# HG changeset patch
# User dholmes
# Date 1259712624 18000
# Node ID 49bd3de668dc35ba7cff876422d114a91f35bbd2
# Parent  b6e6e189e1db90e044c24be709bc581e2356a910
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

diff -r b6e6e189e1db -r 49bd3de668dc src/os/linux/vm/os_linux.cpp
--- a/src/os/linux/vm/os_linux.cpp	Wed Nov 25 19:15:17 2009 -0800
+++ b/src/os/linux/vm/os_linux.cpp	Tue Dec 01 19:10:24 2009 -0500
@@ -4656,6 +4656,7 @@
   // Return immediately if a permit is available.
   if (_counter > 0) {
       _counter = 0 ;
+      OrderAccess::fence();
       return ;
   }
 
@@ -4698,6 +4699,7 @@
     _counter = 0;
     status = pthread_mutex_unlock(_mutex);
     assert (status == 0, "invariant") ;
+    OrderAccess::fence();
     return;
   }
 
@@ -4737,7 +4739,7 @@
   if (jt->handle_special_suspend_equivalent_condition()) {
     jt->java_suspend_self();
   }
-
+  OrderAccess::fence();
 }
 
 void Parker::unpark() {
diff -r b6e6e189e1db -r 49bd3de668dc src/os/solaris/vm/os_solaris.cpp
--- a/src/os/solaris/vm/os_solaris.cpp	Wed Nov 25 19:15:17 2009 -0800
+++ b/src/os/solaris/vm/os_solaris.cpp	Tue Dec 01 19:10:24 2009 -0500
@@ -5803,6 +5803,7 @@
   // Return immediately if a permit is available.
   if (_counter > 0) {
       _counter = 0 ;
+      OrderAccess::fence();
       return ;
   }
 
@@ -5846,6 +5847,7 @@
     _counter = 0;
     status = os::Solaris::mutex_unlock(_mutex);
     assert (status == 0, "invariant") ;
+    OrderAccess::fence();
     return;
   }
 
@@ -5891,7 +5893,7 @@
   if (jt->handle_special_suspend_equivalent_condition()) {
     jt->java_suspend_self();
   }
-
+  OrderAccess::fence();
 }
 
 void Parker::unpark() {