From nobody Wed Dec 17 21:49:47 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1527695961958811.8981977694931; Wed, 30 May 2018 08:59:21 -0700 (PDT) Received: from localhost ([::1]:39320 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fO3VR-0000az-0l for importer@patchew.org; Wed, 30 May 2018 11:59:21 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55396) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fO3T6-0007VZ-T7 for qemu-devel@nongnu.org; Wed, 30 May 2018 11:56:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fO3T6-0006pr-1A for qemu-devel@nongnu.org; Wed, 30 May 2018 11:56:56 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58848 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fO3T2-0006o7-A3; Wed, 30 May 2018 11:56:52 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CA9E4818BAED; Wed, 30 May 2018 15:56:51 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-116-70.ams2.redhat.com [10.36.116.70]) by smtp.corp.redhat.com (Postfix) with ESMTP id 27FE383B6C; Wed, 30 May 2018 15:56:51 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Date: Wed, 30 May 2018 17:56:31 +0200 Message-Id: <20180530155647.14090-2-kwolf@redhat.com> In-Reply-To: <20180530155647.14090-1-kwolf@redhat.com> References: <20180530155647.14090-1-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Wed, 30 May 2018 15:56:51 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Wed, 30 May 2018 15:56:51 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'kwolf@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 01/17] qcow2: Fix Coverity warning when calculating the refcount cache size X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Alberto Garcia MIN_REFCOUNT_CACHE_SIZE is 4 and the cluster size is guaranteed to be at most 2MB, so the minimum refcount cache size (in bytes) is always going to fit in a 32-bit integer. Coverity doesn't know that, and since we're storing the result in a uint64_t (*refcount_cache_size) it thinks that we need the 64 bits and that we probably want to do a 64-bit multiplication to prevent the result from being truncated. This is a false positive in this case, but it's a fair warning. We could do a 64-bit multiplication to get rid of it, but since we know that a 32-bit variable is enough to store this value let's simply reuse min_refcount_cache, make it a normal int and stop doing casts. Reported-by: Peter Maydell Signed-off-by: Alberto Garcia Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- block/qcow2.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 6d532470a8..a007dc4246 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -768,6 +768,7 @@ static void read_cache_sizes(BlockDriverState *bs, Qemu= Opts *opts, BDRVQcow2State *s =3D bs->opaque; uint64_t combined_cache_size; bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_s= et; + int min_refcount_cache =3D MIN_REFCOUNT_CACHE_SIZE * s->cluster_size; =20 combined_cache_size_set =3D qemu_opt_get(opts, QCOW2_OPT_CACHE_SIZE); l2_cache_size_set =3D qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_SIZE); @@ -804,8 +805,6 @@ static void read_cache_sizes(BlockDriverState *bs, Qemu= Opts *opts, } else { uint64_t virtual_disk_size =3D bs->total_sectors * BDRV_SECTOR= _SIZE; uint64_t max_l2_cache =3D virtual_disk_size / (s->cluster_size= / 8); - uint64_t min_refcount_cache =3D - (uint64_t) MIN_REFCOUNT_CACHE_SIZE * s->cluster_size; =20 /* Assign as much memory as possible to the L2 cache, and * use the remainder for the refcount cache */ @@ -825,7 +824,7 @@ static void read_cache_sizes(BlockDriverState *bs, Qemu= Opts *opts, * s->cluster_size); } if (!refcount_cache_size_set) { - *refcount_cache_size =3D MIN_REFCOUNT_CACHE_SIZE * s->cluster_= size; + *refcount_cache_size =3D min_refcount_cache; } } =20 --=20 2.13.6