From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49075) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dAoBl-0006Mi-07 for qemu-devel@nongnu.org; Tue, 16 May 2017 21:55:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dAoBh-0007Q4-1a for qemu-devel@nongnu.org; Tue, 16 May 2017 21:55:45 -0400 Date: Wed, 17 May 2017 09:55:30 +0800 From: Fam Zheng Message-ID: <20170517015530.GD27669@lemon.lan> References: <20170516072414.19025-1-famz@redhat.com> <20170516080737.GB27669@lemon.lan> <20170516122528.GC27669@lemon.lan> <3799c1f5-5b22-fe05-4c98-4cd76c716551@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3799c1f5-5b22-fe05-4c98-4cd76c716551@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2] virtio: Move memory_listener_unregister to .unrealize List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Jason Wang , "Michael S. Tsirkin" , qemu-devel@nongnu.org, qemu-stable@nongnu.org On Tue, 05/16 14:44, Paolo Bonzini wrote: > > > On 16/05/2017 14:25, Fam Zheng wrote: > > You are right. Having had another look, I think it's because of this: > > VirtIODevice is an embeded member of VirtIOSCSIPCI therefore it is never > > "finalized" through QOM reference directly. Am I right? > > What I would expect is: > > virtio_instance_init_common: > - create the VirtIODevice with refcount 1 > - create a child property for the VirtIODevice (refcount is now 2) > - unref the VirtIODevice (refcount is again 1) > > virtio_pci_realize: > - virtio_pci_bus_new creates the virtio bus > - the virtio bus is added as a child property > > virtio_scsi_pci_realize: > - qdev_set_parent_bus links the device to the bus (bus and VirtIODevice > refcounts are now 3) > - the VirtIODevice is realized > > ... > at hot-unplug time: > - the device is unrealized > - the bus is unparented (calling bus_unparent) > - the device is unparented (calling device_unparent) > - bus_remove_child is called (bus and VirtIODevice refcounts are now 1) > - the VirtIODevice child property is deleted by object_unparent and > the VirtIODevice is finalized > - the bus child property is deleted by object_unparent and the > VirtIODevice is finalized Sorry I don't understand. From my debugging, VirtIODevice is not finalized, because it is embeded as VirtIOSCSIPCI.vdev.parent_obj.parent_obj, in non-zero offset. As I understand it, it's the VirtIOSCSIPCI instance that is being finalized, but not VirtIODevice. Because the object_unparent is actually called on the containing object: Thread 4 "qemu-system-x86" hit Breakpoint 1, device_unparent (obj=0x559449824f40) at /stor/work/qemu/hw/core/qdev.c:1078 1078 DeviceState *dev = DEVICE(obj); (gdb) bt #0 0x00005594455f11df in device_unparent (obj=0x559449824f40) at /stor/work/qemu/hw/core/qdev.c:1078 #1 0x00005594457be582 in object_finalize_child_property (obj=0x559447f0d320, name=0x5594498306e0 "scsi1", opaque=0x559449824f40) at /stor/work/qemu/qom/object.c:1369 #2 0x00005594457bc34a in object_property_del_child (obj=0x559447f0d320, child=0x559449824f40, errp=0x0) at /stor/work/qemu/qom/object.c:428 #3 0x00005594457bc42a in object_unparent (obj=0x559449824f40) at /stor/work/qemu/qom/object.c:447 #4 0x00005594455acf19 in acpi_pcihp_eject_slot (s=0x55944967c440, bsel=0, slots=16) at /stor/work/qemu/hw/acpi/pcihp.c:138 #5 0x00005594455ad542 in pci_write (opaque=0x55944967c440, addr=8, data=16, size=4) at /stor/work/qemu/hw/acpi/pcihp.c:272 #6 0x0000559445437667 in memory_region_write_accessor (mr=0x55944967d050, addr=8, value=0x7fdfa7569838, size=4, shift=0, mask=4294967295, attrs=...) at /stor/work/qemu/memory.c:526 #7 0x000055944543787f in access_with_adjusted_size (addr=8, value=0x7fdfa7569838, size=4, access_size_min=1, access_size_max=4, access= 0x55944543757d , mr=0x55944967d050, attrs=...) at /stor/work/qemu/memory.c:592 #8 0x0000559445439fdb in memory_region_dispatch_write (mr=0x55944967d050, addr=8, data=16, size=4, attrs=...) at /stor/work/qemu/memory.c:1319 #9 0x00005594453dfa77 in address_space_write_continue (as=0x559445f1fce0 , addr=44552, attrs=..., buf=0x7fdfb77d2000 "\020", len=4, addr1=8, l=4, mr=0x55944967d050) at /stor/work/qemu/exec.c:2822 #10 0x00005594453dfc31 in address_space_write (as=0x559445f1fce0 , addr=44552, attrs=..., buf=0x7fdfb77d2000 "\020", len=4) at /stor/work/qemu/exec.c:2879 #11 0x00005594453dffbd in address_space_rw (as=0x559445f1fce0 , addr=44552, attrs=..., buf=0x7fdfb77d2000 "\020", len=4, is_write=true) at /stor/work/qemu/exec.c:2981 #12 0x0000559445433797 in kvm_handle_io (port=44552, attrs=..., data=0x7fdfb77d2000, direction=1, size=4, count=1) at /stor/work/qemu/kvm-all.c:1803 #13 0x0000559445433e87 in kvm_cpu_exec (cpu=0x559447f0d560) at /stor/work/qemu/kvm-all.c:2032 #14 0x0000559445419cc6 in qemu_kvm_cpu_thread_fn (arg=0x559447f0d560) at /stor/work/qemu/cpus.c:1118 #15 0x00007fdfb56ba6ca in start_thread () at /lib64/libpthread.so.0 #16 0x00007fdfb1382f7f in clone () at /lib64/libc.so.6 (gdb) p *obj.class.type $1 = {name = 0x559447e57a20 "virtio-scsi-pci", class_size = 280, instance_size = 34688, class_init = 0x55944573573e , class_base_init = 0x0, class_finalize = 0x0, class_data = 0x0, instance_init = 0x559445735837 , instance_post_init = 0x0, instance_finalize = 0x0, abstract = false, parent = 0x559447e57a40 "virtio-pci", parent_type = 0x559447e57520, class = 0x559447e7add0, num_interfaces = 0, interfaces = {{ typename = 0x0} }} Am I missing something? Fam