From patchwork Thu Nov 15 10:07:57 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Wang, Wei W" X-Patchwork-Id: 10684115 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 8919B13B5 for ; Thu, 15 Nov 2018 10:43:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 756D12BEF6 for ; Thu, 15 Nov 2018 10:43:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 69D5A2BF0A; Thu, 15 Nov 2018 10:43:11 +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 154112BEF6 for ; Thu, 15 Nov 2018 10:43:11 +0000 (UTC) Received: from localhost ([::1]:37971 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gNF78-0004IZ-BF for patchwork-qemu-devel@patchwork.kernel.org; Thu, 15 Nov 2018 05:43:10 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57580) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gNF5B-0003hW-KW for qemu-devel@nongnu.org; Thu, 15 Nov 2018 05:41:11 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gNF57-0000pA-BR for qemu-devel@nongnu.org; Thu, 15 Nov 2018 05:41:09 -0500 Received: from mga03.intel.com ([134.134.136.65]:14567) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gNF57-0000oM-2h for qemu-devel@nongnu.org; Thu, 15 Nov 2018 05:41:05 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Nov 2018 02:41:05 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,236,1539673200"; d="scan'208";a="106467266" Received: from devel-ww.sh.intel.com ([10.239.48.119]) by fmsmga004.fm.intel.com with ESMTP; 15 Nov 2018 02:41:02 -0800 From: Wei Wang To: qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org, mst@redhat.com, quintela@redhat.com, dgilbert@redhat.com Date: Thu, 15 Nov 2018 18:07:57 +0800 Message-Id: <1542276484-25508-2-git-send-email-wei.w.wang@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1542276484-25508-1-git-send-email-wei.w.wang@intel.com> References: <1542276484-25508-1-git-send-email-wei.w.wang@intel.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 134.134.136.65 Subject: [Qemu-devel] [PATCH v9 1/8] bitmap: fix bitmap_count_one 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: liliang.opensource@gmail.com, peterx@redhat.com, wei.w.wang@intel.com, pbonzini@redhat.com, nilal@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP BITMAP_LAST_WORD_MASK(nbits) returns 0xffffffff when "nbits=0", which makes bitmap_count_one fail to handle the "nbits=0" case. It appears to be preferred to remain BITMAP_LAST_WORD_MASK identical to the kernel implementation that it is ported from. So this patch fixes bitmap_count_one to handle the nbits=0 case. Inital Discussion Link: https://www.mail-archive.com/qemu-devel@nongnu.org/msg554316.html Signed-off-by: Wei Wang CC: Juan Quintela CC: Dr. David Alan Gilbert CC: Peter Xu --- include/qemu/bitmap.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h index 509eedd..679f1bd 100644 --- a/include/qemu/bitmap.h +++ b/include/qemu/bitmap.h @@ -221,6 +221,10 @@ static inline int bitmap_intersects(const unsigned long *src1, static inline long bitmap_count_one(const unsigned long *bitmap, long nbits) { + if (unlikely(!nbits)) { + return 0; + } + if (small_nbits(nbits)) { return ctpopl(*bitmap & BITMAP_LAST_WORD_MASK(nbits)); } else {