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

["=?big5?b?RG91ZyBLd2FuICjD9q62vHcp?=" <dougkwan at google dot com>]

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.

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.

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

Attachment: diffs-deadlock-fix.txt
Description: Text document