Re: [Boost-bugs] [Boost C++ Libraries] #10213: Reproducible crash with Boost Asio and io_service::post

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #10213: Reproducible crash with Boost Asio and io_service::post
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-07-22 21:09:12

#10213: Reproducible crash with Boost Asio and io_service::post
-------------------------------+----------------------------
  Reporter:  boost-bugs@…      |      Owner:  chris_kohlhoff
      Type:  Bugs              |     Status:  new
 Milestone:  To Be Determined  |  Component:  asio
   Version:  Boost 1.55.0      |   Severity:  Problem
Resolution:                    |   Keywords:
-------------------------------+----------------------------

Comment (by Ben Strong <bstrong@…>):

 We hit this bug and fixed it with the following patch:


 {{{
 --- a/boost/asio/detail/posix_event.hpp
 +++ b/boost/asio/detail/posix_event.hpp
 @@ -58,8 +58,8 @@ public:
    {
      BOOST_ASIO_ASSERT(lock.locked());
      signalled_ = true;
 -    lock.unlock();
      ::pthread_cond_signal(&cond_); // Ignore EINVAL.
 +    lock.unlock();
    }

    // Reset the event.
 }}}
 The issue is that in the task_io_service, the thread_info contains an
 event, and the thread_info lifetime is protected by the mutex associated
 with the lock passed into {{{signal_and_unlock}}}, so there is a race
 where the event is destroyed after the {{{lock.unlock()}}} but before the
 {{{pthread_cond_signal()}}}.

 The "Ignore EINVAL" comment suggests that someone hit this issue before.
 Unfortunately, relying on pthread_cond_signal to return an error (and not
 crash) is not a sufficient solution.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/10213#comment:2>
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