From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id ABDE3383D03B for ; Thu, 24 Jun 2021 09:48:32 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org ABDE3383D03B Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-261-B8JS11h3NimsgtEqzg_prA-1; Thu, 24 Jun 2021 05:48:30 -0400 X-MC-Unique: B8JS11h3NimsgtEqzg_prA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 77968A40D2; Thu, 24 Jun 2021 09:48:29 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-228.ams2.redhat.com [10.36.112.228]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9E91C6090F; Thu, 24 Jun 2021 09:48:28 +0000 (UTC) From: Florian Weimer To: Szabolcs Nagy via Libc-alpha Cc: Szabolcs Nagy Subject: Re: [PATCH v2 08/14] elf: Fix DTV gap reuse logic [BZ #27135] References: <299d28c6695cd2e76f222b0d36b17b7124c549e7.1618301209.git.szabolcs.nagy@arm.com> Date: Thu, 24 Jun 2021 11:48:26 +0200 In-Reply-To: <299d28c6695cd2e76f222b0d36b17b7124c549e7.1618301209.git.szabolcs.nagy@arm.com> (Szabolcs Nagy via Libc-alpha's message of "Tue, 13 Apr 2021 09:20:11 +0100") Message-ID: <878s2zlhjp.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.7 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 24 Jun 2021 09:48:34 -0000 * Szabolcs Nagy via Libc-alpha: > For some reason only dlopen failure caused dtv gaps to be reused. > > It is possible that the intent was to never reuse modids for a > different module, but after dlopen failure all gaps are reused > not just the ones caused by the unfinished dlopened. > > So the code has to handle reused modids already which seems to > work, however the data races at thread creation and tls access > (see bug 19329 and bug 27111) may be more severe if slots are > reused so this is scheduled after those fixes. I think fixing > the races are not simpler if reuse is disallowed and reuse has > other benefits, so set GL(dl_tls_dtv_gaps) whenever entries are > removed from the middle of the slotinfo list. The value does > not have to be correct: incorrect true value causes the next > modid query to do a slotinfo walk, incorrect false will leave > gaps and new entries are added at the end. > > Fixes bug 27135. > --- > elf/dl-close.c | 6 +++++- > elf/dl-open.c | 10 ---------- > elf/dl-tls.c | 5 +---- > 3 files changed, 6 insertions(+), 15 deletions(-) Apparently this broke GNOME Shell: I'm trying to figure out why. Thanks, Florian