Re: [Qemu-devel] [PATCH v4 0/2] ati-vga: Implement DDC and EDID info from monitor

[BALATON Zoltan]

On Tue, 19 Mar 2019, Corey Minyard wrote:
> On Sat, Mar 16, 2019 at 03:23:09PM +0100, BALATON Zoltan wrote:
> > On Sat, 16 Mar 2019, BALATON Zoltan wrote:
> > > Version 4 try to fix an ASan warning about leaking bitbang_i2c.
> >
> > I still get ASan warning but it's about gpio_i2c_init in bitbang_i2c.c which
> > I haven't changed nor using so I think this is pre-existing problem in
> > bitbang_i2c.c which was exposed by touching it now so I'm not trying to fix.
> > (Maybe adding an exit function to free the allocated bitbang_i2c in object
> > state could help but I think it still leaks the bus so I'm not sure how to
> > handle it correctly. Maybe this should be QOMified somehow but cannot be a
> > device because it's not connected to a bus but embedded in other device
> > models.)
>
> It can inherit from I2CBus and then specific devices could inherit from
> the bitbang interface.  That's almost certainly the right way to do this,

It's OK for a QOMified bitbang_i2c to inherit from I2CBus but I don't 
think other devices can inherit from it. I'm using it from devices that 
are PCI (ati-vga) or SysBus devices (ppc4xx_i2c but also the gpio_i2c) but 
happen to have an i2c component so they can't inherit from bitbang_i2c 
only refer to an instance of it.

> but that design issue isn't cause by your changes.
>
> I'll try to poke at this a bit to see if I can clean it up.

I wonder if we really need a QOM object for this or if it would be enough 
to provide a bitbang_i2c_free function that dereferences the I2CBus which 
we can call to finalise a bitbang_i2c created with bitbang_i2c_init?

Regards,
BALATON Zoltan