Re: [Qemu-devel] [PATCH 4/5] qom: delay DeviceState's reclaim to main-loop

[liu ping fan]

On Wed, Jul 25, 2012 at 3:37 PM, Paolo Bonzini <address@hidden> wrote:
> Il 25/07/2012 09:03, Stefan Hajnoczi ha scritto:
>> From: Liu Ping Fan <address@hidden>
>>
>> iohandler/bh/timer may use DeviceState when its refcnt=0,
>
> It's not clear how to me.  The only reference to devices from an
> iohandler/bh/timer can be in the opaque.  Now, if you have a
> iohandler/bh/timer whose opaque is a DeviceState, you should bump the
> refcount before setting it up, and unref after tearing it down.
>
Yes, I admit refcnt is a good solution, but I think it means that we
will fix it with each device's bh. And this way seems lazy.

Thanx pingfan
> See for example how hw/scsi-disk.c bumps the refcount of a request
> before starting asynchronous I/O and calls unref at the end of the
> asynchronous I/O callback.
>
> Paolo