[Boost-commit] svn:boost r84492 - in trunk/boost/asio/detail: . impl

Subject: [Boost-commit] svn:boost r84492 - in trunk/boost/asio/detail: . impl
From: chris_at_[hidden]
Date: 2013-05-25 08:35:44

Author: chris_kohlhoff
Date: 2013-05-25 08:35:43 EDT (Sat, 25 May 2013)
New Revision: 84492
URL: http://svn.boost.org/trac/boost/changeset/84492

Log:
Fix potential data race due to reading the reactor pointer outside the lock.

Text files modified: 
   trunk/boost/asio/detail/impl/epoll_reactor.ipp |     3 ++-                                     
   trunk/boost/asio/detail/scoped_lock.hpp        |    12 +++++++++++-                            
   2 files changed, 13 insertions(+), 2 deletions(-)

Modified: trunk/boost/asio/detail/impl/epoll_reactor.ipp
==============================================================================
--- trunk/boost/asio/detail/impl/epoll_reactor.ipp	(original)
+++ trunk/boost/asio/detail/impl/epoll_reactor.ipp	2013-05-25 08:35:43 EDT (Sat, 25 May 2013)
@@ -607,8 +607,9 @@
 
 operation* epoll_reactor::descriptor_state::perform_io(uint32_t events)
 {
+  mutex_.lock();
   perform_io_cleanup_on_block_exit io_cleanup(reactor_);
-  mutex::scoped_lock descriptor_lock(mutex_);
+  mutex::scoped_lock descriptor_lock(mutex_, mutex::scoped_lock::adopt_lock);
 
   // Exception operations must be processed first to ensure that any
   // out-of-band data is read before normal data.

Modified: trunk/boost/asio/detail/scoped_lock.hpp
==============================================================================
--- trunk/boost/asio/detail/scoped_lock.hpp	(original)
+++ trunk/boost/asio/detail/scoped_lock.hpp	2013-05-25 08:35:43 EDT (Sat, 25 May 2013)
@@ -29,8 +29,18 @@
   : private noncopyable
 {
 public:
+  // Tag type used to distinguish constructors.
+  enum adopt_lock_t { adopt_lock };
+
+  // Constructor adopts a lock that is already held.
+  scoped_lock(Mutex& m, adopt_lock_t)
+    : mutex_(m),
+      locked_(true)
+  {
+  }
+
   // Constructor acquires the lock.
-  scoped_lock(Mutex& m)
+  explicit scoped_lock(Mutex& m)
     : mutex_(m)
   {
     mutex_.lock();