Date: Mon, 28 Dec 2009 15:04:23 -0500 From: Alexander Kabaev <kabaev@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: Eischen <deischen@freebsd.org>, Daniel, David Xu <davidxu@freebsd.org>, freebsd-threads@freebsd.org Subject: Re: first patch for process-shared semaphore Message-ID: <20091228150423.201936b4@kan.dnsalias.net> In-Reply-To: <200912281121.30939.jhb@freebsd.org> References: <4B317741.8080004@freebsd.org> <200912240759.47703.jhb@freebsd.org> <4B385BB9.3010109@freebsd.org> <200912281121.30939.jhb@freebsd.org>
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--Sig_/sKORHipieJpQpE4DcbZMhid Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 28 Dec 2009 11:21:30 -0500 John Baldwin <jhb@freebsd.org> wrote: > On Monday 28 December 2009 2:18:17 am David Xu wrote: > > John Baldwin wrote: > > > On Wednesday 23 December 2009 10:12:19 pm Alexander Kabaev wrote: > > >> On Thu, 24 Dec 2009 09:58:50 +0800 > > >> David Xu <davidxu@freebsd.org> wrote: > > >> > > >>> Alexander Kabaev wrote: > > >>>> On Thu, 24 Dec 2009 09:22:34 +0800 > > >>>> David Xu <davidxu@freebsd.org> wrote: > > >>>>> libthr does not require semaphore, it implements semaphore, > > >>>>> it is easier than other ways to implement the process-shared. > > >>>>> > > >>>> Let me rephrase: I do not think semaphores belong in libthr. > > >>>> They should be either in libc or in librt. > > >>>> > > >>>> > > >>> OK, does others really implement semaphore in librt ? > > >>> unfortunately, the librt already requires libpthread to > > >>> implement SIGEV_THREAD. > > >> I retract that. It appears that there is no consistency - > > >> Solaris put these into libc, Linux into libpthread ans SUSv2 > > >> hints that these belong with realtime functions. libthr is fine. > > >=20 > > > I vote for libc. Single-threaded processes can use sem_open() > > > and PSHARED sem_init() as well. Single-threaded processes can > > > even use non-PSHARED sem_init() by using fork() to create new > > > "threads" that share the=20 > semaphore. > > >=20 > > May I can move all semaphore functions into libc and remove all > > semaphore related symbols from libthr ? In pratical, this is not a > > problem, because libthr itself is not dlopen-safe, all missing > > semaphore functions in libthr will be found in libc by rtld. >=20 > I would go with this approach. There is also some discussion about > moving all of libthr into libc as well and having a dummy libpthread > now that we are back to a single threading library and to avoid > issues with dlopen() of libpthread, etc. >=20 Removing symbols from library, versioned library especially, is a big=20 wrong. You should provide compat symbols for all functions that that were there before. =20 --=20 Alexander Kabaev --Sig_/sKORHipieJpQpE4DcbZMhid Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) iD8DBQFLOQ9LQ6z1jMm+XZYRApnrAKDK1kDOTKhtaXvotDFx/FF65w/TmACg7EAJ 7q8iXn24ZMHtwaFpZMkw4xo= =NVRk -----END PGP SIGNATURE----- --Sig_/sKORHipieJpQpE4DcbZMhid--
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