From owner-freebsd-bugs@FreeBSD.ORG Wed Nov 3 11:00:23 2010 Return-Path: Delivered-To: freebsd-bugs@hub.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0B124106566C for ; Wed, 3 Nov 2010 11:00:23 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id D23068FC1F for ; Wed, 3 Nov 2010 11:00:22 +0000 (UTC) Received: from freefall.freebsd.org (localhost [127.0.0.1]) by freefall.freebsd.org (8.14.4/8.14.4) with ESMTP id oA3B0Mgc062897 for ; Wed, 3 Nov 2010 11:00:22 GMT (envelope-from gnats@freefall.freebsd.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.14.4/8.14.4/Submit) id oA3B0Md4062873; Wed, 3 Nov 2010 11:00:22 GMT (envelope-from gnats) Date: Wed, 3 Nov 2010 11:00:22 GMT Message-Id: <201011031100.oA3B0Md4062873@freefall.freebsd.org> To: freebsd-bugs@FreeBSD.org From: Kostik Belousov Cc: Subject: Re: misc/151861: dlclose() of library causes separately opened libraries to unload as well X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Kostik Belousov List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Nov 2010 11:00:23 -0000 The following reply was made to PR misc/151861; it has been noted by GNATS. From: Kostik Belousov To: Jaakko Heinonen Cc: Arjan van Leeuwen , bug-followup@freebsd.org, kan@freebsd.org Subject: Re: misc/151861: dlclose() of library causes separately opened libraries to unload as well Date: Wed, 3 Nov 2010 12:54:29 +0200 --b2N6ngaUR9vV44n2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Nov 03, 2010 at 12:06:49PM +0200, Jaakko Heinonen wrote: > On 2010-11-02, Kostik Belousov wrote: > > Why do you think that your patch is not correct ? >=20 > Well, I didn't say that I think it's incorrect. :) >=20 > > I feel that more explicit handling of the state of the DAG is cleaner. >=20 > I don't disagree but there is a problem with your patch. If an object > has the DF_1_NODELETE flag set, dag is initialized in > load_needed_objects(). In this case the reference count isn't correctly > bumped in dlopen() because dag_inited is already set. Seems you are right. See that patch below. It changes init_dag() to unconditionally increment refcount. >=20 > (BTW. I think that there shouldn't be the ref_dag(obj1) call in > load_needed_objects(). Now the reference count is increased twice in the > nodelete case.) With init_dag() incrementing the refcount unconditionally, the ref_dag() indeed can be removed. >=20 > > --- a/libexec/rtld-elf/rtld.c > > +++ b/libexec/rtld-elf/rtld.c > > @@ -1275,8 +1275,11 @@ init_dag(Obj_Entry *root) > > { > > DoneList donelist; > > =20 > > + if (root->dag_inited) > > + return; >=20 > Why init_dag() should be allowed to be called multiple times for an > object? If already loaded object is dlopened, dlclosed, and then again dlopened, init_dag() will be called twice, one time for each dlopen. diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c index f1ffc3e..f75ee35 100644 --- a/libexec/rtld-elf/rtld.c +++ b/libexec/rtld-elf/rtld.c @@ -1275,11 +1275,12 @@ init_dag(Obj_Entry *root) { DoneList donelist; =20 - if (root->dag_inited) - return; - donelist_init(&donelist); - init_dag1(root, root, &donelist); - root->dag_inited =3D true; + if (!root->dag_inited) { + donelist_init(&donelist); + init_dag1(root, root, &donelist); + root->dag_inited =3D true; + } + ref_dag(root); } =20 static void @@ -1290,7 +1291,6 @@ init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *= dlp) if (donelist_check(dlp, obj)) return; =20 - obj->refcount++; objlist_push_tail(&obj->dldags, root); objlist_push_tail(&root->dagmembers, obj); for (needed =3D obj->needed; needed !=3D NULL; needed =3D needed->ne= xt) @@ -1438,7 +1438,6 @@ load_needed_objects(Obj_Entry *first, int flags) if (obj1 !=3D NULL && obj1->z_nodelete && !obj1->ref_nodel) { dbg("obj %s nodelete", obj1->path); init_dag(obj1); - ref_dag(obj1); obj1->ref_nodel =3D true; } } @@ -2054,10 +2053,7 @@ dlopen(const char *name, int mode) * already loaded as a dependency, initialize the dag * starting at it. */ - if (obj->dl_refcount =3D=3D 1) - init_dag(obj); - else - ref_dag(obj); + init_dag(obj); =20 if (ld_tracing) goto trace; --b2N6ngaUR9vV44n2 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAkzRP2QACgkQC3+MBN1Mb4hlxQCfVo6OyCtfOu/iMiG444ql0rP8 dT4An2sqpVM/mqJbwYnw2vJoopDqvqqC =rUZc -----END PGP SIGNATURE----- --b2N6ngaUR9vV44n2--