From patchwork Tue Nov 22 17:26:08 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vladimir Sementsov-Ogievskiy X-Patchwork-Id: 697829 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3tNXxP2wPtz9svs for ; Wed, 23 Nov 2016 04:47:53 +1100 (AEDT) Received: from localhost ([::1]:57089 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c9FAb-0000dm-UN for incoming@patchwork.ozlabs.org; Tue, 22 Nov 2016 12:47:49 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53607) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c9EqK-0007L5-3g for qemu-devel@nongnu.org; Tue, 22 Nov 2016 12:26:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c9EqG-0001YV-P0 for qemu-devel@nongnu.org; Tue, 22 Nov 2016 12:26:52 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:48179 helo=relay.sw.ru) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c9EqG-0001To-Bp for qemu-devel@nongnu.org; Tue, 22 Nov 2016 12:26:48 -0500 Received: from kvm.qa.sw.ru. ([10.28.8.145]) by relay.sw.ru (8.13.4/8.13.4) with ESMTP id uAMHQVaQ029558; Tue, 22 Nov 2016 20:26:42 +0300 (MSK) From: Vladimir Sementsov-Ogievskiy To: qemu-block@nongnu.org, qemu-devel@nongnu.org Date: Tue, 22 Nov 2016 20:26:08 +0300 Message-Id: <1479835586-74394-4-git-send-email-vsementsov@virtuozzo.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1479835586-74394-1-git-send-email-vsementsov@virtuozzo.com> References: <1479835586-74394-1-git-send-email-vsementsov@virtuozzo.com> X-detected-operating-system: by eggs.gnu.org: OpenBSD 3.x [fuzzy] X-Received-From: 195.214.232.25 Subject: [Qemu-devel] [PATCH 03/21] hbitmap: improve dirty iter 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, vsementsov@virtuozzo.com, famz@redhat.com, armbru@redhat.com, mreitz@redhat.com, stefanha@redhat.com, pbonzini@redhat.com, den@openvz.org, jsnow@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Make dirty iter resistant to resetting bits in corresponding HBitmap. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Max Reitz Reviewed-by: John Snow --- include/qemu/hbitmap.h | 26 ++++---------------------- util/hbitmap.c | 23 ++++++++++++++++++++++- 2 files changed, 26 insertions(+), 23 deletions(-) diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h index eb46475..2965f01 100644 --- a/include/qemu/hbitmap.h +++ b/include/qemu/hbitmap.h @@ -243,10 +243,9 @@ void hbitmap_free(HBitmap *hb); * the lowest-numbered bit that is set in @hb, starting at @first. * * Concurrent setting of bits is acceptable, and will at worst cause the - * iteration to miss some of those bits. Resetting bits before the current - * position of the iterator is also okay. However, concurrent resetting of - * bits can lead to unexpected behavior if the iterator has not yet reached - * those bits. + * iteration to miss some of those bits. + * + * The concurrent resetting of bits is OK. */ void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first); @@ -285,24 +284,7 @@ void hbitmap_free_meta(HBitmap *hb); * Return the next bit that is set in @hbi's associated HBitmap, * or -1 if all remaining bits are zero. */ -static inline int64_t hbitmap_iter_next(HBitmapIter *hbi) -{ - unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1]; - int64_t item; - - if (cur == 0) { - cur = hbitmap_iter_skip_words(hbi); - if (cur == 0) { - return -1; - } - } - - /* The next call will resume work from the next bit. */ - hbi->cur[HBITMAP_LEVELS - 1] = cur & (cur - 1); - item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + ctzl(cur); - - return item << hbi->granularity; -} +int64_t hbitmap_iter_next(HBitmapIter *hbi); /** * hbitmap_iter_next_word: diff --git a/util/hbitmap.c b/util/hbitmap.c index 5d1a21c..48d8b2d 100644 --- a/util/hbitmap.c +++ b/util/hbitmap.c @@ -106,8 +106,9 @@ unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi) unsigned long cur; do { - cur = hbi->cur[--i]; + i--; pos >>= BITS_PER_LEVEL; + cur = hbi->cur[i] & hb->levels[i][pos]; } while (cur == 0); /* Check for end of iteration. We always use fewer than BITS_PER_LONG @@ -139,6 +140,26 @@ unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi) return cur; } +int64_t hbitmap_iter_next(HBitmapIter *hbi) +{ + unsigned long cur = hbi->cur[HBITMAP_LEVELS - 1] & + hbi->hb->levels[HBITMAP_LEVELS - 1][hbi->pos]; + int64_t item; + + if (cur == 0) { + cur = hbitmap_iter_skip_words(hbi); + if (cur == 0) { + return -1; + } + } + + /* The next call will resume work from the next bit. */ + hbi->cur[HBITMAP_LEVELS - 1] = cur & (cur - 1); + item = ((uint64_t)hbi->pos << BITS_PER_LEVEL) + ctzl(cur); + + return item << hbi->granularity; +} + void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first) { unsigned i, bit;