From patchwork Thu Jul 2 16:10:14 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Juan Quintela X-Patchwork-Id: 490739 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 4D86314027C for ; Fri, 3 Jul 2015 02:23:16 +1000 (AEST) Received: from localhost ([::1]:37622 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZAhGc-0001Xg-Dz for incoming@patchwork.ozlabs.org; Thu, 02 Jul 2015 12:23:14 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59626) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZAh4m-0005eW-2e for qemu-devel@nongnu.org; Thu, 02 Jul 2015 12:11:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZAh4k-0006Bj-AY for qemu-devel@nongnu.org; Thu, 02 Jul 2015 12:11:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46807) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZAh4j-0006BD-EM for qemu-devel@nongnu.org; Thu, 02 Jul 2015 12:10:57 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id 2C281C1F03; Thu, 2 Jul 2015 16:10:57 +0000 (UTC) Received: from trasno.mitica (ovpn-116-56.ams2.redhat.com [10.36.116.56]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t62GAFGB011910; Thu, 2 Jul 2015 12:10:55 -0400 From: Juan Quintela To: qemu-devel@nongnu.org Date: Thu, 2 Jul 2015 18:10:14 +0200 Message-Id: <1435853415-23545-27-git-send-email-quintela@redhat.com> In-Reply-To: <1435853415-23545-1-git-send-email-quintela@redhat.com> References: <1435853415-23545-1-git-send-email-quintela@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: amit.shah@redhat.com, Li Zhijian Subject: [Qemu-devel] [PULL 26/27] migration: protect migration_bitmap X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Li Zhijian Signed-off-by: Li Zhijian Signed-off-by: Wen Congyang Signed-off-by: Juan Quintela --- migration/ram.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 644f52a..9c0bcfe 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -494,6 +494,7 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data, return 1; } +/* Called with rcu_read_lock() to protect migration_bitmap */ static inline ram_addr_t migration_bitmap_find_and_reset_dirty(MemoryRegion *mr, ram_addr_t start) @@ -502,26 +503,31 @@ ram_addr_t migration_bitmap_find_and_reset_dirty(MemoryRegion *mr, unsigned long nr = base + (start >> TARGET_PAGE_BITS); uint64_t mr_size = TARGET_PAGE_ALIGN(memory_region_size(mr)); unsigned long size = base + (mr_size >> TARGET_PAGE_BITS); + unsigned long *bitmap; unsigned long next; + bitmap = atomic_rcu_read(&migration_bitmap); if (ram_bulk_stage && nr > base) { next = nr + 1; } else { - next = find_next_bit(migration_bitmap, size, nr); + next = find_next_bit(bitmap, size, nr); } if (next < size) { - clear_bit(next, migration_bitmap); + clear_bit(next, bitmap); migration_dirty_pages--; } return (next - base) << TARGET_PAGE_BITS; } +/* Called with rcu_read_lock() to protect migration_bitmap */ static void migration_bitmap_sync_range(ram_addr_t start, ram_addr_t length) { + unsigned long *bitmap; + bitmap = atomic_rcu_read(&migration_bitmap); migration_dirty_pages += - cpu_physical_memory_sync_dirty_bitmap(migration_bitmap, start, length); + cpu_physical_memory_sync_dirty_bitmap(bitmap, start, length); } @@ -1017,10 +1023,15 @@ void free_xbzrle_decoded_buf(void) static void migration_end(void) { - if (migration_bitmap) { + /* caller have hold iothread lock or is in a bh, so there is + * no writing race against this migration_bitmap + */ + unsigned long *bitmap = migration_bitmap; + atomic_rcu_set(&migration_bitmap, NULL); + if (bitmap) { memory_global_dirty_log_stop(); - g_free(migration_bitmap); - migration_bitmap = NULL; + synchronize_rcu(); + g_free(bitmap); } XBZRLE_cache_lock();