Date: Wed, 20 Apr 2011 11:04:51 +0800 From: David Xu <davidxu@freebsd.org> To: Ryan Stone <rysto32@gmail.com> Cc: FreeBSD Current <freebsd-current@freebsd.org>, Ed Maste <emaste@freebsd.org> Subject: Re: [PATCH] Call _thr_check_init() from _pthread_once Message-ID: <4DAE4D53.7080602@freebsd.org> In-Reply-To: <BANLkTin5P7bTvUkSLPDLig8nP8dFQkh49g@mail.gmail.com> References: <BANLkTikwT0qOB32DeLMdFkx4vkx6_HAkQg@mail.gmail.com> <4DAE4164.9080006@freebsd.org> <BANLkTin5P7bTvUkSLPDLig8nP8dFQkh49g@mail.gmail.com>
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On 2011/04/20 10:48, Ryan Stone wrote: > On Tue, Apr 19, 2011 at 10:13 PM, David Xu <davidxu@freebsd.org> wrote: >> Have you tested that current code causes segfault ? >> anyway, I can not reproduce it on my machne. >> >> Regards, >> David Xu > > Yes, I had an application where libstdc++ was calling pthread_once > while constructing a static object. As near as I can tell it's pure > luck as to whether you'll hit this crash or not. If the linker > happens to place a static initializer that calls pthread_once first in > the list of static initializers, you crash. If instead something far > more likely like pthread_mutex_lock is called first, you're fine. > > The backtrace for my executable was something like: > #0 0x684dadd4 in _pthread_once (once_control=0x6887fdcc, > init_routine=0x6883d740 <__gthread_trigger()>) > at /usr/src/lib/libthr/thread/thr_once.c:84 > #1 0x6883d992 in __gthread_active_p () > at /tmp/buildutils.x86/x86-i686-pc-freebsd8/i686-pc-freebsd8/libstdc++-v3/include/i686-pc-freebsd8/bits/gthr-default.h:221 > #2 __eh_globals_init () > at gcc/libstdc++-v3/libsupc++/eh_globals.cc:98 > #3 __static_initialization_and_destruction_0 () > at gcc/libstdc++-v3/libsupc++/eh_globals.cc:110 > #4 global constructors keyed to eh_globals.cc(void) () > at gcc/libstdc++-v3/libsupc++/eh_globals.cc:146 > #5 0x68848d06 in __do_global_ctors_aux () > from /usr/local/mumble/lib/libstdc++.so.6 > OK, I understand, that current INPROGRESS will push cleanup routine, so the curthread is used, your patch is right.
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