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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 A2D0EC47095 for ; Wed, 9 Jun 2021 09:06:40 +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 0CB0A610E6 for ; Wed, 9 Jun 2021 09:06:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0CB0A610E6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; 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bh=l9H8xTumUX4s18wQ0TMGvkXpjyRdzzIBBPYCnC6PvHg=; b=bk/r3PKhRHBkkSFBUO6zfC/63hSKFmX7kiJh7fjcFXPEUlojfznzst2v3bCNFTM8h+duvP 90e+o5XZpkm1uFJH+6UDA7EpdRrKwiuxuQ+yHExDDrqnBabx2pUlxdZEWynrJrlbGfBDw8 s5jj9Kh0ghjwbPWzSa/pwRe4YZ8DYq4= 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-586-7pcaAjbMPJqPuZbgwPOVVg-1; Wed, 09 Jun 2021 05:04:39 -0400 X-MC-Unique: 7pcaAjbMPJqPuZbgwPOVVg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5EC76801B12; Wed, 9 Jun 2021 09:04:38 +0000 (UTC) Received: from redhat.com (ovpn-114-230.ams2.redhat.com [10.36.114.230]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9894010016F4; Wed, 9 Jun 2021 09:04:36 +0000 (UTC) Date: Wed, 9 Jun 2021 11:04:35 +0200 From: Kevin Wolf To: Thomas Huth Subject: Re: Prevent compiler warning on block.c Message-ID: References: <1162368493.17178530.1620201543649.JavaMail.zimbra@redhat.com> <62c90da0-b2f9-7068-e84f-c13bb1527191@virtuozzo.com> <9ef22266-25e1-36df-52e9-ad5244a648dc@redhat.com> MIME-Version: 1.0 In-Reply-To: <9ef22266-25e1-36df-52e9-ad5244a648dc@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.197, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, QEMU Trivial , QEMU Developers , Max Reitz , Cleber Rosa , Miroslav Rezanina Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 09.06.2021 um 09:12 hat Thomas Huth geschrieben: > On 05/05/2021 10.05, Vladimir Sementsov-Ogievskiy wrote: > > 05.05.2021 10:59, Miroslav Rezanina wrote: > > > Commit 3108a15cf (block: introduce bdrv_drop_filter()) introduced > > > uninitialized > > > variable to_cow_parent in bdrv_replace_node_common function that is > > > used only when > > > detach_subchain is true. It is used in two places. First if block > > > properly initialize > > > the variable and second block use it. > > > > > > However, compiler treats this two blocks as two independent cases so > > > it thinks first > > > block can fail test and second one pass (although both use same > > > condition). This cause > > > warning that variable can be uninitialized in second block. > > > > > > To prevent this warning, initialize the variable with NULL. > > > > > > Signed-off-by: Miroslav Rezanina > > > --- > > > diff --git a/block.c b/block.c > > > index 874c22c43e..3ca27bd2d9 100644 > > > --- a/block.c > > > +++ b/block.c > > > @@ -4851,7 +4851,7 @@ static int > > > bdrv_replace_node_common(BlockDriverState *from, > > >       Transaction *tran = tran_new(); > > >       g_autoptr(GHashTable) found = NULL; > > >       g_autoptr(GSList) refresh_list = NULL; > > > -    BlockDriverState *to_cow_parent; > > > +    BlockDriverState *to_cow_parent = NULL; > > >       int ret; > > > > > >       if (detach_subchain) { > > > > > > > Reviewed-by: Vladimir Sementsov-Ogievskiy > > This just popped up again here: > > https://lists.gnu.org/archive/html/qemu-devel/2021-06/msg02067.html > > Kevin, Max, could you please pick it up to get this problem fixed? Thanks for pinging, seems the intended refactoring hasn't happened. I've applied this one to my block branch now. Kevin