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 0ABFDC6FA86 for ; Thu, 22 Sep 2022 10:42:04 +0000 (UTC) Received: from localhost ([::1]:48174 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1obJed-0001MJ-W7 for qemu-devel@archiver.kernel.org; Thu, 22 Sep 2022 06:42:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60244) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1obJa7-00073S-39 for qemu-devel@nongnu.org; Thu, 22 Sep 2022 06:37:26 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:53168) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1obJa4-0007Cg-AL for qemu-devel@nongnu.org; Thu, 22 Sep 2022 06:37:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663843038; 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=vWmp2KIjvQ07Zt18EhbBcK6a+wQHyD18ARR2FqaPmTA=; b=Fb3j6eMCjL33U+vY0FrS1rwGz6yqbcpr+1kSv1VEMBZJcyZy/p7kmUjEjGB3lQ7sjj9+8E Mc2Y83As2WDmM3wuzIr6rsRvyxeHUdxE5lrXkj+iRFdidr1xvHsAhr7nEmFekpkVvfs6nU aZ4eIE4bVGKZh/GiQc3owbBwVSNNfAQ= 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-193-UJFvsDD4Pm6_KB0zM5Poyg-1; Thu, 22 Sep 2022 06:37:13 -0400 X-MC-Unique: UJFvsDD4Pm6_KB0zM5Poyg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 346AB1C05AA7; Thu, 22 Sep 2022 10:37:13 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.120]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C5890C15BA5; Thu, 22 Sep 2022 10:37:10 +0000 (UTC) Date: Thu, 22 Sep 2022 11:37:08 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Claudio Fontana Cc: Markus Armbruster , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Paolo Bonzini , Richard Henderson , Kevin Wolf , qemu-devel@nongnu.org, dinechin@redhat.com, Gerd Hoffmann , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Subject: Re: [PATCH v4 2/3] module: add Error arguments to module_load_one and module_load_qom_one Message-ID: References: <20220908183012.17667-3-cfontana@suse.de> <877d23ekj0.fsf@pond.sub.org> <76775f64-e49a-1c3c-0d73-10d93eff34e4@amsat.org> <87y1ucdirx.fsf@pond.sub.org> <878rmc54cw.fsf@pond.sub.org> <5e6d958d-3b69-1472-b1b8-3a63186f0c5b@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.6 (2022-06-05) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, 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" On Thu, Sep 22, 2022 at 11:34:22AM +0200, Claudio Fontana wrote: > On 9/22/22 11:31, Daniel P. Berrangé wrote: > > On Thu, Sep 22, 2022 at 11:20:07AM +0200, Claudio Fontana wrote: > >> On 9/22/22 10:28, Daniel P. Berrangé wrote: > >>> > >>>> Another interface that does: return -1 for error, 0 for module not found > >>>> (no error), and 1 for loaded. > >>> > >>> IMHO this pattern is generally easier to understand when looking at > >>> the callers, as the fatal error scenario is always clear. > >>> > >>> That said I would suggest neither approach as the public facing > >>> API. Rather stop trying to overload 3 states onto an error reporting > >>> pattern that inherantly wants to be 2 states. Instead just have > >>> distinct methods > >>> > >>> bool module_load_one(const char *prefix, const char *name, Error *errp) > >>> bool module_try_load_one(const char *prefix, const char *name, Error *errp) > >> > >> > >> Here we are murking again the normal behavior and the error path. > >> > >> What is the meaning of try? It's not as though we would error out inside the function module_load_one, > >> it's the _caller_ that needs to decide how to treat a return value of found/not found, and the exception (Error). > > > > I suggested "try" as in the g_malloc vs g_try_malloc API naming pattern, > > where the latter ignores the OOM error condition. > > > > So in this case 'try' means try to load the module, but don't fail if > > the module is missing on disk. > > I understand what you mean, but this is wrong in this case. > > We _do not fail_ in module_load_one, whether an error is present > or not, whether a module is found or not. Looking at the callers though, AFAIK there are only two patterns that we need. All callers should report a fatal error if the module exists and loading it failed eg module is from mis-matched build. Some callers also want a failure if the module doesn't exist on disk (module_load_one can be made todo this), but most callers are happy to carry on if the module doesn't exist (module_try_load_one can simply return success status if it doesn't exist). 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 :|