http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55561
--- Comment #26 from Dmitry Vyukov <dvyukov at google dot com> 2012-12-30 17:07:01 UTC --- (In reply to comment #25) > (In reply to comment #24) > > For testing you can comment out first 2 lines of gomp_ptrlock_get(). That > > should fix the race in libgomp. It's not a good fix form performance pov, > > but > > should be OK for testing. > > Thanks.. it turns out that gomp_ptrlock_get is actually used from > > gcc/libgomp/config/linux/ptrlock.h:74 > > on linux... is it still sufficient to comment the first if condition only and > keep the atomic_compare_exchange, or should one directly have the 'return > gomp_ptrlock_get_slow' ? Ah, I was looking at config/posix/ptrlock. For config/linux/ptrlock the changes are: if ((uintptr_t) *ptrlock > 2) return *ptrlock; \/\/\/\/\/\/\/\/\/\/\/\/ uintptr_t v = (uintptr_t)__atomic_load(ptrlock, MEMMODEL_ACQUIRE); if (v > 2) return v; return *ptrlock; \/\/\/\/\/\/\/\/\/\/\/\/ return __atomic_load(ptrlock, MEMMODEL_ACQUIRE); Also loads of intptr needs to be done with __atomic_load(MEMMODEL_RELAXED). and do_spin() needs to load *addr with __atomic_load(MEMMODEL_RELAXED) as well.