Date: Fri, 24 Mar 2006 14:32:25 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Kazuaki Oda <kaakun@highway.ne.jp> Cc: freebsd-hackers@freebsd.org, freebsd-threads@freebsd.org Subject: Re: [patch] Re: dlopen() and dlclose() are not MT-safe? YES, esp. for libthr Message-ID: <20060324123225.GG27116@deviant.kiev.zoral.com.ua> In-Reply-To: <4423DDFA.3090504@highway.ne.jp> References: <44215FE9.2070602@highway.ne.jp> <20060322174312.GB27116@deviant.kiev.zoral.com.ua> <20060322190725.GC27116@deviant.kiev.zoral.com.ua> <4421BA34.8040908@highway.ne.jp> <20060323105440.GD27116@deviant.kiev.zoral.com.ua> <20060324084834.GE27116@deviant.kiev.zoral.com.ua> <4423DDFA.3090504@highway.ne.jp>
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[-- Attachment #1 --] On Fri, Mar 24, 2006 at 08:54:34PM +0900, Kazuaki Oda wrote: > Kostik Belousov wrote: > > I did understand the purpose of the thread mask code in > > libexec/rtld/rtld_lock.c, or, more precisely, the condition where this code > > works (for the context, see the mails with same subject on freebsd-hackers). > > > > Look, that code assumes that blocking async signals would stop thread > > scheduler from doing preemption of the current thread. This works > > for libc_r, but fails in libpthread and libthr cases. libpthread provides > > implementation of the locks for rtld. But libthr does not ! > > > > As result, rtld exhibit races when used with libthr. In other words, > > libthr needs code to do proper locking. > > > > Do you agree ? Does somebody already planned to do this work ? > > > > Best regards, > > Kostik Belousov > > I'm a bit confused. Do you mean the following? > > * The current implementation of rtld has a problem both with > libpthread and libthr. It works only with libc_r. It does not work correctly with libc_r too. > * In libpthread case, the problem goes away if we modify rtld code. Yes. > * In libthr case, in addition to above, we must modify libthr code to > provide implementation of the locks for rtld. Yes. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (FreeBSD) iD8DBQFEI+bYC3+MBN1Mb4gRAj07AJ9juDKTVIIEs+Zt4WiNSO/zPajEYACgrOAG s6fhh4iFaka6huvxUVTOvPY= =e15F -----END PGP SIGNATURE-----help
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