[Bug libstdc++/96817] New: __cxa_guard_acquire unsafe against dynamically loaded pthread

[yshuiv7 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96817

            Bug ID: 96817
           Summary: __cxa_guard_acquire unsafe against dynamically loaded
                    pthread
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yshuiv7 at gmail dot com
  Target Milestone: ---

If pthread is loaded dynamically via dlopen() after libstdc++ is loaded,
__gthread_active_p() would return wrong result, cause guard acquire to be
thread unsafe.

An example of this problem:
https://gitlab.freedesktop.org/mesa/mesa/-/issues/3199