From patchwork Mon Oct 29 21:24:58 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Snow X-Patchwork-Id: 10660263 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6A16714E2 for ; Mon, 29 Oct 2018 21:36:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5C91E28E6C for ; Mon, 29 Oct 2018 21:36:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 50EA02A006; Mon, 29 Oct 2018 21:36:16 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 0191C28E6C for ; Mon, 29 Oct 2018 21:36:15 +0000 (UTC) Received: from localhost ([::1]:49126 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gHFCo-0006qm-Nt for patchwork-qemu-devel@patchwork.kernel.org; Mon, 29 Oct 2018 17:36:14 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45414) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gHF2k-0004bs-UB for qemu-devel@nongnu.org; Mon, 29 Oct 2018 17:25:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gHF2f-0002VL-D0 for qemu-devel@nongnu.org; Mon, 29 Oct 2018 17:25:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55908) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gHF2c-0002Jz-VD; Mon, 29 Oct 2018 17:25:44 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4CFE2308FB85; Mon, 29 Oct 2018 21:25:16 +0000 (UTC) Received: from probe.bos.redhat.com (dhcp-17-171.bos.redhat.com [10.18.17.171]) by smtp.corp.redhat.com (Postfix) with ESMTP id A27EF194AF; Mon, 29 Oct 2018 21:25:15 +0000 (UTC) From: John Snow To: qemu-devel@nongnu.org Date: Mon, 29 Oct 2018 17:24:58 -0400 Message-Id: <20181029212501.5897-17-jsnow@redhat.com> In-Reply-To: <20181029212501.5897-1-jsnow@redhat.com> References: <20181029212501.5897-1-jsnow@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Mon, 29 Oct 2018 21:25:16 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 16/19] bitmap: Update count after a merge 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: peter.maydell@linaro.org, jsnow@redhat.com, qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Blake We need an accurate count of the number of bits set in a bitmap after a merge. In particular, since the merge operation short-circuits a merge from an empty source, if you have bitmaps A, B, and C where B started empty, then merge C into B, and B into A, an inaccurate count meant that A did not get the contents of C. In the worst case, we may falsely regard the bitmap as empty when it has had new writes merged into it. Fixes: be58721db CC: qemu-stable@nongnu.org Signed-off-by: Eric Blake Signed-off-by: John Snow Reviewed-by: Vladimir Sementsov-Ogievskiy Message-id: 20181002233314.30159-1-jsnow@redhat.com Signed-off-by: John Snow --- util/hbitmap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/util/hbitmap.c b/util/hbitmap.c index d5aca5159f..8d402c59d9 100644 --- a/util/hbitmap.c +++ b/util/hbitmap.c @@ -759,6 +759,9 @@ bool hbitmap_merge(const HBitmap *a, const HBitmap *b, HBitmap *result) } } + /* Recompute the dirty count */ + result->count = hb_count_between(result, 0, result->size - 1); + return true; }