diff -rNu  epoll_reactor.ipp.orig epoll_reactor.ipp > /mnt/builder/3rdParty/boost/srcs/epoll_reactor.ipp.patch

--- epoll_reactor.ipp.orig	2012-02-28 17:35:48.000000000 -0500
+++ epoll_reactor.ipp	2012-12-17 11:10:02.000000000 -0500
@@ -205,14 +205,27 @@
     epoll_reactor::per_descriptor_data& descriptor_data,
     reactor_op* op, bool allow_speculative)
 {
-  if (!descriptor_data)
+  // LG
+  epoll_reactor::per_descriptor_data local_descriptor_data = descriptor_data;
+  if (!local_descriptor_data)
+  // LG
   {
     op->ec_ = boost::asio::error::bad_descriptor;
     post_immediate_completion(op);
     return;
   }
 
-  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+  // LG - use local_descriptor_data instead of descriptor_data to access mutex, as descriptor_data might have been reset to 0 by another thread
+  mutex::scoped_lock descriptor_lock(local_descriptor_data->mutex_);
+
+  // LG - have to check descriptor_data again, as another thread might have set it to 0
+  if (!descriptor_data)
+  {
+    op->ec_ = boost::asio::error::bad_descriptor;
+    post_immediate_completion(op);
+    return;
+  }
+  // LG
 
   if (descriptor_data->shutdown_)
   {
@@ -251,10 +264,19 @@
 void epoll_reactor::cancel_ops(socket_type,
     epoll_reactor::per_descriptor_data& descriptor_data)
 {
-  if (!descriptor_data)
+  // LG
+  epoll_reactor::per_descriptor_data local_descriptor_data = descriptor_data;
+  if (!local_descriptor_data)
+  // LG
     return;
 
-  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+  // LG - use local_descriptor_data instead of descriptor_data to access mutex, as descriptor_data might have been reset to 0 by another thread
+  mutex::scoped_lock descriptor_lock(local_descriptor_data->mutex_);
+
+  // LG - have to check descriptor_data again, as another thread might have set it to 0
+  if (!descriptor_data)
+    return;
+  // LG
 
   op_queue<operation> ops;
   for (int i = 0; i < max_ops; ++i)
@@ -275,10 +297,18 @@
 void epoll_reactor::deregister_descriptor(socket_type descriptor,
     epoll_reactor::per_descriptor_data& descriptor_data, bool closing)
 {
-  if (!descriptor_data)
+  // LG
+  epoll_reactor::per_descriptor_data local_descriptor_data = descriptor_data;
+  if (!local_descriptor_data)
+  // LG
     return;
 
-  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+  // LG - use local_descriptor_data instead of descriptor_data to access mutex, as descriptor_data might have been reset to 0 by another thread
+  mutex::scoped_lock descriptor_lock(local_descriptor_data->mutex_);
+  // LG - have to check descriptor_data again, as another thread might have set it to 0
+  if (!descriptor_data)
+    return;
+  // LG
 
   if (!descriptor_data->shutdown_)
   {
@@ -307,10 +337,14 @@
     descriptor_data->descriptor_ = -1;
     descriptor_data->shutdown_ = true;
 
-    descriptor_lock.unlock();
-
-    free_descriptor_state(descriptor_data);
+    //LG 
+    // ensure that descriptor_data is being reset INSIDE protected block (before descriptor_lock.unlock())
+    // code is not strihtforward here because descriptor_lock lock on mutex that resides inside *descriptor_data
+    epoll_reactor::per_descriptor_data descriptor_data_ = descriptor_data;
     descriptor_data = 0;
+    descriptor_lock.unlock();
+    free_descriptor_state(descriptor_data_);
+    //LG
 
     io_service_.post_deferred_completions(ops);
   }
@@ -319,10 +353,18 @@
 void epoll_reactor::deregister_internal_descriptor(socket_type descriptor,
     epoll_reactor::per_descriptor_data& descriptor_data)
 {
-  if (!descriptor_data)
+  // LG
+  epoll_reactor::per_descriptor_data local_descriptor_data = descriptor_data;
+  if (!local_descriptor_data)
+  // LG
     return;
 
-  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
+  // LG - use local_descriptor_data instead of descriptor_data to access mutex, as descriptor_data might have been reset to 0 by another thread
+  mutex::scoped_lock descriptor_lock(local_descriptor_data->mutex_);
+  // LG - have to check descriptor_data again, as another thread might have set it to 0
+  if (!descriptor_data)
+    return;
+  // LG
 
   if (!descriptor_data->shutdown_)
   {
@@ -336,10 +378,14 @@
     descriptor_data->descriptor_ = -1;
     descriptor_data->shutdown_ = true;
 
-    descriptor_lock.unlock();
-
-    free_descriptor_state(descriptor_data);
+    //LG
+    // ensure that descriptor_data is being reset INSIDE protected block (before descriptor_lock.unlock())
+    // code is not strihtforward here because descriptor_lock lock on mutex that resides inside *descriptor_data
+    epoll_reactor::per_descriptor_data descriptor_data_ = descriptor_data;
     descriptor_data = 0;
+    descriptor_lock.unlock();
+    free_descriptor_state(descriptor_data_);
+    // LG
   }
 }