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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 B1313C433E0 for ; Thu, 18 Mar 2021 16:44:48 +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 D347F64ED2 for ; Thu, 18 Mar 2021 16:44:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D347F64ED2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=eik.bme.hu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:41158 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lMvlP-00055Q-0F for qemu-devel@archiver.kernel.org; Thu, 18 Mar 2021 12:44:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58160) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMvRT-0004uj-Sl for qemu-devel@nongnu.org; Thu, 18 Mar 2021 12:24:11 -0400 Received: from zero.eik.bme.hu ([2001:738:2001:2001::2001]:53950) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMvRQ-0004Qc-Kc for qemu-devel@nongnu.org; Thu, 18 Mar 2021 12:24:10 -0400 Received: from zero.eik.bme.hu (blah.eik.bme.hu [152.66.115.182]) by localhost (Postfix) with SMTP id 9897B746398; Thu, 18 Mar 2021 17:24:03 +0100 (CET) Received: by zero.eik.bme.hu (Postfix, from userid 432) id 754B87462D6; Thu, 18 Mar 2021 17:24:03 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by zero.eik.bme.hu (Postfix) with ESMTP id 731E87462E1; Thu, 18 Mar 2021 17:24:03 +0100 (CET) Date: Thu, 18 Mar 2021 17:24:03 +0100 (CET) From: BALATON Zoltan To: =?ISO-8859-15?Q?Philippe_Mathieu-Daud=E9?= Subject: Re: [PATCH for 6.0 v2] hw/intc/i8259: Refactor pic_read_irq() to avoid uninitialized variable In-Reply-To: <20210318160949.3681463-1-philmd@redhat.com> Message-ID: References: <20210318160949.3681463-1-philmd@redhat.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="3866299591-50933082-1616084643=:84870" Received-SPF: pass client-ip=2001:738:2001:2001::2001; envelope-from=balaton@eik.bme.hu; helo=zero.eik.bme.hu X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Christian Borntraeger Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --3866299591-50933082-1616084643=:84870 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8BIT On Thu, 18 Mar 2021, Philippe Mathieu-Daudé wrote: > Some compiler versions are smart enough to detect a potentially > uninitialized variable, but are not smart enough to detect that this > cannot happen due to the code flow: > > ../hw/intc/i8259.c: In function ‘pic_read_irq’: > ../hw/intc/i8259.c:203:13: error: ‘irq2’ may be used uninitialized in this function [-Werror=maybe-uninitialized] > 203 | irq = irq2 + 8; > | ~~~~^~~~~~~~~~ > > Restrict irq2 variable use to the inner statement. > > Fixes: 78ef2b6989f ("i8259: Reorder intack in pic_read_irq") > Reported-by: Christian Borntraeger > Signed-off-by: Philippe Mathieu-Daudé > --- > Supersedes: <20210318154738.27094-1-borntraeger@de.ibm.com> > --- > hw/intc/i8259.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/hw/intc/i8259.c b/hw/intc/i8259.c > index 344fd04db14..52c039c6c03 100644 > --- a/hw/intc/i8259.c > +++ b/hw/intc/i8259.c > @@ -176,10 +176,12 @@ static void pic_intack(PICCommonState *s, int irq) > int pic_read_irq(DeviceState *d) > { > PICCommonState *s = PIC_COMMON(d); > - int irq, irq2, intno; > + int irq, intno; > > irq = pic_get_irq(s); > if (irq >= 0) { > + int irq2; > + > if (irq == 2) { > irq2 = pic_get_irq(slave_pic); > if (irq2 >= 0) { > @@ -189,8 +191,11 @@ int pic_read_irq(DeviceState *d) > irq2 = 7; > } > intno = slave_pic->irq_base + irq2; > + pic_intack(s, irq); > + irq = irq2 + 8; > } else { > intno = s->irq_base + irq; > + pic_intack(s, irq); > } > pic_intack(s, irq); Do you still need this pic_intack() here or did you intend to move it in the if above? Regards, BALATON Zoltan > } else { > @@ -199,10 +204,6 @@ int pic_read_irq(DeviceState *d) > intno = s->irq_base + irq; > } > > - if (irq == 2) { > - irq = irq2 + 8; > - } > - > #ifdef DEBUG_IRQ_LATENCY > printf("IRQ%d latency=%0.3fus\n", > irq, > --3866299591-50933082-1616084643=:84870--