From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 55982C54EED for ; Mon, 30 Jan 2023 09:28:09 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pMQRh-00044K-FB; Mon, 30 Jan 2023 04:27:25 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pMQRf-00043v-2k for qemu-devel@nongnu.org; Mon, 30 Jan 2023 04:27:23 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pMQRc-00062P-OQ for qemu-devel@nongnu.org; Mon, 30 Jan 2023 04:27:22 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675070839; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Mo8Rj0bbiRTGMHwGl/aBCyaZ2MzYHnyuYY8wVZeQb3M=; b=V7YduH+ueLXgfnGQ04Cdar/2ZR+lWtMaJnS4dmnkG6jPHPxcbydF3p5g1UYNQnDtU1doBX +DCfMXMvPvdr2uPBzUO+8h7GX65HZm/4+gVktzu9E7EOO4RiqbXv7P3oMTbQZapJEbFBfj YkU8GQoE1CwrXUHjekWzBef+Q05XQz4= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-76-0IL9D-bvONmoOiUQR7Npog-1; Mon, 30 Jan 2023 04:27:15 -0500 X-MC-Unique: 0IL9D-bvONmoOiUQR7Npog-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id F1E7E1C07547; Mon, 30 Jan 2023 09:27:14 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.49]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A8CAB175AD; Mon, 30 Jan 2023 09:27:13 +0000 (UTC) Date: Mon, 30 Jan 2023 09:27:10 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Emilio Cota Cc: qemu-devel@nongnu.org, Alex =?utf-8?Q?Benn=C3=A9e?= , Richard Henderson , Paolo Bonzini Subject: Re: [PATCH 2/2] tcg: use QTree instead of GTree Message-ID: References: <20230111035536.309885-1-cota@braap.org> <20230111035536.309885-3-cota@braap.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Sun, Jan 29, 2023 at 05:38:08PM -0500, Emilio Cota wrote: > On Wed, Jan 25, 2023 at 15:58:25 +0000, Daniel P. Berrangé wrote: > > On Wed, Jan 11, 2023 at 12:34:29PM +0000, Daniel P. Berrangé wrote: > > > On Tue, Jan 10, 2023 at 10:55:36PM -0500, Emilio Cota wrote: > > > > qemu-user can hang in a multi-threaded fork. One common > > > > reason is that when creating a TB, between fork and exec > > > > we manipulate a GTree whose memory allocator (GSlice) is > > > > not fork-safe. > > > > > > BTW, I just checked latest glib status > > > > > > https://gitlab.gnome.org/GNOME/glib/-/issues/1079 > > > > > > it appears they're pretty close to deciding to delete the > > > GSlice impl and always use system malloc. > > > > They have now merged the code to delete the GSlice custom allocator. > > > > So glib >= 2.76.0 should not exhibit a hang > > > > > So if we do take this patch series it'll hopefully be a time > > > limited thing to carry. > > > > So the question is whether the issue is critical enough that we want > > to carry a workaround for a while, vs telling users to upgrade to > > newer glib (once 2.76 actually gets released) > > That is great news! > > Since this is a correctness issue, I think we should ship with qtree > and use it when configuring with glib <2.76.0. For later glib versions > we would just use gtree, e.g. via typedef + inline functions. > > Once the minimum glib required by the configure script is >= 2.76.0, > then we'd remove qtree. > > If that sounds like a good plan, I can send a v2. I'm fine with it, but be good to have an opinion here from the TCG subsystem maintainers, CC'ing them With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|