[Boost-bugs] [Boost C++ Libraries] #12547: yield_completion in fibers possibly destroys busy mutex

Subject: [Boost-bugs] [Boost C++ Libraries] #12547: yield_completion in fibers possibly destroys busy mutex
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2016-10-24 16:56:27

#12547: yield_completion in fibers possibly destroys busy mutex
-------------------------------------------------+-------------------------
 Reporter:  Thadeu Luiz Barbosa Dias             |      Owner:  matias
  <thadeuluiz@…>                                 |     Status:  new
     Type:  Bugs                                 |  Component:
Milestone:  To Be Determined                     |  Documentation
  Version:  Boost 1.62.0                         |   Severity:  Problem
 Keywords:                                       |
-------------------------------------------------+-------------------------
 Im using something similar to this page:

 http://www.boost.org/doc/libs/1_62_0/libs/fiber/doc/html/fiber/callbacks/then_there_s____boost_asio__.html


 in my project but it contains a bug.
 yield_completion::wait() does not reacquire the lock before returning,
 therefore
 async_result_base::get() and async_result<T>::get() might return before
 the notifying thread(calling async_handler::operator() releases the lock.
 with that, async_result<T> might be destroyed while the lock is being held
 by the notifying thread causing a crash.

 I assumed that the lock gets reacquired on fiber resume, but that is not
 the case, lk.owns_lock() is false after the suspend statement.
 the solution is to simply call lk.lock() after the suspend call on the
 context.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/12547>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.