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Re: [Qemu-devel] [PATCH 1.3 0/5] QOM/qdev lifetime fixes
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH 1.3 0/5] QOM/qdev lifetime fixes |
Date: |
Mon, 26 Nov 2012 15:47:16 -0600 |
User-agent: |
Notmuch/0.13.2+93~ged93d79 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
Paolo Bonzini <address@hidden> writes:
> These patches fix problems in the handling of freeing QOM/qdev
> objects. Together, they fix hot-unplug of USB mass storage devices,
> which crashed with an assertion failure.
>
> I'm not 100% sure, but I think we were always leaking the scsi-disk in
> pre-QOM days. Now we're freeing it properly, and the assertion proves it.
>
> However, I don't like particularly the assertion in object_delete. Once
> we're sure we've fixed all bugs, we should remove it, because it prevents
> a fully correct tracking of references.
>
> In this case, for example, there is still one reference to the scsi-disk
> in the MSDState's scsi_dev member. We don't have neither an object_ref
> nor an object_unref for it, so it happens to work. If we had an
> object_ref, the matching object_unref would be in dc->exit. But then
> we'd trip on the assertion failure again, because the SCSI bus is removed
> (thus calling qdev_free on the scsi-dev) before dc->exit is called.
>
> I have more patches to actually make the reference count of devices
> and buses fully correct, but they are even more scary than these, so
> they should wait for 1.4.
>
Applied. Thanks.
My patches didn't fix Peter's problem but yours do, I figured we'd take
your version in 1.3 and then for 1.4 I can attempt to rework them.
Regards,
Anthony Liguori
> Paolo Bonzini (5):
> qom: fix refcount of non-heap-allocated objects
> qdev: move bus removal to object_unparent
> qom: make object_delete usable for statically-allocated objects
> qdev: simplify (de)allocation of buses
> qom: make object_finalize static
>
> hw/qdev-core.h | 5 -----
> hw/qdev.c | 26 ++++++++++++++------------
> hw/pci.c | 2 +-
> hw/sysbus.c | 2 +-
> include/qemu/object.h | 29 ++++++++++++++++++++---------
> qom/object.c | 12 +++++++++---
> 6 files changed, 45 insertions(+), 31 deletions(-)
>
> --
> 1.8.0
- [Qemu-devel] [PATCH 1.3 1/5] qom: fix refcount of non-heap-allocated objects, (continued)