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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 9F25CC38A2A for ; Thu, 7 May 2020 15:58:31 +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 6626B2082E for ; Thu, 7 May 2020 15:58:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="et/+nqCu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6626B2082E 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]:38916 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jWius-0007Hh-ID for qemu-devel@archiver.kernel.org; Thu, 07 May 2020 11:58:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35280) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jWite-0005MI-LG for qemu-devel@nongnu.org; Thu, 07 May 2020 11:57:14 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:44402 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jWitd-0001eh-UD for qemu-devel@nongnu.org; Thu, 07 May 2020 11:57:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588867033; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=346PQ8E1QbOv6V25nMYzOV257SQXFBHA2If1FR1Wu64=; b=et/+nqCurznZrMvXfOOJicsGnibtNHB1lE6oYMCXwH2/UJ5CxyFc0If8sAXCNKwXcYtfei sSoOPehQ/O3x8CIJneUY0m89OEHqVg00QngfIgeX8CEerZ3UXhsEFrp1wSehTzrO/EVnO9 Ps5KXDEQfvukYMsVRpK7M5HbBpHX6UY= 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-99-pi89rYjPN8qo5MGpsTsoKg-1; Thu, 07 May 2020 11:57:09 -0400 X-MC-Unique: pi89rYjPN8qo5MGpsTsoKg-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 69F42461; Thu, 7 May 2020 15:57:08 +0000 (UTC) Received: from [10.3.114.73] (ovpn-114-73.phx2.redhat.com [10.3.114.73]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E9AFF60C47; Thu, 7 May 2020 15:57:07 +0000 (UTC) Subject: Re: [PATCH 1/2] block/block-copy: Fix uninitialized variable in block_copy_task_entry To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org References: <20200507121129.29760-1-philmd@redhat.com> <20200507121129.29760-2-philmd@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Thu, 7 May 2020 10:57:07 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200507121129.29760-2-philmd@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=207.211.31.120; envelope-from=eblake@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/07 03:56:18 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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: Kevin Wolf , qemu-trivial@nongnu.org, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 5/7/20 7:11 AM, Philippe Mathieu-Daud=C3=A9 wrote: > Fix when building with -Os: >=20 > CC block/block-copy.o > block/block-copy.c: In function =E2=80=98block_copy_task_entry=E2=80= =99: > block/block-copy.c:428:38: error: =E2=80=98error_is_read=E2=80=99 may = be used uninitialized in this function [-Werror=3Dmaybe-uninitialized] > 428 | t->call_state->error_is_read =3D error_is_read; > | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~ >=20 Looks like -Os triggered different inlining of block_copy_do_copy(). I=20 confirm that block_copy_do_copy does NOT initialize error_is_read except=20 when returning < 0, but similarly block_copy_task_entry() does not read=20 error_is_read except in the same setups. So it looks like no actual bug=20 was triggered, but we can definitely aid the compiler's analysis by=20 initializing. > Signed-off-by: Philippe Mathieu-Daud=C3=A9 > --- > block/block-copy.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Eric Blake --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org