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 3FEBBCED240 for ; Tue, 18 Nov 2025 05:46:41 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vLEXN-0007SS-IF; Tue, 18 Nov 2025 00:45:57 -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 1vLEXK-0007Qt-Ux for qemu-devel@nongnu.org; Tue, 18 Nov 2025 00:45:54 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vLEXH-0007xP-Nv for qemu-devel@nongnu.org; Tue, 18 Nov 2025 00:45:54 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1763444749; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=QIey1evpGwk590ZWrlsxF2PPuT93keXOXvXAVejk/pg=; b=AimOBys5OPiyAV8Qm4pv0UKO5MIeUzpMkJPaDyDHPqHq/gszIMlyenJfcCMEDrLjJ06lNM 6KxBfKODJJN9bVAzGl4RQvGhkKMvs9Oj7duNrScwif1naLdYbBEPbA3bqOUwL2sCJQOmJe DBnnFKuSIWTkLakJubs7dFlcHJV+QrE= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-339-ccwVu4JvOH-sJTPqTjVckw-1; Tue, 18 Nov 2025 00:45:45 -0500 X-MC-Unique: ccwVu4JvOH-sJTPqTjVckw-1 X-Mimecast-MFC-AGG-ID: ccwVu4JvOH-sJTPqTjVckw_1763444744 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 415FC1956096; Tue, 18 Nov 2025 05:45:44 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.18]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A99E019560A7; Tue, 18 Nov 2025 05:45:43 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id E064821E6A27; Tue, 18 Nov 2025 06:45:40 +0100 (CET) From: Markus Armbruster To: Dmitry Osipenko Cc: Honglei Huang , alex.bennee@linaro.org, odaki@rsg.ci.i.u-tokyo.ac.jp, mst@redhat.com, cohuck@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org, Ray.Huang@amd.com Subject: Re: [v4] virtio-gpu: use consistent error checking style for virtio_gpu_create_mapping_iov In-Reply-To: (Dmitry Osipenko's message of "Tue, 18 Nov 2025 04:48:23 +0300") References: <20251117105104.258513-1-honghuan@amd.com> <9f547fbe-ea57-4784-9e37-f79b52b551a9@collabora.com> <87bjl0pzeq.fsf@pond.sub.org> Date: Tue, 18 Nov 2025 06:45:40 +0100 Message-ID: <874iqrnbaz.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Dmitry Osipenko writes: > On 11/17/25 16:22, Markus Armbruster wrote: >> Dmitry Osipenko writes: >> >>> On 11/17/25 13:51, Honglei Huang wrote: >>>> diff --git a/hw/display/virtio-gpu-rutabaga.c b/hw/display/virtio-gpu-rutabaga.c >>>> index ed5ae52acb..ea2928b706 100644 >>>> --- a/hw/display/virtio-gpu-rutabaga.c >>>> +++ b/hw/display/virtio-gpu-rutabaga.c >>>> @@ -466,7 +466,7 @@ rutabaga_cmd_attach_backing(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd) >>>> >>>> ret = virtio_gpu_create_mapping_iov(g, att_rb.nr_entries, sizeof(att_rb), >>>> cmd, NULL, &res->iov, &res->iov_cnt); >>>> - CHECK(!ret, cmd); >>>> + CHECK(ret >= 0, cmd); >>> >>> virtio_gpu_create_mapping_iov() doesn't return positive values, don't >>> see how this change improves anything. You now saying that ret > 0 is >>> okay, while it shall never happen. >> >> Please see >> >> Subject: Re: [PATCH] virtio-gpu-virgl: fix error handling in virgl_cmd_resource_create_blob >> Date: Mon, 17 Nov 2025 08:49:42 +0100 >> Message-ID: <87ms4lrtd5.fsf@pond.sub.org> >> https://lore.kernel.org/qemu-devel/87ms4lrtd5.fsf@pond.sub.org/ > > It's a rather common bug when errno isn't negated by mistake and a > positive error code is returned. Ignoring positive values when they > aren't expected opens door to unnecessary problems, IMO. No convention can avoid *all* possible problems there. I know which one has created more grief for *me*. Your experience may be different. virtio_gpu_create_mapping_iov() returns -1 on error, 0 on success. We could change it to return false on error, true on success.