/internal/ppc32/atomic.h
+++ b/erts/include/internal/ppc32/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 +32,7 @@ typedef struct {
     volatile int counter;
 } ethr_native_atomic_t;
 
+#define ETHR_MEMORY_BARRIER __asm__ __volatile__("sync" : : : "memory")
 
 #ifdef ETHR_TRY_INLINE_FUNCS
 
diff --git a/erts/include/internal/sparc32/atomic.h b/erts/include/internal/sparc32/atomic.h
index d6fdc6b2a4..8fde449a52 100644
--- a/erts/include/internal/sparc32/atomic.h
+++ b/erts/include/internal/sparc32/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%
  */
 
@@ -28,6 +28,10 @@ typedef struct {
     volatile long counter;
 } ethr_native_atomic_t;
 
+#define ETHR_MEMORY_BARRIER \
+  __asm__ __volatile__("membar #LoadLoad|#LoadStore|#StoreLoad|#StoreStore\n" \
+                       : : : "memory")
+
 #ifdef ETHR_TRY_INLINE_FUNCS
 
 #if defined(__arch64__)
diff --git a/erts/include/internal/tile/atomic.h b/erts/include/internal/tile/atomic.h
index 59a9250e7c..5e4c7ac9fe 100644
--- a/erts/include/internal/tile/atomic.h
+++ b/erts/include/internal/tile/atomic.h
@@ -32,6 +32,8 @@ typedef struct {
     volatile long counter;
 } ethr_native_atomic_t;
 
+#define ETHR_MEMORY_BARRIER __insn_mf()
+
 #ifdef ETHR_TRY_INLINE_FUNCS
 
 static ETHR_INLINE void
-- 
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