Re: [PATCHES][RFC] Fix a deadlock bug in static variable initialization

["Richard Guenther" <richard dot guenther at gmail dot com>]

On 6/8/07, Doug Kwan (?振德) <dougkwan@google.com> wrote:
> Hi,
>
>     Attached here is patches to both gcc and libstdc++-v3 to fix a
> deadlock problem in function static variables. The patches have been
> applied to gcc-4.1.0 and tested on i486 with a full bootstrap. I've
> also test the trunk it is not stable enough to do a full bootstrap.

Care to explain the deadlock problem?  Also the ChangeLog is
formatted incorrectly (see below).

Richard.

> 2007-06-08  Doug Kwan  <dougkwan@google.com>
>
>         * gcc/gthr-posix.h (__gthread_cond_broadcast, __gthread_cond_wait,
>           __gthread_cond_wait_recursive, __gthread_self, __gthread_equal):
>           Add to extend interface for POSIX conditional variables.
>           (__GTHREAD_HAS_COND): Macro defined to signify support of
>           conditional variables.
>         Likewise
>         * gcc/gthr-single.h (__gthread_cond_broadcast, __gthread_cond_wait,
>           __gthread_cond_wait_recursive, __gthread_self, __gthread_equal):
>           Add to extend interface for POSIX conditional variables.
>         * gcc/gthr.h: Update comments to document new interface.

these should be written as

       * gthr-posix.h (...

omitting gcc/ (and they go to the gcc/ChangeLog).  Also following
lines should be indented a single tab, aligned to the '*'.

>         * libstdc++-v3/include/ext/concurrent.h (class __mutex,
>           class __recursive_mutex): Add new method gthread_mutex to access
>           inner gthread mutex.

omit libstdc++-v3/ (and they go to libstdc++-v3/ChangeLog

>           [__GTHREAD_HAS_COND] (class __concurrence_broadcast_error,
>           class __concurrence_wait_error, class __cond): Add.
>         * guard.cc (random_level, new_skip_list_node, skip_list_search_internal,

where's this file?

>           new_skip_list, skip_list_insert_key, skip_list_delete_key,
>           skip_list_search_key). Add to implement skip list to map guard
>           variables and thread ID's.
>           (recurisve_push, recursive_pop): Delete.
>           (init_in_progress_flag, set_init_in_progress_flag): Add to
>           replace recursive_push and recursive_pop.
>           (throw_recursive_init_exception): Add.
>           (acquire, __cxa_guard_acquire, __cxa_guard_abort and
>           __cxa_guard_release): [__GTHREAD_HAS_COND] Use a conditional
>           for synchronization of static variable initialization.
>           The global mutex is only held briefly when guards are
>           accessed. [!__GTHREAD_HAS_COND] Fall back to the old code,
>           which deadlocks.
>         * testsuite/thread/guard.cc: Add new test. It deadlocks with the
>           old locking code in libstdc++-v3/libsup++/guard.cc.



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