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Date:      Mon, 9 Mar 2009 08:00:24 -0400 (EDT)
From:      Daniel Eischen <deischen@freebsd.org>
To:        David Xu <davidxu@freebsd.org>
Cc:        threads@freebsd.org, Pawel Worach <pawel.worach@gmail.com>
Subject:   Re: libthr does not obey WITHOUT_SYSCALL_COMPAT
Message-ID:  <Pine.GSO.4.64.0903090755350.9700@sea.ntplx.net>
In-Reply-To: <49B4B0EF.5080507@freebsd.org>
References:  <d227e09e0903041123i638a12b8m5d8573cc871d1533@mail.gmail.com> <49B480F7.8040800@freebsd.org> <Pine.GSO.4.64.0903082343280.8064@sea.ntplx.net> <49B4A571.7000302@freebsd.org> <Pine.GSO.4.64.0903090114380.8422@sea.ntplx.net> <49B4B0EF.5080507@freebsd.org>

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On Mon, 9 Mar 2009, David Xu wrote:

> Daniel Eischen wrote:
>> On Mon, 9 Mar 2009, David Xu wrote:
>> 
>>> I don't know when it appeared. Would this patch eliminate the shit ?
>> 
>> I think so.  But I think for future ABI changes to cancellation
>> points, wouldn't we need syscall wrappers in libc?  Reason, libc
>> and libthr are now symbol-versioned, so there will no longer be
>> library bumps for ABI changes.  But if a syscall is a cancellation
>> point and libthr has to play games with it, like fcntl, I think
>> there should be a wrapper around it in libc.  If the ABI changes,
>> then both libc and libthr would need to provide a compat version
>> for it.  I think.  ;-)
>> 
>
> Yes, it is better to use versioning instead, I don't know why fcntl_compat is 
> there without using this feature.

Hmm, looking a little closer at this...  It looks like there
is a wrapper for fcntl in libc (libc/sys/fcntl.c).  But I think
it should always be built.  Currently, it is hidden behind
WITHOUT_SYSCALL_COMPAT in libc/sys/Makefile.  But it never calls
an older fcntl syscall.  It just transforms the old style struct
into new style, then calls the new fcntl syscall.

So I think the mistake is building fcntl.c conditionally, when
it should always be built regardless of WITHOUT_SYSCALL_COMPAT
being defined or not defined.

-- 
DE



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