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Date:      Mon, 01 Sep 2008 15:17:46 +0300
From:      Andriy Gapon <avg@icyb.net.ua>
To:        Kostik Belousov <kostikbel@gmail.com>
Cc:        Daniel Eischen <deischen@freebsd.org>, David Xu <davidxu@freebsd.org>, freebsd-threads@freebsd.org
Subject:   Re: mysterious hang in pthread_create
Message-ID:  <48BBDD6A.60002@icyb.net.ua>
In-Reply-To: <20080901111215.GS2038@deviant.kiev.zoral.com.ua>
References:  <Pine.GSO.4.64.0808291223240.5086@sea.ntplx.net> <20080829190506.GA2038@deviant.kiev.zoral.com.ua> <Pine.GSO.4.64.0808301128410.9898@sea.ntplx.net> <20080830155622.GF2038@deviant.kiev.zoral.com.ua> <Pine.GSO.4.64.0808301200460.9898@sea.ntplx.net> <20080830184512.GH2038@deviant.kiev.zoral.com.ua> <48BBA369.9010108@freebsd.org> <48BBA925.1000303@icyb.net.ua> <20080901084548.GQ2038@deviant.kiev.zoral.com.ua> <48BBC9A3.1050905@icyb.net.ua> <20080901111215.GS2038@deviant.kiev.zoral.com.ua>

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on 01/09/2008 14:12 Kostik Belousov said the following:
> On Mon, Sep 01, 2008 at 01:53:23PM +0300, Andriy Gapon wrote:
>> on 01/09/2008 11:45 Kostik Belousov said the following:
>>> On Mon, Sep 01, 2008 at 11:34:45AM +0300, Andriy Gapon wrote:
>>>> on 01/09/2008 11:10 David Xu said the following:
>>>>> The ancient bug is in rtld, rlock_acquire() and wlock_acquire() test
>>>>> thread_flag as a boolean value, because pt_iterate_phdr() tries to
>>>>> lock two locks at same time, this test will always fail once it
>>>>> acquired first lock.
>>>>>
>>>>> The following silly patch fixes the problem Andriy encountered:
>>>> I can confirm - this fixed the issue for me.
>>>> David, thanks!
>>> Does libc_r still work with patch applied ?
>> In what sense?
>> The test program that I posted seems to hang in both cases (patched and 
>> unpatched rtld).
> 
> The David' patch changes the code used to support libc_r operations.
> Even on CURRENT, if you run 4.x-compiled binary with the support of
> compat-4x libraries, this code from /libexec/ld-elf.so.1 (installed
> by CURRENT buildworld) provides locking for rtld.

I understand, but I am not sure what exactly needs to be tested.
"Still works" is too broad in this context.

-- 
Andriy Gapon



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