From patchwork Fri Nov 4 13:10:17 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Huth X-Patchwork-Id: 691261 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 3t9Mfh1HTdz9vFL for ; Sat, 5 Nov 2016 00:11:24 +1100 (AEDT) Received: from localhost ([::1]:38674 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c2eHB-00060S-Ml for incoming@patchwork.ozlabs.org; Fri, 04 Nov 2016 09:11:21 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35900) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c2eGI-0005Nb-9u for qemu-devel@nongnu.org; Fri, 04 Nov 2016 09:10:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c2eGD-0006Z7-7p for qemu-devel@nongnu.org; Fri, 04 Nov 2016 09:10:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58664) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c2eGD-0006YL-2I for qemu-devel@nongnu.org; Fri, 04 Nov 2016 09:10:21 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 58E3C61BAC; Fri, 4 Nov 2016 13:10:20 +0000 (UTC) Received: from thh440s.redhat.com (ovpn-116-45.ams2.redhat.com [10.36.116.45]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uA4DAIq4026409; Fri, 4 Nov 2016 09:10:18 -0400 From: Thomas Huth To: Juan Quintela , Amit Shah , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" Date: Fri, 4 Nov 2016 14:10:17 +0100 Message-Id: <1478265017-5700-1-git-send-email-thuth@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 04 Nov 2016 13:10:20 +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] [PATCH for-2.8] migration: Fix return code of ram_save_iterate() 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: David Gibson Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" qemu_savevm_state_iterate() expects the iterators to return 1 when they are done, and 0 if there is still something left to do. However, ram_save_iterate() does not obey this rule and returns the number of saved pages instead. This causes a fatal hang with ppc64 guests when you run QEMU like this (also works with TCG): qemu-img create -f qcow2 /tmp/test.qcow2 1M qemu-system-ppc64 -nographic -nodefaults -m 256 \ -hda /tmp/test.qcow2 -serial mon:stdio ... then switch to the monitor by pressing CTRL-a c and try to save a snapshot with "savevm test1" for example. After the first iteration, ram_save_iterate() always returns 0 here, so that qemu_savevm_state_iterate() hangs in an endless loop and you can only "kill -9" the QEMU process. Fix it by using proper return values in ram_save_iterate(). Signed-off-by: Thomas Huth Reviewed-by: Juan Quintela --- migration/ram.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index fb9252d..a1c8089 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1987,7 +1987,7 @@ static int ram_save_iterate(QEMUFile *f, void *opaque) int ret; int i; int64_t t0; - int pages_sent = 0; + int done = 0; rcu_read_lock(); if (ram_list.version != last_version) { @@ -2007,9 +2007,9 @@ static int ram_save_iterate(QEMUFile *f, void *opaque) pages = ram_find_and_save_block(f, false, &bytes_transferred); /* no more pages to sent */ if (pages == 0) { + done = 1; break; } - pages_sent += pages; acct_info.iterations++; /* we want to check in the 1st loop, just in case it was the 1st time @@ -2044,7 +2044,7 @@ static int ram_save_iterate(QEMUFile *f, void *opaque) return ret; } - return pages_sent; + return done; } /* Called with iothread lock */