From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55384) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZH5IZ-00023d-0w for qemu-devel@nongnu.org; Mon, 20 Jul 2015 03:15:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZH5IV-0004ZJ-T1 for qemu-devel@nongnu.org; Mon, 20 Jul 2015 03:15:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38481) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZH5IV-0004ZA-Kv for qemu-devel@nongnu.org; Mon, 20 Jul 2015 03:15:35 -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 338283E5B3 for ; Mon, 20 Jul 2015 07:06:32 +0000 (UTC) Date: Mon, 20 Jul 2015 09:06:28 +0200 From: Igor Mammedov Message-ID: <20150720090628.38e57f68@nial.brq.redhat.com> In-Reply-To: <20150717203355.GA11994@thinpad.lan.raisama.net> References: <1437079157-6316-1-git-send-email-ehabkost@redhat.com> <20150716230214.3a39bd79@igors-macbook-pro.local> <20150717203355.GA11994@thinpad.lan.raisama.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] hostmem: Fix qemu_opt_get_bool() crash in host_memory_backend_init() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: Paolo Bonzini , qemu-devel@nongnu.org, Marcel Apfelbaum On Fri, 17 Jul 2015 17:33:55 -0300 Eduardo Habkost wrote: > On Thu, Jul 16, 2015 at 11:02:14PM +0200, Igor Mammedov wrote: > > On Thu, 16 Jul 2015 17:39:17 -0300 > > Eduardo Habkost wrote: > > > > > This fixes the following crash, introduced by commit > > > 49d2e648e8087d154d8bf8b91f27c8e05e79d5a6: > > > > > > $ gdb --args qemu-system-x86_64 -machine pc,mem-merge=off -object > > > memory-backend-ram,id=ram-node0,size=1024 [...] > > > Program received signal SIGABRT, Aborted. > > > (gdb) bt > > > #0 0x00007ffff253b8c7 in raise () at /lib64/libc.so.6 > > > #1 0x00007ffff253d52a in abort () at /lib64/libc.so.6 > > > #2 0x00007ffff253446d in __assert_fail_base () at /lib64/libc.so.6 > > > #3 0x00007ffff2534522 in () at /lib64/libc.so.6 > > > #4 0x00005555558bb80a in qemu_opt_get_bool_helper > > > (opts=0x55555621b650, name=name@entry=0x5555558ec922 "mem-merge", > > > defval=defval@entry=true, del=del@entry=false) at > > > qemu/util/qemu-option.c:388 #5 0x00005555558bbb5a in > > > qemu_opt_get_bool (opts=, > > > name=name@entry=0x5555558ec922 "mem-merge", defval=defval@entry=true) > > > at qemu/util/qemu-option.c:398 #6 0x0000555555720a24 in > > > host_memory_backend_init (obj=0x5555562ac970) at > > > qemu/backends/hostmem.c:226 > > > > > > Instead of using qemu_opt_get_bool(), that didn't work with > > > qemu_machine_opts for a long time, we can use the machine QOM > > > properties directly. > > > > > > Signed-off-by: Eduardo Habkost > > > --- > > > backends/hostmem.c | 9 +++++---- > > > 1 file changed, 5 insertions(+), 4 deletions(-) > > > > > > diff --git a/backends/hostmem.c b/backends/hostmem.c > > > index 61c1ac0..38a32ed 100644 > > > --- a/backends/hostmem.c > > > +++ b/backends/hostmem.c > > > @@ -10,6 +10,7 @@ > > > * See the COPYING file in the top-level directory. > > > */ > > > #include "sysemu/hostmem.h" > > > +#include "hw/boards.h" > > > #include "qapi/visitor.h" > > > #include "qapi-types.h" > > > #include "qapi-visit.h" > > > @@ -223,10 +224,10 @@ static void host_memory_backend_init(Object > > > *obj) { > > > HostMemoryBackend *backend = MEMORY_BACKEND(obj); > > > > > > - backend->merge = qemu_opt_get_bool(qemu_get_machine_opts(), > > > - "mem-merge", true); > > > - backend->dump = qemu_opt_get_bool(qemu_get_machine_opts(), > > > - "dump-guest-core", true); > > > + backend->merge = > > > object_property_get_bool(OBJECT(current_machine), > > maybe use qdev_get_machine() instead of OBJECT(current_machine) > > What are the advantages you see in the extra layers of indirection of > qdev_get_machine()? (I am not against your proposal, but I would like to > understand the point of qdev_get_machine() yet.) current_machine might be NULL where as qdev_get_machine() always returns /machine object. > > I'd prefer to use something that is guaranteed to be MachineState*, > qdev_get_machine() returns Object*. I am even considering using > current_machine->mem_merge and current_machine->dump_guest_core directly > instead of object_property_get_bool(). That would mean extra > compile-time checks, instead of runtime ones. Check difference 'git grep qdev_get_machine' vs 'git grep current_machine'. I was under impression that policy was trying no to use globals unless one has to, and not introduce new usage in presence of other means to get object.