http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56941
Bug #: 56941
Summary: Thread conflict is reported by helgrind in
_Unwind_IteratePhdrCallback
Classification: Unclassified
Product: gcc
Version: 4.7.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: y...@tsoft.com
I get the following error from helgrind on heavily multi-threaded process
throwing a lot of exceptions. gcc in use is 4.7.2 on amd64 architecture.
Line unwind-dw2-fde-dip.c:212: prev_cache_entry->link = cache_entry->link;
It looks like the error is due to an unprotected cache access.
This should either be fixed, or there should be a good explanation why this
should be considered a non-issue. Data race conditions reported by helgrind
usually correspond to real issues.
---helgrind log---
==83659== Possible data race during write of size 8 at 0x24FECC8 by thread #17
==83659== Locks held: none
==83659== at 0x22FB1D9: _Unwind_IteratePhdrCallback
(unwind-dw2-fde-dip.c:212)
==83659== by 0x14D41: dl_iterate_phdr (in /libexec/ld-elf.so.1)
==83659== by 0x22FB8B1: _Unwind_Find_FDE (unwind-dw2-fde-dip.c:451)
==83659== by 0x22F8D9A: uw_frame_state_for (unwind-dw2.c:1179)
==83659== by 0x22F91F6: uw_init_context_1 (unwind-dw2.c:1500)
==83659== by 0x22F96A6: _Unwind_RaiseException (unwind.inc:88)
==83659== by 0x1E1FAD0: __cxa_throw (eh_throw.cc:78)
==83659== <...user stack omitted...>
==83659==
==83659== This conflicts with a previous write of size 8 by thread #54
==83659== Locks held: none
==83659== at 0x22FB1D5: _Unwind_IteratePhdrCallback
(unwind-dw2-fde-dip.c:211)
==83659== by 0x14D41: dl_iterate_phdr (in /libexec/ld-elf.so.1)
==83659== by 0x22FB8B1: _Unwind_Find_FDE (unwind-dw2-fde-dip.c:451)
==83659== by 0x22F8D9A: uw_frame_state_for (unwind-dw2.c:1179)
==83659== by 0x22F970A: _Unwind_RaiseException (unwind.inc:99)
==83659== by 0x1E1FAD0: __cxa_throw (eh_throw.cc:78)
==83659== <...user stack omitted...>
