From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58195) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ds5o8-0003v1-KI for qemu-devel@nongnu.org; Wed, 13 Sep 2017 07:26:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ds5o2-0003ve-Es for qemu-devel@nongnu.org; Wed, 13 Sep 2017 07:26:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36716) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ds5o2-0003ue-62 for qemu-devel@nongnu.org; Wed, 13 Sep 2017 07:26:10 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 242DF13A49 for ; Wed, 13 Sep 2017 11:26:09 +0000 (UTC) From: Juan Quintela In-Reply-To: <20170811152949.GU2554@redhat.com> (Daniel P. Berrange's message of "Fri, 11 Aug 2017 16:29:49 +0100") References: <20170808162629.32493-1-quintela@redhat.com> <20170808162629.32493-16-quintela@redhat.com> <20170811152949.GU2554@redhat.com> Reply-To: quintela@redhat.com Date: Wed, 13 Sep 2017 13:26:07 +0200 Message-ID: <87r2vadels.fsf@secure.laptop> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v6 15/19] migration: Create thread infrastructure for multifd recv side List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: qemu-devel@nongnu.org, lvivier@redhat.com, dgilbert@redhat.com, peterx@redhat.com "Daniel P. Berrange" wrote: > On Tue, Aug 08, 2017 at 06:26:25PM +0200, Juan Quintela wrote: >> We make the locking and the transfer of information specific, even if we >> are still receiving things through the main thread. >> >> Signed-off-by: Juan Quintela >> >> -- >> >> We split when we create the main channel and where we start the main >> migration thread, so we wait for the creation of the other threads. >> >> Use multifd_clear_group(). >> --- >> migration/migration.c | 7 ++++--- >> migration/migration.h | 1 + >> migration/ram.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++---- >> migration/socket.c | 2 +- >> 4 files changed, 57 insertions(+), 8 deletions(-) > > >> diff --git a/migration/socket.c b/migration/socket.c >> index 5dd6f42..3af9f7c 100644 >> --- a/migration/socket.c >> +++ b/migration/socket.c >> @@ -183,12 +183,12 @@ static gboolean >> socket_accept_incoming_migration(QIOChannel *ioc, >> >> qio_channel_set_name(QIO_CHANNEL(sioc), "migration-socket-incoming"); >> migration_channel_process_incoming(QIO_CHANNEL(sioc)); >> - object_unref(OBJECT(sioc)); > > AFAICT, migration_channel_process_incoming() acquires its own reference > on 'sioc', so removing this object_unref means the code is now leaking a > reference Nack. I did it and ended with a segmentation fault because reference count was bad. (qemu) Thread 6 "multifdrecv_0" received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7fff9f9ff700 (LWP 10065)] 0x00005555559c12f8 in type_is_ancestor (type=0xb60f18247c894860, target_type=0x555556531b30) at /mnt/kvm/qemu/cleanup/qom/object.c:217 217 while (type) { (gdb) bt #0 0x00005555559c12f8 in type_is_ancestor (type=0xb60f18247c894860, target_type=0x555556531b30) at /mnt/kvm/qemu/cleanup/qom/object.c:217 #1 0x00005555559c1dbb in object_class_dynamic_cast (class=class@entry=0x7ffff2cb3ce8 , typename=typename@entry=0x555555aa6d91 "qio-channel") at /mnt/kvm/qemu/cleanup/qom/object.c:691 #2 0x00005555559c1ed2 in object_class_dynamic_cast_assert (class=0x7ffff2cb3ce8 , typename=typename@entry=0x555555aa6d91 "qio-channel", file=file@entry=0x555555b88208 "/mnt/kvm/qemu/cleanup/io/channel.c", line=line@entry=56, func=func@entry=0x555555b884e0 <__func__.22671> "qio_channel_readv_full") at /mnt/kvm/qemu/cleanup/qom/object.c:723 #3 0x0000555555a3d4d7 in qio_channel_readv_full (ioc=0x5555568c5a00, iov=0x7fff900008c0, niov=15, fds=0x0, nfds=0x0, errp=0x7fff9f9fe950) at /mnt/kvm/qemu/cleanup/io/channel.c:56 #4 0x0000555555a3ddc2 in qio_channel_readv (errp=0x7fff9f9fe950, niov=, iov=, ioc=0x5555568c5a00) at /mnt/kvm/qemu/cleanup/io/channel.c:197 #5 0x0000555555a3ddc2 in qio_channel_readv_all_eof (ioc=0x5555568c5a00, iov=, niov=, errp=errp@entry=0x7fff9f9fe950) at /mnt/kvm/qemu/cleanup/io/channel.c:106 #6 0x0000555555a3de79 in qio_channel_readv_all (ioc=, iov=, niov=, errp=errp@entry=0x7fff9f9fe950) at /mnt/kvm/qemu/cleanup/io/channel.c:142 #7 0x0000555555794768 in multifd_recv_thread (opaque=0x5555570e5e00) ---Type to continue, or q to quit---up at /mnt/kvm/qemu/cleanup/migration/ram.c:722 #8 0x00007ffff2cc036d in start_thread (arg=0x7fff9f9ff700) at pthread_create.c:456 #9 0x00007ffff29f8bbf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97 (gdb) up Removing this unref fixed things, so I think that the accounting is good (famous last words). Later, Juan.