From 2bf7be382b9be9de3c008f09fd0861929568c744 Mon Sep 17 00:00:00 2001
From: dholmes <unknown>
Date: Tue, 1 Dec 2009 22:29:02 -0500
Subject: [PATCH] 6822370: ReentrantReadWriteLock: threads hung when there are
 no threads holding onto the lock (Netra x4450) Summary: This day one bug is
 caused by missing memory barriers in various Parker::park() paths that can
 result in lost wakeups and hangs. Reviewed-by: dice, acorn

---
 src/os/linux/vm/os_linux.cpp     | 3 +++
 src/os/solaris/vm/os_solaris.cpp | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/src/os/linux/vm/os_linux.cpp b/src/os/linux/vm/os_linux.cpp
index 281e81c26..6aa3ebc0a 100644
--- a/src/os/linux/vm/os_linux.cpp
+++ b/src/os/linux/vm/os_linux.cpp
@@ -4683,6 +4683,7 @@ void Parker::park(bool isAbsolute, jlong time) {
   // Return immediately if a permit is available.
   if (_counter > 0) {
       _counter = 0 ;
+      OrderAccess::fence();
       return ;
   }
 
@@ -4725,6 +4726,7 @@ void Parker::park(bool isAbsolute, jlong time) {
     _counter = 0;
     status = pthread_mutex_unlock(_mutex);
     assert (status == 0, "invariant") ;
+    OrderAccess::fence();
     return;
   }
 
@@ -4765,6 +4767,7 @@ void Parker::park(bool isAbsolute, jlong time) {
     jt->java_suspend_self();
   }
 
+  OrderAccess::fence();
 }
 
 void Parker::unpark() {
diff --git a/src/os/solaris/vm/os_solaris.cpp b/src/os/solaris/vm/os_solaris.cpp
index 13abbf9d4..b85bcef8c 100644
--- a/src/os/solaris/vm/os_solaris.cpp
+++ b/src/os/solaris/vm/os_solaris.cpp
@@ -5803,6 +5803,7 @@ void Parker::park(bool isAbsolute, jlong time) {
   // Return immediately if a permit is available.
   if (_counter > 0) {
       _counter = 0 ;
+      OrderAccess::fence();
       return ;
   }
 
@@ -5846,6 +5847,7 @@ void Parker::park(bool isAbsolute, jlong time) {
     _counter = 0;
     status = os::Solaris::mutex_unlock(_mutex);
     assert (status == 0, "invariant") ;
+    OrderAccess::fence();
     return;
   }
 
@@ -5892,6 +5894,7 @@ void Parker::park(bool isAbsolute, jlong time) {
     jt->java_suspend_self();
   }
 
+  OrderAccess::fence();
 }
 
 void Parker::unpark() {
-- 
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