------- Comment #2 from bart dot vanassche at gmail dot com 2009-06-07 06:14 ------- (In reply to comment #1) > >==21970== at 0x71A35FD: gomp_iter_dynamic_next (iter.c:190) > > Is a bogus warning as that is thread specific data: > struct gomp_thread *thr = gomp_thread (); > struct gomp_work_share *ws = thr->ts.work_share;
Are you sure that *thr is only modified by a single thread ? The full DRD output for this specific race shows that the data in *thr was modified by thread 4 before thread 2 read that data, and that there was no proper synchronization between the two accesses of *thr: ==14553== Thread 2: ==14553== Conflicting load by thread 2/2 at 0x07b41234 size 4 ==14553== at 0x71A35FD: gomp_iter_dynamic_next (iter.c:190) ==14553== by 0x449AE7: PixelIterateMonoModify.omp_fn.3 (pixel_iterator.c:230) ==14553== by 0x71A6977: gomp_thread_start (team.c:115) ==14553== by 0x4C287BB: vgDrd_thread_wrapper (drd_pthread_intercepts.c:224) ==14553== by 0x73B306F: start_thread (in /lib64/libpthread-2.9.so) ==14553== by 0x769B10C: clone (in /lib64/libc-2.9.so) ==14553== Address 0x7b41234 is at offset 452 from 0x7b41070. Allocation context: ==14553== at 0x4C249E9: malloc (vg_replace_malloc.c:193) ==14553== by 0x71A2068: gomp_malloc (alloc.c:36) ==14553== by 0x71A6FFC: gomp_new_team (team.c:143) ==14553== by 0x71A5B2B: GOMP_parallel_start (parallel.c:108) ==14553== by 0x449D71: PixelIterateMonoModify (pixel_iterator.c:230) ==14553== by 0x431DAF: SetImage (image.c:4527) ==14553== by 0x520198: ReadXCImage (xc.c:118) ==14553== by 0x40B4FF: ReadImage (constitute.c:8478) ==14553== by 0x40A006: main (drawtest.c:380) ==14553== Other segment start (thread 4/4) ==14553== at 0x4C25A56: pthread_mutex_lock (drd_pthread_intercepts.c:489) ==14553== by 0x71A7266: gomp_work_share_start (mutex.h:44) ==14553== by 0x71A466A: GOMP_loop_dynamic_start (loop.c:120) ==14553== by 0x449AE7: PixelIterateMonoModify.omp_fn.3 (pixel_iterator.c:230) ==14553== by 0x71A6977: gomp_thread_start (team.c:115) ==14553== by 0x4C287BB: vgDrd_thread_wrapper (drd_pthread_intercepts.c:224) ==14553== by 0x73B306F: start_thread (in /lib64/libpthread-2.9.so) ==14553== by 0x769B10C: clone (in /lib64/libc-2.9.so) ==14553== Other segment end (thread 4/4) ==14553== at 0x4C25D91: pthread_mutex_unlock (drd_pthread_intercepts.c:535) ==14553== by 0x71A4748: GOMP_loop_dynamic_start (mutex.h:49) ==14553== by 0x449AE7: PixelIterateMonoModify.omp_fn.3 (pixel_iterator.c:230) ==14553== by 0x71A6977: gomp_thread_start (team.c:115) ==14553== by 0x4C287BB: vgDrd_thread_wrapper (drd_pthread_intercepts.c:224) ==14553== by 0x73B306F: start_thread (in /lib64/libpthread-2.9.so) ==14553== by 0x769B10C: clone (in /lib64/libc-2.9.so) -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40362
