[Bug libstdc++/91910] Debug mode: there is a racing condition between destructors of iterator and the associated container.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91910

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:9d0ad2d40ee86ad47913b06b7585d67bd216ce4f

commit r9-8348-g9d0ad2d40ee86ad47913b06b7585d67bd216ce4f
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Mar 5 16:53:20 2020 +0000

    PR libstdc++/91910 fix data race in Debug Mode destructors

    Fix data race when _Safe_iterator_base::_M_detach() runs concurrently with
    the _Safe_container_base destructor.

    Backport from mainline
    2019-09-27  Jonathan Wakely  <jwakely@redhat.com>

        PR libstdc++/91910
        * src/c++11/debug.cc (_Safe_iterator_base::_M_detach()): Load pointer
        atomically and lock the mutex before accessing the sequence.
        (_Safe_local_iterator_base::_M_detach()): Likewise.
        (_Safe_iterator_base::_M_reset()): Clear _M_sequence atomically.