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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B485C43331 for ; Fri, 6 Sep 2019 11:13:55 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 0AFF4206BB for ; Fri, 6 Sep 2019 11:13:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0AFF4206BB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:54710 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i6CBe-0001v2-4W for qemu-devel@archiver.kernel.org; Fri, 06 Sep 2019 07:13:54 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60749) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i6CAY-0001Qh-V0 for qemu-devel@nongnu.org; Fri, 06 Sep 2019 07:12:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i6CAX-0005gS-GT for qemu-devel@nongnu.org; Fri, 06 Sep 2019 07:12:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40616) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i6CAX-0005g8-B0 for qemu-devel@nongnu.org; Fri, 06 Sep 2019 07:12:45 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 698B972659; Fri, 6 Sep 2019 11:12:44 +0000 (UTC) Received: from work-vm (unknown [10.36.118.27]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5F8FC60E1C; Fri, 6 Sep 2019 11:12:25 +0000 (UTC) Date: Fri, 6 Sep 2019 12:12:23 +0100 From: "Dr. David Alan Gilbert" To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Message-ID: <20190906111223.GD2699@work-vm> References: <20190905152136.30637-1-stefanha@redhat.com> <20190905152136.30637-3-stefanha@redhat.com> <20190905172732.GQ2700@work-vm> <20190906102328.GE5900@stefanha-x1.localdomain> <20190906104953.GV5119@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20190906104953.GV5119@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 06 Sep 2019 11:12:44 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [RFC 2/3] virtiofsd: add DBus server to handle log level changes X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Eryu Guan , qemu-devel@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Daniel P. Berrang=E9 (berrange@redhat.com) wrote: > On Fri, Sep 06, 2019 at 11:23:28AM +0100, Stefan Hajnoczi wrote: > > On Thu, Sep 05, 2019 at 06:27:32PM +0100, Dr. David Alan Gilbert wrot= e: > > > * Stefan Hajnoczi (stefanha@redhat.com) wrote: > > > > Introduce a DBus server thread that runs alongside the other virt= iofsd > > > > threads. It processes changes to the /org/qemu/virtiofsd object = which > > > > can be accessed at the org.qemu.virtiofsd location on the bus. > > > >=20 > > > > This code does not use locking because we are the only writer to = the > > > > int current_log_level variable. More advanced management command= s would > > > > require locking to prevent race conditions with the other threads= . > > > >=20 > > > > Signed-off-by: Stefan Hajnoczi > > >=20 > > > OK, that is less complex than I'd feared. > > > I guess there's something probably nice to do with name/integer map= ping > > > for warning levels that we could use from one of the libraries. > >=20 > > I used a free-form string because it's what systemd's LogLevel proper= ty > > also does. But I can investigate the cleanest approach for limiting = it > > to a set of string constants. >=20 > There's no concept of "enums" at the DBus protocol level. Sending enums > in string form is the normal practice - avoiding integer values means > you are not vulnerable to enum values changing if someone inserts a new > constant in the middlle of the enum. This same reason is why QAPI uses > strings for enums instead of ints. Oh, I wasn't talking aobut changing protocol; I just meant there was probably a neater way of doing the string look up than the opencoded way it was done. Dave > Regards, > Daniel > --=20 > |: https://berrange.com -o- https://www.flickr.com/photos/dberr= ange :| > |: https://libvirt.org -o- https://fstop138.berrange= .com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberr= ange :| -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK